July 28, 1997
Media Contact: Nancy Volkers
A long-term study by researchers at the Johns Hopkins Children's Center has found that hemispherectomy, a surgical procedure in which half the brain is removed, does more than stop otherwise uncontrollable and often life-threatening seizures in children. For the vast majority of these children, hemispherectomy also reduces the burden of medication and allows more normal development.
"Parents of these children agonized about whether to allow this radical surgery. The data prove that their courageous decision was correct. Hemispherectomy does relieve the burden of seizures and often the burden of intellectual dysfunction, as well," says Eileen P.G. Vining, M.D., associate professor of neurology and pediatrics and lead author of the study.
From 1968 to 1996, Hopkins physicians followed 58 patients, ages two months to 20 years, who underwent hemispherectomy for Rasmussen's syndrome (a viral-like illness in the brain), cortical dysplasias (irregular brain development), or other congenital vascular problems (strokes). Of the 54 children who survived surgery, 29 are seizure-free. Thirteen children have non-handicapping seizures and 12 have seizures that interfere to some extent with function.
The study appears in the August issue of Pediatrics.
According to the researchers, a decrease in the number of seizures is considered by physicians and patients and their families to be the best measure of the effectiveness of epilepsy surgery. However, for children with severe epilepsy, even complete seizure control may be an inadequate measurement of the success or failure of surgery.
According to John M. Freeman, M.D., director of the Johns Hopkins Pediatric Epilepsy Center, in such cases the burden of illness outweighs the risks of surgery. "This is an incredible operation. Although these kids are still impaired, they are much better than they were before surgery. Half a brain that works well is better than a whole brain that is seizing constantly," he says.
If success is measured by a substantial decrease in seizures, then 89 percent of those patients with Rasmussen's syndrome; two-thirds of infants with dysplasias; and two-thirds of those with vascular problems are now either seizure-free or have only non-handicapping seizures.
Seizure control, however, is not alone an adequate measure of the success of the epilepsy surgery, says Vining. Success of surgery must be measured in terms of the child's preoperative condition and the change in that condition after surgery.
With hemispherectomy, half of the brain is removed, but the deep structures -- the thalamus, brain stem and basal ganglia -- are left intact. The procedure is considered only for patients who have severe seizure disorders originating on one side of the brain and for those who do not improve with medication.
Surgery risks include infection, bleeding into the empty brain cavity, shifts of the brain causing coma, hydrocephalus (fluid buildup in the brain), and death.
Patients who have undergone a hemispherectomy always have some paralysis on the side opposite the removed hemisphere. They usually are able to walk and run with only a slight limp and perhaps an ankle brace. Although they are able to move their elbow and shoulder on the paralyzed side, patients do not have normal function or sensation in the hand and fingers. The paralyzed hand becomes a "helper" hand and never completely recovers. In addition, the left or right eye is affected. However, all these children already had some paralysis prior to surgery due to their illness.
Patients in the study were selected for surgery when the burden of seizures was excessive. The timing of surgery was decided by the severity of the child's condition as defined by the families, in consultation with their physician. The families also understood that surgery would result in the permanent loss of mobility in their child's hand, in exchange for relief from seizures and their treatment.
Hemispherectomy does not appear to decrease a child's intellect; in fact, intelligence usually improves, due to the lack of seizures and the elimination of anti-seizure medications.
Although the surgery can be performed at any age, it appears that younger children do best, because the remaining half of the brain compensates for the removed half more easily and completely. While transference of speech to the remaining hemisphere may occur in children as old as 13, in many hemispherectomy patients damage in the speech area has caused language to be transferred before the operation.
Other collaborators on the study were Benjamin S. Carson Sr., M.D.; Jason Brandt, Ph.D.; Dana Boatman, Ph.D.; Margaret B. Pulsifer, Ph.D., Aaron Zuckerberg, M.D.; Diana Pillas and the late Sumio Uematsu, M.D.
The Johns Hopkins Children's Center is the children's hospital of The Johns Hopkins Medical Institutions. Maryland's most comprehensive acute-care hospital for children, the Center, with its 177-bed hospital and more than 40 divisions and services, treats some 8,000 inpatients annually with more than 64,000 outpatient visits.