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Innumerable subacute lacunar infarcts scattered throughout the cerebellum, and a subacute lacunar infarct in the superior aspect of the right thalamus. Extensive edema in the cortex and subcortical white matter of the cerebral hemispheres, cerebellum, and pons. Moderate narrowing of the supraclinoid ICAs and carotid termini, and questionable mild focal narrowing of the middle of the basilar artery. Findings are most consistent with a cerebritis/encephalitis and vasculitis. Differential considerations include inflammatory/autoimmune cerebritis/vasculitis or infectious meningoencephalitis. Superimposed PRES and/or seizure-related changes may contribute to the edema, although some atypical features make them unlikely to be the primary pathologic process.