Electrocorticography,or ECoG, is the practice of using electrodes placed directly on the exposed surface of the brain, after conducting a craniotomy. It’s goal is to record electrical activity in the production of Epileptic Seizures in search of finding the zones of epileptic origin. Two Forms: Intraoperative and Extraoperative

Types of ECoG electrodes: 16 disposable stainless steal electrodes placed in a ball and socket joint attached to an overlying frame. 16 disposable stainless steal electrodes placed in a ball and socket joint attached to an overlying frame. Grid Electrodes ranging from 4 to 64 electrodes. These are transparent, flexible sheets numbered at each different electrode. (Preferred method due to the ability to slip under the dura matter.) Grid Electrodes ranging from 4 to 64 electrodes. These are transparent, flexible sheets numbered at each different electrode. (Preferred method due to the ability to slip under the dura matter.)

A seizure occurs when a brief, strong surge of an overabundance in electrical activity affects part or all of the brain lasting from a few seconds to a few minutes. It may bring about a change in sensation, awareness or behavior. They are classified as Epileptic if there is a reoccurrence typically more then twice with electrical brain activity.

Intraoperative ECoG: Primary Goal To localize the zone and origin point of seizure activity for mapping and resectioning of brain functions.

From The Beginning…  Dr. Wilder Penfield developed the “Montreal Procedure” in Canada. First to detect “auras” in Epileptic patients.  Rudolf M. Hess conducted first scalp EEG in a 31 year old patient in Switzerland.  Hugo Krayenbuhl and Rudolf M. Hess- First attempt at ECoG surgery performed on May 18 th at University Hospital in Switzerland. Hess and Krayenbuhl worked in union, Krayenbuhl preformed the surgery; Hess monitored the electrical output of the brain.  Dr. Wilder Penfield and Herbert Jasper; began using the Krayenbuhl and Hess experiment and the Montreal Procedure in combination to create further developments, being the current ECoG methods.  Kuruvilla, M.D and Flink, M.D. – Uppsala University Hospital in Sweden. Began taking on the issue of Intraoperative ECoG and its reliability.

 Spontaneous brain activity consisting of unusual spikes and sharp waves for the patient.  Due to the abnormal spikes and brain activity faulty information is being recorded as the origin of epileptic activity.  Seizures are rarely recorded.  Requires quick decisions  Limited Sampling Time  Both the background brain activity and epileptic activity maybe altered by the anesthetics.

Schwartz, Bazil, Walczak, Chan, Pedley, and Goodman  Study consisted of 29 epileptic participants.  All 29 underwent standard resectioning with Intraoperative ECoG.  11 patients (38%) had residual epileptic spikes after resection.  18 (62%) had new spikes post resection.  Conclusion: Spikes persisted in frequency with ill effect from resectioning with Intraoperative ECoG.

Spenser, Tran, Javidan, Pacia, & Marks  Conducted at Yale University School of Medicine; Department of Neurology and Neurosurgery.  Study consisted of 36 patients with epilepsy and present brain tumors. Two groups of 18. Pre Intraoperative ECoG: Group 1: 85% of the participants had spikes (70% over tumor bed, 63% in surrounding tissue) Group 2: 88% of the participants had spikes (55% over tumor bed, 89% in surrounding tissue) Post Intraoperative ECoG: Group 1: 60% of the participants had spikes (46% around of the resectioned area, 26% elsewhere in the brain.) Group 2: 67% of the participants had spikes (50% had spikes around the resectioned area, 67% elsewhere in the brain.) Conclusion: It was not found that Intraoperative ECoG accurately recorded active epileptic activity. The results were found to show post resection spikes and seizure recurrance.

Is It Really What It Seems? Epilepsy- Intraoperative ECoG xUE xUE

Heather Jensen-Siebens “It’s trying. After surgery number two you begin to wonder if the doctors know what they are doing when you, nearly two weeks after surgery, end up having a Tonic-Clonic. You wonder if Electrocorticography is really going to work for you or anyone.” -Heather “…But only by the strength of God and my family have I been able to conquer the ups and downs that this treatment comes with.” -Heather