Effectiveness of neuromodulation in patients with drug-resistant epilepsy after failed surgical treatment

Abstract

Background. In case of ineffective conservative antiepileptic therapy, surgical treatment aimed at removing the epileptogenic focus may be applied. Resection procedures allow to eliminate seizures in most patients, but in 20–30% cases they persist or recur, thereby proposing to use some neuromodulation.Objective: to assess effectiveness of neuromodulation in patients with drug-resistant epilepsy (DRE) after failed resection surgical interventions.Material and methods. A retrospective data analysis was carried out involving 23 DRE patients who had undergone vagus nerve stimulation (VNS) or deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) or hippocampus (HP) after failed surgeries. The VNS system was implanted in 18 (78.3%) patients, the HP-DBS system – in 3 (13.0%), and the ANT-DBS system – in 2 (8.7%). The results after surgical interventions were assessed according to the Engel scale, VNS therapy – by the McHugh (MH) scale, DBS therapy – by the degree of reduced seizure rate as a percentage. The average follow-up was 56.5 months.Results. Patients with implanted VNS system were found to have the outcome presented as MH Ia–IIb in 3 (16.7%) cases, MH IIIa–IIIb in 10 (55.5%) cases, MH IV–V in 5 (27.8%) cases. In HP-DBS group, 2 out of 3 patients showed a decline in seizure rate by more than 50% from the baseline level, and 1 patient experienced an improvement in seizure severity. In the ANT-DBS group, one patient had a 60% reduction in seizure rate and an improvement in seizure severity, another one showed no change in seizure rate.Conclusion. Neuromodulation in DRE patients can significantly lower seizure rate in more than half of patients after failed surgical treatment.