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14. Neurosurgery Primary Examination Review > Section 5 > Flashcards

Section 5 Flashcards

Neurobiology and Critical Care

1
Q

The neurotransmitter from the putamen to globus pallidus (GP) is
A. Dopamine
B. Acetylcholine
C. 5-hydroxytryptamine (5-HT)
D. Glutamate
E. Gamma aminobutyric acid (GABA)

A

E. Gamma aminobutyric acid (GABA)

GABA and enkephalins are neurotransmitters from putamen to GPe, GABA and substance P from putamen to GPi. Dopamine is from substantia nigra pars compacta to striatum (defective in Parkinson’s disease) while Ach from amygdala to cortex (defective in Alzheimer’s disease), from cortex to
caudate, and from caudate to putamen. Serotonin (5-HT) is from dorsal raphe nucleus to substantia nigra and striatum (involved in non-REM sleep) while glutamate is from thalamus to striatum and cortex, from cortex to putamen and subthalamic nucleus, and from subthalamic nucleus to GPe, GPi, and substantia nigra.

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2
Q

Increased pulmonary dead space occurs in
A. Pneumonia
B. Pulmonary edema
C. Pulmonary embolism
D. High altitudes
E. Pneumothorax

A

C. Pulmonary embolism

Pulmonary embolism causes a ventilation-perfusion mismatch where the vessels are occluded causing a dead space effect. When the alveoli are filled with fluid as in pulmonary edema or pneumonia, a shunt effect occurs.

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3
Q

Which of the following values of cerebral blood flow lies within the ischemic penumbra?
A. 1-5 mL/100 g/min
B. 10-20 mL/100 g/min
C. 25-35 mLflOO g/min
D. 40-50 mL/100 g/min
E. 50-55 mL/100 g/min

A

B. 10-20 mL/100 g/min

While the normal cerebral blood flow is 50 mL/100 g/min, with higher flow in the gray matter, the ischemic penumbra occurs at 8-23 mL/100 g/ min.

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4
Q

Botulinum toxin blocks
A. Adrenergic receptors
B. Nicotinic acetylcholine receptors
C. Muscarinic acetylcholine receptors
D. Acetylcholine release at the neuromuscular junction
E. Acetylcholine degradation

A

D. Acetylcholine release at the neuromuscular junction

Botulinum toxin degrades SNARE proteins at the neuromuscular junction. The SNARE (SNAP receptor) complex are essential for acetylcholine release and are composed of: synaptobrevin, syntaxin, and SNAP-25 (synaptosomal-associated protein-25 kDa).

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5
Q

Which receptors are found in the dermal papillae of the finger tips, are rapidly adapting, and are responsible for touch sensation?
A. Meissner’s corpusdes
B. Pacinian corpuscles
C. Ruffini end organs
D. Free nerve endings
E. Hair end organs

A

A. Meissner’s corpusdes

Meissner’s corpuscles are found in the dermal papillae of the finger tips and lips, transmit touch and vibration through type II fibers, are rapidly adapting, and have a small receptive field.

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6
Q

A 72-year-old man is admitted for osteomyelitis and discitis. He has a history of severe chronic obstructive pulmonary disease (COPD) and presents with fever, confusion, respiratory distress, leg pain, and weakness. He has a history of heavy smoking. An ABG shows: pH 7,23, PCO2 72 mmHg, PO2 91 mmHg, and HCO3 28 mEq/L What is the most likely diagnosis?
A. Compensated respiratory acidosis
B. Respiratory acidosis and metabolic acidosis
C. Respiratory acidosis with incomplete metabolic compensation
D. Metabolic acidosis with incomplete respiratory compensation
E. Metabolic acidosis

A

C. Respiratory acidosis with incomplete metabolic compensation

In chronic respiratory acidosis due to COPD, the kidneys respond by retaining HC03 (renal compensation). The expected HCO3 should be: 4 mEq/L for every 10 mmHg increase in PCO2 This patient has a mild metabolic alkalosis that is not completely compensating for the respiratory acidosis noted on the blood gas, indicating that the PCO2 is not chronically elevated enough to drive a significant increase in HCO3.

