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Surgical Treatment for Epilepsy

There are different types of epilepsy surgery. Patients with epilepsy may be considered for surgery if they meet the following criteria:

Seizures are incompletely controlled despite optimal medical management. For most patients, this means a trial of at least three medications that are appropriate for the type of seizure, used in adequate doses.
The patient experiences intolerable side effects from the medications used to control seizures.
A single "spot" or region in the brain can be identified as causing the seizures.
The region causing the seizures can be removed safely without causing harm or loss of important functions such as speech or movement.

Decisions about whether to undergo surgery for epilepsy are different for every patient. No one recommendation fits every patient. A decision to consider epilepsy surgery does not mean that surgery always is possible. The evaluation may show that the patient is not a good candidate for surgery. For example, the evaluation may determine that the patient has seizures arising independently from both sides of the brain. Under these circumstances, surgery is seldom advised.

Amygdalohippocampectomy surgery for
mesial temporal sclerosis.

Neurosurgeons may use one of several different procedures to treat epileptic lesions:

Amygdalohippocampectomy
Temporal Lobectomy
Lesion Resection
Customized Neocortical Resection
Hemispherectomy
Hypothalamic Hamartoma Resection
Multiple Subpial Transection
Corpus Callosotomy

Amygdalohippocampectomy is commonly performed for patients with temporal lobe epilepsy related to mesial temporal sclerosis (scarring and atrophy of the hippocampus in the temporal lobe). Using an operating room microscope, this procedure focuses on minimal resection of the affected tissue and spares the remainder of the temporal lobe.

Standard temporal lobectomy for temporal
lobe epilepsy, arrows indicate removal
of temporal lobe.

Temporal lobectomy, or removal of the temporal lobe, is less commonly performed for temporal lobe epilepsy. It is appropriate for many patients whose temporal lobe seizures are caused by conditions other than mesial temporal sclerosis (cortical malformation, scar, tumor, etc).

Lesion resection is often the preferred operation for patients with a lesion or abnormality visualized on CT or MRI, such as scar, old hemorrhage, tumor, or a cortical malformation that resides outside the temporal lobe. For many patients, simply removing the lesion may alleviate their seizures. Intracranial grid recordings to map seizure onset and brain functions may be appropriate for some patients.

Customized neocortical resection is a highly tailored procedure that may be unique to a particular patient. It is often outside the temporal lobe. Patients may or may not have an area of abnormality on brain imaging studies. Surgery is typically performed with intracranial grid seizure recording and functional brain mapping.

Hemispherectomy is a relatively radical procedure that involves the removal of an entire cerebral hemisphere to control seizures. The procedure is most appropriate for severe and refractory epilepsy in infants and children. Candidates for hemispherectomy may have a congenital condition that affects one hemisphere or an acquired disease such as Rasmussen's encephalitis. Depending on circumstances, the neurosurgeon may perform a total anatomic hemispherectomy (complete removal of the cortical hemisphere sparing deeper structures) or a modified hemispherectomy (partial removal of cerebral hemisphere with disconnection of the remainder of the hemisphere from other brain structures).

Hypothalamic hamartoma resection is performed under the auspices of Barrow's Hypothalamic Hamartoma Program, a multidisciplinary program for treating children and adults with this relatively uncommon disorder. The first such program in the U.S., Barrow's Hypothalamic Hamartoma Program is currently one of the most active programs in the world for the treatment of this lesion.

Multiple subpial transection is performed to improve seizure control when the brain tissue causing the seizures cannot be removed because it serves a critically important function such as speech. The region is "scored" with a probe to disrupt lateral (side-to-side) nerve fibers. The fibers that travel deep, which are more important for local tissue function are spread.

Corpus Callosotomy, before (A) and after (B) MR Studies (arrow indicates area of callosotomy)

Corpus callosotomy is a procedure in which the corpus callosum--the largest white matter tract connecting the two halves of the brain--is surgically divided. Corpus callosotomy does not cure a patient's seizures; rather, it prevents or slows their spread, making them less severe. This procedure is useful for children with severe drop attacks.