Neuro

Question 1

Describe the relationship between CBF and PaCO2

Answer 1

Low CO2 means decreased CBF (In fact, they are directly proportional!) So 1 mmHg less of CO2 means a 1-2 decrease in CBF

Question 2

What is the structure in the carotid artery that contains baroreceptors? What happens when it is stretched? what surgery might you see this in? What contains chemoreceptors?

Answer 2

1. Carotid sinus
2. hypotension, bradycardia
3. CEA
4. Carotid body

Question 3

Describe Charcot Marie Tooth disease

Answer 3

1. demyelinating disease of the peripheral nerves
2. leads to sensory and motor loss of the distal extremities
3. autosomal dominant

Question 4

What part of the brain controls inspiration and expiration?

Answer 4

Medulla
1. ventral: expiration
2. dorsal: inspiration
The lower pontine apneustic center stimulates the dorsal respiratory group while the upper pontine pneumotaxic center inhibits it.

Question 5

What are the afferent and efferent limbs of the corneal reflex?

Answer 5

1. trigeminal

2. facial

Question 6

What defect is most commonly associated with a Myelomeningocele?

Answer 6

Chiari II malformation

Question 7

What fibers run through the grey rami communicates?

Answer 7

post ganglionic sympathetic nerve fibers. The pre- ganglionic fibers run through the white rami communicates

Question 8

What can you give as a pre-med to help with succinylcholine myalgias?

Answer 8

1. lidocaine
2. calcium gluconate
3. vitamin C

Question 9

When is a vasospasm following SAH most likely to occur? When is re-bleeding most likely to occur?

Answer 9

1. 48-72 hrs

2. Within the first 48 hours

Question 10

What are the most accurate sites to measure core temperature?

Answer 10

1. TM
2. distal esophagus
3. pulmonary artery
4. nasopharynx

Question 11

What artery does trans cranial doppler (TCD) use to detect flow velocities during a CEA?

Answer 11

MCA

Question 12

When is it common for women to develop a relapse from MS?

Answer 12

Post-partum

Question 13

What electrolyte abnormality is associated with GBS? And why?

Answer 13

SIADH –> hyponatremia

Question 14

Name two ways that you can decrease CPP

Answer 14

1. directly drain CSF from drain

2. Increase MAP

Question 15

Which nerves have PS pre- gangiolinc neurons? Where do they reside?

Answer 15

1. III, VII, IX, X
2. III: edinger westfall nucleus
3. VII, IX, X: medulla oblongata

Question 16

What drug interferes with microelectrode recordings?

Answer 16

Midazolam, most other IV agents are OK to use

Question 17

True or False: Hyperthermia is brain protective after a neurologic insult

Answer 17

FALSE: HYPOthermia is neuroprotective

Question 18

What tool can be used to help ensure no limb nerve injury occurs during spinal surgery?

Answer 18

SSEPs. These can alert of spinal cord damage or peripheral nerve damage

Question 19

Which position puts you most at risk for post operative vision loss

Answer 19

Horseshoe head rest

Question 20

Explain hyperkalemic periodic paralysis

What receptor is involved in hypokalemic periodic paralysis?

Answer 20

There is a mutation in the Na voltage gated channel that leads to prolonged depolarization, myotonia, and paralysis. Therefore, the patients are dependent on K efflux to start depolarization. If K is HIGH, then K efflux is slowed and the patient remains paralyzed. Can affect the tongue and eyelids

Factors that worsen this are 1) rest after exercise, 2) metabolic ACIDOSIS, 3) hypoglycemia, 4) extremes of temperature 5) depolarizing muscle blockers

Calcium receptor

Question 21

What is a common complication of AVM embolization procedures? How do you treat it?

Answer 21

1. cerebral edema

2. hypotension, hypocapnia, hypothermia, and propofol

Question 22

Describe Autonomic hyperreflexia

Answer 22

1. Happens when damage above T12 occurs
2. Any sort of stimulation to the skin, bladder, uterus, viscera leads to activation of the the sympathetic pre-ganglionic fibers, which then affects the splanchnic outflow tract. However, the inhibitory fibers are damaged: SO below the injury you get uninhibited sympathetic stimuli (vasospasm), while vasodilation and sweating occur ABOVE the lesion

Question 23

Describe some anesthetic considerations in kids with muscular dystrophy. What is an appropriate anesthetic plan?