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7
Q

A 15-year-old girl with sickle cell disease presents with acute right leg weakness. A head CT was performed which shows a small stroke in the ACA territory. The patient recovers well and visits you in clinic having fully recovered. Which of the following interventions reduces the frequency of sickle cell crisis?
A. Antibiotics
B. Hydroxyurea
C. Regular blood transfusions
D. Erythropoietin
E. Splenectomy

A

B. Hydroxyurea

Hydroxyurea increases fetal hemoglobin and decreases platelets and leukocytes, thereby reducing the frequency of sickling and need for blood transfusions after acute crisis.

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8
Q

The most excitable part of a neuron is
A. The dendrites
B. The cell body (soma)
C. The axon hillock
D. The axon at the nodes of Ranvier
E. The axon in-between the nodes of Ranvier

A

C. The axon hillock

The axon hillock is the most excitable part of a neuron. It has a high concentration of Na+ channels, a resting membrane potential of -65 mV, and a threshold for action potential of -45 mV. This is usually where the action potential starts.

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9
Q

Neuronal depolarization is caused by
A. Potassium influx
B. Calcium influx
C. Chloride efflux
D. Sodium efflux
E. Sodium influx

A

E. Sodium influx

During the neuronal action potential, the depolarization is caused by opening of Na+ channels and Na+ influx, while repolarization is caused by closure of Na+ channels (inner inactivation gate) and K+ efflux. At rest, the inactivation gate is open and the outer activation gate is closed. Tetrodotoxin
and saxitoxin block Na+ channels and so do local anesthetics and some seizure medications (phenytoin and carbamazepine).

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10
Q

The optic n fibers arise from which cells?
A. Bipolar
B. Amaaine
C. Horizontal
D. Ganglion
E. Rods and cones

A

D. Ganglion

In the retina, the signal is transmitted from the rods and cones to the bipolar cells to the ganglion cells, whose axons make the optic n.

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11
Q

On an EEG. if the 6 waves constitute >50%, this pattern is consistent with
A. Awake quiet
B. Stage 1 sleep
C. Stage 2 sleep
D. Stage 3 sleep
E. Stage 4 sleep

A

E. Stage 4 sleep

During sleep: Stage 1 is characterized by low-voltage a waves, stage 2 K complexes and sleep spindles, stage 3 some delta waves as well as K complexes and sleep spindles, stage 4 delta waves >50%, and REM sleep beta waves. Awake quiet features a waves and awake alert beta waves.

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12
Q

All of the following drugs inaease the effect of warfarin (Coumadin), except
A. Barbiturates
B. Benzodiazepines
C. Bactrim (trimethoprim)
D. Cimetidine
E. Salicylates

A

A. Barbiturates

Barbiturates, phenytoin, and carbamazepine stimulate liver microsomal enzymes, and therefore increase the degradation of Coumadin. Benzodiazepines, Bactrim, and cimetidine are liver inhibitors, therefore increase the effect of Coumadin, with increased risk of bleeding. Salicylates displace Coumadin from its protein-binding sites in the blood, thus increasing its effect.

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13
Q

A 17-year-old girJ with sickle cell disease presents with a small acute right MCA stroke. What is the most important treatment to reduce morbidity and mortality?
A. Exchange transfusion
B. Aspirin
C. Hydroxyurea
D. Folic acid
E. Erythropoietin

A

A. Exchange transfusion

Blood transfusions decre.lSe the morbidity and mortality in patients with sickle cell crisis, especially with pulmonary and central nervous system complications. Exchange transfusion is even more effective in reducing the level of HgbS by taking out the patient’s own blood and transfusing a donor’s blood. This reduces the risk ofvaso-occlusive disease.

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14
Q

Which anesthetic decreases cerebral blood flow?
A. lsofluorane
B. Ketamine
C. Thiopental
D. Nitrous oxide
E. Halothane

A

C. Thiopental

Thiopental, etomidate, and fentanyl decrease cerebral blood How. Nitrous oxide, isoHurane, ketamine, enHurane, and halothane increase cerebral blood flow.

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15
Q

Red man syndrome can be a side effect of which antibiotic?
A. Penicillin
B. Vancomycin
C. Cephalosporins
D. Aminoglycosides
E. Imipenem

A

B. Vancomycin

Red man syndrome can be associated with rapid infusion ofvancomycin. It is characterized by erythematous rash and pruritus in the upper body, head, and neck with possible hypotension. Treat with anti-histamines.

