Just think about it: a minimally invasive brain stimulator that significantly reduces seizure duration for epilepsy patients. Such a device exists, but sadly, only works in rats so far.

The device was tested on nine rats with a ‘petit mal’ form of epilepsy, and it reduced the length of seizures by approximately 60 percent. Most electrical stimulation devices, most notably those that deliver deep-brain stimulation (DBS) to treat Parkinson and depression patients, work continuously, constantly delivering impulses, regardless of brain activity; this can cause a significant number of problems, most notably – headaches.

However, devices with only work on a seizure basis are finding their way on the market. Such a device was also described by György Buzsáki, a neuroscientist at the New York University School of Medicine; he and his colleagues however managed to create a much less invasive device, one that involves transcranial electrical stimulation (TES) of neurons using electrodes implanted in the skull. What the device does is modify the brain’s cortical (outermost) neurons, which during epileptical seizures become abnormally excited. To detect when a seizure sets in, electrodes were placed at the surface of the brain.

“The difference between a continuous stimulator and an on-demand device is comparable to the difference between an implantable cardiac pacemaker and an implantable defibrillator.”, says Martha Morrell, chief medical officer of NeuroPace and a neurologist at the Stanford School of Medicine in California.

Like DBS devices which are now in use, pacemakers comprise a battery attached to a pulse generator. However, something like an implantable defibrillator requires much more complicated elements, including integrated circuits, capable of sensing, interpreting, and transmitting signals whenever needed – which makes the technology much more complicated.

Still, despite all these impediments, Buzsáki and his team managed to make it work in animal trials, mostly by applying an accelerometer which helps the device filter out signals by correlating electric impulses with muscular signals. Hopefully, they can make the big step for humans in the nearby future.

Journal reference: Berényi, A., Belluscio, M., Mao, D. & Buzsáki, G. Science 337, 735–737 (2012).