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Study investigates implantable device designed to stop seizures

24 August, 2004

A small
electronic device implanted in the skull that detects oncoming seizures
then delivers a brief electrical stimulus to the brain to stop them is
under study at the Medical College of Georgia (MCG).

At
the MCG Medical Center the device will be used in about 20 patients
aged between 18 and 65 whose seizures are uncontrolled, on at least two
medications and have at least four seizures per month.

MCG
neurosurgeon Dr Joseph Smith says if the study proves the device is
effective he can see patients preferring the new approach to today's
standard that often includes removing areas of the brain where abnormal
electrical activity originates.

During
the procedure the device is attached to the skull near the seizure
focus and uses tiny screws to hold it securely in place. Once the
neurosurgeon implants the device, up to two electrodes are placed
within the brain near the seizure focus. Afterward, a modified laptop
computer is used to look at electrical activity picked up by the
neurostimulator and to program the device to recognise the patient's
seizure activity. If the neurostimulator detects abnormal activity, it
sends an electrical stimulus to stop it, a stimulus which, according to
doctors, that appears to go unnoticed by patients. Study patients will
be followed for about two years to assess how well the device works.

MCG
doctors already have used it as a temporary measure to try and stop
seizures in 15 patients whose seizure activity was already being
monitored. In one patient with frequent seizures, they were able to
compare seizure activity with and without the stimulation in an effort
to further analyse its contribution to stopping seizures. The
experience prompted the MCG doctors to want to study the implantable
device.

Doctors
already have experience using electrical activity to help control
seizures. A pacemaker-like device called the vagus nerve stimulator has
been used for about six years that regularly electrically stimulates
the vagal nerve in the neck, sending signals to the brain. The vagus
nerve stimulator has helped reduce seizure frequency but is unlikely,
according to the MCG, to make many patients seizure-free.

The
researchers agree that if the implantable neurostimulator is proven to
be safe and effective it may benefit many epilepsy patients in the
future. They commented that they would would expect that
hospitalisation and risk of complication would be much less than that
of traditional epilepsy surgery. As with other epilepsy surgery, they
also hope this new approach will provide a lifelong solution, requiring
only battery replacement.