What is a hemispherectomy?

A hemispherectomy is where half of your child’s brain is either totally or partly removed or disconnected from the rest of the brain. It is a rare surgical procedure done for epilepsy not responsive to medications. It is typically done in children and occasionally in adults. In these patients, the whole hemisphere is abnormal and responsible for causing seizures.

The “hemi” part of “hemispherectomy” means “half” and refers to the cerebral (brain) hemisphere – half of your brain.

What patients are appropriate for a hemispherectomy? What kinds of conditions can be treated with a hemispherectomy?

Your child might need a hemispherectomy if they have these symptoms:

  • Seizures (epilepsy), not controlled with medication.
  • Weakness on one side of their body. Also, they can’t use their hand as well and they might lose their peripheral vision.
  • Abnormal finding on brain MRI that usually affects one side of the brain.
  • Developmental delay because of seizures.

The symptoms listed above are associated with the following conditions and diseases:

Your child might have started having seizures and weakness early in life. Once your healthcare provider suspects drug-resistant epilepsy, you should be referred to a center that specializes in children with seizures.

What are the types of hemispherectomies?

There are two types of hemispherectomies: anatomic and functional (disconnective).

  • Functional (disconnective): The functional technique involves removing a smaller area of the brain and disconnecting the side from the rest of the brain. It has less risk for complications. Hemispherotomy is a term used when the tissue removed is small.
  • Anatomic: Anatomic hemispherectomies are usually performed on children who have persistent seizures despite the “functional/ disconnective” hemispherectomy. This type of hemispherectomy is where the frontal, parietal, temporal and occipital lobes of the brain are removed. This procedure has higher risk for complications – there can be extra blood loss and fluid buildup.

The two types have fairly equal success. However, when a functional hemispherectomy does not lead to seizure freedom, redoing as anatomic hemispherectomy may lead to seizure freedom in a third of patients.

Is a hemispherectomy inpatient or outpatient?

Inpatient. Your child will have to spend time in the hospital.

Figure 1: Right Anatomic Hemispherectomy

A. Coronal MRI at level of anterior frontal lobe.

B. Coronal MRI at level of brainstem.

C. Sagittal MRI demonstrating removal of right hemisphere.

Figure 2: Left Functional Hemispherectomy

A. Coronal MRI demonstrating central resection and temporal lobectomy.

B. Sagittal MRI demonstrating corpus callosotomy and fronto-basal disconnection.

Last reviewed by a Cleveland Clinic medical professional on 12/14/2020.

References

  • Brain Injury Association of America. Functions of the Brain. Accessed 12/13/2020.
  • National Organization of Rare Disorders. Hemimegalencephaly. Accessed 12/13/2020.
  • Children’s Hemiplegia and Stroke Association. Hemispherectomy. Accessed 12/13/2020.
  • Moosa ANV, Gumpta A, Jehi L, et al. Longitudinal seizure outcome and prognostic predictors after hemispherectomy in 170 children. American Academy of Neurology. 2013;80:253-260. Accessed 12/13/2020.

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