Answer 23

1. Cardiac defects: many of these kids can get CHF and dysrhythmia
2. Respiratory issues: weak respiratory muscles and poor clearance of mucus leads to increased risk for pulmonary infections and therefore possible prolonged intubation following surgery
3. GI dysmotility and gastroparesis: increased risk for aspiration
4. Avoidance of succinylcholine due to up-regulated Ach receptors
5. Avoidance of volatile anesthetics due to increased risk for rhabdomyolysis
6. Induction with IV propofol and rocuronium

Question 24

Which site on the NMJ post junctional nAchR does the Ach bind?

Answer 24

Alpha 1 subunit

Question 25

Describe what a MEP is? When is it most commonly used? What is the pathway that the neurons follow?

Answer 25

1. MEP: motor evoked potential, this is when electrodes are placed transcrianially (over the scalp) or directly on the brain to stimulate the descending motor pathway 2. This is used in surgeries where the artery of adamkiewicz is at risk (the anterior blood supply to the spinal cord) 3. Lower limb cortex --> inter capsule --> brainstem --> corticospinal tract --> peripheral nerve

Question 26

Describe the role of the carotid body vs. the carotid sinus. What CN do each of these utilize to send messages to the brain to increase ventilation? What surgery puts the carotid body at risk?

Answer 26

1. Carotid body is at the branch of the common carotid artery. It is a group of cells that transmits signals to the brain when PaO2 decreases below 100 and then below 50. 2. The carotid sinus is in the proximal internal carotid artery and it detects PaCO2 levels 3. Both use CN IX (glossopharyngeal) to send signals to the brain 4. CEA: if this nerve gets knocked out, the the body is only relying on hypercarbic drive to increase ventilation and this is often times attenuated (or decreased) by narcotics and anesthetic gas

Question 27

What vertebrae differentiates Quad vs. paraplegic?

Answer 27

T1

Question 28

Describe neurogenic pulmonary edema

Answer 28

Following TBI and increased ICP, there is a massive discharge of sympathetic activity that causes pulmonary vasoconstriction. This can happen w/in a few hours

Question 29

Compare tetanus and botulism

Answer 29

1. Tetanus inhibits GABA and Glycine release from at the pre-synaptic channels in the brain, which inhibits the inhibitory neurons --> tetany 2. Botulism inhibits Ach release in the spinal cord, so the alpha motor neurons are not activated --> flaccid paralysis

Question 30

Why should mannitol be given over 10-15 minutes?

Answer 30

It causes brain engorgement and has a vasoDILATORY effect, leading to increased ICP

Question 31

Describe the effect that propofol has on the brain

Answer 31

Decreased CMRO2, cerebral 02 consumption, and decreases ICP. The concern is that a decrease in MAP will lead to a decrease in CPP

Question 32

Describe HYPOkalemic periodic paralysis

Answer 32

1. Defect in the Ca channel | 2. Leads to weakness of the trunk and limbs, but sparing of the diaphragm

Question 33

What are the ICP and CPP goals in a patient with TBI?

Answer 33

ICP < 20-25, CPP > = 60

Question 34

Describe the difference between phase 1 and phase 2 blockade of Succinylcholine?

Answer 34

1. Phase 1: Sux is bound to the POSTsynaptic ach receptors, TOF with NO fade 2. Phase 2: Sux is bound to the PREsynaptic ach receptors, TOF WITH fade

Question 35

What are the goals of fluid management in a neurosurgical patient? Why?

Answer 35

1. Want them euvolemic or slightly hypervolemic to maintain CPP

Question 36

What will you see on ICP waveform when there is a sudden increase in ICP?

Answer 36

A plateau wave (AKA Lundberg's wave): increase in P2 > P1

Question 37

What is another word for myasthenia syndrome?

Answer 37

LE syndrome

Question 38

Describe the effects of anesthetic gas on CMRO2 and CBF at 0.5-1 MAC and 1.5 MAC and above

Answer 38

1. 0.5-1.0 MAC: Leads to decreased CMR02 and CBF | 2. 1.5 and above leads to decreased CMRO2, but vasodilation leads to increased CBF

Question 39

What are the only two agents to not decrease CMRO2?

