Section 8

Question 1

Meissner’s corpuscles have all of the following characteristics, except
A. Presence in the dermal papillae
B. Receptors for touch
C. Rapidly adapting
D. Small receptive field
E. Sending signals through type IV fibers

Answer 1

E. Sending signals through type IV fibers

Meissner’s corpuscles transmit touch and vibration and send signals through type II fibers. Type IV fibers are mainly for pain and temperature.

Question 2

The best target for DBS for essential tremors is
A. Subthalamic nucleus (STN)
B. Vim of thalamus
C. Globus pallidus intemus (GPi)
D. Nucleus accumbens septi
E. Subcallosal cingulate gyrus

Answer 2

B. Vim of thalamus

DBS targets for: Parkinsonism –> SIN, essential tremors –> Vim, dystonia –> GPi, nucleus accumbens septi –> obsessive-compulsive disorder (OCD), subcallosal cingulate gyrus –> depression.

Question 2

In the dorsal horn of the spinal cord, pain sensation is transmitted by
A. Substance P and glutamate
B. Substance P and acetylcholine
C. Substance P and serotonin
D. Serotonin and glutamate
E. Norepinephrine and enkephalins

Answer 2

A. Substance P and glutamate

The neurotransmitters for pain in the dorsal horn are substance P (chronic pain, burning, slow) and glutamate (acute pain, sharp, fast). EnkephaIins are secreted by interneurons and inhibit pain.

Question 2

Succinylcholine is a(n)
A. Ganglionic blocker
B. Depolarizing neuromuscular blocker
C. Competitive neuromuscular blocker
D. Muscarinic acetylcholine receptor inhibitor
E. Acetylcholinesterase inhibitor

Answer 2

B. Depolarizing neuromuscular blocker

Succinylcholine is a paralytic used with general anesthesia, works by persistent depolarization of the neuromuscular junction. Pentolinium is a ganglionic (nicotinic acetylcholine receptor) blocker used to treat hypertension. Curare derivatives are competitive neuromuscular blockers. Atropine is a muscarinic acetylcholine receptor inhibitor. Acetylcholinesterase inhibitors (anticholinesterases),
like neostigmine, are used to treat myasthenia gravis.

Question 2

Peritumoral edema in meningiomas strongly correlate with high expression of
A. Epithelial membrane antigen (EMA)
B. Brain-derived neurotrophic factor (BDNF)
C. Vascular endothelial growth factor (VEGF)
D. Progesterone
E. Chondroitinase

Answer 2

C. Vascular endothelial growth factor (VEGF)

Meningiomas with severe peritumoral edema express high levels of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs).

Question 3

All of the following statements are true regarding
Renshaw cells, except
A. Interneurons in the anterior horn of the spinal
cord
B. Neurotransmitter serotonin
C. Efferents to alpha motor neurons
D. Afferents from alpha motor neurons
E. Inhibitory

Answer 3

B. Neurotransmitter serotonin

Renshaw cells are interneurons in the Rexed laminae VII and VIII in the spinal cord. They provide recurrent inhibition to the alpha-motor neuron. They release glycine, which opens chloride channels. Strychnine is a glycine antagonist; it causes rigidity while tetanus prevents the release of glycine.

Question 3

After a severe motor cycle accident, a patient has
paralysis of the deltoid, infraspinatus, and biceps.
The lesion most likely localizes to which part of the brachia) plexus?
A. Musculocutaneous n
B. Lateral cord
C. Upper trunk
D. Middle trunk
E. Posterior cord

Answer 3

C. Upper trunk

The upper trunk (C5, C6) of the brachial plexus divided into suprascapular n (S) (supraspinatus and infraspinatus), posterior division (P) (axillary n, deltoid), and anterior division (A) (musculocutaneous n, biceps), hence the mnemonic SPA.

Question 3

In the previous patient, pseudomeningoceles are
found on CT-myelogram. The most appropriate
treatment is
A. Nerve grafting
B. Direct repair
C. Tube repair
D. Nerve transfers
E. None of the above

Answer 3

D. Nerve transfers

Pseudomeningoceles most likely signify brachial plexus avulsion. Since these are preganglionic lesions, the best treatment involves nerve transfers. These include ulnar n fascicle to musculocutaneous n (Oberlin transfer), intercostal nn to musculocutaneous n, triceps branch (ofradial n) to
axillary n, and spinal XI to suprascapular n.

