Chapter 8. Pain Management Techniques

Question 1

626. Which of the following is the most common
microbe that grows in cultures of infected
intrathecal pump wounds?
(A) Pseudomonas species
(B) Escherichia coli
(C) Staphylococcus aureus
(D) Staphylococcus epidermidis
(E) None of the above

Answer 1

626. (D)
     A. Pseudomonas species grew in 3% of infected
     wound cultures.
     B. Escherichia coli is probably among the
     unknown or not reported 20% or the multiple
     or other species (7%).
     C. and D. Staphylococcus species grew in cultures
     of infected sites 59% of the time. Most
     reports did not specify whether the cultured
     Staphylococcus organisms were S aureus
     or S epidermidis. However one study specifically
     emphasized S epidermidis, which
     arises from the skin of the patient or operating
     room personnel, as the most likely
     culprit. No growth took place in 9% of the
     infected-wound cultures. No positive fungal
     cultures were reported.

Question 2

627. You think a patient has developed an intrathecal
catheter-tip inflammatory mass. What signs
and symptoms would support this finding?
(A) Diminishing analgesic effects
(B) Pain that mimics nerve root
compression
(C) Pain that mimics cholecystitis
(D) A and B
(E) A, B, and C

Answer 2

627. (E)
     A. Subtle prodromal signs and symptoms
     during early growth of a catheter-tip mass
     include decreasing analgesic effects (loss
     of previously satisfactory pain relief) and
     unusual increase in the patient’s underlying
     pain. Another occurrence was that
     patient required unusually frequent or
     high dose escalations to obtain analgesia.
     In certain instances, dose increases and
     large drug boluses reduced the patient’s
     pain only temporarily or to a lesser degree
     than previous experiences predicted.
     B. Catheter-tip masses in the lumbar region
     sometimes simulated nerve root compression
     from a herniated intervertebral disc
     or spinal stenosis.
     C. When the catheter tip is located in the thoracic
     region, early signs and symptoms of
     an extra-axial inflammatory mass sometimes
     included thoracic radicular pain that
     stimulated intercostal neuralgia or cholecystitis.
     Gradual, insidious neurologic deterioration
     weeks or months after the appearance
     of subjective symptoms was the most
     common clinical course before the onset of
     myelopathy or cauda equina syndrome.
     Myelopathy is a term that means that
     there is something wrong with the spinal
     cord itself. This is usually a later stage of
     cervical spine disease, and is often first
     detected as difficulty while walking
     because of generalized weakness or problems
     with balance and coordination. This
     type of process occurs most commonly in
     the elderly, who can have many reasons for
     troubled walking or problems with gait
     and balance. However, one of the more
     worrisome reasons that these symptoms
     are occurring is that bone spurs and other
     degenerative changes in the cervical spine
     are squeezing the spinal cord. Myelopathy
     affects the entire spinal cord, and is very
     different from isolated points of pressure
     on the individual nerve roots. Myelopathy
     is most commonly caused by spinal stenosis,
     which is a progressive narrowing of the
     spinal canal. In the later stages of spinal
     degeneration, bone spurs, and arthritic
     changes make the space available for the
     spinal cord within the spinal canal much
     smaller. The bone spurs may begin to press
     on the spinal cord and the nerve roots, and
     that pressure starts to interfere with how the nerves function normally. Myelopathy
     can be difficult to detect, because this disease
     usually develops gradually and also
     occurs at a time in life when people are
     beginning to slow down a little bit anyway.
     Many people who have myelopathy will
     begin to have difficulty with activities that
     require a fair amount of coordination, like
     walking up and down the stairs or fastening
     the buttons on clothing. If a patient has
     had a long history of neck pain, changes in
     coordination, recent weakness, and difficulty
     doing tasks that used to be easier
     because your body seemed more responsive
     in the past, are definite warning signs
     that they should see a doctor. Surgery is
     usually offered as an early option for people
     with myelopathy who have evidence of
     muscle weakness that is being caused by
     nerve root or spinal cord compression. This
     is because muscle weakness is a definite
     sign that the spinal cord and nerves are
     being injured (more seriously than when
     pain is the only symptom) and relieving
     the pressure on the nerves is more of an
     urgent priority. However, the benefits of
     nerve and spinal cord decompression have
     to be weighed against the risks of surgery.
     Many people who have myelopathy
     caused by degenerative cervical disorders
     are older and often a bit frail. Spine surgery
     can be a difficult stress for someone who is
     old or who has many different medical
     problems. However, a surgeon will be able
     to discuss the risks and benefits of surgery,
     and what the likely results are of operative
     versus nonoperative treatment.
     Cauda equina syndrome is a serious
     neurologic condition in which there is
     acute loss of function of the neurologic
     elements (nerve roots) of the spinal canal
     below the termination (conus) of the
     spinal cord. After the conus the canal contains
     a mass of nerves (the cauda equina—
     horse tail—branches off the lower end of
     the spinal cord and contains the nerve
     roots from L1-5 and S1-5. The nerve roots
     from L4-S4 join in the sacral plexus which
     affects the sciatic nerve which travels caudally
     (toward the feet). Any lesion which
     compresses or disturbs the function of the
     cauda equina may disable the nerves
     although the most common is a central
     disc prolapse. Other causes include protrusion
     of the vertebra into the canal if
     weakened by infection or tumor and an
     epidural abscess or hematoma. Signs
     include weakness of the muscles innervated
     by the compressed roots (often
     paraplegia), sphincter weaknesses causing
     urinary retention and postvoid residual
     incontinence. Also, there may be
     decreased rectal tone; sexual dysfunction;
     saddle anesthesia; bilateral leg pain and
     weakness; and absence of bilateral ankle
     reflexes. Pain may, however, be completely
     absent; the patient may complain
     only of lack of bladder control and of saddle-
     anesthesia, and may walk into the
     consulting-room. Diagnosis is usually
     confirmed by an MRI scan or a CT scan,
     depending on availability. If cauda equina
     syndrome exists, early surgery is an
     option depending on the etiology discovered
     and the patient’s candidacy for major
     spine surgery.
     Awareness of these two phenomena and
     maintenance of an index of suspicion are
     important factors to help physicians detect
     such inflammatory masses early in the clinical
     course.
     An inflammatory mass or granuloma is
     resulted from a buildup of inflammatory
     material at the tip of the catheter. Signs and
     symptoms that warrant prompt diagnosis
     to rule out the presence of a catheter-tip
     mass include changes in the patient’s neurologic
     condition, including motor weakness,
     such as gait difficulties; sensory loss,
     including proprioceptive loss; hyper- or
     hypoactive lower extremity reflexes; and
     any evidence of bowel or bladder sphincter
     dysfunction. The practitioner should also
     be suspicious of new or different reports of
     numbness, tingling, burning, hyperesthesia,
     hyperalgesia, or the occurrence of pain
     (especially radicular pain that corresponds
     to the level of the catheter tip) during
     catheter access port injections or programmed
     pump boluses. The latter finding should alert the physician to discontinue
     the procedure and perform a diagnostic
     imaging study as soon as possible.
     If signs and symptoms suggestive of a
     catheter-tip mass are detected, the practitioner
     should first review the patient’s
     current issues, history, and neurologic
     examination. Then, a nonsurgical pain practitioner
     should review imaging studies with
     a neurosurgeon. Third, the physician should
     arrange the performance of a definitive
     diagnostic imaging procedure to confirm or
     rule out the suspected diagnosis. Treatment
     should be started in a timely fashion.
     Laboratory tests and electromyography or
     nerve conduction studies are not apparently
     useful in this situation.

Question 3

628. Advantages of intrathecal drug-delivery are
(A) the first-pass effect can be avoided
(B) intrathecal morphine is 300 times as
effective as oral morphine for equipotent
pain treatment
(C) the number of central nervous system
(CNS) derived side effects can be
reduced
(D) B and C
(E) A, B, and C

Answer 3

628. (E)
     A. The premise behind intrathecal drug
     delivery is that by directly depositing
     drugs into the CSF, the first-pass effect is
     avoided.
     B. Intrathecal morphine is 300 times as effective
     as oral morphine for equipotent pain
     treatment. From spinal to epidural morphine
     the conversion is in the ratio of 1:10.
     From epidural to IV morphine the conversion
     is in the ratio of 1:10. From IV to oral
     morphine the conversion is in the ratio of
     1:3, hence 10 × 10 × 3 = 300.
     C. By the direct action of the medication, the
     number of CNS-derived side effects can be
     reduced.

Question 4

629. Which one of the following is not an item to contemplate
prior to placing an intrathecal pump?
(A) Does the patient have an acceptable
physiologic explanation for the pain
syndrome
(B) Does the patient have a life expectancy
of 3 months or longer
(C) Psychologic clearance is not needed in
the patient with cancer pain
(D) How old is the patient
(E) Has the patient been reasonably
compliant with past treatment
recommendations

Answer 4

629. (D) In choosing the right patient for an intrathecal
     drug-delivery system, several important
     questions must be asked, like
     A. Does the patient have an adequate physiologic
     explanation for the pain syndrome?
     Does the diagnosis require aggressive pain
     treatment?
     B. Does the patient have a life expectancy of
     3 months or longer (required for both cancer
     and noncancer patients)?
     C. Is the patient psychologically stable? A
     psychologist should assess the patient’s
     mental status and stability prior to the
     procedure. Outcomes have been shown to
     deteriorate with the presence of untreated
     depression, untreated anxiety disorders,
     and suicidal or homicidal ideation. Results
     have also been negatively influenced by
     the presence of untreated illicit substance
     dependence. The presence of a personality
     disorder such as borderline, antisocial, or
     multiple personality disorder should
     cause extreme caution, with these patient
     receiving implants only in extenuating circumstances.
     Psychologic clearance is not
     needed in the patient with cancer pain, but
     many of these patients may benefit from
     counseling to better cope with the disease
     process.
     E. Has the patient been reasonably compliant
     with past treatments? Has the patient failed
     other, less invasive therapies? What were
     they? Were they documented? Do they
     include physical therapy and oral medications?
     Are more conservative therapies unacceptable,
     not desired, or contraindicated? Do
     the symptoms of pain affect the patient’s
     ability to function? Does the patient have a
     contraindication, such as a bleeding diathesis,
     or a localized or systemic infection? Has
     the patient had a successful intrathecal medication
     trial? The physician should write a
     detailed note regarding symptom relief, side
     effects, and overall patient acceptance. Does
     the patient have a realistic view of expectations?
     Does the patient accept the risks of the
     procedure/device and future medications?

Question 5

630. Prior to implanting an intrathecal pump many
     practitioners perform an intrathecal medication
     trial. Significant parameters to consider
     include
     (A) delivery site
     (B) type of medication
     (C) whether the patient should be admitted
     (D) A and B
     (E) A, B, and C

Answer 5

630. (D)
     A. and B. There is a definite justification for a
     trial that mimics the conditions that will be
     achieved by the implanted system. Important
     parameters include
     • Site of medication delivery (intrathecal
     versus epidural, and spinal level)
     • Whether the medication is delivered as a
     bolus or an infusion
     • Infusion rate
     • Dose/concentration range
     • Length of trial
     • Medication selected for trial
     C. The patient should always be admitted
     and observed after an intrathecal medication
     trial. There was a comparison of trial
     methods in pain patients (nociceptive,
     neuropathic, or mixed) selected to have
     intrathecal pump placement. In the final
     analysis at 12 months after implantation, it
     was determined that there was no significant
     difference in trial method (single-shot
     intrathecal, continuous intrathecal, or continuous
     epidural) in outcomes with nociceptive
     pain. However, in neuropathic
     pain syndromes, the initial success of trial
     was significantly better if a continuous
     method was used. There was no difference
     noted in trial through the epidural route
     versus trial through the intrathecal route.
     The main difference between successful
     trials in patients with neuropathic pain
     and mixed pain syndromes was the inclusion
     of more than one medication to
     improve the success of the trial.
     Morphine has been approved by the
     FDA for intrathecal drug-delivery systems,
     and is often the first choice of drug
     for trial. Local anesthetics or α-receptor–
     acting drugs are sometimes added to the
     trial in patients with burning or lancinating
     extremity pain with hopes of improving
     the success of the trial.
     To be considered a success, the trial
     should induce significant pain relief, with
     minimal side effects, and noncancer patients
     should obtain purposeful improvement of
     function.

