Noninvasive brain stimulation for epilepsy

Epilepsy is typically treated with antiseizure medications or with resective surgery when medications do not provide sufficient control. Neurostimulation, a form of bioelectronic medicine, is an alternative avenue of therapy for epilepsy.1, 2 Therapeutic brain stimulation options for epilepsy have been available for more than two decades. Vagus nerve stimulation (VNS) gained FDA approval for focal epilepsy in 19973,4 and has been implanted in more than 100,000 people.5 Subsequently, responsive neurostimulation (RNS)6, 7 and deep brain stimulation (DBS)8–10 were approved for focal epilepsy, and other similar approaches are under investigation as well.11, 12 These invasive approaches require implantation of an implantable pulse generator (IPG) in the cranium2, 13 or chest wall5 that delivers electricity to the central nervous system on an ongoing basis.1, 13 By contrast, noninvasive brain stimulation (NIBS) does not require surgery, does not permanently alter the brain, and can usually be easily started and stopped, as clinically indicated.14, 15 NIBS is a promising approach for the treatment of epilepsy, though studies have been mixed as to its effect.16–18 Other potential utilities of NIBS for people with epilepsy include optimization of drug therapy,19 obtaining information on cortical plasticity20, 21 and levels of consciousness,22 mapping eloquent brain regions,23 and possibly guiding implantation of permanent devices.24, 25 In this chapter, several existing and emerging modalities of NIBS are reviewed, and the evidence for their use in epilepsy is summarized.