Electroencephalogram and evoked potentials in the primate model of viral encephalitis.

Squirrel monkeys with induced canine distemper virus (CDV) encephalitis showed characteristic clinical signs such as seizures or myoclonus, with EEGs showing periodic synchronized discharge (PSD). Histopathologically, there was gliosis and neuronal degeneration diffusely distributed in both the gray and white matters in the subacute phase, the lesions resembling those found in childhood acute viral encephalitis and subacute sclerosing panencephalitis (SSPE). The auditory brain-stem response (ABR) changes were remarkable in the subacute phase, and the recovery of latency was correlated with survival. The visual evoked potential (VEP) abnormalities disappeared in the acute phase and appeared again with delayed latency in the subacute stage. One monkey which did not show clinical signs but had the pathological changes showed the VEP abnormality. These data suggest that the evoked potentials are helpful in judging the prognosis, and that this model is useful for the analysis of the pathogenesis of viral encephalitis.