Question 6

631. When dealing with an infection, which of the
     following would favor explanting the intrathecal
     device?
     (A) Associated bleeding
     (B) The presence of a seroma
     (C) The presence of a hygroma
     (D) The presence of necrotic tissue around
     the wound
     (E) All of the above

Answer 6

631. (D)
     A. Bleeding at the wound site will be obvious
     with seepage into the dressing. Associated
     signs include edema, discoloration, and
     rubor. It can usually be treated with ice and
     compression; however, surgical exploration
     may be necessary. The presence of an active
     bleed does not necessitate the explantation
     of the intrathecal drug-delivery system.
     B. A seroma is a collection of noninfectious
     fluid. It is usually treated with pressure
     dressings and conservatively allowing for
     resorption. If conservative treatment is not
     efficacious, sterile aspiration may be necessary.
     Its presence does not require the
     removal of the intrathecal pump.
     C. A hygroma is a collection of CSF. Its most
     common cause is leakage of fluid around
     the catheter entry point and into the
     pocket. It can be treated with abdominal
     pressure, caffeine, and increased fluid
     intake.
     D. Infection of the wound may be minor and
     superficial, or it may be severe enough to
     warrant the removal of the pump. An
     infection may present with fever, redness,
     frank pus, or purulent wound drainage.
     Incision and drainage, qualification of
     pathogenic culprit, and antibiotic therapy
     must be undertaken immediately. The
     decision to excise the pump is made based
     on the presence of necrotic tissue, the overall
     condition of the wound, and the condition
     of the patient.
     The two most disastrous complications
     are epidural hematoma and neuraxial
     infection. An epidural hematoma may
     result in paralysis and should be suspected
     with any change in neurologic status
     postoperatively. This is an emergency
     and an immediate MRI and neurosurgical
     consultation should be obtained. The presence
     of an intrathecal pump is not a contraindication
     to MRI, and should not delay
     its use. A neuraxial infection can include
     meningitis or an epidural abscess and they
     must both be diagnosed immediately so
     that treatment can be started expeditiously.

Question 7

632. You have separately tried maximum doses of
     morphine and hydromorphone, in a patient’s
     intrathecal pump without any efficacy. According
     to the 2007 Polyanalgesic Consensus Guidelines,
     which one of the following would not be an
     accepted “next” step?
     (A) Switch to morphine plus bupivacaine
     (B) Switch to ziconotide
     (C) Switch to clonidine
     (D) Switch to fentanyl
     (E) Switch to hydromorphone plus
     ziconotide

Answer 7

632. (C) For the 2007 Polyanalgesic Consensus
     Guidelines, baclofen and midazolam were
     moved to special consideration categories.
     Midazolam may be used in end of life situations
     but only minimal/anecdotal evidence
     exists. Baclofen is to be used in patients that
     have spasticity-related pain, diseases associated
     with dystonia, or unrelenting spasms in
     muscle. It works via blockade of GABAB receptors
     in the spinal cord. Indications for intrathecal
     baclofen therapy: patient is intolerant of
     oral agents, pain is inadequately treated with
     oral agents, need exact control of dosing that only intrathecal delivery allows. Efficacy in
     neuropathic pain has been noted through case
     reports at doses of 100 to 460 μg/d (maximum
     FDA dosing is 900 μg/d). If significant dose
     increases are taking place, consider mechanical
     problems. Very good for exceptional long-term
     tolerability is expected. However, baclofen is
     not without complications. Withdrawal can
     occur secondary to catheter disruption, battery
     failure, or human error. There is a very wide
     spectrum of presentation ranging from asymptomatic
     to death. Granulomas are very rare.
     Overdose is usually results from human error
     and can be reversed with physostigmine, and
     flumazenil.

Question 8

633. Ziconotide was approved for infusion into the
     cerebrospinal fluid (CSF) using an intrathecal
     drug-delivery system by the Food and Drug
     Administration (FDA) in 2004. Its proposed
     mechanism of action is
     (A) it blocks sodium channels
     (B) it blocks α2δ voltage-gated calcium
     channels
     (C) it blocks N-type calcium channels
     (D) it blocks γ-aminobutyric acid (GABAB)
     receptors in the spinal cord
     (E) none of the above

Answer 8

633. (C)
     A. Numerous medications work by blocking
     sodium channels. Ziconotide is not one of
     them.
     B. Pregabalin and gabapentin work by acting
     on α2δ voltage-gated calcium channels. Their
     exact mechanism of action is unknown, but
     their therapeutic action on neuropathic pain
     is thought to involve voltage-gated N-type
     calcium ion channels. They are thought to
     bind to the α2δ subunit of the voltagedependent
     calcium channel in the CNS.
     C. Ziconotide is a nonopioid, non-NSAID
     (nonsteroidal anti-inflammatory drug),
     nonlocal anesthetic used for the amelioration
     of chronic pain. Derived from the cone
     snail Conus magus, it is the synthetic form
     of the cone snail peptide ω-conotoxin MVII-
     A. Previously known as SNX-111, it is a
     neuronal-specific calcium-channel blocker
     that acts by blocking N-type, voltage-sensitive
     calcium channels.
     Scientists have been intrigued by the
     effects of the thousands of chemicals in
     marine snail toxins since the initial investigations
     in the late 1960s by Baldomero
     Olivera, who remembered the deadly
     effects from his childhood in the
     Philippines. Ziconotide was discovered in
     the early 1980s by Michael McIntosh, at
     the time barely out of high school and
     working with Olivera. It was developed
     into an artificially manufactured drug by
     Elan Corporation. It was approved for
     sale under the name Prialt by the FDA in
     the United States on December 28, 2004,
     and by the European Commission on
     February 22, 2005.
     The mechanism of ziconotide has not
     yet been discovered in humans. Results in
     animal studies suggest that ziconotide
     blocks the N-type calcium channels on the
     primary nociceptive nerves in the spinal
     cord.
     As a result of the profound side effects
     or lack of efficacy when delivered through
     more common routes, such as orally or
     intravenously, ziconotide must be administered
     intrathecally (directly into the
     spine). As this is by far the most expensive
     and invasive method of drug delivery and
     involves additional risks of its own,
     ziconotide therapy is generally considered
     appropriate (as evidenced by the range of
     use approved by the FDA in United States)
     only for management of severe chronic
     pain in patients for whom intrathecal (IT)
     therapy is warranted and who are intolerant
     of or refractory to other treatment,
     such as systemic analgesics, adjunctive
     therapies or IT morphine.
     The most common side effects are dizziness,
     nausea, confusion, and headache.
     Others may include weakness, hypertonia,
     ataxia, abnormal vision, anorexia, somnolence,
     unsteadiness on feet, and memory
     problems. The most severe, but rare side
     effects are hallucinations, suicidal ideation,
     new or worsening depression, seizures, and
     meningitis. Therefore, it is contraindicated
     in people with a history of psychosis, schizophrenia,
     clinical depression, and bipolar
     disorder.
     D. Baclofen’s proposed mechanism of action
     is by blocking the GABAB receptors in the
     spinal cord.

Question 9

634. Neurology consults you on a 65-year-old female
     with breast cancer that has diffusely metastasized
     to her bones. She has had an intrathecal
     pump for 4 months, and has just been diagnosed
     with meningitis. Which of the following
     is true?
     (A) The pump must be removed
     (B) Enteral antibiotics must be initiated
     immediately
     (C) If the infection is sensitive to vancomycin,
     and the patient refuses pump
     removal, intrathecal vancomycin may be
     administered
     (D) Intravenous (IV) vancomycin plus
     epidural vancomycin has not been
     found to be effective in resolving infection
     (E) All of the above

Answer 9

634. (C)
     A. The diagnosis of aseptic or viral meningitis
     in the cancer patient with an intrathecal
     pump should not be an automatic reason
     for explantation of the device. Supportive care and neurologic monitoring should be
     provided until the symptoms resolve, but
     the pump and catheter do not need to be
     removed. If the meningitis is of a bacterial
     etiology, risk assessment, pain stratification,
     and life expectancy should be considered.
     Removal of the pump is suggested,
     but is not required because there is a
     potential for severe, uncontrolled pain.
     B. Parenteral (IV) not enteral (via the GI tract)
     antibiotics should be started immediately
     if bacterial meningitis is suspected. More
     specific antibiotics should be administered
     after cerebrospinal bacterial cultures and
     sensitivities are obtained.
     C. If the infection is vancomycin sensitive,
     and the patient refuses pump explantation,
     intrathecal vancomycin may be administered
     at 10 mg/d. Intrathecal vancomycin
     has been used successfully for 6 months in
     such patients.
     D. The same group found that IV vancomycin
     combined with epidural vancomycin
     (150 mg/d for 3 weeks) abolished infection.

Question 10

635. A 72-year-old male with end-stage metastatic
     prostate cancer has a life expectancy of 6 months.
     Which of the following is true with regards to
     managing his intrathecal drug-delivery system?
     (A) Treatment decisions should be made
     based on the 2007 Polyanalgesic
     Consensus Guidelines for management
     of chronic, severe pain
     (B) Fentanyl is considered a first-line
     medication
     (C) Droperidol may be used, intrathecally,
     as a first-line medication for nausea
     (D) A different algorithm is applied when a
     patient’s life expectancy is less than
     18 months
     (E) None of the above

Answer 10

635. (C)
B. and C. Morphine or hydromorphone should
be used for nociceptive pain. Bupivacaine
should be used for neuropathic pain.
Morphine or hydromorphone plus bupivacaine
should be used for mixed pain.
Droperidol is 95% efficacious in the treatment
of nausea and vomiting secondary to opioid
intolerance, abdominal tumors, and/or
chemotherapy/radiation therapy, and can be
added at this point (dose: 25-250 μg/d).
Morphine, hydromorphone, or fentanyl/
sufentanil with bupivacaine and
clonidine for nociceptive or mixed pain.
Morphine, hydromorphone, or fentanyl/
sufentanil with bupivacaine for neuropathic
pain.
Morphine, hydromorphone, or fentanyl/
sufentanil with more than two adjuvants:
the physician should use opiate
plus local anesthetic plus clonidine and
• Baclofen for spasticity, myoclonus, or
neuropathic pain
• Bupivacaine for neuropathic pain
• Second opioid (lipophilic/hydrophilic)
as an adjuvant
Morphine, hydromorphone, or fentanyl/
sufentanil with more than three
adjuvants: in addition to second-line adjuvants,
the physician should add
• Ketamine for neuropathic pain secondary
to cord compression
• Midazolam for neuropathic pain
• Droperidol for neuropathic pain
Tetracaine may be used for chemical
paralysis for inoperable cord compression,
tachyphylaxis, or emergency hyperalgesia
rescue.
Some cases may necessitate six adjuvants
to control pain at the end of life with
minimal side effects.

Question 11

636. Granulomas have been found to occur with all
medications used intrathecally, EXCEPT
(A) clonidine
(B) sufentanil
(C) baclofen
(D) fentanyl
(E) B and D

Answer 11

636. (B) The 2007 Polyanalgesic Consensus
     Guideline panelists have addressed this topic
     fully. All panelists felt that catheter-related
     granulomas still remains one of the most grave
     adverse effects and risks of intrathecal pain
     management and impediments to the widespread
     use of the therapy. Several factors contribute
     to the development of granuloma,
     including the agent used, catheter position
     (majority of granulomas occur in thoracic
     area—where CSF volume and flow are
     reduced), CSF volume (especially if low), and
     the dose and concentration of the drug (low
     CSF volume means higher concentrations of
     drug). With morphine, the preponderance of
     cases have been described in patients receiving
     concentrations of 40 mg/mL or greater. In cases
     where hydromorphone was implicated, the
     majority of cases received concentrations of
     10 mg/mL or greater. Even though some panelists
     felt that positioning the catheter into the
     larger CSF volume of the dorsal intrathecal
     space of the low thoracic cord, granulomas do
     occur even in cases where catheters have been
     inserted into that space. However, concentration
     of the agent used appears to be the major
     causal factor of intrathecal, catheter-related
     granulomas. A., B., C., and D. Inflammatory masses
     have been reported to be associated with all
     medications administered in the intraspinal
     space except for sufentanil and rarely for fentanyl.
     As of this writing, there have been at
     least three reports published in the literature
     of baclofen-related granulomas. Even though
     the literature suggests a granuloma protective
     effect of clonidine, there have been reports of
     patients with intrathecal clonidine, alone, or
     in combination with other intrathecal agents
     developing granulomas.

Question 12

Match the associated side effects with the intrathecal
medication that causes it. Each choice can be used
once, more than once, or not at all, and each question
can have more than one answer.
637. Urinary retention
638. Extrapyramidal side effects
639. Hypotension
640. Auditory disturbances
641. Sedation
642. Nausea
643. Worsening of depression
(A) Opioids
(B) Bupivacaine
(C) Baclofen
(D) Clonidine
(E) Droperidol
(F) Ketamine
(G) Midazolam

Answer 12

637 to 643. 637 (A and B); 638 (E); 639 (B and D);
640 (C); 641 (A, D, and G); 642 (A); 643 (D)
Opioids can cause sedation, edema, constipation,
nausea, and urinary retention.
Bupivacaine can cause urinary retention,
weakness, and hypotension.
Baclofen can cause loss of balance, and auditory
disturbances.
Clonidine can cause orthostatic hypotension,
worsening of depression, edema, and sedation.
Droperidol can cause extrapyramidal side
effects such as tremor, slurred speech, akathisia,
dystonia, anxiety, distress, and paranoia.
Ketamine can cause increased anxiety and
irritability, delusional ideation, and facial
flushing.
Midazolam can cause sedation.
If a medication is not therapeutic for a
patient or is causing significant adverse effects,
it should be properly weaned, and the patient
should be informed of likely withdrawal
symptoms and arrange for outpatient interventions.
Acute baclofen or clonidine termination
can result in hemodynamic derangements,
seizures, or death. To avoid these untoward
effects, physicians should introduce oral
replacement therapy on the stoppage of
intrathecal medications and provide an appropriate
weaning schedule to the patient.

