De Novo Nonepileptic Seizures after Cranial Surgery for Epilepsy: Incidence and Risk Factors

We evaluated the incidence of de novo nonepileptic seizures (NES), confirmed by EEG monitoring, after cranial surgery for intractable epilepsy in 228 surgery patients. Eight patients (3.5%) developed de novo NES at 6 weeks to 6 years (mean, 23 months) after surgery. Six had undergone a resection and two complete callosotomy. They did not differ from a larger surgical group with respect to sex, side of surgery, age at onset, or duration of epilepsy, Full Scale Intelligence Quotient, seizure outcome, or preoperative interictal dysphoric disorder (IDD), but there was a significant excess of postoperative IDD and operative complications (bone flap infections); the callosotomy patients had marked hemisphere disconnection syndromes. Repeat EEG videotelemetry monitoring is important to detect postoperative NES so that inappropriate therapeutic measures may be avoided. Risk factors may be exacerbation or persistence of IDD and surgical complications. The etiology of NES is discussed.