Question 4

Paccioni granulations are involved in
A. Cutaneous touch sensation
B. Hearing
C. Vision
D. CSF production
E. CSF absorption

Answer 4

E. CSF absorption

Paccioni granulations are arachnoid villi that filter the cerebrospinal fluid from the subarachnoid space to the venous sinuses.

Question 4

The Golgi tendon organ sends its signals through
which type of fibers?
A. Ia
B. lb
C. II
D. III
E. IV

Answer 4

B. lb

Golgi tendon organ is stimulated by active muscle contraction or strong passive stretch. It sends signals through lb (Aa) fibers at 120 m/s. This results in stimulation of Renshaw cells which in turn inhibit a-motor neurons by releasing glycine
which opens chloride channels.

Question 4

Frohse arcade can cause entrapment of
A. Suprascapular n
B. Ulnar n
C. Anterior interosseous n (AIN)
D. Posterior interosseous n (PIN)
E. Median n

Answer 4

D. Posterior interosseous n (PIN)

The arcade of Frohse is the edge of the supinator and can compress the PIN. The suprascapular n can be compressed by the suprascapular ligament, the ulnar n by the Osborne band, the arcade of Struthers, or in the Guyon’s canal, the AIN by the
pronator teres or the flexor digitorum superficialis (sublime) arch, and the median n by the ligament of Struthers, pronator teres, sublime arch, or transverse carpal ligament.

Question 4

Regarding core competencies, an awareness of the larger context of health care and an ability to call on resources is called
A. Practice-based learning and improvement
B. Systems-based practice
C. Interpersonal and communication skills
D. Professionalism
E. Patient care

Answer 4

B. Systems-based practice

The 6 Accreditation Council for Graduate Medical Education (ACGME) core competencies are:

Question 5

The organ of Corti responsible for hearing is
located on the
A. fympanic membrane
B. Vestibular (Reissner’s) membrane
C. Basilar membrane
D. Superior olivary nudeus
E. Inferior collicullus

Answer 5

C. Basilar membrane

The organ of Corti is composed of hair cells responsible for hearing. These are located on the basilar membrane that separates scala tympani from scala media and their cilia project into the tectorial membrane. Activation of the hair cells
stimulates the cochlear nerve endings. The vestibular (Reissuer’s) membrane separates scala media from scala vestibuli.

Question 6

The main mechanism of formation of secondary
glioblastoma multiforme (GBM) is
A. TP53 mutation
B. LOH lOq
C. tp19q deletion
D. PTEN mutation
E. EGFR amplification

Answer 6

A. TP53 mutation

TP53 mutations are early and frequent genetic alterations in the pathway leading to secondary glioblastomas (65%) while PTEN mutation (25%) and EGFR amplification (36%) occur in primary GBM. LOH 10q is common in both. Co-deletion ofl pl 9q occurs in oligodendrogliomas.

Question 6

Which of the following proteins is the product of
tuberous sderosis 1 (TSCl) and is located on chromosome 9?
A. Hamartin
B. Tuberin
C. Neurofibromin
D. Tau
E. Alpha-synudein

Answer 6

A. Hamartin

HamartinisthebyproductoITSCl ( chromosome9) and tuberin is from TSC2 (chromosome 16). Neurofibromin is associated with neurofibromatosis. Tau protein is associated with
Alzheimer’s disease causing neurofibrillary tangles. Alpha-synuclein is found in Lewy bodies seen in Parkinson’s disease.

Question 6

Tetrodotoxin is a powerful blocker of
A. Cl- channels
B. Ca++ channels
C. K+ channels
D. Na+ channels

Answer 6

D. Na+ channels

Tetrodotoxin (TIX). a powerful poison in the Spheroides rubripes (puffer fish), selectively blocks voltage-dependent sodium channels. It prevents depolarization and propagation of nerve action potential. Saxitoxin found in shellfish has a similar effect and causes paralytic shellfish poisoning.

