Neurodiagnostics

Question 1

Indications for a lumbar puncture?

2

Answer 1

1. When cerebrospinal fluid is needed for biochemical analysis, cellular examination and culture
2. Also done to introduce drugs into the subarachnoid space for treatment of cancer or to introduce contrast agents

Question 2

Emergent indications for an LP? 2

General indications for LP? 3r

Answer 2

1. Suspected CNS infection
2. Suspected subarachnoid hemorrhage in a pt w/ negative CT scan
3. Diagnosis of CNS malignancies
4. Demyelinating diseases
5. Guillain-Barre syndrome

Question 3

Where are the site of punctures for LPs? 2

Answer 3

1. L3-L4
2. L4-L5

Question 4

1. How do you want the patient in position to take a LP?
2. What do we use a manometer for?
3. How much fluid do we collect? and how many?

Answer 4

1. Patient in left lateral decubitus fetal position or sitting upright with spine curved forward
2. Measure opening pressure with manometer (best if pt in recumbent position)
3. Collect 8-15 cc of cerebral spinal fluid in 4 tubes for lab studies

Question 5

Relative Contraindications to LP 7

Answer 5

1. Local skin infections over proposed puncture site (absolute contraindication)
2. Increased intracranial pressure (ICP); exception is pseudotumor cerebri
3. Suspected spinal cord mass or intracranial mass lesion (based on lateralizing neurological findings or papilledema)
4. Uncontrolled bleeding diathesis, thrombocytopenia or anticoagulation
5. Spinal column deformities (may require fluoroscopic assistance)
6. Suspected spinal epidural abscess
7. Lack of patient cooperation

Question 6

Complications of LP 8

Answer 6

1. Post lumbar puncture headache (10-30% of pt’s)
2. CSF leak
3. Infection
4. Bleeding Spinal hematoma
5. Cerebral herniation (fatal)
6. Minor neurologic symptoms (radicular pain or numbness)
7. Late onset epidermoid tumors of the thecal sac
8. Back pain

Question 7

How can we treat the post lumbar puncture headache?

What is it associated with? 4

How soon does it present after the procedure?

Answer 7

Spinal headache is relieved by laying down,

May be associated with

1. nausea/vomiting,
2. dizziness,
3. tinnitus,
4. visual changes,

Presents 24-48 hours post procedure

Question 8

WHat do we need to rule out before performing an LP?

WHy?

Answer 8

Mass lesion causing ICP High pressure (like papiledema high) released through the lumbar puncture will cause herniation of the brain going down through the spinal column.

Question 9

Patients with the following high risk symptoms for increased intracranial pressure should undergo CT of the head prior to LP (R/O mass lesion)? 5

Some facilities have protocols where CT is done on all pts prior to LP

Answer 9

1. Altered mentation
2. Focal neurologic signs
3. Papilledema
4. Seizure within the previous week
5. Impaired cellular immunity-cancer

Question 10

Describe the following CSF normal values:

1. Pressure
2. Appearance
3. Total protein
4. Glucose
5. Cell count and differential (WBCs and RBCs)

Answer 10

1. 70-180 mmH2O (can be up to 250 in obese pts)-will have to convert if its in mmHg
2. Clear, colorless
3. 15-45 mg/dL
4. 45-85 mg/dL or greater than 2/3 of serum blood glucose
5. WBCs: 0-5 cells/µL RBCs: 0

Question 11

Who is ICP increased in?

Answer 11

Obese pts/increased BMI

Question 12

Elevated ICP can be seen in what disease processes? 3

Answer 12

1. meningitis,
2. ICH,
3. tumors

Question 13

Why might the CSF be cloudy?

Answer 13

1. infection,
2. bloody or
3. colored

Question 14

Xanthochromia will have colored CSF. Why?

Answer 14

yellow, orange or pink from lysis of RBCs (occurs within 2 hours, lasts 2 weeks).

Question 15

What would be elevated in a subarachnoid hemorrhage for CSF? 2

Answer 15

1. increased protein levels,
2. elevated bilirubin

Question 16

Xanthochromia. Describe what the following colors mean:

1. Yellow? 4
2. Orange? 2
3. Pink? 1
4. Green? 2
5. Brown? 1

Answer 16

Yellow

1. Blood breakdown products,
2. hyperbilirubinemia,
3. CSF protein > 150 mg/dL,
4. > 100,000 rbcs per mm3

Orange

1. Blood breakdown products,
2. high carotenoid ingestion

Pink

1. Blood breakdown products

Green

1. Hyperbilirubinemia,
2. purulent CSF

Brown

1. Meningeal melanomatosis (Melanoma of the CNS)

Question 17

What is one of the most sensitive indicators of pathology within the CNS?

