A man in his 50s with an unremarkable medical history began experiencing vertigo 1 week after a viral upper respiratory tract infection. During the next 2 months, vertigo was followed by diplopia, projectile vomiting, dysarthria, scanning speech, urinary retention, and ataxia. He was worked up and diagnosed with a stroke. After quadriparesis developed, the patient was transferred to a tertiary-care hospital. On examination, he was nearly locked in and only able to communicate using voluntary upgaze. This was complicated by spontaneous upbeating nystagmus. He was intubated for airway protection, and a lumbar puncture revealed 0 white blood cells, 0 red blood cells, protein levels of 21 mg/dL (to convert to grams per liter, multiply by 10), and glucose levels of 65 mg/dL (to convert to micromoles per liter, multiply by 0.0555). The IgG index was elevated to 0.7 (reference, 0.3-0.6) and there were 5 unique oligoclonal bands in the cerebrospinal fluid that were not present in the serum (reference, 0-1). Brain magnetic resonance imaging revealed selective T2 signal hyperintensity in the transverse fibers of the pons (Figure, A) with extension along the pontocerebellar tracts into the cerebellar hemispheres (Figure, B), consistent with demyelination. There was no postgadolinium enhancement, and the corresponding T1 signal was hypointense (Figure, C and D).
Schubert RD, Richie MB. Human Immunodeficiency Virus Presenting as Progressive Multifocal Leukoencephalopathy Restricted to the Posterior Fossa. JAMA Neurol. Published online March 27, 2017. doi:10.1001/jamaneurol.2017.0085