Corpus callosotomy is a severing of the network of neural connections between the right and left halves, or hemispheres, of the brain. It is done primarily in children with severe seizures that start in one half of the brain and spread to the other side.
Corpus callosotomy can end drop attacks and other generalized seizures; however, the procedure does not stop seizures in the side of the brain where they originate, and these focal seizures may even increase after surgery.
Hemispherectomy and Hemispherotomy
These procedures remove half of the brain's cortex, or outer layer. They are used predominantly in children who have seizures that do not respond to medication because of damage that involves only half the brain, as occurs with conditions such as Rasmussen's encephalitis, Sturge-Weber syndrome, and hemimegalencephaly.
While this type of surgery is very radical and is performed only as a last resort, children often recover very well from the procedure, and their seizures usually cease altogether. With intense rehabilitation, they often recover nearly normal abilities. Because the chance of a full recovery is best in young children, hemispherectomy should be performed as early in a child's life as possible. It is rarely performed in children older than 13.
The vagus nerve stimulator was approved by the U.S. Food and Drug Administration (FDA) in 1997 for use in people with seizures that are not well-controlled by medication. The vagus nerve stimulator is a battery-powered device that is surgically implanted under the skin of the chest, much like a pacemaker, and is attached to the vagus nerve in the lower neck. This device delivers short bursts of electrical energy to the brain via the vagus nerve.
On average, this stimulation reduces seizures by about 20 to 40 percent. Patients usually cannot stop taking epilepsy medication because of the stimulator, but they often experience fewer seizures and they may be able to reduce the dose of their medication.
Side effects of the vagus nerve stimulator are generally mild but may include hoarseness, ear pain, sore throat, or nausea. Adjusting the amount of stimulation can usually eliminate most side effects, although the hoarseness typically persists. The batteries in the vagus nerve stimulator need to be replaced about once every five years; this requires a minor operation that can usually be performed as an outpatient procedure.
Several new devices may become available for epilepsy in the future. Researchers are studying whether transcranial magnetic stimulation (TMS), a procedure that uses a strong magnet held outside the head to influence brain activity, may reduce seizures. They also hope to develop implantable devices that can deliver drugs to specific parts of the brain.