We investigated the prevalence of post–epilepsy surgery psychogenic nonepileptic seizures (PNES) in patients with drug-resistant epilepsy and the possible influence of risk factors on these seizures.
In this retrospective study, we examined data from all patients with a clinical diagnosis of drug-resistant epilepsy who underwent epilepsy surgery at Graduate Hospital and the Jefferson Comprehensive Epilepsy Center between 1986 and 2016. Postsurgical outcome was identified for up to 15 years after surgery. Diagnosis of PNES was verified in the epilepsy monitoring unit with video–electroencephalography (EEG) ictal recording. Potential associated factors were assessed by comparing patients with or without postoperative PNES.
A total of 1,105 patients were studied; 697 patients had postoperative seizures, and, of these, 27 patients (3.9%) had documented PNES after surgery. A full-scale intelligence quotient (IQ) <80 was significantly associated with post-epilepsy surgery PNES (odds ratio [OR] 2.89, p = 0.007, 95% confidence interval [CI] 1.33–6.29). A history of a preoperative psychiatric diagnosis was also significantly associated with post–epilepsy surgery PNES (OR 4.67, p = 0.0001, 95% CI 2.01–10.82). Other factors were not significantly associated with post–epilepsy surgery PNES.
Post–epilepsy surgery PNES should be considered when patients report recurrent seizures after epilepsy surgery. Although these seizures probably occur relatively infrequently, attention to factors such as appearance of new ictal behaviors, a preoperative history of a psychiatric disorder, and a low full-scale IQ should raise suspicion and lead to appropriate diagnostic measures.