Question 6

Of the medulloblastoma subgroups, which one has the best prognosis?
A. WNT
B. Sonic hedgehog (SHH)
C. Group 3
D. Group 4

Answer 6

A. WNT

In the medulloblastoma subtypes, WNT has the best prognosis with a 5-year overall survival of 95% in children and 100% in adults. Group 3 has the worst prognosis.

Question 6

The depolarization part of the nerve action potential is caused by
A. K+ influx
B. K+ effux
C. Ca++ influx
D. Na+-K+ pump
E. Na+ influx

Answer 6

E. Na+ influx

Rush of Na+ inside the nerve causes its depolarization. Repolarization is caused by K+ efflux while the Na+ channels are dosed. The Na+-K+ pump is an ATP-dependent mechanism to maintain a high concentration of Na+ outside the cell and K+ inside the cell at the resting state. The axon hillock has the largest concentration of Na+ channels and is the most excitable part of the neuron.

Question 6

Neurotransmitter release from the presynaptic
terminal is caused by
A. Na+ influx
B. Ca++ influx
C. K+ influx
D. K+ efflux
E. Closure of voltage-gated Na+ channels

Answer 6

B. Ca++ influx

Once the action potential reaches the axon terminal, it activates Ca+ channels. Ca++ influx causes synaptic vesicles to fuse with the presynaptic membrane through SNARE complex and release neurotransmitters by exocytosis. Neurotransmitters are inactivated by reuptake or degradation.
In Lambert-Eaton myasthenic syndrome (LEMS), antibodies inhibit presynaptic voltage-gated calcium channels (VGCC) while botulinum toxin inhibits SNARE.

Question 7

The muscle stretch reflex includes all of the following components and features, except
A. Muscle spindle
B. Dorsal root ganglion
C. Interneuron
D. Anterior horn cell
E. It is ipsilateral and affects the same segment

Answer 7

C. Interneuron

The muscle stretch reflex is monosynaptic, no intemeurons are involved.

Question 7

The rate-limiting step in dopamine synthesis uses
A. Tyrosine hydroxylase
B. L-Aromatic amino acid decarboxylase (AADC)
C. Dopamine P-hydroxylase (DBH)
D. Phenylethanolamine N-methyltransferase
(PNMT)

Answer 7

D. Phenylethanolamine N-methyltransferase
(PNMT)

Tyrosine hydroxylase mediates the transformation of tyrosine to L-dihydroxyphenylalanine (L-DOPA). It is the rate-limiting step in catecholamine synthesis because TH saturates with
tyrosine. L-Aromatic amino acid decarboxylase transforms L-DOPA to dopamine (DA). Dopamine beta-hydroxylase transforms DA to norepinephrine (NE). Phenylethanolamine N-methyltransferase transforms NE to epinephrine.

Question 8

During EMG, the H-reflex
A. Is produced by supramaximal stimulation
B. Bypasses the spinal cord
C. Occurs 3-6 ms after the stimulation
D. Is the electrical equivalent of the muscle
stretch reflex

Answer 8

D. Is the electrical equivalent of the muscle stretch reflex

The H-reflex (Hoffmann’s reflex) on EMG is the electrical equivalent of the muscle stretch reflex. It occurs 28-35 ms after submaximal stimulation, goes through the spinal cord, and afferents travel through Ia fibers. The M-wave is a direct motor response at 3-6 ms that bypasses the spinal cord.
Supra.maximal stimulation is used to generate an F-response through antidromic activation of alpha-motor neurons.

Question 9

All of the following statements are true regarding
the climbing fibers in the cerebellum, except
A. They arise from the inferior olivary complex
B. They are inhibitory
C. They travel through the inferior cerebellar
peduncle
D. They synapse on Purkinje cell dendrites

Answer 9

B. They are inhibitory

The dimbing fibers are excitatory, secrete glutamate, arise from the contralateral inferior olivary complex, travel through the inferior cerebellar peduncle, and synapse on Purkinje cell dendrites and to a lesser extent granule cell parallel fibers.
basket and stellate cells. In the cerebellum, climbing fibers, mossy fibers, and granule cells are excitator.

