Late-onset persistent visual hallucinations with epileptiform discharge.

We report the case of a 58-year-old female without a history of psychosis or epilepsy presenting with abrupt late-onset persistent visual hallucinations that had prominent epileptiform discharges with a diffuse sharp and slow wave complex on electroencephalography. Except for the visual hallucinations, other psychotic symptoms and epileptic seizures, such as disturbance of consciousness and convulsion, were not observed. The epileptiform discharge disappeared within 20 days after initiation of treatment with sodium valproate. Clinical improvement commenced after the electroencephalography improvement was complete. The cause remains obscure, but it was suggested that there were some organic factors in the aetiology of this late-onset visual hallucination.