Palliative surgery for drug resistant epilepsy in adult patients. A systematic review of the literature and a pooled analysis of outcomes

Background: Several types of palliative surgery to treat drug resistant epilepsy (DRE) have been reported, but the evidence that is currently available is insufficient to help physicians redirect DRE patients to the most appropriate kind of surgery. Methods: A systematic search in the PubMed and Scopus databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines to compare different clinical features, outcomes and complications of adult patients submitted to callosotomy, vagal nerve stimulation (VNS), multiple subpial transections (MST), deep brain stimulation (DBS) or responsive neurostimulation (RNS). Results: After screening 3447 articles, 36 studies were selected, including the data of 1628 patients: 76 were treated with callosotomy, 659 were treated with VNS, 416 were treated with DBS, and 477 were treated with RNS. No studies including patients treated with MST met the inclusion criteria. The global weighted average seizure frequency reduction was 50.23%, while the global responder rate was 52.12%. There were significant differences among the palliative surgical procedures in term of clinical features of patients and epilepsy, seizure frequency reduction and percentage of responders. Complications were differently distributed as well. Conclusions: Our analysis highlights the necessity of prospective studies, possibly randomized controlled trials, to compare different forms of palliative epilepsy surgery. Moreover, by identifying the outcome predictors associated with each technique, the "best responder" may be profiled for each procedure.