What Is a Functional Hemispherectomy?

This type of brain surgery helps control severe seizures that come from one side of your brain.

Doctors use it only when:

  • Medication doesn’t control your seizures
  • One side of your brain is working so poorly that losing part of it won’t affect you very much

Afterward, you may have fewer seizures or none at all. If a child has the operation, the healthy side of his brain should take over and do everything the missing parts used to do.

How It Works

Your brain is divided into two halves called hemispheres. They’re split by a deep groove, but they talk to each other through a thick band of nerves called the corpus callosum. Each hemisphere has four lobes.

The doctor will make a cut in your scalp, then take out a piece of bone from your skull. He’ll move aside part of the dura, a tough membrane that covers your brain. Then he’ll take out parts of the hemisphere where your seizures start. Usually it’s the temporal lobe.

Finally, he’ll cut the corpus callosum so the hemispheres of your brain can’t send signals to each other anymore. This way, if a seizure starts in the hemisphere that doesn’t work right, it can’t spread to the healthy one.

Once the surgery is finished, your doctor will put the dura and bone back, then close up the wound with stitches or staples.

What Are the Risks?

Some are the same as with any major surgery:

Others are specific to this procedure:

  • Loss of movement or feeling on the opposite side of your body (the left side of your body if the operation was on the right side of your brain, and vice versa)
  • Swelling in your brain
  • Loss of side vision

Before Surgery

You’ll have a lot of tests. This helps your doctor figure out where in your brain the seizures start. This might mean you’ll stay in a hospital or treatment center for a few days.

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Scans. You might get an MRI, PET scan, or other kind of brain test.

Video EEG monitoring. In this test, you wear a transmitter that lets the doctor record your brain waves. At the same time, a video records what you’re doing, like napping, talking, or watching TV. If you have a seizure, the doctor can compare your brain waves with what you were doing when the seizure started. This tells him if the seizure was due to electrical activity in your brain and where it started.

Wada test. This checks speech and memory on one side of your brain at a time. Your doctor looks at which side of your brain controls your speech and which side has better memory (it might not be the same side). He compares the results with other tests that tell him where your seizures start. If they start in the same side that controls your speech or has better memory, he might do more tests to lower the chances that surgery will affect your speech or memory. The Wada test can also tell him if you need to be awake during part of your surgery.

During the Wada test, the doctor puts one side of your brain to sleep with a special medicine that goes into an artery in your neck. Another doctor shows you different things and pictures. When the medicine wears off, they’ll ask you about what you saw. They’ll test the other side of your brain the same way.

After Surgery

You’ll be in intensive care for a day or two, and then go to a regular hospital room for another 3 or 4 days. The stitches or staples will come out 10 to 14 days after surgery.

You might have some side effects in the first few weeks. Usually these go away slowly. They may include:

  • Headaches
  • Trouble concentrating
  • Forgetfulness
  • Trouble finding the right words
  • Feeling tired
  • Numbness in your scalp
  • Nausea
  • Muscle weakness on one side of your body (the side controlled by the part of the brain the doctor operated on)
  • Puffy eyes
  • Feeling depressed

Most people feel normal and can go back to work, school, and their usual lives about 6 to 8 weeks after surgery.

You’ll most likely have to keep taking your seizure medication for at least 2 years, even if you don’t have any seizures. Your doctor will tell you if and when it’s OK to lower your dose or stop taking it.

WebMD Medical Reference Reviewed by Neil Lava, MD on July 19, 2017

Sources

SOURCES:

UCSF Medical Center: “Disconnection Procedures.”

Cleveland Clinic: “Functional Hemispherectomy.”

The Epilepsy Foundation: “Video EEG,” “Video-EEG Monitoring,” “Wada Test.”

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