Question 13

644. A 43-year-old female has 8-month history of
     axial low back pain and pain radiating to the
     left leg. The magnetic resonance imaging (MRI)
     of lumbosacral spine shows severe degenerative
     disc disease at L3-4 through L5-S1 with
     mild disc protrusions at these levels. She is a
     possible candidate for
     (A) transforaminal epidural steroid injection
     (B) facet joint medial branch diagnostic
     block
     (C) spinal cord stimulator (SCS) trial
     (D) all of the above
     (E) none of the above

Answer 13

644. (D)
     A. The epidural steroid injections (ESI) and
     SCS are treatment choices for radicular
     pain caused in particular by disc herniation causing mechanical and chemical irritation
     of the nerve root.
     B. Presence of axial low back pain even in
     absence of MRI changes can indicate possible
     facet arthropathy. Facet and medial
     branch diagnostic blocks are likely the
     most sensitive and specific diagnostic test
     for facet pain. Facet radiofrequency (RF)
     denervation seems to be the best treatment
     choice for patients with short-term relief
     with facet blocks.
     C. The SCS trial may be an excellent choice
     for radiating pain down the leg.

Question 14

645. The causes of axial low back pain are
(A) sacroiliac (SI) arthropathy
(B) internal disc disruption
(C) quadratus lumborum and psoas
syndrome
(D) all of the above
(E) none of the above

Answer 14

645. (D)
     A. SI joint injection with local anesthetics and
     steroids may have good diagnostic and
     possibly therapeutic value if the pain is
     located in the SI joints.
     B. Internal disc disruption or discogenic
     pain can be diagnosed with provocative
     discography.
     C. Quadratus lumborum and psoas muscle
     pain represent a form of myofascial pain
     that can be a cause of low back pain.
     Diagnostic blocks may have a value in diagnosis
     of this type of myofascial pain.

Question 15

646. The false-positive rate of diagnostic lumbar
facet medial branch blocks are
(A) 8% to 14%
(B) 15% to 22%
(C) 3% to 5%
(D) 25% to 41%
(E) 41% to 50%

Answer 15

646. (D) Diagnostic medial branch blocks have a
     very high false-positive rate as reported in
     studies. This can potentially decrease the success
     rate of RF denervation of facet joints since
     this procedure is based on good short-term
     results with diagnostic medial branch blocks.
     For this reason repeated confirmatory diagnostic
     block and use of small dose of local anesthetics
     (0.3-0.5 mL) is recommended by many.

Question 16

647. Percentage of cases where the pain relief is
caused by placebo response following interventional
procedures are
(A) 12%
(B) 35%
(C) 20%
(D) 15%
(E) 28%

Answer 16

647. (B) Placebo effect is responsible for pain relief
     in up to 35.2% interventional procedures.
     Despite the high rates of placebo response it is
     not recommended for routine clinical use.

Question 17

648. The complication of sphenopalatine ganglion
radiofrequency thermocoagulation is
(A) infection
(B) epistaxis
(C) bradycardia
(D) all of the above
(E) none of the above

Answer 17

648. (D)
     A. Infection is a rare complication that can be
     difficult to treat.
     B. It seems that the epistaxis is more common
     than thought and can occur if too much pressure is applied to the RF cannula.
     Hematoma can occur if maxillary artery of
     venous plexus is punctured.
     C. Bradycardia is likely caused by reflex similar
     to the oculocardiac reflex.

Question 18

649. The complication of third occipital nerve (TON)
radiofrequency thermocoagulation is
(A) change in taste
(B) ataxia
(C) dysphagia
(D) all of the above
(E) none of the above

Answer 18

649. (B)
     A. Change in taste would more likely be associated
     with glossopharyngeal nerve, lingual
     nerve, and chorda tympani.
     B. Ataxia can occur in up to 95% cases of RF
     denervation of the TON, numbness in 97%,
     dysesthesia in 55%, hypersensitivity in
     15%, and itching in 10% of cases. Third
     occipital neurotomy almost always partially
     denervates semispinalis capitis muscle
     and so interferes with tonic neck
     reflexes and causes ataxia in particular on
     looking downward. The sensation is readily
     overcome by relying on visual cues such
     as fixing on the horizon.
     C. Dysphagia is not associated with TON
     thermocoagulation

Question 19

650. Positive lumbar provocative discogram for
     mechanical disc sensitization includes reproduction
     of patient’s pain with injection of the
     contrast in nucleus pulposus at what pressure
     above the “opening pressure”?
     (A)

Answer 19

650. (D)
     A. Provocative discography is best done while
     pressure of contrast has been continuously
     measured. Reproduction of pain at 6/10
     and pain location and quality should be
     similar to the chronic low back pain.

Question 20

651. The technique of cervical discography includes
needle entry through the skin from the
(A) anterior right side of the neck
(B) posterior right side of the neck
(C) anterior left side of the neck
(D) posterior left side of the neck
(E) median posterior side of the neck

Answer 20

651. (A) Cervical discography is performed with
     patient in supine position, using oblique
     approach, similar to the stellate ganglion block.
     The esophagus is normally positioned slightly toward the left side of the neck. To prevent
     puncturing it, the best technique for needle
     insertion for cervical discography is anterior
     right-sided approach.

Question 21

652. When performing intralaminar cervical epidural
     steroid injections without fluoroscopic guidance,
     the chances of having false positive loss
     of resistance are close to
     (A) 15%
     (B) 25%
     (C) 35%
     (D) 50%
     (E) 40%

Answer 21

652. (D) The ligamentum flavum is discontinuous
     in cervical levels, therefore allowing for very
     high chances of false loss of resistance technique
     and therefore mandates the use of fluoroscopy
     and contrast administration. The use of
     fluoroscopy may improve the safety of this procedure,
     medication delivery to the site of
     pathology, and potential outcomes. In lumbar
     levels it seems that the false loss of resistance in
     nonfluoroscopically performed epidural
     steroid injections occurs in up to 30% of cases.

Question 22

653. When performing intralaminar cervical epidural
     steroid injections, the unilateral contrast (and
     medication) spread is expected in what percentage
     of cases?
     (A) 50%
     (B) 30%
     (C) 25%
     (D) 10%
     (E) 40%

Answer 22

653. (A)
     A. Although there is no median septum of fat
     in cervical epidural levels the unilateral
     medication spread is common. Therefore
     injections should be performed toward the
     laterality of pathology.
     B. False loss of resistance technique when not
     performed under fluoroscopy is 30% in
     lumbar levels and 50% in cervical levels.
     C. Ventral epidural spread in cervical levels is
     close to 25%.
     D. Too low.
     E. Unilateral contrast spread in intralaminar
     cervical epidural injections may occur in
     roughly 50% of all cases.

Question 23

654. Which of the following is a complication of
lumbar sympathetic block?
(A) Genitofemoral neuralgia
(B) Retrograde ejaculation
(C) Intravascular injection
(D) All of the above
(E) None of the above

Answer 23

654. (D)
     A. Genitofemoral neuralgia is very rare complication
     of lumbar sympathetic block but
     can occur since the genitofemoral nerve
     originates from L1 and L2 nerve root.
     B. In retrograde ejaculation, the bladder
     sphincter does not contract and the sperm
     goes to the bladder instead of penis. This
     can lead to infertility.
     C. Intravascular injection of large dose of
     local anesthetics can lead to seizures.

Question 24

655. What is the best method for evaluating the adequacy
of lumbar sympathetic block?
(A) Increase in temperature by 2°F
(B) Increase in temperature by 5°F
(C) Increase in temperature by 10°F
(D) Temperature change
(E) Decrease in temperature by 2°F

Answer 24

655. (D) Any temperature change in comparison to
     preprocedure temperatures is adequate enough
     to assess the adequacy of successful block.

Question 25

``` 656. Stellate ganglion is located between the (A) C6-C7 (B) C7-T1 (C) C5-C7 (D) C5-C6 (E) T1-T2 ```

Answer 25

656. (B) The stellate ganglion is formed by fusion of inferior cervical ganglion resting over the anterior tubercle of C7 and first thoracic ganglion resting over the first rib.

Question 26

``` 657. In relation to the stellate ganglion the subclavian artery is located (A) anteriorly (B) posteriorly (C) laterally (D) medially (E) none of the above ```

Answer 26

657. (A) In relation to stellate ganglion the subclavian artery is located anteriorly. For this reason, care should be taken not to inject

Question 27

658. Despite satisfactory stellate ganglion block for sympathetic-mediated pain, the pain relief in upper extremity is inadequate. The technical explanation for this may lie in inadequate spread of local anesthetics to (A) C5 nerve root (B) inferior cervical ganglion (C) first thoracic ganglion (D) T2 and T3 gray communicating rami (E) C7 nerve root

Answer 27

658. (D) A. C5 nerve root injection may provide analgesia by sensory block. B. Inferior cervical ganglion is part of the stellate ganglion. C. First thoracic ganglion is part of the stellate ganglion. D. The T2 and T3 gray rami do not pass through the stellate ganglion but join the brachial plexus and innervate the upper extremity. Failure to block these structures may result in inadequate block (Kuntz nerves).

Question 28

659. When performing lumbar discography, the “opening pressure” is the recorded pressure signifying (A) first appearance of the contrast in nucleus pulposus (B) opening of the annular tear to the contrast (C) reproduction of concordant pain (D) resting pressure transduced from the nucleus (E) a dural leak

Answer 28

``` 659. (A) A. The opening pressure is always subtracted from pressure reproducing pain in final calculations (eg, positive discography means: pressure with pain reproduction— opening pressure ```

Question 29

``` 660. Intradiscal electrothermal coagulation (IDET) outcomes are adversely affected by (A) appearance of the disc on T2-weighted MRI images (B) obesity (C) age (D) coexisting radicular pain (E) gender ```

Answer 29

660. (B) A. Discs are usually dark (dehydrated) on T2- weighted MRI images and this can only suggest discogenic pain. B. Morbid obesity can decrease the success rate and increase the risks of IDET. C. There are no studies proving that age influences outcomes of IDET but it seems that advanced age may decrease the rate of success of IDET treatment. D. Radicular pain directly does not predict the outcome of IDET. Discogenic pain (referred pattern) can sometimes mimic radicular pain.

Question 30

661. When performing lumbar discography, in relation to the laterality of pain, which of the following should be the needle entry site? (A) Ipsilateral (B) Contralateral (C) Laterality does not make a difference (D) Guided by MRI images (E) None of the above

Answer 30

661. (C) It does not seem that the outcomes of discography are affected by laterality of needle insertion site.

Question 31

662. Apatient with painful sacroiliac joint syndrome had only short-term relief with two sacroiliac (SI) injections using local anesthetics and steroids. Which of the following is the next treatment option? (A) SI joint fusion (B) S1, S2, S3, S4 radiofrequency denervation (C) L5, S1, S2, S3 radiofrequency denervation (D) L4, L5, S1, S2, S3 radiofrequency denervation (E) None of the above

Answer 31

662. (D) SI joint fusion has been used in the past as a treatment of SI pain with unfavorable results. The L4, L5, S1, S2, and S3 radiofrequency denervation is shown to be beneficial longterm treatment option in patients with SI pain.

