Hypoperfusion following encephalitis: SPECT with acetazolamide.

At 4 weeks and 8 months following initial symptoms, we performed single-photon emission computed tomography (SPECT) with acetazolamide (ACZ) testing in a patient recovering from acute encephalitis, possibly acute disseminated encephalomyelitis (ADEM). Both regional hypoperfusion at baseline and diminished cerebrovascular reserve were seen after focal hyperintensities had disappeared in magnetic resonance imaging (MRI). The time course of SPECT abnormalities reflected the clinical course more closely than the time course of MRI abnormalities. Thus, persistent cerebral circulatory impairment probably contributed to cognitive and language deficits observed at the subacute stage.