Question 10

Bill’s bar separates
A. The cochlear n from the inferior vestibular n
B. The facial n from the cochlear n
C. The superior and inferior vestibular nn
D. The facial n from the inferior vestibular n
E. The facial n from the superior vestibular n

Answer 10

E. The facial n from the superior vestibular n

Bill’s bar separates facial n from superior vestibular n.

Question 11

All of the following statements are true regarding
the pelvic incidence, except
A. It is the angle between the perpendicular to
the sacral plate at its midpoint and the line
connecting the sacral plate midpoint to the
axis of the femoral heads
B. It is an important parameter of sagittal
balance
C. It changes as the person ages
D. It should be within <10 degrees of lumbar lordosis
E. Its normal value is 55 degrees ± 10 degrees

Answer 11

C. It changes as the person ages

The pelvic incidence is essentially constant.

Question 12

Nitric oxide (NO) has all of the following features,
except
A. It is formed by nitric oxide synthetase (NOS)
B. It is stored in presynaptic vesicles
C. It is an unconventional neurotransmitter
D. It causes vasodilatation
E. It causes intestinal relaxation

Answer 12

B. It is stored in presynaptic vesicles

Nitric oxide is an unconventional transmitter since it is not stored in cells, is not released by exocytosis, does not act on specific receptors, and lacks a specific inactivation process.

Question 13

The plateau phase of the cardiac Purkinje cell
action potential is caused by
A. Na+ influx
B. Na+ efflux
C. Ca++ influx
D. Ca++ efflux
E. K+ infiux

Answer 13

C. Ca++ influx

The plateau phase in the cardiac muscle action potential is caused by a slow Ca++ influx along with a K+ efflux. Depolarization is caused by Na+ influx, while repolarization is caused by K+ efflux.

Question 14

Chorea is caused by
A. Loss of gamma-aminobutyric acid (GABA)
outflow from the corpus striatum to the globus pallidus externus (GPe).
B. Loss of dopamine (DA) output from substantia
nigra (SN) to the corpus striatum.
C. A lesion in the subthalamic nucleus (STN).
D. Decreased glutamate output from the cerebral cortex to the putamen.
E. Degeneration of the cerebellar dentate nucleus.

Answer 14

A. Loss of gamma-aminobutyric acid (GABA) outflow from the corpus striatum to the globus pallidus externus (GPe).

Chorea is caused by loss of gamma-aminobutyric acid (GABA) outflow from the striatum to the globus pallidus externus (GPe). Parkinson’s disease is caused by loss of dopamine (DA) output from substantia nigra (SN) to the striatum. Hemiballismus is caused by an injury in the contralateral STN.

Question 14

The re-rupture rate after untreated aneurysmal
subarachnoid hemorrhage at 2 weeks is
A. 1%
B. 5%
C. 10%
D. 20%
E. 50%

Answer 14

D. 20%

The re-rupture rate after untreated aneurysmal subarachnoid hemorrhage is 20% at 2 weeks (highest within the first 24 hours) and 50% at 6 months.

Question 15

At 2 years, surgical treatment of symptomatic
carotid a stenosis >70% reduces the stroke risk from
A. 5% to 0%
B. 11% to 5%
C. 15% to 9%
D. 26% to 9%
E. 26% to 2%

Answer 15

D. 26% to 9%

Based on NASCET (North American Symptomatic Carotid Endarterectomy Trial), surgical treatment of symptomatic carotid a stenosis <70% resulted in reducing the stroke risk from 26% to 9% at 2 years. Based on ACAS (Asymptomatic Carotid Atherosclerosis Study), carotid endarterectomy
resulted in reduced stroke risk from 11% to 5% over 5 years for stenosis <60%.

Question 16

Tetraethylammonium (TEA) blocks which channels?
A. Na+
B. Cl-
C. Ca++
D. K+

Answer 16

C. Ca++

Tetraethylammonium is a ganglion blocker. It inhibits nicotinic acetylcholine receptors and K+ channels in autonomic ganglia. It can cause vasodilatation.

Question 17

The endolymph is present in all of the following
structures, except
A. Membranous labyrinth
B. Utricle
C. Saccule
D. Semicircular canals
E. Scala vestibuli

Answer 17

E. Scala vestibuli

The endolymph fills up the membranous labyrinth, including scala media. Its composition is similar to the intracellular fluid and it plays a role in both the auditory and the vestibular systems. The perilymph is between the membranous labyrinth and the bony labyrinth. It fills up the scala vestibuli and the scala tympani.

