Electrostimulation for Refractory Epilepsy: A Review

Epilepsy is a neurological disorder that has been diagnosed in approximately 1% of the world's population. In North America alone, more than 3 million individuals suffer from epilepsy. Antiepileptic drugs are not fully effective in some patients, and most drugs have adverse side effects. Recently, several stimulation techniques (responsive neural, vagal nerve, transcranial magnetic, and deep brain) have been used as adjunct therapies to treat medically refractive seizures. Since its Food and Drug Administration approval in 2013, responsive neural stimulation (RNS), a closed-loop electrical stimulation system, has emerged as a potential therapeutic alternative to treat patients with epilepsy (PWE). RNS consists of a cranially implantable neurostimulator that sends electrical pulses using depth electrodes to epileptic foci/focus after the device senses irregular electrical activity, thus avoiding the onset of a seizure. In a long-term study that lasted 7 yr and involved more than 245 patients using RNS, results showed that16% of patients were seizure free, 60% had 50% or greater seizure reduction, and 84% had some improvement. Quality of life improved in 44% of the patients by the end of the second year. There is a need for more, larger, well-designed, randomized, controlled trials to validate and optimize efficacy and safety of invasive intracranial neurostimulation treatments in PWE. This article highlights the effects of treating patients with medically refractive seizures using RNS.