Printer-friendly format

Live surgical Web cast of pediatric hemispherectomy at Le Bonheur Children's Medical Center.

Epilepsy and seizures affect 2.7 million Americans and approximately 200,000 new cases occur each year, according to the Epilepsy Foundation.

While many seizures are manageable by medication, some types are so severe that they limit quality of life and can lead to more health problems, even death.

One particularly severe form of epilepsy produces seizures on one side of the brain, which adversely affects the opposite side of the body. For this type of condition, a functional hemispherectomy has been effective in allowing patients release from relentless seizures.

The procedure is a dramatic operation in which half the brain is disconnected from the other half to relieve frequent, severe seizures that medication cannot control.

In October, neurosurgeons at Le Bonheur Children's Medical Center hosted a live surgical Web cast of a pediatric hemispherectomy in order to raise awareness about the surgery. Le Bonheur is one of the few pediatric centers in the United States with the experience and equipment to do such complicated procedures. Medical director of pediatric neurology Dr. Frederick Boop performed the procedure while Dr. James Wheless, medical director of the Neuroscience Institute at Le Bonheur, hosted the Web cast to answer questions about the procedure.

"What's unique in this is it is truly one of the more dramatic pediatric neurosurgeries we do and we want to draw attention to the procedure to show kids are not stuck with (severe epilepsy)," said Wheless. "This is a good solution."

The origins of the hemispherectomy reach back to the early 20th century, explained Wheless, with observations of tumors during neurosurgery. As tumors grew and destroyed the connection between the cerebral hemisphere, seizures were reduced. Traditionally hemispherectomies were done by removing the entire half of the brain but that led to bleeding and impaired balance. Now the frontal, parietal, temporal and occipital lobes are left in place, partially or completely, and are simply disconnected.

Hemispherectomy is only considered for patients who have severe epilepsy with seizures arising from only one side of the brain. Typically the patients are children, although it is also performed on adults. The procedure is performed only if that hemisphere is already functioning very poorly, so the patient loses little or no additional function.

Surgeons are effectively disconnecting the cerebral hemisphere from the corpus callosum, the large bundle of fibers that connects the left and right cerebral hemispheres. When seizures start on one side of the brain, the electrical surge spreads them to the other side by passing through the corpus callosum.

"Think of it as disconnecting telephone wires," explained Boop. "Telephone wires are sending out messages to the cortex; even if a seizure occurs it can't be sent anywhere. Any messages from the bad half of the brain won't be sent because the corpus callosum wires have been cut."

The surgery takes six hours and includes a comprehensive neurological team. Candidates for the surgery are evaluated for five to seven days before the procedure with sensory and motor function tests to confirm the seizures a patient is suffering are indeed coming from opposite side of the brain. After surgery, patients are in the ICU for one day and are inpatients for up to six days. The success rate is high, with 75 to 90 percent of patients experiencing complete or nearly complete seizure control.

"After surgery life is dramatically improved, patients are generally more alert; we see cognitive improvements," said Wheless. "We've removed the bad element causing the problem."

Wheless said there are 150 to 200 hemispherectomies performed in the country annually, yet there are probably more candidates for the procedure. In fact, many children who could be candidates in early childhood aren't evaluated for the surgery until their teenage years either due to a lack of knowledge or fear of the complexity of the procedure.

"There is fear that this is a drastic surgery but nowadays this is safer than seizures," Wheless added. "With current neurosurgery techniques, the risk of the procedure is less than the risk of epilepsy. Epilepsy has a higher risk of death."

The patient undergoing the procedure in the Web cast was a 6-year-old girl who had a stroke in utero, which developed into severe epilepsy affecting the left hemisphere of her brain and leaving her unable to speak. Wheless explained that after a hemisphere is disconnected, motor and sensory functions can eventually switch over to the good side of the brain. Cognition improves over time since the patient will no longer be bombarded by seizures nor has to be on heavy seizure medication. Patients are followed for two years, after which families and their doctor can decide whether to back off medication.





January 2007

Tags:

None