Below, find frequently asked questions about hemispherectomy.

What is hemispherectomy?

Hemispherectomy is a surgical procedure which involves total, or partial removal of an affected cerebral hemisphere or disconnecting the affected cerebral hemisphere from the unaffected side.

What is the history of hemispherectomy?

Dr. Walter Dandy first performed anatomical hemispherectomy in 1928 for the treatment of a malignant brain tumor. In the 1950s, Dr. H.G. McKenzie did the first anatomic hemispherectomy as a treatment option for patients with intractable epilepsy.

Over the years, anatomic hemispherectomy was modified through various techniques to achieve complete disconnection with less tissue removal and to decrease the incidence of postoperative complications. The modified technique includes modified anatomic hemispherectomy, functional hemispherectomy and hemispherectomies, such as the peri-insular hemispherotomy. All of these techniques include some modifications of the original anatomic technique and have been shown to have similar seizure-free rates.

What patients are appropriate for a hemispherectomy?

Patients with the following clinical and neuroimaging features may be appropriate for a hemispherectomy procedure.

  • Medically intractable epilepsy with seizures arising from the pathological side.
  • Weakness of one side of the body with loss of dexterity of the hand with, or without, peripheral visual loss.
  • Developmental retardation or arrest of maturation due to intractable seizures.
  • Diffuse abnormality of one cerebral hemisphere which is contributing to the intractable epilepsy.

Diseases presenting with these symptoms include malformations of cortical development, perinatal infarction (stroke), hemimegalencephaly, Sturge-Weber-Dimitri disease, and Rasmussen's encephalitis. Most of these patients start having seizures and weakness early in life. Once the diagnosis of epilepsy is suspected, the patient should be referred to a center specialized in the evaluation and management of pediatric epilepsy.

What are the various types of hemispherectomy?

Two types of hemispherectomies commonly performed include anatomic and functional (disconnective) as shown in Figures 1 and 2. Anatomic hemispherectomy involves the removal of the frontal, parietal, temporal, and occipital lobes. The deeper structures, such as the basal ganglia, thalamus and brain stem are left in place. The anatomic hemispherectomy has a slightly higher risk of blood loss and delayed hydrocephalus. It is typically performed for patients with hemimegalencephaly. The functional technique involves removing a smaller area of the affected hemisphere and disconnecting the remaining brain tissue. This disconnection includes a corpus callosotomy and allows for electrical isolation of the hemisphere that is left in place. This technique involves less risk of blood loss and hydrocephalus but is not appropriate for all patients. Outcomes after both types of epilepsy surgery are reported to be equal and approach 70% seizure freedom.

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.

How long is the hospital stay after hemispherectomy?

After epilepsy surgery, children will spend 2-3 days in the pediatric intensive care unit (PICU) for close monitoring of their neurological status. Antiepileptic medications are continued at previous doses. Antiepileptic drug levels in the blood for some anti-epileptics, like carbamazepine and oxcarbazepine, are monitored during this period because of the drug interaction with anesthesia. An MRI is performed on the first postoperative morning to assess the brain after resection. Once the surgical drains are removed, the patient will be transferred to a regular pediatric nursing floor. PT, OT and speech therapy will be consulted based on the child’s needs. An average hospital stay slightly varies between patient to patient and usually ranges from 5 to 7 days. Length of stay decisions are made by the surgical team and are based on the child’s condition and recovery.

What happens after being discharged from hemispherectomy?

Upon discharge, rehabilitation services are often required to enhance recovery from a hemispherectomy. If medically indicated, the child may be transferred to a rehab facility for intensive physical, occupational and speech therapy. This is usually followed by home or outpatient services. If inpatient rehabilitation is not required, home or outpatient therapy visits are often indicated. Outpatient therapy can be provided through hospitals and free-standing facilities and schools. Parents should check with individual school systems to see if this is a service provided.

What complications are possible following hemispherectomy?

  • Most children have excellent long-term results following hemispherectomy with no unexpected adverse outcomes. Occasionally, however, some complications may occur.
  • Early complications, which occur either during the intraoperative or immediate postoperative period include intraoperative blood loss, electrolyte changes, hypothermia and aseptic meningitis.
  • Late onset complications can occur months or years after the hemispherectomy. These hydrocephalus and recurrence of seizures, though rare, can be life threatening and need to be treated urgently.

Treatment Outcomes

Access success rates for patients at Cleveland Clinic following hemispherectomy surgery.


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