Question 32

``` 663. Which of the following includes published complications that may follow cervical transforaminal epidural steroid injection? (A) Epidural abscess (B) Neuropathic pain (C) Quadriplegia and death (D) All of the above (E) None of the above ```

Answer 32

663. (D) A. Epidural abscess should be suspected if increased pain and new neurologic symptoms occur after the cervical epidural steroid injection. B. Neuropathic pain may occur following epidural steroid injection. C. If the steroid solution is injected intravascularly serious complications including possible spinal cord infarction may occur. The digital subtraction fluoroscopy and blunt needle use may help to minimize its occurrence if this procedure is performed.

Question 33

664. In order to minimize the risk for complications when cervical transforaminal epidural steroid injection is performed how should the needle be positioned in relation to the neural foramina? (A) Anteriorly (B) Posteriorly (C) Superiorly (D) Inferiorly (E) None of the above

Answer 33

664. (B) Placing needle posteriorly may minimize | the risk of intravascular injection.

Question 34

665. The single-needle approach to medial branch block diagnosis in comparison to standard multiple-needle approach (A) causes less discomfort for the patient (B) decreases the volume of local anesthetics used for the skin and subcutaneous tissues (C) takes less time to perform (D) all of the above (E) none of the above

Answer 34

``` 665. (D) A. The use of single-needle technique may decrease procedural discomfort during medial branch blocks. B. By minimizing the amount of local anesthetics for the skin and subcutaneous tissues the rate of false-positive blocks caused by treatment of myofascial pain may be diminished. C. This approach may take less time to perform than the traditional multiple-needle technique. ```

Question 35

``` 666. The incidental intrathecal overdose of intrathecal morphine while performing a pump refill should be treated by (A) intrathecal and IV naloxone (B) airway protection (C) possible irrigation of the CSF with saline (D) all of the above (E) none of the above ```

Answer 35

666. (D) A. If IV naloxone is inadequate, intrathecal naloxone may be considered. B. Airway protection may be needed because of respiratory depression. C. Possible irrigation of CSF with saline may be necessary.

Question 36

667. While analyzing a malfunctioning SCS implanted device, a sign of lead breakage or disconnect is a measured impedance of (A) 1500 Ω (C) 4000 Ω (E)

Answer 36

667. (D) Increased impedance may mean that there is lead fracture, disconnect, fluid leakage causing short circuit. The exactly same impedance at multiple leads may mean that there is a communication and short circuit between the leads.

Question 37

668. Accurate placement of a stimulator lead for occipital nerve peripheral stimulation is (A) posterior to the C3 spinous process (B) lateral to the pedicles of C2 and C3 (C) 2 mm lateral to the odontoid process (D) posterior to the C2 spinous process (E) none of the above

Answer 37

668. (D) The lead should be positioned subcutaneously posterior to the C2 spinous process and perpendicular to the cervical spine.

Question 38

``` 669. Adequate SCS introducer needle epidural space at entry level for the desired coverage of the foot pain is (A) L3-4 interspace (B) L1-L2 interspace (C) T12-L1 interspace (D) T8-T9 interspace (E) T10-T11 interspace ```

Answer 38

669. (A) For the coverage of the foot, the SCS electrode position should be at the T11-T12 level. The more caudal entry level is desired in order to leave enough of the SCS lead in the epidural space and prevent dislodgement.

Question 39

``` 670. The placement of SCS electrodes for coverage of intractable chest pain caused by angina should be at the epidural level of (A) T6 (B) C4-C5 (C) T1-T2 (D) C6-C7 (E) C3-C4 ```

Answer 39

670. (C) In order to position the lead at T1-T2 level commonly the entry site may be at lower thoracic levels owing to the narrow space in between the laminae in thoracic spine.

Question 40

``` 671. Most effective approach for performing lumbar epidural steroid injections is (A) caudal (B) interlaminar (C) paramedian approach (D) transforaminal (E) Taylor approach ```

Answer 40

671. (D) Although there is insufficient evidence, one study reported that transforaminal approach has better outcomes in comparison to interlaminar approach for epidural steroid injections. The caudal approach requires diluted solution and may not reach the area of pathology in some cases.

Question 41

``` 672. During interlaminar epidural steroid injections contrast should be (A) used in the anteroposterior view (B) used in the lateral view (C) used in oblique view (D) no contrast should be used (E) A, B, and C ```

Answer 41

672. (A) Contrast media should be administered in anteroposterior view in order to rule out intravascular uptake.

Question 42

673. Which of the following is the most likely complication after successful SCS implant? (A) Infection (B) Persistent pain at the implant site (C) Lead breakage or migration (D) CSF leak requiring surgical intervention (E) Paralysis or severe neurologic deficit

Answer 42

673. (C) A. Infection rate of implanted hardware has been estimated at 3% to 5%. B. Persistent pain at the implant site has been estimated at approximately 5%. C. Lead breakage or migration has been estimated at 11% to 45%. D. CSF leak requiring surgical intervention has been reported. E. Paralysis or severe neurologic deficit is possible as with any type of spine surgery, but is not cited as a frequent occurrence.

Question 43

674. Which of the following is the most accurate statement regarding efficacy of SCS? (A) For failed back surgery patients, SCS in addition to conventional medical management can provide better pain relief and improve health-related quality of life as compared to conventional medical management alone (B) SCS is inefficacious for the indication of angina pectoris (C) SCS for CRPS is efficacious for only about a year only then the efficacy diminishes (D) SCS is not an effective treatment for sympathetically mediated pain (E) Nociceptive pain is considered a better indication for SCS than neuropathic pain

Answer 43

674. (A) A. One study which validates this statement was published in the journal Pain in 2007. A randomized, crossover study was performed with intent-to-treat analysis for more than 12 months. One hundred patients were randomized to either SCS and conventional medical management or conventional medical management only. More patients in the SCS group achieved the primary outcome of 50% or more pain relief in the legs. Other secondary measures were also improved in the SCS group. [Kumar K, Taylor RS, Jacques L, et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a multicenter randomized controlled trial in patients with failed back surgery syndrome. Pain. 2007;132(1-2):179-188.] B. In a 2009 review article it was determined that SCS decreases use of short-acting nitrates, improves quality of life, and increases exercise capacity. [Deer TR. Spinal cord stimulation for the treatment of angina and peripheral vascular disease. Curr Pain Headache Rep. 2009;13(1):18-23.] C. Many follow-up studies have been published showing efficacy with short-term follow- ups such as 6 months. A recent 5 year follow-up of a randomized, controlled trial of SCS for CRPS revealed that 95% of patients would repeat the treatment for the same result. Aretrospective telephone questionnaire study was performed in 21 CRPS patients with average follow-up at 2.7 years. Reduced pain and improved quality of life was sustained at long-term follow-up. [Kemler MA, de Vet HC, Barendse GA, et al. Effect of spinal cord stimulation for chronic complex regional pain syndromes type I: five-year final follow-up of patients in a randomized controlled trial. J Neurosurg. 2008;108(2):292-298.] D. SCS is effective for the treatment of sympathetically mediated pain. E. This is a false statement. Neuropathic pain has traditionally been considered an indication for SCS. Nociceptive pain is considered not amenable to treatment with SCS.

Question 44

``` 675. Which of the following is not a relative contraindication to SCS? (A) Unresolved major psychiatric comorbidity (B) A predominance of nonorganic signs (C) Spinal cord injury or lesion (D) Alternative therapies with a risk to benefit ratio comparable to that of SCS remain to be tried (E) Occupational risk ```

Answer 44

675. (C) In 2007, an article published an evidencebased literature review and consensus statement which addressed over 60 questions relating to clinical use of SCS. Spinal cord injury or lesion, is an etiology of neuropathic pain and is an indication for SCS. Certain occupations such as an electrician’s are considered a relative contraindication to SCS therapy.

Question 45

676. Which of the following statements is most accurate regarding cost-effectiveness of SCS? (A) Nobody opines of its cost-effectiveness and the issue has not been addressed in literature (B) The literature is clear and consistent; SCS is not cost-effective (C) Although published conclusions may vary, a consensus of professionals has determined that SCS stimulation is not cost-effective (D) Although published conclusions may vary, a consensus of professionals has determined that SCS is cost-effective for certain indications (E) All published literature on the topic concludes that SCS is cost-effective

Answer 45

676. (D) Some published articles concluded that SCS is cost-effective. Some have concluded that SCS is not cost-effective, at least in certain patient populations. Variation may relate to specific parameters and patient inclusions in the study. Recent practice parameters concluded that SCS is cost-effective in the treatment of failed back surgery syndrome and CRPS and might be cost-effective in the treatment of other neuropathic pain indications. Furthermore it was concluded that cost-effectiveness can be optimized by adjusting stimulation parameters to prolong battery life, by minimizing complications, and by improving equipment design. [Mekhail NA, Aeschbach A, Stanton- Hicks M. Cost benefit of neurostimulation for chronic pain. Clin J Pain 2004;20(6):462-468. Klomp HM, Steyerberg EW, van Urk H, et al. Spinal cord stimulation is not cost-effective for non-surgical management of critical limb ischemia. Eur J Vasc Endovasc Surg. 2006;31(5): 500-508. North R, Shipley J, Prager J, et al. Practice parameters for the use of spinal cord stimulation in the treatment of chronic neuropathic pain. Pain Med 2007;8(suppl 4):S200-S275.]

Question 46

``` 677. Which of the following are specifications for current SCS systems? (A) Constant voltage, pulse width up to 2000 milliseconds (B) Constant current, volume less 10 cm3 (volume less than a standard matchbook) (C) Constant resistance, pulse width up to 1000 milliseconds, cordless recharging (D) Constant current, pulse width up to 1000 milliseconds, cordless recharging (E) Constant current and constant resistance, cordless recharging, pulse width up to 1000 milliseconds ```

Answer 46

677. (D) A. One of the three commonly used manufacturers does use a constant voltage technology. None of the three manufacturers have a system allowing pulse width much over 1000 milliseconds. B. Two of the three commonly used manufacturers do use a constant current technology. Although battery sizes as small as 22 cm3 are available with two companies, no company currently has a battery smaller than that in current clinical usage. This may change in the near future. C. No SCS system relies on maintaining constant resistance. Resistance is not in the physician’s control and varies with factors such as scar tissue formation. Cordless recharging is available with several manufacturers’ systems. D. This is a specification set that is currently available. Aconstant voltage system is also now available with pulse widths up to 1000 milliseconds. E. Maintaining both constant current and constant resistance would not be achievable because resistance is not a controllable factor. Voltage, current, and resistance vary according to Ohm’s law: voltage = current × resistance. New batteries have reached the market including ones with constant voltage, pulse width of 1000 milliseconds, and battery size of about 22 cm3.

Question 47

678. Which of the following is true? (A) Dorsal column pathways do not play a role in visceral pain and therefore there is no role of SCS for visceral pain (B) Pelvic pain has been demonstrated to consistently fail treatment with SCS (C) The midline dorsal column pathway has been the proposed target for stimulation for chronic visceral pain (D) Pelvic pain stimulation can best be achieved by first targeting the S2 foramen in a retrograde approach (E) There is no therapeutic potential for treatment of chronic visceral pelvic pain with SCS

Answer 47

678. (C) A. Dorsal column pathways have been demonstrated to play a role in transmission of visceral pain. B. Case reports have been published showing successful treatment of pelvic pain with SCS. One such report was a case series of six patients with pelvic pain of multiple diagnoses all treated successfully with SCS. Diagnoses included vulvar vestibulitis, endometriosis, pelvic adhesions, uterovaginal prolapsed, and vulvodynia. C. Midline myelotomy may relieve visceral cancer pain. This is a deep pathway and therefore a tightly spaced lead which can drive the stimulation deeper would be advantageous for attempted SCS for visceral pain. D. The stimulation “sweet spot” for pelvic pain has been reported to be around T12. E. Case study evidence supports the role for SCS for chronic visceral pelvic pain. Further well-designed studies are needed.

Question 48

``` 679. Which of the following is the best answer regarding lead geometry and spacing? (A) The goal of SCS in treatment of bilateral lower extremity neuropathy pain is most frequently to stimulate the dorsal roots rather than the dorsal columns (B) Tight lead spacing increases the ratio of dorsal column to dorsal root stimulation (C) Too much stimulation of the dorsal columns results in motor side effects (D) As the distance from the contact to the spinal cord increases, stimulation becomes more specific for the dorsal columns as opposed to the dorsal roots (E) Rostrocaudal contact size (contact length) is less important than lateral contact size (contact width) ```

Answer 48

679. (B) A. The dorsal columns contain the primary cutaneous afferents which are the usual targets. Stimulation of a nerve root will lead to segmental paresthesia and will not be likely to encompass the entire area of the bilateral lower extremity neuropathic pain. B. This is a correct statement and was supported by computer-modeled analysis. C. To the contrary, motor side effects usually indicates stimulation of dorsal roots rather than the dorsal column. D. This statement is incorrect because as the contact to spinal cord distance increases, stimulation becomes less specific and there is an increased chance of dorsal root stimulation. E. This is a false statement because fiber type preference is more sensitive to rostrocaudal contact size then to lateral contact size.

Question 49

680. The gate control theory is one postulated mechanism of action for SCS. Which of the following is the most accurate application of SCS to this postulated mechanism of action? (A) Activation of large-diameter afferents thereby “closing the gate” (B) Activation of large-diameter afferents thereby “opening the gate” (C) Activation of small-diameter afferents thereby “closing the gate” (D) Activation of small-diameter afferents thereby “opening the gate” (E) Activation of both large- and smalldiameter afferents equally

Answer 49

680. (A) Ronald Melzack and Patrick Wall published the landmark gate control theory in the journal Science in 1965. According to this theory as published in 1965, large and small fibers project to the substantia gelatinosa. The substantia gelatinosa exerts an inhibitory effect on afferent fibers. Large fibers increase the inhibitory effect, “close the gate,” and decrease the afferent pain signal. Small fibers decrease the inhibitory effect, “open the gate,” and increase the afferent pain signal. This gate control theory is commonly cited as the mechanism of action of SCS, but a 2002 review concludes that other mechanisms must also play a role. [Oakley JC, Prager JP. Spinal cord stimulation: mechanisms of action. Spine. 2002;27(22):2574-2583. Melzack R, Wall PD. Pain Mechanisms: a new theory. A gate control system modulates sensory input from the skin before it evokes pain perception and response.