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16
Q

A 23-year-old obese woman presents with progressive blindness over the past week. Recent ophthalmologic examination reveals grade 3 papilledema and an afferent pupillary defect (APD) in the right eye with 20/200 vision in the left eye. The patient undergoes a diagnostic angiogram Which venous structme is identified by the arrow?
A. Superior sagittal sinus
B. Superior petrosal sinus
C. Inferior sagittal sinus
D. Inferior petrosal sinus
E. Thalamostriate vein

A

D. Inferior petrosal sinus

The patient has a clinical picture of pseudotumor cerebri. The inferior petrosal sinus courses along the petroclival fissure and connects the cavernous sinus anteromedially to the jugular bulb posterolaterally.

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17
Q

The same patient was subsequently evaluated with a dedicated venogram which reveals the following findings (arrow). Which intervention can help predict success after transverse sinus stenting?
A. Weight loss
B. Acewolamide (Diamox) therapy
C. Manometry aaoss the site of stenosis
D. Heparin drip
E. Coumadin

A

D. Heparin drip

The arrow points to transverse sinus stenosis. Manometry across the site of stenosis with significant pressure differentials is a positive predictor of success after transverse sinus stenting. Weight loss and Diamox are viable treatment options for pseudotumor cerebri.

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18
Q

Gelastic seizures are typically observed with
A. Hypothalamic hamartomas
B. Tectal gliomas
C. Dysembryoplastic neuroepithelial tumors (DNET)
D. Subependymal giant cell astrocytoma (SEGA)
E. Ganglioglioma

A

A. Hypothalamic hamartomas

Gelastic seizures manifest as a sudden burst of laughter. Hypothalamic hamartomas are characterized by gelastic seizures, precocious puberty, and developmental delay.

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19
Q

The main neurotransmitter output of the locus ceruleusis
A. Serotonin
B. Glutamate
C. GABA (gamma-amino butyric acid)
D. Norepinephrine (NE)
E. Acetylcholine

A

D. Norepinephrine (NE)

The main output oflocus ceruleus is NE and it is responsible for REM sleep.

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20
Q

Clarke’s nucleus gives origin to the
A. Ventral spinothalamic tract
B. Lateral spinothalamic tract
C. Ventral spinocerebellar tract
D. Dorsal spinocerebellar tract
E. Spino-olivary tract

A

D. Dorsal spinocerebellar tract

Clarke’s nucleus is present in lamina VII of the spinal cord gray matter (C8-L2) and conveys proprioception from the lower extremities. It forms the uncrossed dorsal spinocerebellar tract that travels through the inferior cerebellar peduncle.

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21
Q

Internuclear ophthalmoplegia (INO) is caused by a lesion of the
A. Medial forebrain bundle (MFB)
B. Medial longitudinal fasciculus (MIF)
C. Diagonal band of Broca (DBB)
D. Stria tenninalis
B. lndusium griseum

A

B. Medial longitudinal fasciculus (MIF)

INO is caused by a lesion of the MLF and causes inability of the ipsilateral eye to adduct, while the normal side abducts. Posterior INO is caused by a pontine lesion and has preserved convergence. Anterior INO is caused by a midbrain lesion and
has decreased convergence.

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22
Q

Kluver-Bucy syndrome is assodat.ed with bilateral damage of
A. Amygdala
B. Hippocampus
C. Fomix
D. Lateral hypothalamic nuclei
B. Thalamic fasciculus

A

A. Amygdala

Kluver-Bucy syndrome is associated with bilateral damage of the amygdala. It causes hyperorality, hyperphagia, hypersexuality, amnesia, tameness, and visual agnosia.

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23
Q

Vision occurs when metarhodopsin 2 activates
A. cAMP
B. G protein
C. Calcium channels
D. Acetylcholine receptors
E. Potassium channels

A

B. G protein

Light converts retinal rhodopsin into metarhodopsin 2. The latter activates G protein, which stimulatesphosphodiesterase, thus converting cGMP to 5’GMP. Na* channels close, resulting in hyperpolarization and a graded electric conduction.

