Abstracts

RATIONALE: At the end of this activity the participants should be able to discuss the implementation of an external responsive neurostimulator.
There is growing interest in responsive neurostimulation to terminate epileptic seizures. An external Responsive Neurostimulator (eRNS) and Programmer System (PS) were developed and tested as a prototype for a future implantable device. The eRNS is a battery powered device capable of detection and storage of EEG activity, seizure detection that can be screened and customized by the clinician for the patient[ssquote]s unique seizure pattern with delivery of automated responsive stimulation programmed by the PS.
METHODS: Informed consents were obtained consistent with FDA and IRB regulations. Patients studied were selected from those determined to require intracranial electrode arrays. Patients were then connected in parallel to both the eRNS and the usual video EEG monitoring equipment in their institution. Sensitive but non-specific detection algorithms derived from the individual[ssquote]s baseline data were programmed to trigger the storage of potential epileptiform ECoG[ssquote]s. Clinicians then used the PS to review stored ECoG[ssquote]s for identification of seizures along with baseline and EEG and false positivie, the information was submitted to the [italic]Proposer[/italic], an expert system in the PS which perfoms a multi-dimensional parametric search to determine detection parameters tuned to the patient[ssquote]s unique electrographic seizure onset pattern. Up to 3 seizure onset patters using multiple detection tools on multiple EEG channels could be configured. Real-time processing was implemented in an energy efficient manner. After sufficient seizures were recorded for pre-surgical evaluation, but prior to electrode explant, the eRNS was programmed to deliver responsive electrical stimulation upon seizure detection to desynchronize developing epileptiform activity.
RESULTS: The eRNS study began in April 2002. The results from the application of this system to patients through late 2002 will be presented.
CONCLUSIONS: Heretofore, stimulation therapy for epilepsy using open-loop, continuous paradigms, or closed loop systems used high power computing devices to implement detection and decision making algorithms. The eRNS is a system that uses the same resources and algorithms that will be available in a fully implanted neurostimulator. The potential for the eRNS to modify and reduce seizure evolution and propagation represents a novel and targeted approach using neurostimulation in the treatment of epilepsy.
[Supported by: NeuroPace, Inc. Sunnyvale, California]; (Disclosure: Grant - Clinical Research Study with NeuroPace, Inc. Sunnyvale, CA. for the Automated Response to spontaneous Epileptiform Activity using the external Responsive Neurostimulator (eRNS), Consulting - Received consulting fees from NeuroPace, Inc. Sunnyvale, CA.)