Researchers from the Johns Hopkins Children's Center report that hemispherectomy – a procedure in which half the brain is removed -– may reduce or eliminate severe seizures even in older children with a rare congenital disorder associated with epilepsy. The findings are published in the December issue of Neurology.
Contrary to results of previous studies, the Hopkins research found that in children with Sturge-Weber syndrome, delaying hemispherectomy even for years had no apparent effect on seizure control or learning ability. Some 80 percent of Sturge-Weber patients develop epilepsy.
"In fact, older patients were statistically more likely to be seizure-free after surgery," said the study's lead author, Eric Kossoff, M.D., a pediatric neurologist at the Children's Center. "However, in general, the child's age at surgery did not have an adverse effect on either their intellectual abilities or seizure reduction."
Sturge-Weber syndrome is a rare disorder of unknown incidence and cause that is characterized by a vascular birthmark known as "port wine stain" and neurological abnormalities, including a weakening or loss of use of one side of the body. For most patients, seizures begin before the age of one year and are difficult to control. When the seizures do not respond to anticonvulsant medications and stem from one side of the brain, hemispherectomy may be advised.
While children with Sturge-Weber syndrome make up only a small percentage of all hemispherectomy patients, results from this and other studies suggest that older children may also benefit from the surgery, regardless of the cause of their seizures, according to Kossoff.
Kossoff and his colleagues examined data from questionnaires completed by the families of 32 Sturge-Weber patients identified by the Sturge-Weber Foundation as having had a hemispherectomy from 1979 to 2001. Surgeries were done worldwide in 18 centers. Information was collected regarding the child's preoperative condition, details of the surgical procedure and hospital stay, and the child's current neurological status.
The average age that patients began experiencing seizures was four months and the median age at the time of surgery was just over one year. Children averaged almost 400 seizures per month and had been unsuccessfully treated with approximately four different kinds of medications before the hemispherectomy was performed.
More than 80 percent of patients were reported to be seizure-free following the surgery and more than half were off anticonvulsants. The type of hemispherectomy that was performed, or the amount of brain matter actually removed, did not influence the child's seizure outcome.
"Most interestingly, we found the child's cognitive skills were not impacted by the child's age at operation or delay of surgery. This is contrary to all other previous studies on Sturge-Weber s yndrome and hemispherectomy, which emphasized early surgery to avoid cognitive decline," said Kossoff. "However, there was a trend toward poorer cognitive outcomes if seizures persisted after surgery."
Hemispherectomy is performed at Hopkins on children with Rasmussen 's syndrome, a variety of developmental abnormalities on one side of the brain, and on those who have had disabling strokes. First attempted by Johns Hopkins surgeon Walter Dandy, M.D., in the late 1920s, the operation was reintroduced at Hopkins in 1968 and refined in the mid-1980s by Benjamin S. Carson, M.D., director of pediatric neurosurgery.
John M. Freeman, M.D., a pediatric neurologist at the Children's Center, and Carol Buck of the Sturge-Weber Foundation contributed to this study.
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