[Psychotic disorder revealing epilepsy linked to a dysembryoma of the left hippocampus]

Psychotic symptoms are a rare but well-known complication of epilepsy. The prevalence is estimated between 4 and 9%.

We report a case of a 40-year-old patient, unrecognized epileptic, who presented an acute psychotic syndrome which seemed to be of functional origin, the EEG performed during the episode, and the cerebral CT scan being normal. Nevertheless, the clinical presentation, especially the sudden ending of delusions, led to further investigations. Careful history taking and repeated EEG recordings allowed the diagnosis of partial epilepsy that had begun 17 years earlier and symptomatic of a dysembryoplastic tumour of the left hippocampus revealed by MRI.

Search for an epileptic origin of an acute psychotic syndrome must always be undertaken by systematic EEG. The possibility of a symptomatic temporal tumor must not be overlooked.