A 45-year-old woman is evaluated in hospital. She has a history of HIV managed with HAART therapy and TMP/SMX. Her CD4 count is 87/μL.

Which of the following is the most likely explanation for this patient’s presentation?

A) Acute CNS infection
B) Hyperproliferation of B cells
C) Liquefaction
D) Reactivation of latent infection
E) T cell-mediated immune response

A 6-year-old boy is brought to the pediatric neurologist for a follow-up appointment. He has a several-month history of difficulty with upward gaze. A sagittal MRI is shown. A disruption of which of the following is most likely to be seen in this patient?

A) Circadian rhythm
B) Finger-to-nose test
C) Globus pallidus internus stimulation
D) Recognizing familiar faces
E) Romberg test

A 31-year-old woman comes to the physician because of a 2-month history of an intractable need to move her legs and feet at night in bed. This has awoken her husband from sleep on numerous occasions and they have started sleeping in separate rooms. Hemoglobin is 10 g/dL. MCV is 72 fL. Vitals are normal. Which of the following is the most likely explanation for this patient’s presentation?

A) Decreased tyrosine hydroxylase activity
B) Decreased glutaminergic activity on the striatum
C) Decreased subthalamic nucleus activity
D) Increased globus pallidus internus activity
E) Parkinson disease

A 19-year-old man comes to the physician for a 4-month history of frequently burning himself on the stove without realizing it until later. He describes diminished awareness of hot and cold sensations in his upper extremities. On examination, he has bilateral muscle wasting of the hand muscles, with decreased strength when gripping objects. Neurologic testing shows absent pain and temperature sensation across both shoulders and arms, while vibration and position sense remain intact. Reflexes are brisk in the upper extremities. He denies trauma, but recalls that his symptoms began gradually and have steadily worsened. Which of the following is the most likely diagnosis?

A) Chiari type I
B) Chiari type II
C) Dandy-Walker
D) Lou-Gehrig disease
E) Sirenomelia

A 68-year-old woman is brought to emergency by her husband for a 20-minute episode of numbness of her left leg and disorientation to person, place, and time. She has long-standing hypertension managed with hydrochlorothiazide and nifedipine. A non-contrast CT of the head is performed. Which of the following brain locations is most likely to be affected in this patient?

A) Left lateral hemisphere; anterior to central sulcus
B) Left lateral hemisphere; posterior to central sulcus
C) Left medial hemisphere; anterior to central sulcus
D) Left medial hemisphere; posterior to central sulcus
E) Right lateral hemisphere; anterior to central sulcus
F) Right lateral hemisphere; posterior to central sulcus
G) Right medial hemisphere; anterior to central sulcus
H) Right medial hemisphere; posterior to central sulcus

A 72-year-old man is brought to hospital by his wife after a 30-minute episode of confusion and disorientation that was associated with the right side of his face and right arm becoming weak. He has a history of hypertension managed with hydrochlorothiazide. Physical and neurologic examination shows a slightly sluggish patient with no overt abnormalities. Temperature is 98.2 F, HR 72, RR 16, BP 140/90. Which of the following anatomic locations is the most likely downstream site of the thromboembolus in this patient?

A) Anterior cerebral artery; anterior to central sulcus; lateral hemisphere
B) Anterior cerebral artery; anterior to central sulcus; medial hemisphere
C) Anterior cerebral artery; posterior to central sulcus; lateral hemisphere
D) Anterior cerebral artery; posterior to central sulcus; medial hemisphere
E) Middle cerebral artery; anterior to central sulcus; lateral hemisphere
F) Middle cerebral artery; anterior to central sulcus; medial hemisphere
G) Middle cerebral artery; posterior to central sulcus; lateral hemisphere
H) Middle cerebral artery; posterior to central sulcus; medial hemisphere
I) Posterior cerebral artery

A 16-year-old boy is brought to the physician for a 4-month history of progressively worsening changes in his vision. He says he feels slightly “crowded” and has occasionally bumped into pillars in the bus station during busy commutes. Which of the following is the most likely embryologic etiology of this patient’s findings?

A) 2nd pharyngeal arch maturation
B) 3rd and 4th pharyngeal pouch migration
C) Ectoderm of anterior pituitary
D) Endoderm of foramen cecum
E) Roof of primitive oropharynx

A 55-year-old man is brought to hospital by his girlfriend for a 3-hour episode of confusion and unusual behavior. Vitals are: temp 102.1 F, HR 80, RR 16, BP 135/85. Past medical history is remarkable for dyslipidemia managed with a low-dose statin. He does not take blood pressure medication. HbA1c at his last office visit was sub-6%. Non-contrast CT of the head shows no abnormalities. CSF analysis shows glucose and protein within the normal range; lymphocytes are elevated, with RBCs at 30/hpf. Which of the following is the most likely explanation for this patient’s findings?

A) DNA virus; enveloped; double-stranded linear
B) Gram-negative diplococcus
C) Gram-positive diplococcus
D) RNA virus; non-enveloped; single-stranded positive-sense non-segmented
E) Yeast demonstrating narrow-based budding on India ink and mucicarmine preps

A 3-month-old boy is brought to the physician due to several days of poor feeding, weak cry, and progressive generalized weakness. The parents report the baby has been increasingly constipated and now appears “floppy.” On examination, the infant has diminished gag reflex and decreased muscle tone throughout. Which of the following best describes the mechanism responsible for this presentation?

A) Blocks acetylcholine receptors at the neuromuscular junction
B) Inhibits presynaptic calcium influx
C) Inhibits presynaptic release of glycine
D) Inhibits synaptobrevin
E) Targets elongation factor-2 (EF-2)

A 46-year-old man is brought to the physician by his girlfriend 1-hour after having a tonic-clonic seizure that self-resolved after about 10 seconds, but nevertheless has scared both of them. Past medical history is unremarkable. He takes no medications. Vitals are: temperature 98.7 F, RR 12, HR 76, BP 130/80. Laboratory studies show mild eosinophilia. A CT of the head is shown.

Which of the following is most likely to be part of this patient’s history?

A) Bear meat consumption
B) Beef consumption
C) Fish consumption
D) Pork consumption
E) Walking barefoot