Psychotic episodes during zonisamide treatment. 
Several articles have appeared over the last years devoted to mental side effects during zonisamide (ZNS) treatment.  In this study, we were particularly interested in psychotic episodes.  Seventy-four epileptic patients with a history of ZNS treatment were surveyed retrospectively over the period spanning 1 March 1984 to 30 June 1994.  They were divided into two groups according to the presence or absence of psychotic episodes during ZNS treatment.  We analysed various factors pertaining to psychotic episodes during ZNS treatment.  Of the 74 patients 14 had psychotic episodes.  We found that the incidence of psychotic episodes during ZNS treatment was several times higher than the previously reported prevalence of epileptic psychosis, and that the risk of psychotic episodes was higher in young patients.  In 13 patients, psychotic episodes occurred within a few years of commencement of ZNS.  In children, obsessive-compulsive symptoms appeared to be related to psychotic episodes.  It is important to terminate ZNS as soon as possible if psychotic episodes develop and never restart, even if seizures become worse.  It cannot definitely be proved that ZNS causes psychotic episodes, as information on mental side effects during ZNS monotherapy is scant, but it does appear likely that ZNS contributes to psychotic episodes during polytherapy.