Question 50

681. Which of the following is most accurate regarding indications for SCS? (A) Nociceptive pain is traditionally considered a better indication than neuropathic pain (B) Receptor mediated pain is traditionally considered a better indication than neurogenic pain (C) SCS tends to more effectively treat sympathetically mediated pain than pain of the somatic nervous system (D) Intractable angina is not effectively treated with SCS (E) Persisting neuropathic extremity pain following spinal surgery is a better indication than pain of CRPS

Answer 50

681. (C) A. The opposite of the given statement would be more accurate (ie neuropathic pain is traditionally considered a better indication than nociceptive pain). B. This is a restatement of (A). The term “receptor mediated” is substituted for and synonymous with nociceptive. The term “neurogenic” is substituted for and synonymous with neuropathic. C. Multiple authors have described beneficial results of SCS for sympathetic-mediated pain [Stanton-Hicks M. Complex regional pain syndrome: manifestations and the role of neurostimulation in its management. J Pain Symptom Manage. 2006;31(suppl 4): S20-S24. Kumar K, Nath RK, Toth C. Spinal cord stimulation is effective in the management of reflex sympathetic dystrophy. Neurosurgery. 1997;40(3):503-508. Harke H, Gretenkort P, Ladlef HU, et al. Spinal cord stimulation in sympathetically maintained complex regional pain syndrome type I with severe disability. A prospective clinical study. Eur J Pain. 2005;9(4):363-373.] D. This is a false statement as some consider intractable angina to be the pain most effectively treated with SCS, with up to 90% effectiveness. E. Both persisting neuropathic pain of the extremity following spinal surgery and pain of CRPS are indications for SCS. However, persisting neuropathic extremity pain following spinal surgery is not a better indication. In fact, SCS is considered by some to be a more effective treatment of CRPS than persisting neuropathic pain of the extremity following spinal surgery.

Question 51

682. Which of the following correctly arranges intraspinal elements from highest to lowest conductivity? (A) CSF, longitudinal white matter, gray matter, transverse white matter, dura (B) Longitudinal white matter, gray matter, CSF, transverse white matter, dura (C) Longitudinal white matter, transverse white matter, dura, gray matter, CSF (D) Gray matter, longitudinal white matter, transverse white matter, CSF, dura (E) Dura, transverse white matter, gray matter, longitudinal white matter, CSF

Answer 51

682. (A) The conductivity of intraspinal elements has clinical significance. While some tissues have sufficient conductivity to allow stimulation to reach afferent fibers and initiate a depolarization, other tissues provide an insulation-like effect to protect visceral organs. One would not have to know the actual conductivities of intraspinal elements to answer this question.

Question 52

683. Which of the following is the most accurate explanation why thoracic level cord stimulator leads do not commonly stimulate intrathoracic structures such as the heart? (A) Thoracic placement of SCS leads is contraindicated and is therefore not a clinically used technique (B) The CSF is highly conductive and therefore diverts the stimulation into a different direction (C) The stimulation is very specific for neural tissues rather than visceral tissues (D) The dura has a very low conductivity and therefore insulates visceral structures from stimulation (E) The vertebral bone has a very low conductivity and therefore insulates visceral structures from stimulation

Answer 52

683. (E) A. Thoracic placement of SCS leads is very common. Contacts are often placed at the T8 level for instance for treatment of lower extremity pain. B. While it is true that CSF is highly conductive, it does not divert the stimulation away from thoracic structures. C. While it is true that various fibers have differing thresholds for recruitment, a negatively charged electrode (a cathode) will cause a neuron to become more electrically charged and depolarized, regardless of the tissue of origin. D. It is true that dura has a very low conductivity similar to vertebral bone. However, because the dura is so thin, it does not present significant resistance. This should also be instinctively false because if the dura insulated structures from stimulation, then it would not be possible to stimulate the neural structures of the spinal cord. E. This is a true statement. The conductivity of vertebral bone is very low compared to other intraspinal tissues.

Question 53

684. Which of the following best describes the proposed mechanism of action of SCS? (A) There is evidence that during SCS large myelinated afferent fibers are activated in an antidromic manner (B) There is a measurable increase in endogenous opioids in response to SCS (C) Spinothalamic tract activation during SCS leads to an analgesic effect (D) SCS causes an inhibition of ascending and descending inhibitory pathways (E) SCS has no effect on abnormal A-β activity

Answer 53

684. (A) A. Antidromic responses can be measured at the sural nerve during SCS. This was described in a 2002 review of SCS mechanisms and also demonstrated in 21 measurements in 16 patients in another study in 2008. [Oakley JC, Prager JP. Spinal cord stimulation: mechanisms of action. Spine. 2002;27(22):2574-2583. Buonocore M, Bonezzi C, Barolet G. Neurophysiological evidence of antidromic activation of large myelinated fibers in lower limbs during spinal cord stimulation. Spine. 2008;33(4):E90-E93.] B. SCS efficacy is not reversed by naloxone and there is no relation of SCS to endogenous opioid levels. C. This would be a mechanism of algesic effect. In fact, one of the proposed mechanisms of action of SCS is spinothalamic tract inhibition. D. This would be a mechanism of algesic effect. In fact, one of the proposed mechanisms of action of SCS is activation of ascending and descending inhibitory pathways. On review of the mechanisms of action of SCS, one possible mechanism of action was cited as activation of supraspinal loops relayed by the brain stem or thalamocortical systems resulting in ascending and descending inhibition. [Oakley JC, Prager JP. Spinal cord stimulation: mechanisms of action. Spine. 2002;27(22):2574-2583.] E. According to a 2002 review, the predominant effect of SCS is on abnormal activity in A-β neurons related to the perception of pain. [Oakley JC, Prager JP. Spinal cord stimulation: mechanisms of action. Spine. 2002;27(22):2574-2583.]

Question 54

685. Which of the following is true? (A) Phenol theoretically carries a higher risk for neuroma formation than alcohol (B) Radiofrequency ablation is particularly useful for field neurolysis (C) Phenol is a particularly useful neurolytic agent for localized targets (D) Alcohol is a particularly useful neurolytic agent because there is no pain upon injection (E) Phenol causes wallerian degeneration

Answer 54

685. (A) Because phenol destroys the basal neurolemma, wallerian degeneration does not occur and there is a higher risk for neuroma formation. Lesion size is more difficult to precisely control with a liquid neurolytic injectate as compared to radiofrequency ablation in which the lesion size occurs in a known distance around the needle tip. On the other hand, when a field lesion is needed, a liquid neurolytic may be a more practical approach.

Question 55

``` 686. Which of the following is most painless upon delivery? (A) Phenol (B) Alcohol (C) Radiofrequency (D) Cryoanalgesia (E) Cold knife excision of a nerve ```

Answer 55

686. (A) Phenol is not painful upon injection | whereas the other listed techniques are painful.

Question 56

``` 687. Which of the following neurolytic techniques is most concerning for the side effect of arrhythmia? (A) Laser neurolysis (B) Cryoanalgesia (C) Radiofrequency (D) Alcohol (E) Phenol ```

Answer 56

687. (E) Phenol is concerning for arrhythmias, seizure, destruction of Dacron grafts, vasospasm, and vascular proteins. Alcohol is more concerning for vasospasm than phenol. Caution when considering radiofrequency neurolysis includes interference with electrical implants. Risks of cryoneurolysis include frostbite to adjacent tissues.

Question 57

688. Which of the following statements is the most accurate comparison of radiofrequency ablation and cryoablation? (A) Cryoanalgesia probes are generally smaller in diameter than the large-diameter probes used for radiofrequency procedures (B) One disadvantage of cryoanalgesia technique is the operator must support a heavier instrument while maintaining the probe tip in accurate position (C) The cryolesion and the radiofrequency lesion are similar in size (D) Cryoanalgesia and radiofrequency lesion techniques have equal precision capability (E) Cryoanalgesia is inferior to radiofrequency ablation because cryoanalgesia causes wallerian degeneration

Answer 57

688. (B) A. Cryoanalgesia probes are generally larger in diameter than radiofrequency probes. Current cryoanalgesia probes range in size from 1.4 to 2 mm. The 1.4-mm cryoprobe is used with a 14- or 16-gauge catheter. A 2-mm cryoprobe is inserted into a 12- gauge catheter. Radiofrequency procedures are commonly performed using a 22-gauge needle. A22-gauge needle has an outside diameter of about 0.7 or 0.72 mm. B. The cryoanalgesia instrument may be cumbersome to support while simultaneously maintaining accurate needle-tip position. The smaller and lighter probes used with radiofrequency lesioning machines are less cumbersome to manage. C. The ice ball formed at the tip of the cryoprobe is larger in size than what can be obtained with radiofrequency lesions. D. Because of the smaller obtainable lesion size with the radiofrequency techniques, a more precise target lesion can be achieved. E. Both cryoanalgesia and radiofrequency techniques cause wallerian degeneration and therefore less risk for neuroma formation compared to phenol.

Question 58

689. Which of the following is most accurate regarding the electric field generated at the tip of a radiofrequency electrode? (A) Flat conductors generate larger, stronger electric fields than round conductors (B) With round conductors, the charge density is directly proportional to the radius of the circle (C) The electric field around a radiofrequency cannula is more dense around the exposed shaft and becomes less dense at the tip (D) Voltage, current, and power are the three basic variables governing formation of heat surrounding a radiofrequency cannula tip (E) The heat lesion formed around the radiofrequency cannula is slightly pearshaped with the base of the pear around the proximal end of the active tip and less projection of the heat at the needle tip

Answer 58

689. (E) A. Round conductors generate larger, stronger electric fields than flat conductors. B. With round conductors, the charge density is inversely proportional to the radius of the circle. C. The electric field around the exposed shaft of a radiofrequency cannula is less dense and becomes more dense at the tip. D. The three basic variables of electric current are voltage, current, and resistance. These are the three factors in Ohm’s law. E. Although the electric field is less dense around the shaft but more dense around the tip of the cannula, the shape of the heat lesion is different. The heat lesion is slightly larger around the proximal end of the active tip and smaller at the needle tip.

Question 59

690. Which of the following is the most accurate statement regarding neuraxial neurolysis? (A) Phenol has significant proven benefit over alcohol (B) The technique is 100% efficacious (C) The average pain relief is less than 6 months (D) Bladder paresis and motor weakness occurs in close to 100% of those treated with neuraxial neurolysis (E) Epidural neurolysis has a proven favorable risk to benefit ratio compared to subarachnoid neurolysis

Answer 59

690. (C) A. While phenol may be useful for its hyperbaric property, there is no clear benefit versus alcohol. B. Excellent results are reported in 50% to 75% of patients. C. The average duration of pain relief after neuraxial neurolysis has been reported at 4 months. D. Bladder paresis and motor paresis occurs in approximately 5% of treated patients. Bowel paresis occurs in approximately 1% of treated patients. E. There is no evidence for greater efficacy or lower risk for epidural neurolysis compared to subarachnoid neurolysis.

Question 60

691. While performing an intradiscal radiofrequency procedure using a posterior-oblique approach, the needle tip is advanced into the annulus fibrosus using fluoroscopic guidance. Impedance is noted. The needle tip is then advanced a little further. Adrop in impedance is noted. Which of the following is the most likely explanation? (A) Malfunction of radiofrequency machine (B) Needle-tip entry into CSF (C) Needle-tip entry into spinal cord (D) Needle-tip has dry blood on it (E) Needle-tip entry into nucleus pulposus

Answer 60

691. (E) From the described approach, further advancement of the needle tip should either remain in annulus fibrosis or enter the next tissue layer, nucleus pulposus. CSF and spinal cord are not expected in the described trajectory.

Question 61

692. Which of the following is appropriate safety consideration when performing a radiofrequency ablation procedure? (A) Motor stimulation is not needed if meticulous fluoroscopic technique is used (B) A radiofrequency probe should be the length of the cannula or shorter, but never longer than the cannula (C) The pain physician should always turn off a patient’s sensing pacemaker prior to a radiofrequency procedure (D) Complications during radiofrequency ablation are rare and need not be considered prior to the procedure (E) A SCS should be turned off prior to a radiofrequency procedure

Answer 61

692. (E) A. Motor stimulation can detect and prevent unexpected improper heat lesioning. For example, a break in the insulation of the needle shaft can allow current to leak into unexpected tissues. B. The radiofrequency probe should extend to the tip of the cannula. Too short of a radiofrequency probe will result in temperature measurements that are lower than the actual tissue temperature. This is especially concerning as a radiofrequency unit with automatic temperature control would increase the output in this situation, leading to even higher tissue temperatures. C. It is usually best to consult a cardiologist prior to radiofrequency procedures when the patient has a pacemaker. If the pacemaker is a sensing pacemaker, then changing the setting to a fixed rate is suggested. D. It is best to prevent complications rather than treat complications. E. The SCS should be turned off prior to radiofrequency procedures.

