Mystery case: cerebral amyloid angiopathy-related inflammation.

A 59-year-old man was arrested for unruly public behavior. He was subsequently found unresponsive with bilateral upper extremity extensor posturing and lower extremity triple flexion when stimulated. Over the next 48 hours, he awoke and became belligerent. MRI revealed innumerable cortical microhemorrhages on susceptibility-weighted imaging (figure, A) and asymmetric subcortical T2 hyperintensities (figure, B) consistent with cerebral amyloid angiopathy–related inflammation (CAA-ri). With corticosteroid treatment, he rapidly became calm and conversant, returning to near his premorbid baseline with only mild residual confusion within 1 week. CAA-ri is an uncommon, possibly autoimmune variant of CAA characterized by cognitive changes, seizures, headaches, and often, responsiveness to immunosuppressive therapy.