Pediatric epilepsy surgery fails to aid later cognitive function.
While findings from previous studies have shown that the surgery has no short-term effect on childhood cognition, little was known until now about its long-term effect on adult cognition, noted Dr. Olds, a psychologist at the Children's Hospital of Eastern Ontario.
She assessed cognitive function in 50 adults (mean age 22 years) with a history of childhood epilepsy; 34 had undergone epilepsy surgery at least 2 years prior to assessment.
Of these, 21 were seizure-free and 13 continued to have seizures. The other 16 subjects, who served as controls, had never had surgery for their epilepsy as children and continued to have seizures as adults.
Seizure-free surgical subjects were taking a mean of one antiepileptic drug. Both the surgical group with continued seizures and the nonsurgical group were taking a mean of two antiepileptic drugs.
All of the subjects completed a neuropsychological assessment consisting of measures of intelligence, memory, and executive functioning (Wechsler Adult Intelligence Scale, vocabulary and block design; Wechsler Memory Scale, logical memory and memory for faces; Wisconsin Card Sort Test). Scores were compared with the subjects' pre- and postsurgical scores on the same tests.
There were no group differences in problem solving as reflected in the Wisconsin Card Sort Test. Surgery subjects who continued to have seizures scored lower on vocabulary and verbal memory tests, compared with both the seizure-free surgery group and the no-surgery group.
When the scores in two surgical groups were compared, the seizure-free group did better on vocabulary and block design, compared with the group still having seizures. However, there were no differences in scores across the three test periods, indicating no significant change in functioning over time.
It's important to include a discussion of cognitive function when counseling parents about the potential impact of epilepsy surgery, said Mary Lou Smith, Ph.D., the study's principal investigator. The majority of research suggests that cognitive skills won't change--a fact that can be construed in a positive, as well as potentially negative, light.
"In essence, this is good news, although not necessarily the good news those parents would like to hear," Dr. Smith, of the University of Toronto, said in an interview. "[Parents] may wish, and often do, that their child will show improved cognitive function after surgery."
She added that it is important to remember that the study's conclusions are based on group numbers and that within each group, some children do better or worse than the study's findings indicate.
Unfortunately, Dr. Smith said, there's no consensus on what factors predict who will improve and who will deteriorate.
"The few studies that have included a comparison group of children with intractable epilepsy who don't have surgery show that the proportion who shows increases or decreases is the same in both surgical and nonsurgical groups," she commented.
The general conclusion is that as long as the eloquent cortex remains intact, there is no particular cognitive risk or benefit associated with the surgery, said Dr. Smith.
BY MICHELE G. SULLIVAN
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|Title Annotation:||care and treatment|
|Author:||Sullivan, Michele G.|
|Publication:||Clinical Psychiatry News|
|Date:||Apr 1, 2006|
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