Recurrent postictal psychosis after remission of interictal psychosis: Further evidence of bimodal psychosis

Purpose: To ascertain whether bimodal psychosis (i.e., independent postictal and interictal psychosis) in patients with epilepsy can be characterized by postictal psychosis that develops after interictal psychosis remits. Methods: We reviewed the records of 14 patients with bimodal psychosis treated at a national center hospital. Clinical and psychopathological characteristics of the patients were examined. Results: Among the 14 patients with bimodal psychosis, four initially had interictal psychosis, and 10 initially had postictal psychosis. That is, interictal-antecedent bimodal psychosis characterized four cases, and postictal-antecedent bimodal psychosis characterized 10 cases. Patients with interictal-antecedent bimodal psychosis composed 2.2% of the total patients with epilepsy and psychosis (n = 180) and 28.5% of total patients with bimodal psychosis. All four patients with interictal-antecedent bimodal psychosis had partial epilepsy with complex partial seizures, bilateral EEG abnormalities, and borderline (or decreased) intellectual functioning. Most of these clinical features are common to both types of bimodal psychosis. Among patients with interictal-antecedent bimodal psychosis, the mean age at the onset of the initial symptoms was 10.8 years (SD, 4.3 years) for epilepsy, 24.4 (6.1) years for interictal psychosis, and 33.8 (4.5) years for postictal psychosis. Conclusions: In a few patients, postictal psychosis develops after the remission of interictal psychosis. Interictal-antecedent bimodal psychosis is not likely a discrete entity because of several characteristics common to both types of bimodal psychosis. Patients may have greater vulnerability to psychosis and develop psychotic episodes easily, regardless of the presence of preceding seizures.