Hippocampal deep brain stimulation for drug-resistant epilepsy: Insights from bilateral temporal lobe and posterior epilepsy cases

Purpose: This study evaluates the long-term efficacy of hippocampal deep brain stimulation (Hip-DBS) in patients with drug-resistant epilepsy (DRE), specifically focusing on bilateral temporal lobe epilepsy (BTLE) and posterior epilepsy (PE). Methods: A retrospective analysis was conducted on 15 DRE patients (11 BTLE, 4 PE) who underwent bilateral Hip-DBS at Samsung Medical Center over an eight-year period. Medical records, seizure diaries, and neuropsychological assessments were reviewed. The surgical and follow-up protocols were adapted from our previous clinical research. Results: The median seizure reduction rate was 77.8 % for disabling seizures (DS) and 47.9 % for non-disabling seizures (NDS). Subgroup analysis revealed a 77.8 % reduction in DS for BTLE patients and 68.8 % for PE patients. The overall responder rate was 86.7 % for DS and 50 % for NDS. Neuropsychological evaluations showed stable cognitive functions post-treatment, with a non-significant trend towards improvement in non-verbal and visuo-spatial cognitive domains. Conclusion: This study provides preliminary evidence supporting the efficacy of Hip-DBS in reducing seizure frequency in both BTLE and PE patients, with a more pronounced effect on disabling seizures. The potential cognitive preservation and possible enhancement in specific domains warrant further investigation. Despite limitations such as the retrospective design and reliance on self-reported seizure frequencies, these findings encourage further exploration of Hip-DBS as a treatment modality for DRE, particularly in cases where resective surgery is contraindicated.