[Subacute encephalitis/encephalopathy with residual cognitive deficit].

We studied clinical features of 5 patients with subacute encephalitis/encephalopathy with residual cognitive deficit. In all patients, impairment of consciousness was mild at the onset, progressed between 4 and 15 days after the onset, and reached its peak at 6-18 days after the onset. Neuroradiological or electrophysiological examinations at the onset showed normal or mildly abnormal findings. In accordance with the clinical deterioration, brain atrophy was detected on cranial magetic resonance imaging (MRI) in 3 patients, and electroencephalogram revealed slowing of the background activities in all patients. Single photon emission computed tomography (SPECT) showed hypoperfusion in the fronto-temporal areas in all patients at the recovery stage. Three patients had severe mental deficits, and the other two had mild cognitive deficit. Motor impairment was observed in one patient.