Question 18

Which of the following drugs decreases acetylcholine degradation and can be used to treat myasthenia gravis?
A. Reserpine
B. Phentolamine
C. Pyridostigmine
D. Pyridoxine
E. Methacholine

Answer 18

C. Pyridostigmine

Pyridostigmine is a reversible anticholinesterase used for myasthenia gravis. Reserpine is an antihypertensive drug that blocks the synthesis and storage of norepinephrine and serotonin. Phentolamine is also an antihypertensive through
competitive non-selective a-adrenergic antagonism. Methacholine is a parasympathomimetic which causes bronchospasm, and is used to test for asthma. Pyridoxine is vitamin 86.

Question 19

The effects of cocaine in the central nervous system are mediated by
A. Increased dopamine (DA)
B. Decreased dopamine
C. Increased acetylcholine
D. Decreased acetylcholine
E. Decreased norepinephrine (NE)

Answer 19

A. Increased dopamine (DA)

Cocaine blocks the uptake and transport of dopamine (DA), norepinephrine (NE), and serotonin (5-HT). It produces its “high” effects by causing excessive levels of dopamine in the brain. It is also used as a local anesthetic by blocking Na+ channels and as a vasoconstrictor.

Question 20

The receptors for sweating are
A. Muscarinic acetylcholine
B. Nicotinic acetylcholine
C. Alpha adrenergic
D. Beta adrenergic
E. Serotonergic

Answer 20

A. Muscarinic acetylcholine

Sweating, despite being a sympathetic function, is mediated by muscarinic acetylcholine receptors.

Question 21

Nimodipine reduces the severity of neurological
deficits from vasospasm by
A. Direct neuromuscular blockade
B. Ca++ channel blockade
C. Sympathetic ganglion blockade
D. Alpha receptor blockade
E. Parasympathomimetic effect

Answer 21

B. Ca++ channel blockade

Nimodipine is a L-type voltage-gated ca++ channel blocker, thus inhibiting vascular smooth muscle contraction. It should be given prophylactically after aneurysmal subarachnoid hemorrhage to help prevent serious consequences of cerebral vasospasm. Dose is 60 mg orally every 4 hours for 3 weeks.

Question 22

The neuroleptic effects of haloperidol are caused by
A. Blocking histamine receptors
B. Blocking serotonin receptors
C. Blocking a-adrenergic receptors
D. Blocking dopamine receptors
E. Blocking acetylcholine receptors

Answer 22

D. Blocking dopamine receptors

Haloperidol is a powerful neuroleptic (antipsychotic), used to treat schizophrenia, by blocking dopamine receptors in the limbic system. Side effects are caused by blocking histaminergic, serotonergic, and a-adrenergic receptors.

Question 23

All of the following statements are true regarding
the carotid sinus reflex, except
A. Caused by stimulation of baroreceptors in the
carotid bulb
B. Mediated through cranial nerve XI
C. Relay in the brain stem
D. Causes bradycardia
E. Can cause death

Answer 23

B. Mediated through cranial nerve XI

Carotid sinus reflex afferents: IX (Hering’s n), efferents X

Question 23

All of the following statements are true regarding
Merkel’s discs, except
A. Present in the dermal papillae
B. Sense vibrations
C. Slow to adapt
D. Have a small receptive field
E. Signals travel through type II fibers

Answer 23

B. Sense vibrations

Merkel’s discs transmit touch and pressure sensations.

Question 23

Serotonin syndrome can be caused by any of the
following drugs, except
A. Duloxetine (Cymbalta)
B. Venlafaxine (Effexor)
C. Swnatriptan (Imitrex)
D. Fluoxetine (Prozac)
E. Phenytoin (Dilantin)

Answer 23

E. Phenytoin (Dilantin)

Serotonin syndrome is a serious interaction when two or more serntonergic drugs are used. Symptoms include agitation, dilated pupils, tachycardia, diarrhea, sweating, fever, seizures, and death. causes include Prozac (fluoxetine) (a selective serotonin reuptake inhibitor), Cymbalta and Effexor (5-HT and NE reuptake inhibitors), amitriptyline (a tricydic antidepressant). monoamine oxidase inhibitors, and anti-migraine medications (lmitrex). Phenytoin is an anti-epileptic drug that does not increase serotonin levels, it works by Na+ channel blockade.

