Epilepsy Center – Surgical Procedures
Surgery for the treatment of epilepsy involves resection, disconnection, stereotactic radiosurgery or implantation of neuromodulation devices. Within these categories are multiple options, depending on the clinical scenario.
Surgical resections: Surgical resection (removal of abnormal tissue) for epilepsy may fall into the following broad categories:
Lesionectomy: A lesion is a generic term for brain abnormalities that show up on imaging. Some types of lesions — such as cavernous malformations (blood vessel abnormality) and tumors — are prone to cause seizures. When preoperative testing indicates that these lesions are the cause of the epilepsy, they can be removed surgically.
Lobectomy: Each hemisphere, or half, of the brain is divided into four main lobes—the frontal, temporal, parietal and occipital. Seizures may arise within any of the lobes. A lobectomy is an operation to remove a lobe of the brain. Removal of one of the temporal lobes — called a temporal lobectomy — is the most common type of epilepsy surgery performed. Other types of lobectomies may rely on more specialized testing and surgery to prove a lack of vital function, such as speech, memory, vision or motor function.
Multilobar resection: A multilobar resection involves removal of parts or all of two or more lobes of the brain. It is reserved for more widespread abnormalities causing seizures, providing that no vital functions are in those regions.
Hemispherectomy: The brain is divided into a left and right hemisphere. In rare instances, children may have severe, uncontrollable and devastating seizures that can be associated with weakness on one side of the body. This may occur with a large amount of damage or injury to one of the hemispheres. Surgery to remove or disconnect a hemisphere, a hemispherectomy, may be curative. There are many subtypes of this surgery. The two main divisions are anatomic and functional hemispherectomy.
- Anatomic hemispherectomy involves removing the entire half of the brain that is injured and is generating the debilitating seizures. This includes the four lobes of the hemisphere — frontal, temporal, parietal and occipital.
- Functional hemispherectomy involves separating the abnormal hemisphere from the normal one by disconnecting fibers that communicate between the two. Often, some portions of the abnormal brain are surgically removed in order to perform this disconnection.
These surgeries involve cutting and dividing fiber bundles that connect portions of the brain. The rationale is to separate the area of the brain that is generating the seizures from the normal brain.
Corpus callosotomy: The corpus callosum is one of the main fiber bundles that connect the two hemispheres. When debilitating generalized seizures or falling-type seizures start on one side of the brain and quickly spread to the other, patients may be candidates for this procedure. A large part of this fiber bundle may be cut. The procedure is palliative, meaning that although seizures may improve, they usually do not disappear.
Functional hemispherectomy: Functional hemispherectomy involves separating the abnormal hemisphere from the normal one by disconnecting fibers that communicate between the two. Often, some portions of the abnormal brain are surgically removed in order to perform this disconnection.
Stereotactic radiosurgery: Stereotactic radiosurgery involves the delivery of a focused beam of radiation to a specific target area. Gamma Knife radiosurgery, one of the most common forms of radiosurgery, uses gamma rays to target the area to be treated. In epilepsy, it is generally reserved for small, deep-seated lesions that are visible on MR imaging.
Vagus nerve stimulation: The vagus nerve stimulator (VNS) is an FDA-approved device for the treatment of epilepsy that is not controlled with antiepileptic medications. It involves the surgical placement of electrodes around the vagus nerve in the neck and a generator placed below the collar bone in the upper chest region. It requires two separate incisions, but is an outpatient procedure. Subsequently, a programmer can be used by the epileptologist (from outside the skin) to change the intensity, duration and frequency of stimulation to optimize seizure control. Vagus nerve stimulation rarely cures seizures but may decrease the frequency and severity of seizures. It is an option for those who are not candidates for other types of surgery.