Optimal closed loop cortical stimulation therapy in patients with focal epilepsy in primary motor cortex
Location: Room 101 - 11/2/23, 4:30 PM - 11/2/23, 5:00 PM (Europe/Amsterdam) (30 minutes)
Optimal closed loop cortical stimulation therapy in patients with focal epilepsy in primary motor cortex
Geertjan Huiskamp, PhD

Geertjan Huiskamp obtained his PhD degree at the University of Nijmegen in 1989 on work on the inverse problem of electrocardiography. After having spent post-doc research at the University of California at Irvine on inverse methods and again at the University of Nijmegen on propagation models for ventricular activation, in 1996 he moved to the department of Clinical Neurophysiology of the University Medical Center Utrecht, the Netherlands, where he got involved in source localization for pre-surgical evaluation of epilepsy patients. Since 2000 he is staff physicist at the department of Neurology and Neurosurgery, University Medical Center Utrecht, where his main tasks are research and technology assessment centered around the invasive epilepsy monitoring unit. His current interests are in advanced signal processing of spontaneous and evoked EEG in epilepsy patient

For patients with epilepsy where the focus of the seizures is in primary motor cortex (M1), treatment options are limited. About 33% does not respond to medication, and epilepsy surgery, which in other patient leads to seizure freedom in about 75% of cases, is not an option since loss of motor function after resection is very likely. A remaining option is Intracranial open or closed loop electrical stimulation. However, direct stimulation of motor cortex might lead to unwanted side effects like twitches. Here we studied optimal stimulus location for closed loop cortical electrical stimulation in this patient group.

Patients for which seizures were suspected to arise from M1 were admitted for presurgical intracranial EEG grid monitoring. During the monitoring, the exact location where seizures started (SOZ) was determined. We applied Single Pulse Electrical Stimulation to detemine connections between cortex outside and the SOZ inside M1. From these we chose an optimal location for therapeutic stimulation. After the monitoring session grid electrodes were removed, and two subdural strips (Medtronic, clinical investigational device) were placed, on the SOZ and on the optimal stimulus location, and the skull was closed. Strips were connected to a subcutaneous neurostimulator with recording and signal processing capabilities (Activa® PC+S, Medtronic, off-label use). Seizure data was collected for three to five months, and an optimal detection algorithm was devised. Next, closed loop cortical stimulation was applied for seven to nine months, while keeping track of seizure frequency. The neurostimulator was implanted in five subjects (two females, mean age 34 years, range: 21-51 years). One subject remained seizure free for 17 months after implantation, without any stimulation. Two subjects responded to the stimulation therapy with a mean reduction of seizure frequency of 73%. In two other subject reduction was lower, about 35%. This clinical pilot trial resulted in a reduction of seizure frequency in all participating patients. It can thus be seen as a proof of concept of effective cortical stimulation in an optimal location outside the SOZ