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24
Q

Concerning the muscle spindle, the nuclear bag fibers have all of the following characteristics, except
A. Dynamic firing
B. Tonic firing
C. Central location
D. Annulospiral ending
E. Flower-spray ending

A

E. Flower-spray ending

The intrafusal muscle fibers of the muscle spindle are responsible for proprioception. The nuclear bag fibers are larger, dynamic, tonic, central, with primary annulospiral endings, carried by type la fibers (120 m/s). The nuclear dtain fibers are smaller, sttatic, tonic, eccentric, with primary
annulospiral and secondary flower-spray endings, carried by type II fibers, traveling at thirty to seventy m/s.

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25
Q

All of the following is true about Na valproate, except
A. Decreases Na conductance
B. can be hepatotoxic
C. can be teratogrnic (myelo-meningocele)
D. can cause tremors
E. can cause polycystic ovarian disease

A

A. Decreases Na conductance

Concerning the mechanism of action of antiepileptic drugs: Na valproate increases GABA, benzodiazepines and barbiturates stimulate GABA A receptors, while phenytoin and carbamazepine decrease Na conductance by blocking Na channels.

26
Q

A 42-year-old otherwise healthy man presents for an elective microdiscectomy for 15 radiculopathy. The patient undergoes general anesthesia and his ventilation is on a volume control mode. During surgery, ABG shows: pH 7.22, PCO2 70 mmHg, PO2 92 mmHg, and HCO3 27 mEq/L The best next step is
A. Increase the respiratory rate
B. Decrease the tidal volume
C. Change the mode of ventilation to pressure support
D. Increase the FiO2
E. Cancel the surgery

A

A. Increase the respiratory rate

The patient is suffering from acute respiratory acidosis due to hypoventilation. HCO3 increase is as expected, 1 mEq/L for every 10 mmHg increase in PCO2; therefore, there is no associated metabolic component This is due to reduced expiration of PCO2, and therefore increasing the respiratory rate or tidal volume would correct this problem.

26
Q

Spike-dome waves on EEG at 3 Hz are observed in
A. Lennax-Gastaut syndrome
B. Grand mal seizures
C. Absence seizures
D. REM sleep
E. Stage 4 sleep

A

C. Absence seizures

Spike-dome waves at 1-2 Hz are characteristic of Lennax-Gastaut syndrome, at 3 Hz absence seizures, at 4-6 Hz juvenile myodonic epilepsy.

27
Q

Which drug has no positive inotropic effect (beta-1)?
A. Dopamine
B. Dobutamine
C. Epinephrine
D. Phenylephrine (Neosynephrine)
E. Norepinephrine (Levophed)

A

D. Phenylephrine (Neosynephrine)

Phenylephrine is predominantly a stimulant, isoproterenol beta, NE alpha-1 alpha-2 beta-1, and epinephrine alpha-1 alpha-2 beta-1 beta 2.

28
Q

A 33-year-old otherwise healthy woman presents for an elective craniotomy. The patient undergoes general anesthesia and her ventilation is under pressure-regulated volume control (PRVC). During
surgery, an ABG was sent and shows: pH 7.52, PCO2 20 mmHg, PO2 92 mmHg, and HCO3 22 mEq/L . What is the diagnosis?
A. Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Metabolic acidosis
E. Mixed respiratory and metabolic acidosis

A

A. Respiratory alkalosis

The patient has a pure respiratory alkalosis from hyperventilation.

29
Q

A 72-year-old man presents with chest pain, syncope. dizziness, vertigo, and headache. He is admitted to the hospital where telemetry reveals intermittent episodes ofbradycardia and tachycardia. What is the most likely diagnosis?
A. Supraventricular tachycardia
B. Atrial flutter
C. Atrial fibrillation
D. Sick sinus syndrome
E. Vasovagal episode

A

D. Sick sinus syndrome

Sick sinus syndrome is due to dysfunction of the SA (sinoatrial) node and is commonly seen in the elderly. It often manifests as periods of intermittent bradycardia and tachycardia on cardiac rhythms.

30
Q

A 22-year-old man with bacterial endocarditis due to IV drug use presents with headache, confusion, and left arm weakness. He is admitted to the hospital where a head CT reveals a right parietal mass with surrounding edema. An abscess is suspected. What is the most likely bacterial agent?
A. Viridans streptococci
B. Enterococci
C. Staphylococcus aureus
D. Escherichia coli
E. Pseudomonas

A

C. Staphylococcus aureus

Staphylococcus aureus is the most common causative organism in the majority of bacterial endocarditis cases especially those associated with IV drug abuse.