Answer 39

1. Ketamine: minor effect, increase in CBF, Increases ICP | 2. N20: increases CMR02, CBF, and ICP

Question 40

What criteria are used to determine if a patient with MG needs post operative ventilation?

Answer 40

1. NIF < 20 2. VC < 2.9 3. other compounding lung disease 4. Disease > 6 years 5. Daily pyridostigmine dose > 750

Question 41

What receptors and neurotransmitters to pre and post ganglionic neurons of the 1. Sympathetic and 2. PS systems use?

Answer 41

1. sympathetic: PRE: Ach/nAchR, POST: NE,E, Alpha/beta | 2. PS: PRE: Ach/nAchR, POST: Ach/mAchR

Question 42

How does Mg cause muscle weakness?

Answer 42

Blocks Ca influx into the presynaptic terminal, leading to decreased Ach release

Question 43

What is the path that CSF drainage takes?

Answer 43

Lateral ventricles --> third ventricle --> 4th ventricle --> cisterna magna via the foramen magendie (median aperture)

Question 44

Sacral spinal nerves affect which types of nerves?

Answer 44

parasympathetics!

Question 45

How would you describe the TOF ratio between the upper limb and the lower limb in a paraplegic patient? Why is this the case?

Answer 45

1. The TOF ratio will INCREASE | 2. This is due to up regulation of Ach receptors in the injured limb

Question 46

What is important to ensure following deep hypothermic cardiac arrest in attempts at neuro protection?

Answer 46

CPB is maintained for 20-30 minutes once the blood has reached a temp of 15-22 C. This is because there is no way to directly correlate blood temp to brain temp.

Question 47

What is a paradoxical reaction that is associated with succinylcholine?

Answer 47

Laryngospasm

Question 48

Describe the neurologic changes seen with aging

Answer 48

1. Increased BBB permeability 2. Preserved cerebral auto regulation of blood flow 3. Increased sensitivity to LA 4. uneven distribution of neuronal cell loss

Question 49

What is a normal serum osmolality?

Answer 49

Hypo-osmolar: < 280 | Hyper osmolar: > 285

Question 50

What is the effect of barbiturates on cerebral auto-regulation?

Answer 50

It is maintained!

Question 51

Describe SSEPs

Answer 51

Somatosensory Evoked Potential: Stimulation of a peripheral sensory nerve leads to activation of the sensory cortex (supplied by the MCA, which is important in CEA surgery when the carotid is clamped)

Question 52

What hormones are released from the pituitary?

Answer 52

Anterior: ADH, oxytocin Posterior: ACTH, LH, FSH, GH, prolactin, TSH

Question 53

Describe the defect in mitochondrial disorders. How can we mitigate this in the perioperative period?

Answer 53

1. inability to make ATP | 2. limit stressors, such as hypoglycemia, emotional stress, hypothermia, or hyperthermia, acidosis

Question 54

Describe the blood flow in the spinal cord

Answer 54

There are two posterior and one anterior artery. The ASA supplies 75% of blood flow to the spinal cord (supplies motor tracts), whereas the posterior two supply blood to the sensory tracts

Question 55

Why is it safe to use succinylcholine in MG and LE syndrome?

Answer 55

there is NO up regulation of the the nAchR

Question 56

Compare persistent vegetative state to a coma

Answer 56

PVS is when a person in a coma has made a small improvement. They can open their eyes, cry, laugh, make NON-purposeful movements, but cannot think, communicate, or move in a purposeful way Coma: GCS < = 8 for > = 6 hours

Question 57

What drug can be used to treat paralysis in both hypo and hyperkalemic periodic paralysis?

Answer 57

acetazolamide, for reasons unknown

Question 58

True or false: Ketamine can induce seizures

Answer 58

TRUE, esp in those patients with a lower seizure threshold

Question 59

What agents should be used in ECT? What are some reasons to not use one of them?

Answer 59

1. Methohexital "gold standard" | 2. Etomidate: does not blunt the sympathetic response to seizures, so should be avoided in those with HTN and CAD