Abstracts

Rationale: We aimed to evaluate the clinical outcomes of surgical re-evaluation of patients with intractable epilepsy who were previously treated with a vagus nerve stimulation (VNS) device.

Methods: We retrospectively reviewed the medical charts of consecutive patients with intractable epilepsy with a VNS device (age ≥18 years), who presented at our level 4 epilepsy center between 2010 and 2022. Patients included in the study underwent a comprehensive pre-surgical evaluation, which included neuroimaging (MRI and PET) and non-invasive scalp EEG monitoring. Patients with VNS who were unable to complete the surgical evaluation were excluded from the analysis. Engel Classification was used to measure clinical outcomes after the surgical re-evaluation and the subsequent intervention.

Results: Our cohort included 88 patients with a mean age of 41.5 ± 13.1 years. The mean age at surgical re-evaluation and the time interval between VNS implantation and surgical re-evaluation were 34.5 ± 12.9 and 7.10 ± 5.11 years, respectively. The mean duration of follow-up after the surgical re-evaluation was 4.36 ± 3.24 years. Of the 88 patients, 54 (61%) were not considered for a second surgery and were treated by optimizing their current anti-seizure medication regimen and adjusting their VNS settings. 20 (23%) patients underwent a second neurostimulator device implantation, with DBS implanted in 6 patients (6.8%) and RNS implanted in 14 patients (16%). 12 patients (14%) underwent a resection: 8 anterior temporal lobectomies (9.1%), 2 frontal lobe resections (2.3%), 1 frontotemporal resection (1.1%), and 1 perisylvian resection (1.1%). Laser interstitial thermal therapy (LITT) ablation was used for corpus callosotomy in 1 patient (1.1%) and amygdalohippocampectomy in another (1.1%). At the most recent follow-up, 11 patients (13%) achieved Engel class 1, and 3 patients (3.4%) achieved Engel class 2 outcomes. Engel class 3 was found in 21 patients (24%), and Engel class 4 in 37 patients (42%). Of the 11 patients who achieved Engel class 1 outcome, 4 patients (36%) underwent resection, specifically an anterior temporal lobectomy.

Conclusions: Re-evaluation and surgical reconsideration of patients with intractable seizures who previously underwent VNS implantation is warranted, as additional surgical interventions could improve overall clinical outcomes. Our results demonstrate that a proportion of patients benefit from a repeat surgical re-evaluation, including a possibility of seizure freedom.

Funding: None