Corpus callosotomy for Epilepsy

Overview

Approximately 20 percent of people with epilepsy cannot adequately control their seizures with anti-epileptic drugs (AEDs). Other people experience serious side effects from AEDs that impact their quality of life. Some of these people may be candidates for surgery.

Corpus callostomy is a type of brain surgery used to treat people with epilepsy. The goal of corpus callostomy surgery is to reduce the frequency of some types of seizures. Corpus callostomy is also referred to as split-brain surgery or callosal sectioning.

The largest part of the brain, the cerebrum, is divided into left and right halves known as hemispheres. The two hemispheres are divided by a deep groove. A dense band of nerves called the corpus callosum connects the two halves and allows them to communicate. Seizures can pass from one hemisphere to the other via the corpus callosum. During a corpus callostomy, the neurosurgeon severs part or all of the corpus callosum so that seizures cannot pass from one hemisphere to the other. Corpus callostomy may be performed alone or with another surgery such as functional hemispherectomy[LINK].

Not everyone with intractable epilepsy is a good candidate for corpus callostomy. Corpus callostomy is most effective at reducing atonic seizures (also known as drop attacks), tonic seizures, and tonic-clonic seizures. Corpus callostomy is not effective in reducing partial seizures. In order to qualify for corpus callostomy, you must have tried several different AEDs for significant periods of time. Finally, you and your doctors must agree that the benefits you might gain by undergoing the surgery outweigh the risks of performing the procedure.

What does it involve?
In order to decide whether you are a good candidate for corpus callostomy, your neurologist will perform extensive testing. The pre-surgical evaluation tests may include seizure monitoring, magnetic resonance imaging (MRI) scans, positron emission tomography (PET) scans, magnetoencephalography (MEG) tests, Wada tests, and electroencephalography (EEG) monitoring. The EEG monitoring may be performed externally or invasively, using electrodes that are placed inside your skull. Pre-surgical evaluation is very thorough in order to ensure you will receive the maximum possible benefit from the surgery and avoid disruptions of normal brain function as much as possible. You and your doctor should decide together whether a corpus callostomy may be right for you. Do not be afraid to ask questions about any aspect of the surgery or recovery.

You will be given instructions to stop eating a few hours or possibly the night before surgery. When you arrive at the hospital, vital signs will be taken, and blood will be drawn for testing. A portion of your head may be shaved. When it is time for the surgery, you will receive an intravenous (IV) line and anesthetic medication to make you sleep.

During the corpus callostomy, the neurosurgeon will make an incision in your scalp and retract a flap of skin. The neurosurgeon will then remove a section of your skull in a procedure known as a craniotomy. Next, the neurosurgeon will retract a section of the dura mater, the tough outer covering of the brain. Viewing your brain through a surgical microscope, the surgeon will insert instruments. The neurosurgeon will carefully separate the two hemispheres. Most often, the neurosurgeon will sever the front two-thirds of the corpus callosum. This procedure is considered a partial callostomy. Leaving the rear third intact helps preserve visual function. If the partial corpus callostomy fails to control seizures adequately, the remainder of the corpus callosum may be severed in a later surgery known as a complete callostomy. When the surgeon is finished performing the corpus callostomy, they will close the dura mater, fix the skull back in place, and finally close your scalp with staples or stitches.

You can expect to stay in the hospital for two to four days after receiving corpus callostomy surgery. Once you return home, it will take six to eight weeks to recover completely from surgery and resume work, school, or other normal activities. You may need to receive speech, physical, or occupational therapy during your recovery. Your hair will hide the scar when it grows back.

You will continue taking your AEDs after surgery. You may eventually be able to reduce the number or dosage of your medications. You should never suddenly stop taking an AED. Always consult your neurologist for a plan to taper off gradually in order to avoid withdrawal.

Intended Outcomes
Corpus callostomy may help significantly reduce some types of seizures.

Results
Corpus callostomy eliminates atonic seizures in 50 to 75 percent of people. Partial callostomy can reduce the frequency of some types of seizures by 70 to 80 percent, while complete callostomy provides reductions of 80 to 90 percent.

Constraints
Corpus callostomy surgery may not be successful in reducing your seizures.

Complete corpus callostomy causes some permanent visual deficits. With your eyes closed, your right and left hands and feet will have trouble cooperating in tasks.

In rare cases, some people experience a stroke, stuttering, decreased awareness of one side of the body, or an increase in partial seizures as a result of corpus callostomy.

Corpus callostomy surgery can cause pain and swelling, and you will most likely need pain medication for some weeks during recovery. Other temporary side effects may include personality changes, fatigue, depression, headaches, numbness in your scalp, nausea, and trouble remembering or speaking some words.

Any surgery carries risks including blood clots, blood loss, infection, breathing problems, reactions to medication, and heart attack or stroke during the surgery.

Possible complications of corpus callostomy include swelling in the brain and damage to healthy brain tissue.

It may be challenging to travel to multiple therapy appointments during rehabilitation.