Answer 17

CSF protein concentration

Question 18

WHat are the normal amounts of protein in the CSF:

Newborns?

Adults?

Answer 18

1. Newborns (up to 150 mg/dL)
2. Adults (15-45 mg/dL) same as for kids at 6-12 months

Question 19

Can differentiate protein types for conditions such as what? 2

Answer 19

Guillan Barre’ and MS

Question 20

Low protein in the CSF indicates what?

Answer 20

1. Repeated LPs,
2. CSF leak,
3. acute water intoxication

Question 21

Elevated CSF indicates what? 7

Answer 21

1. Infections,
2. ICH,
3. MS,
4. Guillain Barre’,
5. malignancy,
6. some endocrine abnormalities,
7. inflammatory conditions

Question 22

Falsely elevated in traumatic tap how would we correct this?

Answer 22

Correction factor: subtract 1 mg/dL for every 1000 RBCs

Question 23

1. As a general rule the CSF glucose level is about ___ of the serum glucose measured during the preceding 2-4 hours
2. What condition can the glucose levels be normal in? 1
3. When would the glucose be low? 3
4. When would the glucose be high? 1

Answer 23

1. 2/3
2. Can be normal in CNS viral infection

3.

• CNS bacterial infection,
• neoplasm
• fungal infection

4.

• When peripheral glucose levels are elevated
• Above a serum glucose of 300 the CSF glucose does not increase that much

Question 24

1. Normal WBC in adults?
2. Newborns?
3. How can this help us differenciate if its viral or bacterial menigitis?
4. INcreased from what other conditions? 4

Answer 24

1. 0-5 mm3*adults,
2. up to 20 mm3 newborns
3. Meningitis less than 1000 more likely viral, > 1000 more likely bacterial meningitis
4. Increased
   - post seizure,
   - ICH,
   - malignancy,
   - inflammatory conditions

Question 25

CSF analysis: Cell differential 1. Normal WBC: Is what percent of what cells? 2. In meningitis, predominance of what tells us its bacterial? 3. In meningitis, predominance of _________ = viral, fungal, tuberculosis 4. Increased eosinophils = what?

Answer 25

1. Normal WBC 70% lymphocytes, 30% monocytes 2. In meningitis, predominance of neutrophils = bacterial 3. lymphocytes 4. parasitic infection

Question 26

1. What will tell us if a traumatic tap occurred? 2. If the RBCs dont decrease then what do we assume

Answer 26

1. Traumatic tap: measure cell counts in 3 consecutive tubes and the number of RBCs should decrease with each. 2. If RBC numbers don’t decrease then assume from intracranial hemorrhage

Question 27

What would we do for microscopic examination of CSF?

Answer 27

1. Gram stain

Question 28

1. What is an india stain positive in? 2. What is a Wright or Giemsa stain positive in? 3. Acid fast stain?

Answer 28

1. cryptococcus 2. toxoplasmosis 3. TB

Question 29

Why would we do a latex agglutination?

Answer 29

1. Allows for rapid detection of baterial antigens in CSF --Variable sensitivity and specificity

Question 30

- Why would we do a polymerase chain reaction? 2 - Particularly useful in what? 7

Answer 30

1. High sensitivity and specificity 2. Fast 3. - Viral meningitis, - HSV-1, - EBV, - enterovirus, - CMV, - TB, - acute neurosyphilis

Question 31

State the pressure, color, total protein, glucose, and cell count for the following: 1. Bacterial meningitis? 2. Viral (aseptic meningitis)? 3. Fungal meningitis? 4. Multiple sclerosis? 5. Guillian-Barre’? 6. SAH?

Answer 31

See picture

Question 32

Interpret these results - 1

Answer 32

Bacterial Meningitis

Question 33

Interpret these results -2

Answer 33

Aseptic (viral) meningitis

Question 34

Interpret these results - 3

Answer 34

Fungal meningitis

Question 35

Interpret these results - 4

Answer 35

Multiple sclerosis

Question 36

Interpret these results - 5

Answer 36

Guillan Barre

Question 37

Interpret these results - 6

Answer 37

Subarachnoid hemorrhage

Question 38

What are the two types of nerve conduction studies are there?

Answer 38

1. Nerve conduction velocity 2. Electromyelography (EMG)

Question 39

1. Nerve conduction velocity measures what? 2. What disease processes does it evaluate? 2

Answer 39

1. Measures how well and how fast the peripheral nerves send the signals 2. Evaluation of - entrapment neuropathies - Guillian-Barre’

Question 40

What does Electromyelography (EMG) measure?

Answer 40

Measures the electrical activity of muscles during rest and contraction

Question 41

1. Nerve conduction studies test what nerves only? 2. Can diagnose what kind of disorders? 2 3. What is its main use? !!!!!! 4. How would you sort this out?