31
Q

A 60-year-old woman with uncontrolled hypertension presents with acute onset right-sided weakness, aphasia, and left gaze preference. He was last seen well the evening prior to presentation. On examination, the patient has GCS of 7 and the left pupil is dilated and poorly reactive. The head CT shows a large left-sided MCA infarct. Which of the following measures most effectively reduces mortality?
A. IV mannitol 1 g/kg
B. Hyperventilation
C. IV tPA
D. Hemicraniectomy
E. Mechanical thrombectomy

A

D. Hemicraniectomy

Surgical decompression has been shown to reduce the mortality of patients with malignant cerebral edema after a large territory infarct. Hyperventilation and mannitol are temporizing. Thrombectomy should not be performed as the
infarction has been completed.

32
Q

A 62-year-old diabetic woman presents with acute onset left-sided weakness, with last known well 6 hours prior to presentation. The head CT shows a hyperdense right MCA sign with areas of hypodensity in the basal ganglia and insula. The CT perfusion imaging reveals a large area of prolonged mean transit time, reduced cerebral blood flow, but maintained cerebral blood volume. Which of the following measures has been shown to reduce mortality?
A. IV Mannitol 1 g/kg
B. Hyperventilation
C. IV tPA
D. Hemicraniectomy
E. Mechanical thrombectomy

A

E. Mechanical thrombectomy

Thrombectomy has been shown to be effective in reducing mortality and improving functional outcomes after acute large vessel occlusions. In cases of large territory penumbra, thrombectomy should be performed.

33
Q

A 13-year-old boy with sickle cell disease presents with acute left arm weakness. A head CT was performed which shows a small stroke in the MCA territory involving the internal capsule and basal ganglia. His blood pressure is 130/79, blood glucose is 152 rng/dl, and sodium of 140 mEq/L CTA was normal. The patient recovers well and visits you in clinic after having fully recovered. Which of the following interventions will reduce his risk for further strokes?
A. EncephaloduroarterioSYnagiosis (EDAS)
B. Aspirin
C. Adequate hydration
D. Insulin
E. Antihypertensive medications

A

C. Adequate hydration

Dehydration precipitates sickling of red blood cells and development of subsequent stroke.

34
Q

A 29-year-old female is postpartum day 1 from a normal uncomplicated delivery. She received epidural anesthesia during delivery and developed a post procedure CSF leak with headaches especially in an upright position. By day 2 she was scheduled to discharge but she was more obtunded in the afternoon and was difficult to arouse. A head CT as performed which reveals an intraparenchymal hemorrhage, cerebral edema, and multiple dilated vessels at the vertex. What is the most likely diagnosis?
A. Dural arterial venous fistula
B. Arteriovenous malformation
C. Cerebral sinus thrombosis
D. Brain sag Syndrome
E. Hemorrhagic Encephalitis

A

C. Cerebral sinus thrombosis

Postpartum females are at high risk for developing cerebral venous sinus thrombosis which should be suspected with severe headaches, cerebral hemorrhage (usually flame-shaped), and cerebral edema.

35
Q

For the above patient, what is the treatment of choice?
A. Craniotomy for decompression
B. Heparin drip
C. Endovascular treatment
D. Stereotactic Radiation
E. IV hydration

A

B. Heparin drip

Despite intracranial hemorrhage, anticoagulation with heparin is the treatment of choice because it reduces the venous outflow obstruction, thereby reducing cerebral edema. Endovascular therapy is used only as a last resort.

36
Q

A 65-year-old man involved in an MVC was diagnosed with an aortic injury. He became hemodynamically unstable and was taken to surgery for an exploratory laparotomy. Postoperatively he is weak in the lower extremities. The most appropriate next step is
A. MRI of the lumbar spine
B. MRI of the head
C. Reduce mean arterial blood pressure
D. Blood transfusion
E. Placement of a lumbar drain

A

E. Placement of a lumbar drain

Placement of a lumbar drain reduces intrathecal hydrostatic pressure and therefore increases spinal cord perfusion. Increasing the MAP can also be helpful.

