Postictal psychosis (PIP) represents 25% of the psychoses seen in epileptic patients. A high frequency of bilateral independent epileptiform activity has been observed in patients with PIP. The objective of this study was to determine the frequency of PIP in patients with temporal lobe epilepsy (TLE) who underwent video-EEG monitoring and to investigate possible differences between PIP and control patients.
Methods: Clinical, electroencephalographic and neuroimaging data of 5 PIP patients with TLE were compared with data of 50 patients with TLE without psychotic antecedents. Patients with a past history of interictal psychosis were excluded.
Results: From 55 patients, 5 were patients with PIP and 50 controls. 31 (62%) were men, 9 (16.4%) had a previous history of encephalitis and 6 (10.9%) of status epilepticus. The mean age was 42.2 years (S.D. 12.93). Mean age at epilepsy onset was 16.95 years (S.D. 12.93) and mean seizure frequency 5seizures/month (S.D. 1.87). The frequency of PIP was 5/55 (9.1%). Previous history of status epilepticus was more frequent in PIP patients than in controls (p: 0.019). PIP patients more frequently had a non-lateralizing ictal EEG than controls (p: 0.001). Bitemporal lobe dysfunction revealed by neuropsychological studies was greater than expected by the observed lesion on MRI studies in patients with PIP. Moreover, the presurgical study was less conclusive in PIP than in control patients (p: 0.049).
Conclusions: PIP is observed in up to 9% of patients with TLE undergoing video-EEG monitoring and most often develops in patients with bitemporal lobe dysfunction.