Thread: A 22-year-old woman has noticed blurry vision. On examination her pupils are equal in size.

Cranial Nerves- MCQs


Question 7

The patient has difficulty visually tracking a horse and rider moving from left to right. Which one of the supranuclear gaze systems is affected?


A. Frontal gaze center.
B. Parietal-occipital gaze center.
C. Vestibuloocular system.
D. Occipital mesencephalic pathways.

Answer:

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The correct answer is B.

The parietal-occipital gaze center is important for smooth pursuit eye movements used to keep a moving image centered on the fovea.

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Cranial Nerves- MCQs


Question 8

A 60-year-old man has decreased sensation to pin prick over the left cheek but the forehead and jaw area are normal. This finding is most consistent with a sensory loss of which one of the following?


A. Left ophthalmic division of the 5th cranial nerve.
B. Left mandibular division of the 5th cranial nerve.
C. Left maxillary division of the 5th cranial nerve.
D. Left descending tract of the 5th cranial nerve.

Answer:

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The correct answer is C.

The sensory field for the maxillary division of the 5th cranial nerve is the cheek and the roof of the mouth.

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Cranial Nerves- MCQs


Question 9

On examination a patient has the following on the Rinne-Weber test: The tuning fork on the forehead lateralizes to the right ear and air conduction is greater than bone conduction in both ears. These findings are most consistent with what type of hearing loss?


A. Conductive hearing loss.
B. Neurosensory hearing loss.
C. Combined conductive and neurosensory hearing loss.
D. Cannot determine type of hearing loss without further testing.

Please cross check your Diognosis:

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The correct answer is C.

The sensory field for the maxillary division of the 5th cranial nerve is the cheek and the roof of the mouth.

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Cranial Nerves- MCQs


Question 10

A 38-year-old woman has noticed asymmetry of her smile and drooling from the left side of her mouth. On examination, she can wrinkle her forehead bilaterally. She most likely has which one of the following?


A. Right 5th cranial nerve palsy.
B. Left 7th cranial nerve palsy.
C. Right central 7th paresis.
D. Left central 7th paresis.
E. Right 7th cranial nerve palsy.
F. Left 5th cranial nerve palsy.

Please cross check your Diognosis:

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The correct answer is D.

The patient has sparing of the frontalis muscle so this is an upper motor lesion affecting the left side of the face. The lesion is in the corticobulbar tract coming from the right cerebral cortex.

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Cranial Nerves- MCQs


Question 11

When the patient sticks out her tongue, it deviates to the right. This finding is most likely secondary to which one of the following?


A. Left 12th cranial nerve palsy.
B. Right 12th cranial nerve palsy.
C. Bilateral 12th cranial nerve palsies.
D. Right 10th cranial nerve palsy.
E. Left 10th cranial nerve palsy.

Please cross check your Diognosis:

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The correct answer is B.

The tongue deviates toward the side of the abnormal 12th cranial nerve.

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Cranial Nerves- MCQs


Question 12

The patient has difficulty seeing objects on the left side of space. He closes one eye, then the other, and it doesn't make any difference. He cannot see things superiorly or inferiorly on the left. Where is the lesion that has caused the patient's problem?


A. Optic chiasm.
B. Left optic nerve.
C. Right optic nerve.
D. Left optic radiation.
E. Right optic tract.

Please cross check your Diognosis:

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The correct answer is E.

Because the optic tract is posterior to the optic chiasm the fibers that are contained in it "see" the same side of space although from different eyes. So a lesion of the right optic tract would result in a left hemianopsia that is present when testing each eye together or separately.


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Cranial Nerves- MCQs


Question 13

A lesion of the right medial longitudinal fasciculus (MLF) would cause which one of the following?


A. Incomplete abduction of the left eye.
B. Incomplete adduction of the right eye.
C. Incomplete adduction of the left eye.
D. Incomplete abduction of the right eye.
E. Incomplete adduction of both eyes.

Please cross check your Diognosis:

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The correct answer is B.

A lesion of the right MLF would cause incomplete adduction of the right eye because the MLF is the tie rod connecting the 6th cranial nerve nucleus with the contralateral 3rd nerve nucleus. This is called internuclear ophthalmoplegia (INO).


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Cranial Nerves- MCQs


Question 14

A patient has excessive nasal air escape when saying "ka, ka, ka." Then when he says "ah" there is incomplete elevation of the palate. When you gag him, there is a strong gag reflex. The most likely cause of this patient's problem is which one of the following?


A. Unilateral lower motor neuron lesion affecting cranial nerves 9 and 10.
B. Unilateral upper motor neuron lesion affecting cranial nerves 9 and 10.
C. Bilateral lower motor neuron lesion affecting cranial nerves 9 and 10.
D. Bilateral upper motor neuron lesion affecting cranial nerves 9 and 10.

Please cross check your Diognosis:

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The correct answer is D.

Patients with a bilateral upper motor weakness will lack voluntary movement of the palate but reflex activity will be preserved and even be hyperactive ( just like hyperreflexia in the upper motor neuron syndrome).


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Cranial Nerves- MCQs


Question 15

A 60-year-old male has a stroke which gives him a right 5th cranial nerve lesion. What would you expect to see on examination?


A. Jaw deviation to the right on opening to resistance.
B. Jaw deviation to the left on opening to resistance.
C. A positive jaw jerk.
D. An incomplete opening of the jaw to resistance.

Please cross check your Diognosis:

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The correct answer is A.

The jaw deviates toward the side of the lesion because of the unopposed action of the pterygoid muscle on the normal side.


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Which of the following findings suggests an opiate overdose?

A. Anion gap metabolic acidosis with a normal lactate
B. Hypotension and bradycardia in an alert patient
C. Mydriasis
D. Profuse sweating and drooling
E. Therapeutic response to naloxone

Answer / Explanation:

[HIDE]E. Therapeutic response to naloxone

Opiate overdose falls broadly into a toxidrome characterized by physiologic depression and sedation. If a history is obtained suggesting a toxic ingestion or injection, then the diagnosis is straightforward. However, this history is often absent and it can be a challenge initially to differentiate opiate toxicity from other central nervous system (CNS) and physiologic depressants. Therefore, naloxone should always be given as a diagnostic and therapeutic trial under circumstances of unexplained altered mental status, especially in the presence of coma or seizures. An immediate clinical improvement characterizes opiate overdose.

In opiate overdose, abnormal vital signs occur exclusively as a result of central respiratory depression and the accompanying hypoxemia. Low blood pressure in an alert patient should prompt a search for an alternative explanation for the hypotension. An anion gap metabolic acidosis with normal lactate is seen in syndromes such as methanol or ethylene glycol ingestion: mental status change usually precedes vital sign changes, and vital signs are often discordant as a result of physiologic adjustments to the severity of the acidosis. Mydriasis is a result of stimulant use. Miosis is associated with CNS depression. Sweating and drooling are manifestations of cholinergic agents such as muscarinic and micotinic agonists.[/HIDE]

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