A new neuroprosthetic on the market at the end of 2009, is an attempt to actually combine a neural activity detector and a neurostimulator into one package. Traditionally this never worked because once the neurostimulator activates, it blocks out all underlying brain activity in the area - the implant is only reading itself. But, what if that is the desired outcome?
Enter American firm Neuropace. Their initial offering is an implant designed to combat epileptic seizures by reading the electrical activity pattern, and immediately transmitting an inverse signal into the brain to cancel it out. Once the neurotransmitter has started transmitting, the whole area of the brain should go silent as the two signals cancel out, so any signal at all, is a sign of failure.
Whilst it is inadvisable for most applications, to essentially shut down a portion of the brain for a period of time, for those whose epilepsy is completely uncontrollable and represents a serious risk to their quality of life, this solution is one of the best around.
A clinical trial was conducted on approximately 200 epilepsy patients who failed to respond to medication. The device was able to reduce the seizure frequency by 29 percent. This equates to approximately 100 patients seeing a 50 percent or greater reduction in seizure frequency.
The implantable portion of the device is half the depth of a pack of playing cards, and of similar cross-section dimensions. Because this amount of brain tissue cannot be removed without severe detrimental effects being encountered, a piece of the skull is removed instead. Thus the device pokes slightly proud of the head, and tendrils tipped with electrodes are inserted into the affected areas of the brain itself.
Prior to surgery, brain imaging, EEG or ECoG is used to record brain activity in order to determine the area of the brain the seizures originate from. The device does of course have EcoG capability built in as part of it's function, but a whole-head scan is beyond it's capabilities.
After implantation, there is an optimisation period in which a medical specialist programs the device to recognise an individual patient's seizure pattern. This is performed by artificially triggering seizures whilst the implant is in place, so that the neural reader component can identify the firing patterns. Once this is done, the medical professional builds up a profile of the specific counter-signal needed and supplies the implant with this. Trial runs with artificially induced seizures are triggered again. If the implant is working properly, the strength of the attack is significantly reduced.
Patients also need to learn to how to wave a wand over their head, where the implant is located, and download data recorded before and after brain stimulation. This data provides doctors with information to see how well the device is working and make any necessary adjustments.
The system is a long way from ideal, of course, however, since it has proven itself capable of increasing quality of life in a large trial group, it is one of the best methods for combating this brain dysfunction we currently possess.