Responsive neurostimulation (RNS)

RNS is an FDA-approved closed-loop system for drug-resistant focal epilepsy that continuously monitors electrocorticography from one or two leads placed at the seizure focus, detects epileptiform patterns with on-device detectors (line-length, area, and half-wave analyses), and delivers brief electrical stimulation intended to abort the incipient seizure. Unlike adaptive DBS with its graded, continuously modulated output, RNS is event-triggered: it detects, then stimulates.

Clinical benefit accrues gradually over years, which suggests the therapy works partly through long-term network reorganization and reduced seizure tendency rather than only acute abortion of each detected event. A valuable by-product is the chronic ambulatory electrocorticography the device stores, which has become a research window onto human seizure dynamics and circadian patterns that scalp recordings cannot provide.