Hypomanic symptoms caused by herpes simplex encephalitis.

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