Neurostimulator by Neuropace.

An interesting piece in this week's Science Times describes an increasingly popular way of treating intractable epilepsy with an implanted stimulation device. The surgical implant, called an RNS device, reads signals from electrodes placed deep in the brain. When its processors determines that a seizure is mounting, the device delivers a strategically-placed current custom designed to interrupt the attack.

Approved by the FDA for marketing in 2013, the system seems to be particularly helpful in quieting epilepsies with a one or two foci, or spots in the brain where the seizures start. Electrodes are implanted near those foci--the hippocampus is often one--and deliver a limited shock just to those parts of the brain. A much older technology, called Vegus Nerve Stimulation, or VNS, gives the brain a much more distributed shock that is periodic, and not tied to specific brain activity.

In addition to reducing seizures in about half of the patients who receive them (which is a big deal, since these are very difficult cases!), the RNS may have a side effect not mentioned in the story. Data are constantly being gathered from the brain by the device and are wirelessly downloadable with a wandlike reader that is waved over the skull near the implant. Having a continuous live stream of data from the seizure focus of an epileptic brain presents a huge research opportunity as well as an important clinical one.