Question 23

Pedicle subtraction osteotomy (PSO) produces
what degree of correction in sagittal balance?
A. 5°
B. 10°
C. 30°
D. 45°
E. 60°

Answer 23

C. 30°

PSO creates a wedge in the vertebral body and achieves 30°-35° of sagittal balance correction. It is usually performed in the mid-lumbar spine (13 or 12). Ponte osteotomy creates a wedge in the lamina and facets and achieves 10°-15° correction per level. Smith-Peterson osteotomy (SPO) in addition creates a distraction opening of the anterior longitudinal ligament, thus increasing the risk of vascular injuries. For optimal deformity correction, pelvic incidence-lumbar lordosis should be <10°.

Question 23

The most common neurological complication after lateral trans-psoas procedures for lumbar spine is
A. Hip flexor and quadriceps weakness
B. Hamstring weakness
C. Footdrop
D. Plantar Hexion weakness
E. Hip extensor weakness

Answer 23

A. Hip flexor and quadriceps weakness

The incidence of hip flexor and quadriceps weakness after lateral trans-psoas procedures (DLIF: direct lateral interbody fusion, or XLIF: extreme lateral interbody fusion) is 25%. This is
due to damage to the lumbar plexus and/or the psoas muscle.

Question 24

All of the following are true regarding Cowden’s
syndrome, except
A. PTEN mutation
B. Breast cancer
C. Thyroid cancer
D. Medulloblastoma
E. Lhermitte-Dudos disease

Answer 24

D. Medulloblastoma

Cowden’s syndrome is an autosomal dominant multiple hamartoma syndrome with mutation of PTEN, a tumor-suppressor gene on chromosome 10q. It affects 1 in 200,000 people. It can cause Lhermitte-Dudos disease, breast, thyroid, and uterine cancer.

Question 24

The normal atlantodental interval (ADI) in an adult
is less than
A. 1 mm
B. 3 mm
C. 5 mm
D. 7 mm
E. 9 mm

Answer 24

B. 3 mm

The normal ADI is less than 3 mm in adults, 5 mm in children. However, recent CT data suggest that the normal interval in most normal adults is less than 2 mm.

Question 24

Sectioning the corpw callosum in a right-handed
person can result in all of the following, except
A. Left-hand motor apraxia to verbal commands
B. Left auditory suppression
C. Anomia for objects in the left visual field
D. Anomia fur objects in the left hand when the
eyes are dosed
E. Left constructional apraxia

Answer 24

E. Left constructional apraxia

One of the main risks of corpus callosotomy is disconnection syndrome. Constructional apraxia is inability to perform tasks requiring spatial processing (e.g., copying geometric forms). This is processed in the right hemisphere. Therefore, in
disconnection syndrome, the left hand is intact but the right hand is affected. A, C and Dare left hemispheric functions, they are normal on the right side of the body and lost on the left side. If different words are presented to each ear simultaneously (dichotically), the left ear signal is suppressed by the stronger contralateral signal.

Question 24

Injury to the cerebellar vermis causes
A. Truncal ataxia
B. Dysmetria
C. Hypertonia
D. Intention tremors
E. Nystagmus

Answer 24

A. Truncal ataxia

Injury to the vermis causes truncal ataxia and hypotonia. Dysmetria and intention tremors are caused by injury to the neocerebellum (lateral zone and dentate nucleus). Nystagmus is caused by injury to the flocculonodular lobe.

Question 25

The efferent component of the light reflex arises
from which nucleus of the oculomotor n?
A. Edinger- Westphal nucleus
B. Central nucleus
C. Medial nucleus
D. Lateral nucleus

Answer 25

A. Edinger- Westphal nucleus

Parasympathetic preganglionic efferents of the light reflex arise from the Edinger-Westphal nucleus of the oculomotor n (III). They travel bilaterally through the inferior division of III to relay in the ciliary ganglion and supply the constrictor pupillae muscle causing the direct (ipsilateral) and consensual (contralateral) light reflex. The central nucleus supplies the levator palpebrae superioris bilaterally, the medial nucleus the contralateral superior rectus, and the lateral nucleus the ipsilateral inferior oblique, medial rectus, and inferior rectus.