Answer 41

1. Tests the peripheral nerves only 2. can diagnose a focal or generalized disorder 3. Used to differentiate muscle disorders from nerve disorders!!!! Sorting it out: 4. Is the nerve signal adequate but the muscle is not responding vs. altered nerve signals and intact muscle response

Question 42

Indications for Nerve conduction studies 3

Answer 42

1. Evaluation of paresthesias of the arms and legs 2. Evaluation of weakness of the arms and legs 3. Some disorders that can be diagnosed by nerve conduction studies:

Question 43

What disorders can be diagnosed by nerve conduction studies? 6

Answer 43

1. Carpal tunnel syndrome, 2. ulnar neuropathy, 3. spinal disc herniation, 4. Guillian-Barre’, 5. peripheral neuropathy 6. Myasthenia Gravis

Question 44

Classification of nerve fibers: What are size of the fibers and what do they sense? 1. A-alpha? 2. A-delta? 3. C fibers?

Answer 44

1. Large myelinated fibers Touch, vibration, position 2. Small myelinated fibers Cold and pain sensation 3. Unmyelinated fibers Warm and pain

Question 45

1. Nerve conduction velocity can only study which kind of fibers? 2. Can appear normal in who?

Answer 45

1. largest A-alpha fibers Touch, vibration, position 2. polyneuropathies with primarily small fiber involvement

Question 46

Nerve conduction velocity 2

Answer 46

Useful in studying 1. demyelinating polyneuropathy (Guillain-Barre’ Syndrome) or 2. focal demyelination (entrapment neuropathies such as carpal tunnel syndrome)

Question 47

Nerve conduction velocity 1. Normal velocity if myelin is what? 2. Slow conduction velocity if what?

Answer 47

1. Normal velocity if myelin is intact 2. Slow conduction velocity if demyelination or destruction of large fibers

Question 48

What does an EMG find damage in? 3 Specific diseases? 3

Answer 48

Find diseases that : 1. damage muscle tissue, 2. nerves 3. the junctions between nerve and muscle Specific diseases: 1. Herniated disc, 2. amyotrophic lateral sclerosis (ALS) or 3. myasthenia gravis

Question 49

Describe the process of EMG?

Answer 49

Needle is placed into the muscle (motor unit) Electrical stimulus delivered and a motor unit action potential is created

Question 50

1. What nerve conduction tests should we always order together? 2. Characterizes disorders of the what? 4 3. These should not be the first tests ordered but should be used to do what?

Answer 50

1. Should always order nerve conduction velocity and electromyelography together 2. Characterizes disorders of the - motor neuron, - neuromuscular junction, - primary nerve disorder - nerve root disorders 3. These should not be the first tests ordered but should be used to confirm a diagnosis or judge severity of disease

Question 51

Clinical utility of EEG 4

Answer 51

1. To distinguish epileptic seizures from ---Psycogenic spells, syncope, movement disorders, migraine variants 2. Differentiate organic causes of encephalopathy or delirium from psychiatric causes 3. Testing for brain death 4. Determining whether or not to wean anti-epileptic meds

Question 52

1. Electrodes on the scalp record what? 2. What is the electrical activity recorded as? 3. The wave forms are labeled according to their what? 4. What are the categories of wave forms? 4

Answer 52

1. Electrodes on the scalp record the synaptic activity of the brain 2. This electrical activity is recorded as a wave form 3. The wave forms are labeled according to their amplitude 4. - Delta 0-4 Hz, - Theta 4-8 Hz, - Alpha 8-12 Hz, - Beta greater than 12 Hz

Question 53

1. Increased slow wave activity in an awake pt may = what? 2. With increased slow activity what will we see? 3. Increased slow wave acitivity is almost always abnormal at what time? 4. Focal delta activity is usually irregular in configuration and is termed what? What is this indicative of?

Answer 53

1. focal brain lesion 2. theta and delta waves 3. Increased slow wave activity when awake is virtually always abnormal 4. Focal delta activity is usually irregular in configuration and is termed polymorphic delta activity (PDA). PDA is usually indicative of a focal brain lesion.

Question 54

1. Generalized theta and delta activity is an indication of what? 2. As a general rule, EEG is a sensitive test for what?

Answer 54

1. encephalopathy 2. encephalopathy

Question 55

1. EEG is very useful in the diagnosis of what?

Answer 55

seizure disorders

Question 56

EEG techniques that are useful in inducing epileptic activity and increasing test sensitivity are? 5

Answer 56

1. Hyperventilation, 2. photic stimulation, 3. sleep, 4. sleep deprivation, and 5. drugs,

Question 57

What are the three things that EEGs are used to diagnose?

Answer 57

Able to diagnose seizures, encephalopathy, focal brain lesions