Effect of vagal nerve stimulation on patients with bilateral temporal lobe epilepsy

Abstract

Objective

To investigate the effects of vagus nerve stimulation (VNS) on the seizure frequency in patients with drug-resistant epilepsy (DRE) and bilateral temporal lobe epilepsy (bi-TLE). Additionally, we aimed to determine the safety of VNS and its side effects.

Methods

Our retrospective study included 17 patients with bi-TLE who underwent VNS-device implantation at our center from 1997 to 2019. The main outcome was a reduction in seizure frequency. Bitemporal cases were confirmed using scalp electroencephalography (EEG) or invasive electroencephalography (iEEG).

Results

The median age at seizure onset was 18 years. Bi-TLE was confirmed by scalp EEG in 47 % and by iEEG in 53 % of the patients. The median follow-up period was 36 months. The median seizure frequency per month before and after VNS was 9.5 (IQR = 4.3–35.3) and 2 (IQR = 0.8–4.2), respectively. Compared to baseline, 70.5 % of the patients achieved ≥ 50 % reduction in seizure frequency, whereas 35.3 % experienced either no or minimal reduction in seizure frequency. The response rate (>50 % reduction in seizure frequency) was 87.5 % in patients who underwent scalp EEG and 55.5 % in those who underwent iEEG. For VNS treatment, the median follow-up was at 36 months (IQR = 17–46.5). Adverse effects were observed in 59 % of the patients, including cough and hoarseness.

Discussion

Therapeutic choices are limited in cases of drug-resistant bi-TLE. Our study on VNS-device implantation in bi-TLE suggests a positive outcome.