Question 25

At. normal intraaanial pressure. autoregu]ation
maintains a constant cerebral blood flow for changes in the mean arterial blood pressure between
A. 20 and 60 mmHg
B. 40 and 80 mmHg
C. 60 and 160 mmHg
D. 80 to 180 mmHg
E. 100-180 mmHg

Answer 25

C. 60 and 160 mmHg

Cerebral autoregulation maintains a constant cerebral blood flow despite fluctuations in mean arterial blood pressure (MAP): If the systemic blood pressure drops, the brain vessels dilate to accommodate more blood; ifthe blood pressure is
high the cerebral blood vessels constrict. Autoregulation fails at extremes of MAP. The exact number varies according to the source. Some say that the range of autoregulation is MAP 60-160 mmHg, some MAP 50-150 mmHg, and others CPP 60-160
mmHg. Note that CPP = MAP - ICP and MAP= DBP + 1/3 (SBP - DBP); where CPP, cerebral perfusion pressure; ICP, intracranial pressure; DBP, diastolic blood pressure; SBP, systolic blood pressure.

Question 26

Myelination in the central nervous system occurs
by which cells?
A. Astrocytes
B. Oligodendrocytes
C. Microglia
D. Schwann cells
E. Ependymal cells

Answer 26

B. Oligodendrocytes

Oligodendrocytes myelinate the CNS, while Schwann cells myelinate the peripheral nervous system. The transition zone between central myelin and peripheral myelin is called the Obersteiner-Redlich zone. This was once thought to be where vestibular nerve schwannomas originate. However, most tumors actually originate lateral to this zone.

Question 27

Which of the following cdh are an important component of the blood-brain barrier?
A. Astrocytes
B. Oligodendrocytes
C. Microglia
D. Neurons
E. Ependymal cells

Answer 27

A. Astrocytes

The main components of the blood-brain barrier (BBB) are vascular endothelial cells with their tight junctions and basement membranes as well as astrocytic foot processes. Most circumventricular organs are deficient in blood-brain barrier: pineal gland, median eminence and posterior pituitary, area postrema (paired), organum vasculosum of the lamina terminalis, and subfomiceal organ. The only circumventricular organ with intact BBB is the subcommissural organ.

Question 28

A 34-year-old male with history of diabetes mellitus, alcohol abuse, and hemochromatosis presents with right eye sweling, proptosis, and ophthalmoplegia together with diabetic ketoacidosis. This progressed to blindness within 3 days. He then developed headache, nuchal rigidity, and confusion. The patient died within 3 weeks despite maximum surgical and medical management The MRI images are shown below. The most likely diagnosis is
A. Staphylococcal brain abscess
B. Meningococral meningitis
C. Herpes encephalitis
D. Mucomycosis
E. Gliomatosis cerebri

Answer 28

D. Mucomycosis

Aggressive rhinocerebral mucormycosis (zygomycosis or phycomycosis) occurs in patients with poorly controlled diabetes mellitus. a. Coronal T2 fat suppressed MRI shows involvement of bilateral nasal sinuses and frontal lobes. b. Axial cut shows diffusion restriction. Treatment includes surgical debridement and antifungals. Prognosis is poor.
Herpes encephalitis preferentially affects medial temporal lobes. Staphylococcus aureus is common after neurosurgical procedures or trauma. Meningococcal meningitis is common in school age ( children and young adults), especially in poor crowded areas like sub-Saharan Africa. The incidence is less
after widespread vaccination

Question 29

A 68-year-old male presents 6 hours after dense left hemiparesis with the following CT head. The patient is awake and follows commands with the right side. The most important next step in this patient management that will affect his functional recovery is
A. Right decompressive hemicraniectomy
B. Endovascular coiling
C. Intra-arterial thrombolysis
D. Intravenous tPA
E. Intravenous heparin

Answer 29

C. Intra-arterial thrombolysis

Hyperdense right MCA sign seen on the CT is a sign of ischemic stroke. The patient’s symptoms are >4.5 hours which is out of the window for IV tPA (0.9 mg/kg [maximum 90 mg], 10% of dose as IV bolus over t minute). He is still a candidate for intra-arterial revascularization (tPA or mechanical
thrombectomy). Decompressive hemicraniectomy is not indicated since the patient is wide awake with no midline shift.

