Long-term significance of postictal psychotic episodes I. Are they predictive of bilateral ictal foci?

OBJECTIVE

The aim of this study was to determine the degree to which postictal psychotic episodes (PIPE) are predictive of bilateral independent ictal foci.

METHODS

This was a retrospective study of 18 consecutive adults with a partial seizure disorder and PIPE (study group) and 36 patients with a partial seizure disorder but without PIPE (control group). The two groups were compared with respect to the number and location of ictal foci identified with video/EEG monitoring, seizure type, etiology, age at seizure onset, duration of seizure disorder, MRI abnormalities, and psychiatric history prior to the index video/EEG monitoring (other than PIPE). Statistical analyses consisted of logistic regression models, one to identify the variables predictive of bilateral ictal foci and the other to identify the variables predictive of PIPE.

RESULTS

The occurrence of PIPE (P<0.0001) and cryptogenic partial epilepsy (P=0.004) was predictive of bilateral independent ictal foci in univariate analyses. In multivariate analyses, cryptogenic partial epilepsy was the only significant variable (P=0.03). Conversely, bilateral independent ictal foci on video/EEG monitoring (P<0.0001) and having secondarily generalized tonic-clonic seizures (P=0.035) were independent predictors of the development of PIPE in univariate and multivariate analyses. Surgery was performed in 20 controls and 3 patients with PIPE; 17 controls and 2 patients with PIPE became seizure-free.

CONCLUSIONS

The presence of PIPE appears to be a predictor of bilateral ictal foci.