Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Epilepsy Health Center

Select An Article

Epilepsy and Functional Hemispherectomy

Font Size

What Is a Functional Hemispherectomy?

The largest part of the brain, the cerebrum, can be divided down the middle lengthwise into two halves, called hemispheres. A deep groove splits the left and right hemispheres, which communicate through a thick band of nerve fibers called the corpus callosum. Each hemisphere is further divided into four paired sections, called lobes -- the frontal, parietal, occipital, and temporal lobes.

The two different sides or hemispheres are responsible for different types of activities. The left side of the brain controls the right side of the body and vice versa. For most people, the ability to speak and understand the spoken word is a function of the left side of the brain. A functional hemispherectomy is a procedure in which portions of one hemisphere -- which are causing the seizures -- are removed, and the corpus callosum, which connects the two sides of the brain, is cut. This disconnects communication between the two hemispheres, preventing the spread of electrical seizures from one side of the brain to the other. As a result, the person usually has a marked reduction in physical seizures.

Recommended Related to Epilepsy

Understanding Temporal Lobe Seizure -- Symptoms

A seizure originating in the temporal lobe of the brain may be preceded by an aura or warning symptom, such as: Abnormal sensations (which may include a rising or "funny" feeling under your breast bone or in the area of your stomach) Hallucinations (including sights, smells, tastes) Vivid deja vu (a sense of familiarity) or recalled memories or emotions A sudden, intense emotion not related to anything happening at the time During the seizure, a person may experience motor disturbances,...

Read the Understanding Temporal Lobe Seizure -- Symptoms article > >

Who Is a Candidate for a Functional Hemispherectomy?

This procedure generally is used only for people with epilepsy who do not experience improvement in their condition after taking many different medications and who have severe, uncontrollable seizures. This type of epilepsy is more likely to be seen in young children who have an underlying disease, such as Rasmussen's encephalitis or Sturge-Weber syndrome, that has damaged the hemisphere.

What Happens Before a Functional Hemispherectomy?

Candidates for functional hemispherectomy undergo an extensive pre-surgery evaluation -- including seizure monitoring, electroencephalography (EEG), and magnetic resonance imaging (MRI). These tests help the doctor identify the damaged parts of the brain and confirm that it is the source of the seizures. An intracarotid amobarbital test, also called a WADA test, is done to determine which hemisphere is dominant for critical functions such as speech and memory. During this test, each hemisphere is alternately injected with a medication to put it to sleep. While one side is asleep, the awake side is tested for memory, speech, and ability to understand speech.

Next Article:

Today on WebMD

human head and brain waves
Causes, symptoms, and treatments.
Grand mal seizure
How is each one different?
marijuana plant
CBD, a plant chemical, may cut down seizures.
prescription bottle
Which medication is right for you?
Seizures Driving
Questions for Doctor Epilepsy
Graces Magic Diet
Pills spilling from bottle in front of clock
first aid kit
Caring Child Epilepsy
Making Home Safe
epilepsy monitoring

WebMD Special Sections