VNS (Vagus Nerve Stimulation) therapy has been approved by the FDA as an adjunctive treatment for medically refractory partial onset seizures. Now scientists from the MIT and clinicians at Beth Israel Deaconess Medical Center are trying to “upgrade” a VNS device from Cyberonics Inc. to detect and prevent epileptic seizures before they manifest themselves.
The new device would sense the oncoming seizure and then activate the VNS, in principle halting the seizure before it becomes manifest…
The detector works by measuring brain activity with electrodes placed on the patient’s scalp. In its current form, the patient wears something resembling a bathing cap, in which electrodes are embedded. In order to adapt the detector to work with the VNS, researchers connected wires from the cap to a laptop computer or microprocessor that activates the implanted defibrillator.
Guttag said he believes the technology could be refined so the electrodes could be worn inside of a headband or baseball cap, making the device less obvious to observers.
Each epilepsy patient has different brain activity patterns, so the detector is programmed to measure an individual’s patterns to determine what the precursors to a seizure look like for each patient.
“It’s quite tricky to try to detect very early signs of seizures because there are abnormal electrical signals that don’t evolve into seizures,” Guttag said. “If we can learn what the right profile is for an individual, we can build a seizure onset detector that works really well for that person.”
Ideally, when the device senses an impending seizure, it sends a magnetic signal to the implanted stimulator, which in turn activates the left vagus nerve. The vagus nerve sends electrical signals up to the brain as well as down toward the viscera, controlling heart rate, gastrointestinal peristalsis, sweating and keeping the larynx open for breathing. The mechanism by which VNS prevents seizures is not known, but the technique has been FDA approved to treat epilepsy for about 10 years.
About 20,000 epilepsy patients already have VNS implants, according to Guttag. Some of them are able to use a handheld magnet to activate the VNS on demand, but many cannot. If the new detection device is successful, it would allow many more patients to use the VNS on demand.
The device could also be adapted to provide warnings for patients who don’t need or want VNS implants. Once the device alerts the patient that a seizure is imminent, that person could take steps to minimize injury, such as sitting down or moving away from potentially dangerous objects, such as a hot stove.
“If you could just give someone a little bit of warning they’re about to have a seizure, it could be hugely valuable,” Guttag said. “The seizures themselves aren’t usually damaging to the brain in the long term. It’s mostly about the collateral damage.”
Although the seizure detector could have a huge impact on epilepsy patients, there are plenty of other potential applications for technology that analyzes electrical activity in individual brains, Guttag said. Depression, schizophrenia and attention deficit disorder are just a few of the conditions that could be studied.