Question 62

``` 693. Coulomb per kilogram (C/kg) is (A) the unit used to measure electrical charge produced by x- or γ-radiation similar to previous roentgen unit (B) used to measure dose equivalent (C) the daily radiation exposure per kilogram of body weight (D) the intensity of radiation (E) used to measure the amount of radiation absorbed ```

Answer 62

693. (A) Coulomb per kilogram is used to measure electrical charge produced by x- or γ-radiation similar to previous roentgen unit in a standard volume of air by ionization. Sievert (Sv) is used to measure dose equivalent

Question 63

``` 694. Gray (Gy) is used to measure (A) yearly background exposure (B) absorbed dose (C) dose equivalent (D) daily radiation exposure (E) yearly radiation exposure ```

Answer 63

694. (B) Gray (Gy) measures absorbed dose (energy deposited per unit mass). One gray is equal to 1 J/kg.

Question 64

``` 695. Maximum total permissible dose equivalents (in mSv) for a year is (A) 75 mSv (B) 100 mSv (C) 150 mSv (D) 50 mSv (E) 25 mSv ```

Answer 64

695. (D) Individual doses may vary (eg, eye 12.5 mSv).

Question 65

``` 696. How low should a clinician’s hourly radiation exposure be? (A) Less than 0.01 mSv/h (B) Less than 0.05 mSv/h (C) Less than 0.15 mSv/h (D) As low as reasonably achievable (E) Less than 0.25 mSv/h ```

Answer 65

696. (D) As low as reasonably achievable is also known as ALARA (As low as reasonably achievable).

Question 66

``` 697. Most operator exposure during fluoroscopically guided blocks is when (A) the lateral views are taken (B) the x-ray tube is above the patient (C) the patient is obese (D) the anteroposterior views are taken (E) none of the above ```

Answer 66

697. (B) The x-ray tube above the patient provides most operator exposure because the scattered beam is greater at the entrance site of the skin compared to exit site.

Question 67

698. The intensity of scattered beam is greater at the radiation entrance on the skin than exit site (A) 3 times (B) 10 times (C) 30 times (D) 985 times (E) 1000 times

Answer 67

698. (D) As the intensity of scattered beam is greater at the radiation entrance on the skin than exit site the radiation exposure to the operator is significantly increased when the x-ray tube is above the patient.

Question 68

699. Average patient radiation exposure dose during pain procedures is (A) 10 times less than during angiography (B) same as during angiography (C) 10 times more than during angiography (D) less than computed tomographic (CT) scanning (E) 20 times more than during angiography

Answer 68

699. (C) The patient radiation doses of angiography are on the other hand 10 times higher than gastrointestinal fluoroscopy and CT imaging.

Question 69

``` 700. Radiation dose to the patients and medical personnel can be reduced by (A) decreasing the distance between the image intensifier and the patient (B) increasing the distance between the image intensifier and the patient (C) using continuous fluoroscopy (D) oblique views (E) none of the above ```

Answer 69

700. (A) Oblique views can also increase the radiation | to the patients and operators.

Question 70

``` 701. Personnel radiation protection can be achieved by (A) lead aprons (B) glasses (C) increased distance from the x-ray (D) all of the above (E) none of the above ```

Answer 70

701. (D) Lead aprons contain equivalent of 0.5 mm of lead and can reduce the radiation exposure by 90% from scatter.

Question 71

``` 702. Lead aprons should be always hung: (A) So that space is saved (B) As the lead can be broken if folded (C) They can be safely folded as well (D) So they can be conveniently available (E) None of the above ```

Answer 71

702. (B) Broken lead in aprons can provide suboptimal | radiation protection.

Question 72

703. A patient with severe spasticity is a candidate for an intrathecal baclofen pump. He and his family have heard that “these pumps get infected.” How do you respond? (1) Device-related infection is the most common, potentially reducible, serious adverse event associated with intrathecal pumps (2) The majority of infections occur at the lumbar site (3) Management of infections associated with drug-delivery systems usually involves the administration of antibiotics and explantation of the device (4) The chances of the pump getting infected are minimal and the family should only focus on the benefits that the device provides

Answer 72

703. (B) The diagnosis of an implantable devicerelated surgical-site infection is definitively made by identification or culture of microorganisms (most commonly bacteria) or both on specimens from a clinically suspected surgical wound or implant site. Signs of wound infection include fever, erythema, edema, pain, wound exudates, poor healing, or skin erosion at the implant site. Meningismus indicates CSF involvement. 1. Infections related to the implantation of a SCS or an intrathecal drug-delivery system is the most common, potentially reducible, serious adverse events associated with these devices. 2. In the comparison of drug-delivery devicerelated infections in multicenter studies the pump pocket was the site of infection between 57.1% and 80% of the time, the lumbar site was the infection location between 13% and 33% of the time, and meningitis was the infection between 10% and 14.3% of the time. 3. Management of infections associated with drug-delivery and SCS systems typically involves administration of antibiotics and explantation of the devices. 4. You should always worry about potential complications. The infection rates, based on the number of infections that occurred and the number of patients that were evaluated have varied from 2.5% to 9.0% of implanted patients. The highest infection rate (9%), occurred in the 10-mL SynchroMed pump that was used in pediatric patients with spasticity of cerebral origin (n = 100), predominantly spastic cerebral palsy. The lowest infection rate, (2.5%), occurred in the group that received intrathecal recombinant methionyl human brain-derived neurotrophic factor (BDNF) to treat amyotrophic lateral sclerosis. 36 infections in 35 patients were described in a total of 700 patients (5% overall infection rate).

Question 73

704. When trialing intrathecal medication and placing intrathecal pumps, which of the following is considered good technique? (1) Antibiotics are given during the course of the trial, and for 7 to 10 days after permanent implant (2) If the entry point is above L2, the patient should be conversant, and the angle of entry should be as shallow as possible (3) Placing the patient in the lateral decubitus position with the hips flexed, and the knees bent (4) Electrocautery is now considered the gold standard for controlling bleeding

Answer 73

704. (A) 1. The most common antibiotics used are a third-generation cephalosporin or vancomycin. Intraoperatively, many physicians irrigate the wound with antibiotic solution. Adjustments to antibiotic regimens should be made based on the most common pathogens seen in the community and medical center. 2. In most instances the needle entry point into the intrathecal space is below L2. Sometimes, although rare, the entry point is at the level of the cord. If the entry point is above L2, the patient should be communicating with the physicians and nurses, and the angle of entry should be as small as possible. If any paresthesia is experienced, the needle should be removed and repositioned. Once the catheter is properly positioned, a purse-string suture should be fashioned to secure the tissue around the catheter. Then, an anchor should be used to fasten the catheter to fascia. Given recent studies on inflammatory masses at catheter tips, whether the distal end of the catheter should be placed near the supposed pain generator or not is still up for debate. 3. While the patient may be positioned prone for catheter placement, placing them in the lateral decubitus position precludes having to reposition them for pocket creation. The usual site for pump placement is the lateral anterior abdominal wall at the level of the umbilicus. The pump should be anchored in a manner to prevent flipping. 4. The physician should meticulously obtain proper hemostasis during the case. Small venous and arterial bleeders can be recognized by retracting the wound after antibiotic irrigation. Numerous techniques exist to obtain hemostasis: • Simple pressure • Sponges soaked in 3% hydrogen peroxide solution may be packed into the wound for 3 to 5 minutes (may be very helpful with small vessels) • Electrocautery for more pronounced bleeding [Note: overheating tissue can cause trauma or seroma formation, which can lead to delayed healing, dehiscence, or infection of the wound] • Suturing a vessel is still the gold standard A large sterile pressure dressing should be applied over the wound plus/minus an abdominal binder to reduce the risk of seroma formation and bleeding. Antibiotic ointment is also frequently used immediately over the incision; it may help in preventing the spread of infection. When considering dressing changes, the physician should be judicious—they can take place daily or only if the dressing is excessively saturated.

Question 74

705. Which of the following is (are) disease state(s) that are amenable to treatment by intrathecal drug-delivery system? (1) Intractable spasticity related to cerebral palsy and spinal cord injuries (2) Interstitial cystitis (3) Cancer-related syndromes (4) Rheumatoid arthritis

Answer 74

705. (E) In the early 1980s intrathecal drug-delivery was initiated for the treatment of intractable spasticity related to cerebral palsy and spinal cord injuries. This therapy eventually evolved to use in implacable cancer pain. Intrathecal preservative-free baclofen and morphine are FDAapproved for the treatment of moderate to severe spasticity and moderate to severe pain, respectively. A study in oncology patients showed a major improvement using intrathecal medication delivery in cancer pain versus thorough medical management in the areas of tiredness, level of consciousness, and survival. [Smith TJ, Staats PS, Deer T et al. Randomized clinical trial of an implantable drug delivery system compared with comprehensive medical management for refractory cancer pain: impact on pain, drug-related toxicity, and survival. J Cli. 2002;20(19):4040-4049.] Other disease states found to be responsive to intrathecal drug-delivery systems are • Spinal stenosis • Radiculitis • Compression fractures • Spondylosis • Spondylolisthesis • Foraminal stenosis • Arachnoiditis • Syrinx • Ankylosing spondylitis • Spinal cord trauma • Spinal infarction • Paraplegia • Cauda equina syndrome • Peripheral neuropathy • Phantom limb pain • Rheumatoid arthritis • Radiation neuritis • Postherpetic neuralgia • Postthoracotomy syndrome • Interstitial cystitis • Chronic pain of the abdomen and pelvis

Question 75

706. A 56-year-old female who had an intrathecal pump placed secondary to metastatic renal cell carcinoma is having pain equivalent to a 6 on the visual analog scale (VAS). What is the proper titration regimen? (1) Increase dose 10% to 25% over 3 to 4 days (2) Increase dose 25% to 50% daily (3) Hourly rates should be adjusted 35% to 50% twice daily until pain relief is achieved (4) A therapeutic bolus should be considered

Answer 75

706. (C) Patients with a VAS pain scale of 7 to 10 may necessitate inpatient/hospice care for pain treatment. For those who wish to remain in a home environment, a 50% to 100% increase in their medication dose may be in order. Therapeutic boluses should be administered to an end point of pain relief, as well as daily medication adjustments to the same end point. Significant, abrupt increase in medication may cause severe side effects, and physicians should be available in the first 12 hours following the modification, to manage potential complications.

Question 76

707. A 52-year-old female with pancreatic cancer and her family are trying to decide between continued medical management for pain versus an intrathecal drug-delivery system. Believing that this patient would most benefit from an intrathecal pump, you tell them that studies have shown that (1) overall toxicity is better with intrathecal pumps (2) pain relief is better with intrathecal pumps (3) intrathecal pumps improve fatigue and level of consciousness in patients versus medical management (4) there is a trend to increased survival in patients who have intrathecal pumps versus those continuing with medical management

Answer 76

707. (E) A multicenter, randomized, prospective study compared intrathecal drug delivery to comprehensive medical management. The results showed a statistically significant advantage of intrathecal pumps on • Overall toxicity • Pain relief • Fatigue and level of consciousness • Improved survivability The study hinted that more patients with moderate to severe cancer pain should be considered for intrathecal pumps. [Smith TJ, Staats PS, Deer T et al. Randomized clinical trial of an implantable drug delivery system compared with comprehensive medical management for refractory cancer pain: impact on pain, drug-related toxicity, and survival. J Clin. 2002;20(19):4040-4049.]

Question 77

708. Third occipital nerve (1) innervates C2-3 facet joint (2) curves around superior articular process of the C2 vertebrae (3) curves around superior articular process of the C3 vertebrae (4) innervates C3-4 facet joint

Answer 77

708. (B) The third occipital headache is caused by third occipital neuralgia. The TON innervates the C2-3 zygapophysial joint and curves around the superior articular process of the C3 vertebral body. Among patients with whiplash injuries, third occipital headache is common, with a prevalence of 27%.

Question 78

709. For the peripheral stimulation of the occipital nerve (1) the electrode should be parallel to the occipital nerve in the occipital area of the scull (2) only a “paddle-” type electrode should be used (3) the entry site of the introducer needle should be at T1-T2 level (4) the electrode should be placed subcutaneously at the C1-C2 level

Answer 78

709. (D) The occipital nerve stimulator is a useful tool in managing occipital neuralgia. Although paddle electrodes are not necessary they may provide better coverage than the regular electrode.

