Abstracts

The Medical College of Georgia (MCG) is participating in a multicenter study approved by FDA and MCG IRB to evaluate feasibility, safety, and efficacy of a Responsive Neurostimulator System (RNS) in subjects with medically intractable seizures. Eight patients have been implanted with the RNS at MCG. Implanted patients are trained to upload data from their RNS to the Patient Data Management System (PDMS) by using a data transmitter (DTR) that downloads RNS[apos] stored data to a portable computer and then uploads it through a telephone line into PDMS. Investigators can access PDMS through the Internet and review stored ECoGs and diagnostics. Using these resources, we are studying the relationship between clinical reported seizures and stored electrographic seizures (EGSz). All data from six randomly chosen patients was reviewed marking all electrographic seizures date/times. This information was correlated with the clinical seizures reported in the patients[apos] seizure diaries. The RNS has a limited storage capability; therefore, in some instances stored ECoG(s) were overwritten by most recent ones. All patients except one with bilateral foci, have their focus on the left hemisphere. In the six patients analyzed a total of 170 seizures were stored until the moment of this analysis. From these EGSzs stored 28% (range:11%-75%) were clinical seizures. The patients with neocortical focus (2/6), hippocampal focus (2/6), and hipocampal/anterior subtemporal focus (2/6) reported 61%, 25%, and 12% of their EGSzs as clinical seizures, respectively. These observations suggest that neocortical patients have less subclinical seizures (39%) than hippocampal patients (75%), and the patients with diffuse ictal zone (hippocampal/anterior subtemporal) exhibited the highest rate of subclinical seizures (88%). The RNS feasibility study has made possible for the first time, monitoring these patients intracranial EEG activity and storing their electrographic seizures on a daily basis, for an unlimited period of time, currently reaching up to 11 months in our first implanted patient. It is not surprising to find out that these patients experience many EGSz that either not noticed or have not clinical manifestations. The observations obtained in this initial phase of our on-going study are preliminary, and as time progresses with more patients added to the study results with statistical significance are expected. (Supported by NeuroPace, Inc.)