Neocortical electrical stimulation for epilepsy: Closed-loop versus open-loop

The aim of this review is to evaluate whether open-loop or closed-loop neocortical electrical stimulation should be the preferred approach to manage seizures in intractable epilepsy. Twenty cases of open-loop neocortical stimulation with an implanted device have been reported, in 5 case studies. Closed-loop stimulation with an implanted device has been investigated in a larger number of patients in the RNS System clinical trials. With 230 patients enrolled at the start of the Long-term Treatment Trial, 115 remained at the last reported follow-up. Open-loop stimulation reduced seizure frequency in patients on average with over 90% compared to baseline. Closed-loop stimulation reduces seizure frequency with 60%–65%. Even though open-loop neocortical electrical stimulation has only been reported in 20 patients, and closed-loop in much a larger sample, evidence suggests that both approaches are effective in reducing seizures. It remains an open question which should be clinically preferred. Therefore, a head-to-head adaptive clinical study comparing both approaches is proposed.