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. Typically,children who have the procedure are functionally impaired and delayed due to the frequency of seizures and underlying brain injury. If a child has the operation, the healthy side of their brain may help with some function of the other side.

How It Works

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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. They’ll move aside part of the dura, a tough membrane that covers your brain. Then they’ll take out parts of the hemisphere where your seizures start. Usually it’s the temporal lobe.

Finally, they’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. This allows the healthy hemisphere to continue to properly develop without the danger of damage by seizures.

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:

  • Infection
  • Bleeding
  • Allergic reaction to the anesthesia

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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)
  • Fluid on your brain which may require a second procedure, such as a VP shunt
  • Loss of visual field

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.

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

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). They compare the results with other tests that tell them where your seizures start. If they start on the same side that controls your speech or has better memory, they might do more tests to lower the chances that surgery will affect your speech or memory. The Wada test can also tell them 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 is delivered through a catheter inserted in an artery in your leg. 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

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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.

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