37
Q

A 34-year-old woman presents with hypotension and a sodium of 124 mEq/L On examination, she is a thin and tan woman who appears lethargic and is hypotensive. She notes having recent weight loss and loss of appetite but is otherwise neurologically intact. Which of the following should be uspected?
A. Addison’s disease
B. Alcoholism
C. Congestive heart failure
D. SIADH
E. Hypothyroidism

A

E. Hypothyroidism

Addison’s disease presents with hypotension, hyponatremia, hyperkalemia, and skin hyperpigmentation (the precursor of ACTH also produces MSH which increases melanin on the skin).

38
Q

A 3-year-old boy is being treated for a pseudomonas infection with antibiotics. A week after initiation of treatment he begins to develop renal failure secondary to non-oliguric acute tubular necrosis. Which of the following antibiotics is the likely cause?
A. Cefuroxime
B. Penicillin
C. Tetracycline
D. Tobramycin
E. Bactrim

A

D. Tobramycin

Tobramycin is an aminoglycoside and frequently causes acute tubular necrosis in addition to hearing loss and vestibular dysfunction. Vancomycin is also nephrotoxic and ototoxic.

39
Q

A 3-year-old boy was abused and presents with multiple skull base fractures after non-accidental trauma and has a CSF leak. He develops meningitis 5 days later and antibiotics are initiated. What is the most likely causative agent?
A. Staphylococcus aureus
B. Escherichia coli
C. Streptococcus pneumoniae
D. Listeria monocytogenes
E. Enterococcus

A

C. Streptococcus pneumoniae

Streptococcus pneumoniae is the most common pathogen after skull base fractures and meningitis. A third-generation cephalosporin is usually effective for treatment.

40
Q

A 14-year-old boy with sickle cell disease presents with acute left arm weakness. A head CT was performed which shows a small stroke in the right MCA territory. CTA was within normal limits. Which of the following follow-up studies should be performed annually?
A. Transcranial Doppler
B. CTA
C. Digital subtraction angiography
D. MRI of the head
E. MRA of the head

A

A. Transcranial Doppler

Patients are recommended to be evaluated with transcranial Dopplers annually for preventive management of stroke. Exchange transfusions should be considered when there is an abnormal finding on ultrasound.

41
Q

Which Brodmann’s area of the somatosensory cortex is associated with deep pressure and joint position?
A. 1
B. 2
C. 3a
D. 3b
E. 4

A

B. 2

Brodmann’s area 4 is the motor cortex, 3a is for muscle and tendon stretch, 3b is for skin receptors (slow and rapid adapting), 1 is for rapid adapting skin (fine touch), and 2 pressure and joint position .

41
Q

Which of the following is not a Vitamin K-dependent dotting factor?
A. Factor II
B. Factor V
C. Factor VII
D. Factor IX
E. Factor X

A

B. Factor V

Vitamin K-dependent clotting factors are II (prothrombin), VII, IX, X, protein C and S.

41
Q

Which of the following nerve fiber types transmits prickling pain and temperature?
A. Ia
B. lb
C. II
D. III
E. IV

A

D. III

Type III fibers (Alpha-delta) are associated with sharp pain and temperature (cold) transmission. Type IV fibers (C) are associated with burning pain and temperature (cold and heat) sensation.

42
Q

Which of the following neurotransmitter receptors is associated with Ca++ influx and cell death?
A. Nor-epinephrine
B. Glutamate
C. Serotonin
D. Dopamine
E. GABA

A

B. Glutamate

The NMDA receptor which is inhibited by magnesium and activated by glutamate is associated with calcium influx and regulates cell death. It is both voltage-gated and ligand-gated. The non-NMDA receptors (kainate) are only ligand-gated and can also be implicated in cell death.

42
Q

Which of the following thalamic nuclei is associated with the spinothalamic tracts?
A. Ventral anterior
B. Medial dorsal
C. VPLc (ventral posterolateral, pars caudalis)
D. Pulvinar
E. Medial geniculate

A

C. VPLc (ventral posterolateral, pars caudalis)

The spinothalamic tracts relay in the VPLc, the latter projects to the sensory cortex (areas 3,1,2). The ventral spinothalamic tract also relays in the intralaminar nuclei and the periaqueductal gray.

