Neurostimulation Devices Used in Treatment of Epilepsy

Epilepsy is a chronic neurological disorder frequently requiring lifelong treatment. In 70% of epilepsy patients, seizures are well controlled by antiepileptic medications. About 30% of epilepsy patients remain refractory to medical treatments and may need surgical interventions for better seizure control. Unfortunately and not infrequently, surgical intervention is not feasible due to various reasons such as multiple seizure foci, not resectable focus because of eloquent cortex location, or inability to tolerate surgery due to ongoing concomitant medical conditions. Neurostimulation devices have provided possible seizure control for refractory epilepsy patients who are not candidates for surgical intervention. Among them, vagal nerve stimulation (VNS) has been the oldest, in use since 1997. VNS was followed by responsive nerve stimulation (RNS) after obtaining FDA approval in 2013. Deep brain stimulation (DBS) has not yet met approval in the USA, but has been in clinical practice in Europe since 2010. Neurostimulation devices vary in how they are inserted and their mechanisms of action. VNS has been easily accepted by patients since it is placed extracranially. By contrast, DBS and RNS require invasive procedures for intracranial implantation. As use of these devices will continue to increase in the foreseeable future, we aimed to contribute to the foundation for new research to expand on current knowledge and practice by reviewing the current status of the literature.