Question of the Week
For July 19, 2016
An 80-year-old woman is hospitalized for dizziness and malaise. She has had several episodes of vertigo in the past several days. Her family reports that she has had persistent headaches, malaise, stiffness, anorexia, and low-grade fevers for 2 weeks.
The patient has a history of urge incontinence, osteoarthritis in the hands, hypertension, and depression. Her medications include acetaminophen, oxybutynin, hydrochlorothiazide, and citalopram.
Her temperature is 38.1°C, her heart rate is 85 beats per minute, her blood pressure is 110/65 mm Hg, and her respiratory rate is 12 breaths per minute. She has no lymphadenopathy or rash.
Her cardiorespiratory and abdominal examinations are unremarkable. Her musculoskeletal examination shows restricted range of motion to both shoulders and tenderness to palpation, without obvious effusions. Neurologic examination shows normal cognition, intact cranial nerves, and normal strength. Her gait is ataxic, and her Romberg test is positive.
MRI of the brain reveals several acute cerebellar strokes in the vertebrobasilar circulation.
Laboratory testing yields the following results:
12.0 – 16.0
Leukocyte count (per mm3)
4500 – 11,000
Platelet count (per mm3)
150,000 – 350,000
Erythrocyte sedimentation rate (mm/hr)
C-reactive protein (mg/liter)
0.08 – 3.10
Creatine kinase (U/liter)
Urinalysis is negative for white cells, leukocyte esterase, red cells, nitrites, and protein.
Which one of the following tests is most likely to be diagnostic for this patient?