43
Q

A 65-year-old man was diagnosed with an aortic dissection and was taken emergently to surgery for vascular repair. Surgery went uncomplicated but postoperatively the patient becomes paraplegic. What treatment strategies could have prevented these symptoms?
A. MRI of the lumbar spine prior to surgery
B. MRI of the head prior to surgery
C. Reduce mean arterial blood pressure
D. Blood transfusion
E. Distal bypass during surgery

A

E. Distal bypass during surgery

Distal bypass during aortic repair can restore spinal cord perfusion during cross clamping of the aorta. Lumbar drain or increasing MAPs can also be helpful.

44
Q

Which Rexed lamina represents the second-order neuron for fast pain transmission?
A. Lamina l
B. Lamina II
C. Lamina III
D. Lamina IV
E. Lamina V

A

A. Lamina l

Lamina I (marginal zone) transmits fast (sharp) pain while lamina II (substantia gelatinosa) transmits slow (burning) pain.

45
Q

Which of the following is not a side effect of DBS of the periaqueductal gray for treatment of chronic pain?
A. Diplopia
B. Oscillopsia
C. Fear
D. Dysphagia
E. Anxiety

A

D. Dysphagia

Dysphagia can result in dysfunction of the lower cranial nerves. The periaqueductal gray is at the level of the midbrain and is unlikely to result in dysphagia.

45
Q

Which of the following is false regarding G protein receptors in phototransduction?
A. Metarhodopsin 2 activates G protein receptors
B. The alpha subunit binds GTP
C. cGMP converts to 5’ GMP
D. There is increased current through Na channels
E. It results in an electric-graded conduction

A

D. There is increased current through Na channels

Decreased current through the cGMP activated Na+ channels, resulting in hyperpolarization. Light converts retinal rhodopsin into metarhodopsin 2. The latter activates G protein, which stimulates phosphodiesterase, thus converting cGMP to 5’GMP. Na+ channels dose, resulting in hyperpolarization and a graded electric conduction.

45
Q

A 37-year-old female presents to the ER after being found down outside a bar in the early morning. A head CT revealed a large intrapamichymal hemorrhage. She is extensor posturing. Which of the following nuclei is associated with this reflex?
A. Cochlear nucleus
B. Superior vestibular
C. Inferior vestibular
D. Lateral vestibular
E. Medial vestibula

A

D. Lateral vestibular

Lateral vestibular nucleus (Dieter’s) is involved with extensor posturing and is inhibited by the Purkinje cells of the anterior lobe of the cerebellum. This decerebrate rigidity also occurs due to loss ofinput from the rubrospinal tract.

45
Q

Which of the following afferent tracts transmit motor, premotor, and sensory information from the pons to the contralateral cerebellar hemisphere?
A. Juxtarestiform body
B. Restiform body
C. Middle cerebellar peduncle
D. Superior cerebellar peduncle
E. Dorsal columns

A

C. Middle cerebellar peduncle

The superior and inferior (restiform body) cerebellar peduncles transmit information to the cerebellum from the spinal cord input rather than the cortex. Information from different areas of the cerebral cortex terminate in the ipsilateral pontine nuclei, then cross the midline to the contralateral cerebellar hemisphere through the middle cerebellar peduncle.

46
Q

Which of the following nerve fiber type is associated with muscle spindles, annulospiral type?
A. Ia
B. lb
C. II
D. III
B. IV

A

A. Ia

Both type la (Alpha-alpha) and II (Alpha-beta-gamma) fibers are associated with transmission of neuronal signals arising from the muscle spindle, the former for annulospiral and the latter for flower-spray. Type lb is associated with Golgi tendon organ, Ill sharp pain and gamma motor neuron, and type IV burning pain

46
Q

Which of the following cells provide lateral inhibition to increase contrast in phototransduction?
A. Retinal cells
B. Horizontal cells
C. Bipolar cells
D. Amacrine cells
B. Ganglion cells

A

B. Horizontal cells

Horizontal cells transmit signals horizontally and laterally inhibit other cells to increase contrast.

