Unexpected increase of seizures in a patient treated with responsive neurostimulation: Check the lead!

(eng) The NeuroPace RNS System provides closed-loop brain stimulation in patients with refractory multifocal epilepsy who are not candidates for resective surgery. The system acts as a sensing and stimulation device by continually monitoring the intracranial EEG (ICEEG) at the seizure focus and delivering brief electrical stimulation pulses as soon as an epileptiform activity is detected. Typically, two depth and/or subdural cortical strips are implanted in the epileptogenic focus. We report here a patient who presented with an acute increase of seizure frequency as a consequence of a lead break, which was not visible on CT scan. Retrospectively, the lead break was confirmed by an increase in lead impedance and presence of artifacts on the ICEEG recordings. [...]