Hemispherectomy

Overview

A hemispherectomy is a surgical procedure that partially or entirely removes or disconnects one hemisphere of a child’s brain from the other. Individuals, including both children and occasionally adults, often undergo a surgical procedure for epilepsy when medications fail to provide relief. In cases of this particular condition, the entire hemisphere of the brain is affected and contributes to the occurrence of seizures.

A hemispherectomy is an uncommon operation that is usually carried out in a hospital setting. This is primarily employed to address epilepsy that is unresponsive to medication. After the surgery, patients typically spend five to seven days in the hospital and then undergo a rehabilitation phase.

Types

There are two categories of hemispherectomies: anatomic and functional. Both types of surgeries exhibit similar success rates. In some cases, if a functional hemispherectomy does not stop seizures, trying an anatomic hemispherectomy next can stop seizures in one-third of children that underwent surgery.

• Functional or disconnective: This procedure carries a lower risk of complications. The functional procedure involves hemispherotomy or the removal of a small amount of tissue of the child’s brain and isolating that side from the rest of their brain.
• Anatomic: Unlike the functional approach, this method comes with a higher risk of complications, including increased blood loss and fluid buildup. This is only recommended when the child continues to experience seizures despite a functional hemispherectomy. The child’s frontal, parietal, temporal, and occipital lobes are removed during an anatomic hemispherectomy.

Reasons for undergoing the procedure

A hemispherectomy may be recommended if a child exhibit symptoms such as seizures that are unresponsive to medication, and weakness on one side of the body leading to impaired hand use and potential peripheral vision loss.

People with abnormal findings on a brain MRI affecting one side of the brain, or developmental delays attributed to seizures may also benefit from a hemispherectomy.

Symptoms such as seizures and weakness can be attributed to several medical conditions, such as:

• Malformation of cortical development: If something inhibits the normal development of the cerebral cortex, this condition may arise.
• Perinatal infarction: A stroke that occurs while the fetus’s brain is developing.
• Hemimegalencephaly: This condition causes the affected side of the brain to enlarge in contrast to the unaffected side. It is also known as unilateral or one-sided megalencephaly.
• Sturge-Weber syndrome: Angiomas, or excessive blood vessel growth, can develop in the brain as a result of this illness.
• Rasmussen’s encephalitis: This inflammatory illness affects half of the brain and results in convulsions.

Children who experience early-onset seizures and weakness may be suspected of having drug-resistant epilepsy and may be referred to a specialized healthcare provider.

Risk

A hemispherectomy is a major procedure that carries risks. Early complications arising during or immediately after the operation may encompass issues such as blood loss or bleeding into the empty cavity, electrolyte imbalances, hypothermia, aseptic meningitis, and infections. One may also experience excessive blood loss, which might necessitate a blood transfusion.

A potential complication that may arise early or later in life is the accumulation of fluid in the brain, known as hydrocephalus. This occurs in fewer than 5% of individuals undergoing a functional hemispherectomy. However, this risk is slightly elevated with anatomic hemispherectomy.

However, it should be noted that despite the potential complications, the majority of children who get hemispherectomy experience great long-term outcomes.

Before the procedure

If the child is old enough to understand, explaining to them what is happening is important. The healthcare provider will advise on the things to do in the days leading up to surgery.

Prior to the surgery, the child’s hair will be washed, trimmed, or shaved. Preparation may also include avoiding food and water after a specific time the day before the surgery and adjustments to medication intake, when necessary.

During the procedure

A hemispherectomy may last around five hours or longer. The procedure involves a craniotomy to remove a portion of the skull, followed by the elimination of non-functioning brain tissue.

The healthcare provider will then perform a corpus callosotomy, which involves disconnecting the fibers between the two brain hemispheres. After which, the removed skull portion will be replaced and carefully stitched back in place

Periodic updates will be given during the surgery. To ensure that the child does not experience pain, they will be given general anesthesia for the surgery.

After the procedure

Post-hemispherectomy, the child may need some support initially, but the working side of their brain compensates for the affected side. Overall, things like walking, reading, and behavior tend to be positive, although there may be some vision loss.

Post surgery, the child will undergo close monitoring in the pediatric intensive care unit for a minimum of two to three days. During this period, they will continue to receive antiepileptic medications.

Following discharge from the hospital, they may require rehabilitation services to facilitate their recovery. This involves transitioning to a rehabilitation facility for intensive physical, occupational, and speech therapy. Home or outpatient services for these children are typically suggested, and these can be offered by hospitals, standalone facilities, or schools.

Outcome

Like any surgery, a hemispherectomy comes with potential complications. Generally, it is advisable to contact the healthcare provider or seek medical assistance if the child exhibits signs or symptoms of:

• Infection, such as a fever, pus, or discoloration at the surgery site
• Occurrence of a seizure
• Hydrocephalus, such as vomiting, headaches, or changes in behavior

Generally, hemispherectomy is an effective treatment, with various studies showing that 66% and more than 80% of children who undergo this procedure become completely seizure-free. Optimal outcomes are typically observed in children who have few or no seizures following the surgery.

If the child still experiences ongoing seizures after the first procedure, the healthcare provider will conduct a comprehensive assessment to determine whether second surgery could be beneficial.