Question 79

710. T2 and T3 sympathetic block (1) is used for treatment of upper extremity complex regional pain syndrome (CRPS) (2) will help by denervating the Kuntz nerves (3) can lead to pneumothorax (4) should avoid radiofrequency of T2 and T3 sympathetic ganglia

Answer 79

710. (A) T2 and T3 sympathetic blocks are a useful tool in conjunction with stellate ganglion block for upper extremity CRPS. By blocking them, Kuntz nerves will be blocked that bypass the stellate ganglion. RF denervation of these nerves may lead to prolonged pain relief.

Question 80

711. Vertebroplasty may be indicated for (1) multiple myeloma (2) chronic compression fractures of vertebral body (3) osteolytic metastatic tumors (4) facet arthropathy

Answer 80

711. (A) Vertebroplasty is best used for acute vertebral fracture where bone cement is percutaneously injected into a fractured vertebra in order to stabilize it. Alternatively, kyphoplasty involves placement of a balloon into a collapsed vertebra, followed by injection of bone cement to stabilize the fracture. It is not clear if one procedure has an advantage over the other. Both procedures may obtain almost immediate pain relief. And they are indicated for painful compression fractures because of osteoporosis and metastatic tumors.

Question 81

712. Complications from vertebroplasty include (1) pulmonary embolus (2) intradiscal leak of polymethyl methacrylate (3) paraplegia (4) psoas muscle leak of polymethyl methacrylate and femoral neuropathy

Answer 81

712. (E) Complications from vertebroplasty can be serious. Intravascular injection of polymethyl methacrylate can lead to pulmonary embolus and spinal cord damage and leak into intrathecal space can cause spinal cord injury. Lumbar procedures may lead to leak into psoas muscle and femoral neuropathy.

Question 82

``` 713. Which of the following is (are) correct with regards to piriformis muscle injection? (1) Should be done at medial part of a muscle (2) Botox can be used (3) Nerve stimulation may aid in muscle location (4) Identification of the muscle can be done through rectal examination ```

Answer 82

713. (E) Piriformis injection should be done in the medial part of a muscle since the lateral part contains more ligaments. If injection of local anesthetics and steroids provides short-term pain relief only, the injection of botulinum toxin type Amay provide longer pain relief. The use of nerve stimulator, fluoroscopy, and contrast administration may help to assure proper needle placement. Tenderness over the piriformis muscle, positive Pace and Freiberg signs and rectal examination can be helpful in examining the piriformis muscle

Question 83

714. SI joint pain (1) is transmitted by the S1-S4 levels of spinal nerves (2) has been treated by the SI joint fusion (3) can be relieved by blind steroid injections (4) is transmitted by L4 medial branch, L5 dorsal ramus, and S1-3 lateral branches

Answer 83

714. (D) 1. The innervation of the SI joint is from L4 medial branch, L5 dorsal ramus, S1, S2, and S3 lateral branches. Some authors also state that the L3 medial branch may be involved. 2. SI joint fusion is used only in cases where serious anatomical problems (eg, fracture) are present in addition to pain. 3. SI joint injection should be done under fluoroscopic guidance to assure accuracy of needle placement.

Question 84

715. Celiac plexus block can be performed by (1) anterior approach (2) retrocrural approach (3) anterocrural approach (4) lateral approach

Answer 84

715. (B) 1. Anterior approach was initial approach described for blocking celiac plexus. Its advantage is that patient can be in more comfortable, supine position. 2. Although the retrocrural block may partially block the nerve supply to the celiac plexus actually blocks the splanchnic plexus. 3. Anterocrural approach is done with patient in prone position using one or two needles. Transaortic and transdiscal variation of this approach has been published as well. 4. Lateral approach is not used for celiac plexus block.

Question 85

716. Ganglion impar block (1) is indicated for testicular pain (2) is indicated for sympathetically maintained pain in perineal area (3) is best performed by anococcygeal approach (4) can be complicated by perforation of rectum

Answer 85

716. (C) 1. Testicular pain is treated by ilioinguinal block or lumbar sympathetic block. 2. Ganglion impar is the most caudal sympathetic ganglion. 3. The ganglion impar is located at the level of the sacrococcygeal junction that marks the termination of the paired paravertebral sympathetic chains. Initial approach described was through anococcygeal ligament. However, the trans-sacrococcygeal approach seems much safer way to perform this procedure. 4. Perforation of rectum may occur in particular if anococcygeal approach is used.

Question 86

717. With cervical interlaminar epidural steroid injection (1) loss of resistance technique can be inaccurate in up to 50% cases (2) unilateral medication spread can be achieved in 50% cases (3) contrast spread should be checked in lateral views (4) transforaminal approach is safer than interlaminar

Answer 86

717. (A) 1. As a result of discontinuous ligamentum flavum the loss of resistance is often inaccurate in cervical levels and more often in comparison to lumbar levels (30%). 2. The fluoroscopic guidance should be used and medication should be deposited ipsilateral to the pathology. 3. Final needle advancement and contrast spread should be first checked in lateral fluoroscopic views. 4. Transforaminal approach (most likely because of intravascular particulate steroid uptake) can lead to serious complications such as spinal cord infarction, quadriplegia, and death.

Question 87

718. Which of the following includes complication( s) of intrathecal pump? (1) Granuloma formation (2) CSF leak (3) Pump rotation (4) Hormonal imbalance

Answer 87

718. (E) 1. Granuloma formation can occur at the tip of the intrathecal catheter and can lead to serious complications including spinal cord injury. 2. CSF leak is a relatively common complication of intrathecal pump placement. 3. Pump rotation can cause kinking of the catheter and symptoms of increased pain and withdrawal. 4. Intrathecal opioids can lead to serious hormonal changes including weight gain.

Question 88

``` 719. In relation to increased pain in patient with intrathecal opioid delivery which of the following is (are) true? (1) It can mean progression of disease (2) Catheter kink should be considered (3) One should look for withdrawal symptoms (4) Opioids should be increased first ```

Answer 88

719. (A) Increased pain, in particular with withdrawal symptoms should be considered as a pump failure and treated promptly.

Question 89

720. Which of the following is (are) drug(s) used in decompressive neuroplasty? (1) Hyaluronidase (2) Hypertonic saline (3) Steroids (4) Local anesthetics

Answer 89

720. (E) Combination of hyaluronidase and hypertonic saline seems to increase the duration of procedure effect. Intrathecal injection of hypertonic saline can lead to serious complications and should be performed carefully.

Question 90

721. SCS been used for the treatment of (1) interstitial cystitis (2) postlaminectomy syndrome (3) CRPS (4) sympathetically mediated pain

Answer 90

721. (E) Traditional indications for SCS include postlaminectomy syndrome and CRPS. Indications have been expanding. Intestinal cystitis is now a commonly accepted indication. SCS is an accepted method for effective treatment of sympathetically mediated pain.

Question 91

722. Spinal cord stimulation (1) should be used early in the course of the postherpetic neuralgia pain syndrome (2) has been found efficacious for the failed back surgery syndrome (3) has been used for peripheral vascular disease and ischemic disease (4) has a proven and elucidated mechanism of action

Answer 91

722. (A) According to a review in 2008, SCS should be considered early in the course of postherpetic neuralgia and peripheral nerve stimulation should be considered if SCS fails. SCS is about 50% effective for failed back surgery syndrome and more so effective for peripheral vascular disease and ischemic disease. Although the gate control theory is a commonly cited mechanism of action for SCS, literature reflects that this one mechanism alone is not sufficient to explain the mechanism of action. According to a 2002 review article, there are 10 proposed mechanisms of action found in literature. [Oakley JC, Prager JP. Spinal cord stimulation: mechanisms of action. Spine. 2002; 27(22): 2574-2583.]

Question 92

723. The transverse tripolar SCS arrangement (1) involves a central anode surrounded by cathodes (2) contributes maximum dorsal column stimulation with minimal dorsal root stimulation (3) is most frequently used to improve stimulation of the feet (4) usually involves an octapolar spinal midline lead and two adjacent quadripolar leads

Answer 92

723. (C) Transverse tripolar SCS on involves a central cathode surrounded by anodes. This is proposed to drive current deeper and thus stimulate fibers innervating the back. Therefore is it used to cover back pain, not foot pain. Statement (4) is also correct as most current SCS systems allow up to a total of 16 leads.

Question 93

724. Which of the following is (are) true for SCS for the indication of angina pectoris? (1) Improves exercise capacity (2) Probably only helps for a year and then the stimulator should be removed (3) In addition to providing antianginal effects it also provides a reduction in ischemia (4) Is contraindicated because it masks significant ischemic events

Answer 93

724. (B) In a 2006 review article SCS was concluded to increase exercise capacity as well as decrease use of short-acting nitrates and improve quality of life. The review also found that at 5 years 60% of patients still had beneficial effects. Exercise stress testing and electrocardiogram (ECG) monitoring evidence showed reduced ischemia in addition to the antianginal effects. Pain perception remains intact and patients were still able to detect significant ischemic events. .]

Question 94

``` 725. Which of the following is (are) the risk(s) associated with SCS? (1) Epidural hematoma (2) Spinal cord injury (3) Implanted pulse generator failure (4) Electromechanical failure of lead or extension cable ```

Answer 94

725. (E) All listed factors are risks of SCS. Other risks include nerve injury, dural puncture, infection, and electrode migration.

Question 95

726. Which of the following is (are) true regarding SCS for visceral pain? (1) SCS suppresses visceral response to colon distention in animal models (2) SCS is a first-line treatment for visceral pain (3) Case studies have indicated SCS may be helpful for visceral pain but at this time there is a lack of supporting randomized controlled trials (4) A good lead placement for stimulation of chronic pancreatitis would logically be around T12 or L1

Answer 95

726. (B) In animal models, SCS has been shown to suppress visceral responses. There have been multiple case reports of SCS being used successfully for visceral pain; however, current practice parameters do not address treatment of such pain. Since the pancreas is innervated by spinal segments around T5-T11, a lead placement would be much too low of a logical starting place. One case study reported placing the lead at T6 resulting in appropriate stimulation for treatment of chronic pancreatitis.

Question 96

727. Which of the following is (are) the best answer(s) regarding lead spacing and electrical fields created by a dual-lead stimulation system as pictured? (1) With larger distances between anodes and cathodes, the electric field tends to form a sphere (2) With tighter lead spacing and smaller distances between anodes and cathodes, the electric field is pulled towards the anode (3) Tight lead spacing increases the ratio of dorsal column to dorsal root stimulation (4) The anode is the positive contact and the cathode is the negative contact

Answer 96

727. (E) Anode is the correct designation for a positive contact and cathode is the correct designation for a negative contact. With a dual-lead system as pictured, the electric field would be pulled toward the anode if lead spacing were tight. With larger lead spacing, the electric field would tend to be more spherical and positioned around the cathode. Tight lead spacing increases the dorsal column to dorsal root stimulation ratio because the less spherical electric field would stimulate less laterally and therefore would have less stimulation in the areas of the nerve roots.

Question 97

``` 728. Which of the following should be considered when selecting patients for SCS? (1) Disease pathology (2) Untreated drug addiction (3) Patient comorbidities (4) Physician’s monthly case quota ```

Answer 97

728. (A) According to a review article on selection criteria for SCS, selection criteria may relate to the patient’s disease state or to other important patient characteristics. Current randomized controlled trials or prospective trials support efficacy of SCS for certain disease states such as failed back surgery syndrome, CRPS, axial back pain, postherpetic neuralgia, neuropathy, and pelvic pain. Current case report evidence exists for SCS in the treatment of ischemic limb pain, and visceral pain. Anginal pain has also been investigated. Patient characteristics of concern include systemic disease such as diabetes, immunocompromised, degree of stenosis especially for cervical placed leads, anticoagulation, psychologic comorbidities, unrealistic outcome expectations, and, untreated drug addictions. [Oakley JC. Spinal cord stimulation: patient selection, technique, and outcomes.

Question 98

729. Which of the following is (are) considered indication( s) for SCS? (1) Phantom limb pain (2) Spinal cord injury pain (3) Intractable abdominal or visceral pain (4) Neurogenic thoracic outlet syndrome

Answer 98

729. (E) The indications for SCS are expanding. All of the listed etiologies are now considered indications for SCS.

