Cerebral amyloid angiopathy-related inflammation (CAARI) has been described as a distinct syndrome with subacute cognitive decline or seizure symptoms. Previous studies have established diagnostic criteria for this entity and proposed a treatment strategy. However, the precipitating factors behind developing CAARI in a subset of patients with CAA are unclear. We present a case of CAARI in a patient with no underlying diagnosis of dementia that was found to be positive for HHV-6 in serum and CSF and treated successfully with steroids.

An 83-year-old woman presented with a first-time generalized tonic-clonic seizure with postictal confusion. On presentation, her systolic blood pressure was elevated at 150-170, and she was tachycardic to 160 with a temperature of 38.4. A contrasted MRI brain showed multifocal vasogenic edema, sulcal FLAIR hyperintensity, and innumerable lobar microhemorrhages. Black blood contrast MRI brain angiogram was unremarkable, with no evidence of vasculitis. At this point, the patient had clinically improved but remained slightly encephalopathic with word-finding difficulties. Continuous EEG monitoring showed diffuse background slowing. Initial CSF studies revealed an isolated mildly elevated protein of 49 and negative cytology. Therefore, based on the clinical and radiographic evidence, a decision was made to undergo five days of high-dose methylprednisolone for probable CAARI. However, days later, HHV-6 in CSF resulted positive with 249 copies/ml, and a serum sample showed 1100 copies/ml.