Case 346

History A 66-year-old man with a history of hypertension presented with left-sided jaw jerking, repetitive movements, aphasia, and dysarthria. He was afebrile and in no acute distress, with mild hypertension (153/81 mm Hg). Routine laboratory studies were unremarkable. Brain MRI showed multiple nonenhancing supratentorial, cortical, and subcortical hyperintensities on T2-weighted fluid-attenuated inversion recovery images, which were nonspecific for infectious, inflammatory, vascular, or neoplastic etiologies. CT of the chest, abdomen, and pelvis and MRI of the cervical and thoracic spine were unremarkable. CT angiography of the head and neck showed no areas of stenosis or occlusion. Extensive infectious, autoimmune, and paraneoplastic serologic tests were negative, including serum acetylcholinesterase, antinuclear antibody, erythrocyte sedimentation rate, C-reactive protein, aquaporin 4 and myelin oligodendrocyte glycoprotein (MOG) antibodies, treponemal testing, Tropheryma whipplei, human immunodeficiency virus, tick-borne disease panel, and COVID-19. Lumbar puncture showed 2% neutrophils (reference range,