News Feature | November 16, 2016

Cellophane-Like Electrode Implant Records Brain Activity During Epilepsy Surgery

By Suzanne Hodsden


Early human trials with a thin sheet of electrodes that wraps over the human brain during surgery have demonstrated the successful recording of brain activity, including specific monitoring of individual neurons. NYU researchers believe the tech could assist surgeons in removing the source of seizures in patients with drug-resistant epilepsy.

Epilepsy is the fourth most common neurological disorder, with seizure symptoms and condition severity that varies widely. According to a study in Epilepsy & Behavior, between 30 and 40 percent of patients with active epilepsy do not respond to anti-epileptic drugs (AEDs). Though more “aggressive treatments” like surgery carry significant risk, letting the condition progress without management can be equally dangerous.

Surgeons attempting to excise or ablate brain tissue at the root of epileptic seizures typically implant an electrode grid over the surface of the brain, but information from existing electrocorticography (ECoG) technology is broad and must be monitored for several days or weeks. A team led by György Buzsáki, a neuroscientist at NYU Langone Medical Center, designed the sheet-like implant to help reduce risk of surgery by providing a more precise measurement of brain activity, according to IEEE Spectrum.

Buzsáki’s team published a study in Nature last year demonstrating the success of their implant in rats. The technology — called “NeuroGrid” — is made of a polymer approximately four micrometers thick, carries 120 conductive polymer electrodes, and sticks to wet surfaces, such as the brain. Study authors concluded that the material interfaced well with the brain and was a good conductor of electricity — providing “highly localized performance.”

In a recent study published in Science Advances, Buzsáki’s team tested NeuroGrid on human patients undergoing brain surgery and “demonstrated the feasibility and safety of intraoperative recording with NeuroGrids” in anesthetized and awake subjects. According to researchers, application of NeuroGrid could improve diagnostic precision and localizing the source of seizure activity, making surgical interventions more precise. Additionally, the system is less rigid and less likely to cause inflammation, versus traditional ECoG technology.

Mikhail Lebedev, a neuroscientist at Duke who was not involved in the study, told IEEE Spectrum that the technology could “allow [us] to localize the epileptic focus more accurately” and could one day be used to control prosthetics.

The Centers for Disease Control and Prevention (CDC) estimates nearly 2.9 million Americans have a history of epilepsy or seizure disorder, which — in severe cases — can cause disability. The total direct and indirect cost of epilepsy on the U.S. economy is around $15.5 billion, said the CDC, accounting for both healthcare costs and loss of productivity.

A proof-of-concept animal study conducted by Penn Medicine demonstrated the potential of a silicone electronic device that records brain activity and then dissolves, eliminating risk associated with the surgical retrieval of recording devices. Measurements were collected for 30 days before the system was absorbed.

IBM currently is working on a computing system that could predict and potentially prevent epileptic seizures. The technology will eventually be incorporated into a wearable device that can warn the patient of an impending seizure attack.