This is a case report of a brief episode of rather typical hypomanic s
ymptoms in the acute phase of presumed herpes simplex encephalitis in
a young woman. I infer that the hypomanic episode was triggered from t
he anterior inferomedial temporal lobe or limbic system, the presumed
cerebral substrate of the emotions in general, and review the literatu
re relating to the occurrence of hypomania associated with structural
disease of the nervous system.