Conference Coverage

Resection, neurostimulation combo found successful in eloquent cortical regions



– Concurrent surgical resection and implanted strip electrodes eliminated refractory focal seizures in two patients with focal cortical dysplasia and reduced them by 62% in a third patient, according a report presented at the annual meeting of the American Epilepsy Society.

None of the patients had been considered surgical candidates because their seizure foci were in eloquent cortical regions; if fully resected, patients would have experienced marked neurologic deficits. But the combination procedure of flanking the incomplete resected foci with implanted electrodes allowed neurosurgeons to remove less tissue, preserving function while effectively treating previously untreatable seizures, Emily Mirro said at the meeting.

The two-in-one technique makes good surgical sense for these patients, she said in an interview. “If we simply performed the resection and closed without implanting the electrodes, just waiting to see if seizures develop or not, then going back to implant the electrodes, the surgery is riskier and more difficult,” said Ms. Mirro, director of field clinical engineering for NeuroPace, which makes the stimulator system.

At the meeting, she presented three case studies on behalf of primary authors Lawrence Shuer, MD, and Babak Razavi, MD, PhD, both of Stanford (Calif.) University.

The first patient was a 26-year-old with a focal cortical dysplasia in the right parietal region, causing about six seizures each month. At the time of surgery, surgeons flanked the resected region with four cortical strip leads over sensory cortex. The RNS System detected the first postsurgical seizure 1 month afterward. Five months later, the system was enabled at 0.5 milliamps. For the next year, the patient received about 100 stimulations per day, amounting to a total daily stimulation time of about 20 seconds. Electrographic seizures did return, at which point the system increased neurostimulation to about 2,000 per day (a total stimulation time of about 7 minutes per day). At 1.3 years, the patient remains seizure free.

Patient two was a 20-year-old with a left frontal transmantle cortical dysplasia that involved the inferior frontal sulcus. The baseline seizure frequency was about two per day. Surgeons removed the dysplastic area with a 2.0 cm x 0.5 cm resection; the deficit was flanked with two left-front cortical strip leads. In the following 9 days, the patient experienced eight seizures. At 14 days out, the system was enabled at 1 milliamp. This patient became seizure free and remains so at 1.3 years, with about 100 stimulations per day to suppress electrographic abnormalities.

The third patient, also 20 years old, had a left-parietal resection to the margin of the motor cortex. The baseline seizure frequency was up to 150 nocturnal events per month and several seizures during each day as well. The resection was flanked by one strip lead over the motor cortex; one depth lead implanted into it. Immediately after surgery, the patient experienced both electrographic and clinical seizures. The stimulator was enabled a week after surgery at 0.5 milliamps; this was titrated to 3 milliamps over 1.4 years. At last follow-up, the patient had about a 62% reduction in seizure frequency; all are now nocturnal.

None of the patients experienced any peri- or postoperative surgical complications.

Ms. Mirro is an employee of NeuroPace.

SOURCE: Razavi B et al. AES 2018, Abstract 2.315

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