46
Q

Which optic pathway projection transmits to the basal brain for behavioral functions?
A. Suprachiasmatic nudeus
B. Pretectal nudew
C. Superior colliculus
D. Ventral lateral geniculate body (LGB)
B. Dorsal lateral geniculate body

A

D. Ventral lateral geniculate body (LGB)

Ventral LGB (magnocellular, layers 1 and 2) projects to the basal brain for behavioral functions. Both ventral and dorsal (parvocellular, layers 3-6) LGB project to the primary visual cortex (area 17). Superior colliculus is involved in conjugate
eye movements, pretectal nucleus is associated with pupillary reflexes, and the suprachiasmatic nucleus regulates the circadian rhythm.

47
Q

A 16-year-old boy attends a loud concert. When he comes home his mother notices that he yells
whenever he speaks and she swpects he is having hearing difficulty. The muscle involved in a
reflex that protects the cochlea by attenuating loud sounds is
A. Muller’s
B. Short ciliary
C. Tensor veli palatini
D. Stapedius
E. Posterior belly of the digastric

A

D. Stapedius

The stapedius muscle (supplied by VII) and tensor tympani (supplied by V) are involved with the attenuation of loud noise to protect the auditory system.

47
Q

A 40-year-old man presents after a motorcycle accident. He is awake but unable to move his arms and legs and has no appreciable tone or reflexes. You suspect spinal shock. Which rellex is the first to return after conclusion of spinal shock?
A. Babinski
B. Hoffman
C. Suprapatellar
D. Abdominal
E. Bulbocavrrnosus (Osinski)

A

E. Bulbocavrrnosus (Osinski)

Osinski (bulbocavemosus) reflex involves anal sphincter contraction in response to squeezing the glans or tugging on an indwelling urinary catheter. It is the first to return after spinal shock.

48
Q

A newborn girl presents with tachypnea, hepatosplenomegaly, and ventriculomegaly. Diagnostic angiogram is shown below. Given the imaging findings (arrow), which of the following is the strangest determining factor for urgent endovascular intervention?
A. Risk of intracranial hemorrhage
B. Risk of seizures
C. Development or hydrocephalus
D. Renal failure
E. Heart failure

A

E. Heart failure

Cardiac failure in choroidal type Vein of Galen malformations (arrow) is the strongest factor for determining timing of surgical intervention.

48
Q

A 37-year-old man presents after being ejected from a vehicle at high speed. He has a dilated pupil and was given 100 g mannitol IV immediately prior to arriving at your hospital. He has a serum sodium of 131 mEq/L. The emergency medicine physician who is evaluating him is concerned about pseudohyponatremia. All of the following would lead to pseudohyponatremia, except
A. Elevated BUN (blood urea nitrogen)
B. Elevated serum glucose
C. Mannitol
D. 0.45% saline
E. Hyperproteinemia

A

D. 0.45% saline

All answers except for D can cause a pseudohyponatremia, where the sodium level when corrected for the extra water brought into the vascular space by the osmotic load is otherwise normal. 0.45% saline can cause hyponatremia by
directly diluting the sodium level and thus is not a pseudohyponatremia.

49
Q

A 45-year-old man presents with a history of elevated ICP treated with 3% hypertonic saline. The critical care nurse obtains an ABG which shows: pH 7.31, PCO2 40 mmHg, PO2 92 mmHg, and HCO3 17 mEq/L The basic metabolic panel shows serum Na 140 mEq/L, Cl 116 mEq/L, and HCO3 17 mEq/L. What is the most likely diagnosis?
A. Methanol Poisoning
B. Ethylene Glycol Poisoning
C. Hyperchloremia
D. Uremia
E. Salicylate Poisoning

A

C. Hyperchloremia

The anion gap= Na+- (Cl-+ HCO3-) = 140- (116 + 17) = 140-133 = 7 mEq/L, which is normal (<12). The patient has metabolic acidosis (low pH, low HCO3), non-anion gap. The other answers indicate an anion gap acidosis but hyperchloremia is the only non-gap acidosis. Causes of high anion gap acidosis: MUD PILES: methanol, uremia, diabetic ketoacidosis, paracetamol, isoniazid, lactic acidosis, ethylene glycol, and salicylates. Causes of non gap acidosis: USED CARP: ureterostomy, small bowel fistula, excess Cl, diarrhea, carbonic anhydrase inhibitors, Addison’s disease, renal tubular acidosis, and pancreatic fistula.

14. Neurosurgery Primary Examination Review (10 decks)

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