Question 1

A 25-year-old bull rider developed neck pain and vertigo after landing head first when he was thrown from a bull. Physical examination in the emergency department revealed that the man had decreased pain and temperature sense on the left half of his face and right side of his body, a Horner's syndrome on the left, and hoarseness and unsteady gate. An occlusion in which of the following vessels would most likely explain the deficits experienced by this patient?

A) Posterior inferior cerebellar artery
B) Anterior inferior cerebellar artery
C) Basilar artery
D) Vertebral artery
E) Anterior spinal artery

A

Accepted Answer

The symptoms described are consistent with lateral medullary syndrome (Wallenberg syndrome), which is typically caused by an occlusion of the posterior inferior cerebellar artery (PICA). The deficits such as decreased pain and temperature sensation on one side of the face and the opposite side of the body, Horner's syndrome, hoarseness, and ataxia are characteristic of this condition.

Question 2

A 74-year-old man was playing poker with his neighbors when he noticed that he was having difficulty picking up his cards with his left hand. Determining that he was fatigued from his day of yard work, he went home and to bed. The next morning he staggered and nearly fell making his way to the bathroom. Concerned about her husband's condition his wife takes him to the emergency room. Neurological examination indicates that the man is unable to elevate and adduct his right eye; however, abduction and depression of his right eye is normal. The eye movement abnormalities in this patient are most indicative of which of the following?

A) Right trochlear nerve palsy
B) Right abducens nerve palsy
C) Right oculomotor nerve palsy
D) Left trochlear nerve palsy
E) Left oculomotor nerve palsy

C

Accepted Answer

The inability to elevate and adduct the right eye, while still being able to abduct and depress it, suggests a right oculomotor nerve palsy. The oculomotor nerve (cranial nerve III) innervates most of the extraocular muscles, including those responsible for elevation and adduction of the eye. Abduction is controlled by the abducens nerve (cranial nerve VI), and depression in the abducted position is primarily controlled by the superior oblique muscle, which is innervated by the trochlear nerve (cranial nerve IV).

Question 3

A 29-year old man was brought to the emergency department following a motor vehicle collision. He has normal pupillary light reflexes, unsteady gait, and loss of pain and temperature sense on the left side of his body and right side of his face. He most likely has a lesion in which of the following areas?

A) Periventricular area of the rostral midbrain
B) Tegmentum of the rostral pons
C) Ventrolateral medulla
D) Periventricular medulla
E) Thalamus bilaterally

B

Accepted Answer

B

Question 4

After suffering a stroke, a 62-year-old man is unable to abduct his right eye. In addition, he has muscle weakness in his upper and lower left limb as well as the right side of his face. The combined deficits in this patient can most accurately be attributed to damage in which of the following vessels?

A) Long circumferential branches of the basilar artery
B) Superior cerebellar artery
C) Anterior inferior cerebellar artery
D) Paramedian branches of basilar artery
E) Short circumferential branches of basilar artery

Accepted Answer

The patient's symptoms indicate a combination of cranial nerve and long tract signs, which are characteristic of a brainstem stroke. The inability to abduct the right eye suggests damage to the abducens nerve (CN VI), which controls the lateral rectus muscle. The muscle weakness in the upper and lower left limbs indicates a contralateral hemiparesis, which is a sign of damage to the corticospinal tract. The right-sided facial weakness can be attributed to involvement of the facial nerve (CN VII) or corticobulbar tract affecting the lower motor neurons or their pathways that innervate the facial muscles. These combined deficits are most consistent with a lesion in the paramedian branches of the basilar artery, which supply the medial part of the brainstem, where these pathways are located.

Question 5

A 52-year-old woman sustains a hemorrhagic stroke to the left anterior inferior cerebellar artery. Which of the following symptoms is this patient most likely to experience?&#10;A) Unilateral hearing loss&#10;B) Inability to abduct the ipsilateral eye&#10;C) Contralateral Horner's syndrome&#10;D) Bilateral trochlear nerve palsy&#10;E) Ipsilateral tongue deviation

Accepted Answer

Unilateral hearing loss is the most likely symptom because the anterior inferior cerebellar artery (AICA) supplies blood to parts of the inner ear, including structures involved in hearing. A hemorrhagic stroke affecting this artery can therefore lead to unilateral hearing loss on the same side as the stroke.

Question 6

After graduation an 18-year-old girl and her boyfriend ride his motorcycle to the lake to meet some friends. As they travel the winding road to the lake, a logging truck turns in front of them, causing them to crash. Upon reaching the hospital the girl's upper and lower extremities are extended, and her head is arched back. The posturing exhibited by this patient suggests the damage within the brain is most likely

A) Extending to a supratentorial location
B) Extending to an infratentorial location
C) Extending through the foramen magnum
D) Extending from the pons to the medulla
E) Extending from the pons to the cerebellum

Accepted Answer

The posturing described is decerebrate posturing, which indicates damage to the brainstem, typically at or below the level of the red nucleus, which is infratentorial.

Question 7

A 22-year-old woman complains to her family physician of headaches and difficulty looking up. She explains that the symptoms have developed gradually over a period of several weeks. Physical examination reveals that the woman has large irregular pupils, paralysis of upward gaze in both eyes, impaired convergence, and bilateral ptosis. A magnetic resonance imaging scan is most likely to show a tumor in which of the following areas?

A) Ventral midbrain
B) Caudal medulla
C) Pontine tegmentum
D) Pineal region

Accepted Answer

The symptoms described, including difficulty looking up (paralysis of upward gaze), impaired convergence, and bilateral ptosis, along with large irregular pupils, suggest Parinaud's syndrome. This syndrome is often associated with a tumor in the pineal region, which can compress the tectal plate of the midbrain, affecting the vertical gaze centers.

Question 8

Which of the following postures is indicative of someone with compression at the level of the mesencephalon?&#10;A) Upper and lower extremities are extended&#10;B) Upper and lower extremities are flaccid&#10;C) Upper and lower extremities are flexed&#10;D) Upper extremities are extended and lower extremities are flexed&#10;E) Upper extremities are flexed and lower extremities are extended

Accepted Answer

Compression at the level of the mesencephalon (midbrain) often results in decorticate posturing, where the upper extremities are flexed and the lower extremities are extended.

Deck 3: Gross Anatomy and General Organization of the Central Nervous System