Smart Implants Intercept Seizures

Image by Henrik Jonsson

A good piece by Aliyah Baruchin in the July SciAm looks at how a new generation of implantable devices may help people with epilepsy squelch seizures before they get out of control. For more than a decade doctors have been implanting Vagus Nerve Stimulators (VNS) into patients who are unresponsive to anti-seizure meds. VNS either sends a periodic stimulating pulse through the vagus nerve or allows patients, when they sense a seizure coming on, to shock themselves with a magnet passed over the implanted device. The electrical stimulation defuses the mounting synchronized brain activity that would, if allowed to mount, culminate in a seizure. VNS works pretty well for a small fraction of patients whose seizures aren't responsive to anti seizure medications.

The avant-garde in implants promises to be much more subtle and targeted. The devices will read signals from the brain and "write" back to it with appropriately limited intervention. By tracking electrical activity (or temperature) in the part of the brain causing the seizures, these devices can tell when seizure activity is imminent and then can have one of three responses to intercept the seizure before it blossoms into disabling spasms or impaired consciousness.

One of these devices, under development at the University of Kansas Medical Center, address a coming seizure by cooling the area of the brain where they are kindling. Others do so by sending an electrical pulse to the offending area as a seizure mounts. A third type delivers anti-seizure medication locally and in limited doses that do not effect the entire brain.

The big advantage of all three delivery systems is that they tailor treatment to actual brain activity rather than constantly treating a brain that may only occasionally be seizure prone.

This will be a big deal for people with epilepsy. But the practice doctors get with implanted read/write devices will change the course of neuroscience and, sooner or later, it will effect everyone. The real-time data that will be collected by these implanted devices will give scientists a huge new window into all kinds of brain activity. And once installing electrodes in brains becomes routine, applications will go well beyond treating brain disorders or enabling prosthetic devices. The Brain Machine Interface is coming; fasten your seat belts.