Functional Hemispherotomy

What is a functional hemispherotomy?

A functional hemispherotomy is a surgical procedure to disconnect the outer portion (the cortex) of one half of the brain (hemisphere) from the other half and from the brainstem. It is used to isolate abnormal brain activity in one half of the brain in order to cure serious seizures.

By separating the connection between the abnormal half of the brain from the healthy half and brainstem, seizures that originate in one half of the brain can no longer spread to the other, healthy half or to the muscles of the body.

In appropriately selected patients, functional hemispherotomy is among the most successful surgeries for epilepsy.

Who is a candidate for functional hemispherotomy?

Functional hemispherotomy is considered as an option for children with severe seizures that originate in multiple locations within one brain hemisphere and spread to the other, and that aren’t controlled by medication. These are known as uncontrolled, refractory, or drug-resistant seizures.

The more significant the problems in the half of the brain that is the source of the seizures, the higher the chance that the other, healthy half of the brain has assumed many of the functions of the affected hemisphere. In these cases, the short-term impact of a functional hemispherotomy on a child's motor function, vision and other cognitive skills may be minimal, while the benefit in reducing seizure activity is likely to be large.

Common indications for hemispherotomy include:

  • Perinatal stroke
  • Rasmussen’s encephalitis
  • Hemimegalencephaly or other hemispheric malformations
  • Sturge-Weber Syndrome

How is functional hemispherotomy surgery performed?

Functional hemispherotomy surgery is performed by pediatric neurosurgeons while your child is under general anesthesia.

A small incision is made above the ear, and a portion of the skull is temporarily removed to access the brain. Using MRI scans to visualize the brain, a neurosurgeon removes the amygdala and the hippocampus from the temporal lobe of the abnormal hemisphere, removes the insula, disconnects each lobe from the brainstem, and disconnects the corpus callosum, the main neural conduit between the two hemispheres.

When the separation of the hemispheres is complete, a flexible tube is placed in the ventricle to drain fluid from the brain during the first days of recovery. The portion of skull removed at the start of the procedure is replaced and fixed in position, and the skin incision is closed.

What to expect during functional hemispherotomy

On the day of the surgery and immediately after functional hemispherotomy

On the day of the surgery, your child will undergo general anesthesia. At Children’s Hospital of Philadelphia, you can trust our specially trained pediatric anesthesiologists to keep your child comfortable and safe before, during and after their procedure. Read more about our dedicated pediatric anesthesiology team.

The surgery itself takes four to five hours.

For the first few days after the procedure, your child will be monitored in the Pediatric Intensive Care Unit (PICU), where physical and occupational therapies begin. Your child will then be moved to the epilepsy monitoring unit to continue recovering.

Our specialized physical and occupational therapists will work with your child on any movement abilities that may need to be relearned after the procedure, as the healthy hemisphere takes on functions previously handled by the abnormal hemisphere.

Going home after functional hemispherotomy

After functional hemispherotomy surgery, your child may continue physical or occupational therapy at home, on an outpatient basis, or here at Children’s Seashore House, our specialized pediatric rehabilitation hospital here at CHOP. 

Your child will gradually be able to resume normal activities over the next one to two months.

Anti-seizure medications will generally be continued unchanged after functional hemispherotomy for a period determined by your child’s doctor, then the doses will gradually be reduced.

Your child will come back to CHOP for periodic follow-up visits after the procedure, on a schedule determined by your child’s medical team.

The vast majority of children who have a functional hemispherotomy experience complete resolution of their seizures.

Why choose CHOP for functional hemispherotomy

At Children’s Hospital of Philadelphia, your child will have access to pediatric experts from the Division of Neurosurgery, the Pediatric Epilepsy Program and others who specialize in the care of children with epilepsy and seizures. This approach has led to truly outstanding outcomes from this surgery.

Our team of experts work closely together to ensure that candidates are screened appropriately for functional hemispherotomy, and to provide the full range of supportive therapy before and after epilepsy surgery to optimize outcomes.

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