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RNS – Closed-Loop Neurostimulation — SCE Neurology MCQ

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HardEpilepsy & Seizure DisordersRNS – Closed-Loop NeurostimulationSCE Neurology

A 55-year-old man with drug-resistant focal epilepsy asks about responsive neurostimulation (RNS). What is the principle?

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Correct answer: ARNS uses an implanted device that continuously monitors ECoG and delivers targeted electrical stimulation ONLY when it detects seizure-related electrographic activity — a 'closed-loop' system that treats seizures as they begin

Responsive neurostimulation (RNS/NeuroPace) is a closed-loop neuromodulation system consisting of an implanted cranial neurostimulator connected to depth or cortical strip electrodes placed at the seizure focus. It continuously monitors ECoG and delivers targeted electrical stimulation only when it detects patterns associated with seizure onset, aborting the seizure before it clinically manifests. This contrasts with open-loop devices (VNS, DBS for epilepsy) which deliver stimulation on a fixed schedule regardless of brain activity. RNS is particularly useful when the seizure focus overlaps with eloquent cortex (making resection risky). A: RNS is responsive/on-demand, not continuous. C: AEDs are typically continued alongside. D: VNS is open-loop. E: Available in specialised centres.

Reference: NICE; RNS (NeuroPace) System