Epilepsy-related psychoses and psychotic symptoms are significantly reduced by resective epilepsy surgery and are not associated with surgery outcome or epilepsy characteristics: A cohort study.

We examine epilepsy-related psychoses and psychotic symptoms (ERPs) and the effects of epilepsy surgery on inter-ictal, aura, ictal and peri-ictal (pre- and post-ictal) psychoses. We included 189 patients with refractory epilepsy both before and 24 months after surgery. Engel's classification was the primary outcome measurement. Epilepsy surgery reduced the prevalence of ERPs from 17.5% to 4.2%, psychotic aura from 7.9% to 0.5%, ictal psychoses from 3.7% to 1.1% and peri-ictal psychoses from 4.2% to 0.5%. The prevalence of inter-ictal psychoses decreased from 5.3% to 0.5%, but 4 new cases of inter-ictal psychoses were found following surgery. Interictal dysphoric disorder significantly predicted surgery outcome. In patients with and without ERPs, epilepsy surgery induced seizure reduction in more than 90% of the cases, showing that both groups benefit equally from surgery. No associations between ERPs and epileptic characteristics were found, including laterality, type of lesion, type of epilepsy, number of seizures, duration of illness or age at onset. Epilepsy surgery significantly improves ERPs particularly psychotic aura and peri-ictal psychoses. Although inter-ictal psychoses are successfully treated, new inter-ictal psychoses appear in a few cases either as alternative psychoses or a possible switch from pre-surgery episodic into inter-ictal psychoses.