Question 99

730. Which of the following is (are) true regarding the history of electrical stimulation for the treatment of pain? (1) Electrical stimulation for the treatment of pain dates back to the first century ad when electrical fish were documented to be used in the treatment of gout (2) Implantable SCS were used for treatment of pain for a decade prior to the published gate control theory of pain (3) Early stimulation case reports were of peripheral nerve stimulation; later emphasis turned toward SCS (4) Psychiatric and/or psychologic screening evaluation prior to implants was a new idea imposed upon physicians by health maintenance organizations in the 1990s

Answer 99

730. (B) 1. Scribonius Largus documented application of the live black torpedo fish under the foot for treatment of the pain of gout. “For any type of gout a live black torpedo should, when the pain begins, be placed under the feet. The patient must stand on a moist shore washed by the sea and he should stay like this until his whole foot and leg up to the knee is numb. This takes away present pain and prevents pain from coming on if it has not already arisen. In this way Anteros, a freedman of Tiberius, was cured.” 2. The gate control theory of pain was published in 1965. This laid the theoretical foundation for electrical stimulation for pain. The first modern case report of electrical stimulators for treatment of pain was 2 years later. It described eight cases in which sensory nerves or roots were stimulated resulting in relief of pain. [Melzack R, Wall PD. Mechanisms: a new theory. A gate control system modulates sensory input from the skin before it evokes pain perception and response. Science. 1965;150(3699). Wall PD, Sweet WH. Temporary abolition of pain in man. Science. 1967;155(758):108-109.] 3. In the peripheral nerves, motor and sensory fibers are within closer vicinity. The window of amplitude available to provide analgesia without excessive motor stimulation is therefore much less than in the spinal cord where sensory and motor fibers run in more discrete and separate pathways. This played a role in switching emphasis from peripheral nerve stimulation toward SCS. 4. The first documented cases of modern day stimulation for pain was a case series of eight patients published in 1967. This case series reported three of the eight patients received psychiatric evaluation prior to the procedures. The psychiatric/psychologic evaluation gives the patient an opportunity to belay anxiety, ask questions, address body image issues, and communicate expectations

Question 100

731. Which of the following is (are) accurate statement( s) regarding neuromodulation of the sacral nerves? (1) Sacral neuromodulation is not effective for idiopathic urinary frequency (2) Both percutaneous and surgical lead placement techniques have been described (3) Must be performed by a surgeon because only a surgical technique is available (4) Urgency and urge incontinence are indications

Answer 100

731. (C) Sacral neuromodulation has been reported as effective for idiopathic urinary frequency, urgency, and urge incontinence. Both percutaneous and surgical sacral neuromodulation procedures have been described. Percutaneous techniques include (1) placement of a lead directly into the sacral nerve root foramen and (2) a percutaneous retrograde approach. Surgical techniques include (1) performing a sacral laminectomy and attaching the electrodes directly to the sacral nerve roots and (2) dissection to sacral periosteum where a plastic anchor is used to affix a transforaminal lead. Techniques that are limited to one lead placement may have limitations in terms of efficacy for certain indications. While a single lead has been generally efficacious for voiding dysfunctions, chronic neuropathic pain syndromes may benefit from a more extensive field of neuromodulation with additional electrodes

Question 101

732. Which of the following is (are) true regarding radiofrequency procedures? (1) Pulsed radiofrequency lesioning temperature goal is generally around 42°C to 43°C (2) Prior to application of the radiofrequency lesion, sensory testing should be applied at 2 Hz (3) The standard pulsed radiofrequency lesion is 500,000 Hz for 20 milliseconds pulses once every 0.5 second for 90 to 240 seconds (4) Prior to application of the radiofrequency lesion, motor testing should be applied at 50 Hz

Answer 101

732. (B) 1. Temperatures above 45°C cause irreversible neural tissue damage. If temperatures of 45°C are reached, then the voltage should be decreased to compensate. 2. Sensory testing is applied at 50 Hz. 3. The pulsed technique allows tissues to cool somewhat between cycles. A voltage of 45 V generally corresponds to a 43°C tip temperature. If the tip temperature exceeds 43°C, then the voltage should be reduced. 4. Motor testing is applied at 2 Hz.

Question 102

733. Which of the following element(s) is (are) necessary to complete a radiofrequency circuit? (1) The radiofrequency generator (2) Insulated needle cannula with radiofrequency probe (3) Dispersive electrode (grounding pad) (4) The patient

Answer 102

733. (E) All the options mentioned in the question are required elements to complete the circuit. The current goes from the probe tip, through the patient and to the grounding pad which carries the current back to the radiofrequency generator.

Question 103

``` 734. Which of the following is (are) the possible mechanism(s) of action of radiofrequency ablation? (1) Vascular injury causing endoneural edema (2) Formation of a static electric field (3) Lipid extraction with protein precipitation (4) Generation of heat ```

Answer 103

734. (C) Formation of a static electric field and generation of heat are two phenonemon that have been postulated as possible mechanisms of action of radiofrequency ablation. The mechanism of action of cryoablation involves vascular injury which causes severe endoneural edema. The mechanism of action of alcohol ablative techniques is lipid extraction with protein precipitation.

Question 104

735. Which of the following is (are) the most accurate answer(s) regarding radiofrequency treatment of the SI joint? (1) Evidence is strong for efficacy of radiofrequency ablation techniques for SI joint pain (2) The universally accepted screening protocol prior to SI joint injection involves SI tenderness, positive SI provocative maneuvers, and two positive local anesthetic– only SI joint injection procedures (3) There is no evidence for the role of pulsed radiofrequency treatment of SI joint pain (4) Radiofrequency treatment of sacral lateral branches have been proposed for efficacious treatment of SI joint pain

Answer 104

735. (D) 1. Although there are several studies looking at radiofrequency neuroablation for the SI joint, according to a recent systematic review evidence is still limited for its therapeutic value. 2. Although there are guidelines such as those posed by International Association for the Study of Pain (IASP), evidence and universal acceptance are still lacking. Some studies have refuted SI provocative maneuvers as predictive at all while others found that three of five positive provocative maneuvers provide predictive value. The role of adding steroids to diagnostic SI injections is similarly debated. 3. Pulsed radiofrequency treatment was given to 22 patients with injection evidence of SI pain. Sixteen patients (73.9%) had 50% or better relief for more than 3 months. 4. In a 2003 pilot study, 8 of 9 patients experienced 50% or better pain relief after radiofrequency lesioning at L4 primary dorsal rami and S1-S3 lateral branches. Relief persisted at 9 month follow-up.

Question 105

736. Purported advantages of percutaneous radiofrequency lesions over other neuroablative techniques include (1) predictable and quantifiable lesions (2) avoids the extensive soft tissue damage of surgical techniques (3) ability to confirm needle-tip proximity to sensory and motor nerves (4) ability to cover a wide field

Answer 105

736. (A) Other advantages of radiofrequency lesions include avoids sticking and charring (in contrast to direct current electrical lesions), no gas formation (in contrast to direct current electrical lesions), impedance monitoring, and amenable to fluoroscopic and CT guidance. Ability to identify needle-tip proximity to motor and sensory nerves is a characteristic of radiofrequency procedures, although cryoanalgesia probes are also available with built-in nerve stimulators. Ability to cover a wide field is not an advantage of percutaneous radiofrequency lesion. Percutaneous radiofrequency techniques deliver relatively smaller, more defined treatment areas and therefore a great deal of lesions would be needed in order to cover a wide field target.

Question 106

737. Which of the following is (are) accurate regarding the history of ablation techniques? (1) Norman Shealy reported the first use of radiofrequency lesioning for treatment of facet pain in 1975 (2) The first report of percutaneous radiofrequency lesioning for treatment of pain came in 1981 (3) Slappendel reported the first clinical use of pulsed radiofrequency lesioning in 1997 (4) Although a modern cryoneuroablation device was developed and refined in the 1960s, the application for pain management gained popularity in the 1980s

Answer 106

737. (E) These are all accurate historical events as described and cited in current literature reviews. Pulsed radiofrequency techniques have received growing interest since 1997, when treatment of the cervical spinal dorsal root ganglions with pulsed radiofrequency suggested efficacy and safety. In 1961, Cooper described a device which used liquid nitrogen in a hollow tube that was insulated at the tip and achieved temperatures as low as −190°C. He published his description in a hospital bulletin. Six years later an ophthalmic surgeon by the name of Amoils improved on the device. Lloyd coined the term “cryoanalgesia” in 1976. The technique was popularized in the 1980s, but publications have declined since. [Cooper IS, Lee AS. Cryostatic congelation: a system for producing a limited, controlled region of cooling or freezing of biologic tissues.

Question 107

738. Which of the following is (are) accurate regarding lesion size? (1) The size of a continuous radiofrequency lesion depends on temperature induced (2) The size of a continuous radiofrequency lesion depends on the width of the needle (3) A 2 mm cryoanalgesia probe forms an ice ball about 5.5 mm thick (4) A 1.4 mm cryoanalgesia probe forms an ice ball about 3.5 mm thick

Answer 107

738. (E) The size of a continuous radiofrequency lesion depends on temperature, width of needle, and length of exposed (uninsulated) cannula. The 1.4-mm cryoanalgesia probe forms an ice ball about 3.5 mm thick, while the larger 2-mm probe forms and ice ball about 5.5 mm thick. Thus the ice ball is about 2.5 to 2.75 times larger than the probe for these size probes.

Question 108

739. Which of the following is (are) components of a cryoanalgesia system? (1) Outer tube with smaller inner tube (2) Pressurized gas in inner tube (3) Fine aperture in tip of inner tube which allows gas to rapidly expand in tip of outer tube (4) Fine aperture in tip of outer tube which allows gas to escape the tube system

Answer 108

739. (A) Acryoprobe is comprised of a tube within a tube. The inner tube is pressurized with a gas such as nitrous oxide or carbon dioxide at 600 to 800 psi. As the gas escapes through a narrow aperture at the tip of the inner tube, it (the gas) abruptly expands in the larger outer tube at a lower pressure of about 10 to 15 psi. As the gas expands, it (the gas) cools. This is known as the Joule-Thompson effect. An ice ball then forms at the tip of the probe. The gas does not escape out through a fine aperture in the tip of the outer tube. This would allow the gas to enter the patient’s tissues. Instead, gas escapes back up the larger outer tube in a closed system design

Question 109

740. Which of the following is (are) potential neuroablative procedure treatment options? (1) Radiofrequency ablation of the L2 ramus communicans for treatment of L4-L5 discogenic pain (2) Phenol neurolysis for treatment of the lumbar sympathetic plexus for treatment of CRPS of the lower extremity (3) Radiofrequency ablation for treatment of the lumbar sympathetic plexus for treatment of CRPS of the lower extremity (4) Cryoablation for the treatment of pain owing to superior gluteal nerve entrapment

Answer 109

740. (E) 1. It has been postulated that the sinuvertebral nerves at each lumbar level transmit sensory information from the intervertebral discs to the paravertebral chain on each side. The rami communicans then communicate this sensory information to the dorsal root ganglia at L1 and L2. 2. and 3. Both radiofrequency and phenol lumbar sympathetic neurolytic techniques have been described for the treatment of lower extremity CRPS. 4. Cryoablation has been utilized for pain of the superior gluteal nerve. (Trescot, Pain Physician, 2003, v. 6, p. 345-360, Cryoanalgesia in interventional pain management)

Question 110

741. Which of the following is (are) potential advantage( s) of pulsed radiofrequency procedure over continuous radiofrequency ablation? (1) Pulsed radiofrequency procedure is virtually painless as compared to continuous radiofrequency ablation during which patients often complain of pain (2) Overwhelming evidence of greater efficacy with pulsed radiofrequency procedure over continuous radiofrequency ablation (3) As compared to pulsed radiofrequency ablation, continuous radiofrequency ablation of lumbar medial branches carries a higher risk of inducing spinal instability secondary to multifidus muscle denervation (4) Complications caused by needle injury of tissues is less with pulsed radiofrequency procedure compared to continuous radiofrequency ablation

Answer 110

741. (B) 1. Pulsed radiofrequency procedure is virtually painless. Continuous radiofrequency ablation is painful with application. 2. There is debate in literature as to whether pulsed radiofrequency procedure is as efficacious as radiofrequency ablation. 3. In addition to innervating the zygapophysial joint, the medial branch of the dorsal ramus also innervates the multifidus, interspinales, and intertransversarii mediales muscles, the interspinous ligament, and, possibly, the ligamentum flavum. 4. In both cases a cannula and radiofrequency probe of similar size are inserted.

Question 111

742. Which of the following is (are) correct regarding impedance measurement during radiofrequency procedures? (1) While performing a radiofrequency procedure, the lower the impedance value the better the expected outcome (2) Impedance measurement can detect needle-tip entry into different mediums such as vascular structures or periosteum (3) Impedance values are neither customary nor necessary when using fluoroscopic guidance (4) Impedance measurement can detect breaks or short circuits in the electrical circuit

Answer 111

742. (C) 1. Too low an impedance may indicate the needle tip is in nontarget tissues such as vasculature, CSF, or nucleus pulposus. 2. This statement is correct. 3. It is traditional to use impedance information in assisting needle-tip placement even during fluoroscopically guided procedures. 4. This statement is correct. Superior gluteal nerve entrapment is amenable to cryoablation.