Question 29

In the following endoscopic view of the lateral ventricle, the fomix is represented by number
A. 1
B. 2
C. 3
D. 4
E. 5

Answer 29

A. 1

Endoscopic view of the right lateral ventride. 1, fornix: forms the superior and anterior boundary of the foramen of Monro (4). The choroid plexus is observed between the septum pellucidum (3) and thalamus (2); 5, head of caudate.

Question 30

The nerve supply to the skin of the dorsum of the
first web space of the foot is
A. Sural n
B. Saphenous n
C. Medial plantar n
D. Superficial peroneal n
E. Deep peroneal n

Answer 30

E. Deep peroneal n

The majority of the dorsum of the foot is supplied by the superficial peroneal n, except for the first web space, which is supplied by the deep peroneal n. The sural n supplies the lateral aspect of the foot toward the little toe. The saphenous n (femoral n branch) supplies the area of the medial malleolus. The medial and lateral plantar nn (tibial n branches) supply the sole of the foot.

Question 31

The best medical treatment of Paget’s disease of
the spine includes
A. Parathyroid hormone (PTH)
B. Bisphosphonates
C. Calcium supplements
D. Methotrexate
E. Azathioprine

Answer 31

B. Bisphosphonates

Bisphosphonates like pamidronate as well as calcitonin (salmon-derived) are used to treat severe Paget’s disease. Patients usually have hypercalcemia and hypercalciuria and are prone to kidney stones. Lab work also shows increased
serum alkaline phosphatase and urine hydroxyproline. PTH increases serum calcium and is contraindicated.

Question 32

Which of the following nuclei correspond with Lateral amygdala to cerebral cortex?
A. Glycine
B. GABA
C. Acetylcholine
D. Dopamine
E. 5-HT (serotonin)

Answer 32

C. Acetylcholine

Acetylcholine is the main output from the lateral amygdala to the cerebral cortex. This is lost in Alzheimer’s disease. Aricept (donepezil) is an acetylcholinesterase inhibitor that can improve symptoms of dementia.

Question 33

Which of the following nuclei correspond with
Dorsal raphe nucleus?
A. Glycine
B. GABA
C. Acetylcholine
D. Dopamine
E. 5-HT (serotonin)

Answer 33

E. 5-HT (serotonin)

Output from the dorsal raphe nucleus (DRN) to substantia nigra indudes 5-HT and cholecystokinine and to the corpus striatum includes 5-HT and enkephalins. DRN is involved in non-REM sleep.

Question 34

Which of the following nuclei correspond with
Globus pallidus externus to subthalamic nucleus?
A. Glycine
B. GABA
C. Acetylcholine
D. Dopamine
E. 5-HT (serotonin)

Answer 34

B. GABA

Output from GPe to STN is GABA, from GPe to GPi is GABA and substance P, and from GPi to thalamus GABA.

Question 35

Which of the following nuclei correspond with
Renshaw cells?
A. Glycine
B. GABA
C. Acetylcholine
D. Dopamine
E. 5-HT (serotonin)

Answer 35

A. Glycine

Renshaw cells are inhibitory to motor neurons in the spinal cord through the neurotransmitter glycine, which increases chloride influx. Tetanus inhibits the release of glycine, while strychnine inhibits glycine receptors, both leading to contractures.

Question 36

Which of the following nuclei correspond with
Substantia nigra, pars compacta?
A. Glycine
B. GABA
C. Acetylcholine
D. Dopamine
E. 5-HT (serotonin)

Answer 36

D. Dopamine

Substantia nigra pars compacta exerts its effect on corpus striatum through dopamine (DA1 is excitatory and DA2 is inhibitory). Tyrosine hydroxylase catalyzes the rate-limiting step in catecholamine synthesis. SN degeneration causes
Parkinson’s disease. Treatment includes L-dopa.