Impact of Failed Intracranial Epilepsy Surgery on the Effectiveness of Subsequent Vagus Nerve Stimulation

Abstract

Using the Cyberonics registry, Amar and colleagues reported poorer efficacy of vagus nerve stimulation (VNS) in patients who failed intracranial epilepsy surgery (IES). To study the impact of failed IES and other surrogate marker of severe epilepsy on VNS effectiveness in a large cohort with treatment-resistant epilepsy (TRE). We retrospectively reviewed 376 patients (188 female patients; 265 adults; mean age, 29.4 years at implantation) with TRE who underwent VNS implantation between 1997 and 2008 and had at least 1 year of follow-up. One hundred ten patients (29.3%) had failed ≥ 1 prior craniotomies for TRE, and 266 (70.7%) had no history of IES. The mean duration of VNS therapy was 5.1 years. Patients with prior IES were more commonly male and adult, had a greater number of seizure types, and more commonly had focal or multifocal vs generalized seizures (P < .05). There was no significant difference in the mean percentage seizure reduction between patients with and without a history of IES (59.1% vs 56.5%; P = .42). There was no correlation between type of failed IES (callosotomy vs resection) and seizure reduction with VNS therapy. Failed IES did not affect the response to VNS therapy. Unlike prior reports, patients with callosotomy did not respond better than those who had resective surgery. Nearly 50% of patients experienced at least 50% reduction in seizure frequency. For patients with TRE, including patients who failed cranial epilepsy surgeries, VNS should be considered a palliative treatment option.