There are many types of seizure disorders. In the best cases, children respond well to medication. But for those who don't, surgery may offer the best option for control or elimination of seizures. Diagnostic tests (such as PET scans, CT scans, EEG and video monitoring) will help determine if the child is a good candidate for the many types of surgery available.
The most common epilepsy operation is a temporal lobectomy, which aims to control seizures originating from the temporal lobe. The temporal lobe is located above the ear on either side of the head and is the part of the brain that controls emotions. A temporal lobectomy is considered an option for patients with abnormal brain tissue, such as tissue marked by a scar or some kind of anatomical defect. Some patients with temporal lobe seizures may even have small, non-cancerous tumors in the temporal lobe.
During this type of operation, the surgeon may remove just a portion of the brain or, if necessary, the entire temporal lobe. After a temporal lobectomy, seizures will stop in many patients. The remainder of patients may experience fewer seizures.
In some cases, neurosurgeons can remove the tissue causing seizures in the area of the brain outside of the temporal lobe. Resection is possible if a child’s seizures are caused by an area of the brain that does not control speech, movement or some other critical function. Finding the precise area can be very difficult. To find the exact area, the surgery may be completed in steps. In the first operation, surgeons place electrodes on the brain's surface. For several days, the child is monitored by video and EEG in the epilepsy monitoring unit, where the electrodes feed key information to the surgeon and physician about the precise area of the brain where seizures occur and direct them to the area of the brain that must be resected. The local area identified as the problem may be a lesion (such as a tumor), a malformation of a blood vessel or a malformation of the brain tissue. After surgery, many patients have dramatically fewer seizures, or in the best case, are seizure-free.
Hemispherectomy: Removal of a total hemisphere
Hemispherotomy: Removal of part of the hemisphere
These types of surgeries treat seizures originating in an entire side, or hemisphere, of the brain. The two hemispheres control speech, memory and intelligence. The right hemisphere controls movement on the left side of the body and the left hemisphere controls movement on the right side. During the operation, surgeons disconnect the affected hemisphere from the other areas of the brain by cutting the electrical nerve pathways. The goal is to prevent seizures by separating the abnormal, seizure-causing tissues from the rest of the brain. Neurological function from the part of the hemisphere that has been removed sometimes relocates to the healthy side of the brain both before and after the surgery. A large percent of children may be seizure-free after the procedure.
After surgery, a child is often weak on one side. If surgery was in the right hemisphere, the left side of the body is weak and vice versa. The weakness can be permanent. Therefore, we limit this operation to children who either have severe seizures that greatly limit the quality of their life or are already weak on the affected side because of underlying brain illness, such as a stroke. Most children need to stay in the hospital after surgery for rehabilitation to help improve or manage this physical weakness.
The corpus callosum is a bundle of fibers connecting the right and left hemispheres of the brain. A corpus callosotomy involves cutting these fibers to prevent seizures from spreading from one hemisphere to the other. Neurosurgeons do this by cutting the front two-thirds of the corpus callosum. This surgery may be recommended for a child with seizures that do not involve a specific area of brain tissue that can be removed. It helps a child who has a type of seizure in which the child’s muscles suddenly contract, causing collapse. After surgery, the child’s seizures may lesson dramatically. At times, our neurosurgeons perform another operation to divide the remaining area of the corpus callosum if the child’s seizures aren’t reduced enough by the first surgery.
Vagal Nerve Stimulator
Some children are not candidates for surgery if they suffer from certain types of seizures:
Seizures that begin in several areas of the brain
Seizures that spread to both sides of the brain
Seizures that are not well controlled, after trying several medications
In these cases, surgeons may try an alternative involving the vagus nerve, which is a nerve that starts in the brainstem and goes down the neck and into the chest. The battery-operated vagal nerve stimulator is put in under the skin on the child’s left side of the chest near the armpit. During surgery, the neurosurgeon implants the stimulator and tunnels its wires under the skin to the vagus nerve in the neck.
After the area heals, the neurologist controls the stimulator. It delivers a gentle intermittent current to the vagus nerve to prevent seizures. If a child senses a seizure is imminent, or the parent observes the warning signs, they can place a magnet over the child’s body where the stimulator is located. This can prevent the seizure from starting. The stimulator’s battery needs changing every few years. It isn't known just how the stimulation affects a child’s seizures, but many patients with a stimulator are able to reduce their seizures significantly. The vagal nerve stimulator is approved for use with patients 12 years of age and above.