ROCHESTER, N.Y. -- Surgery for intractable temporal lobe epilepsy may cause a decline in verbal recall memory in about a third of patients, but the opportunity to end seizures may be worth the risk, investigators here said.
ROCHESTER, N.Y., June 4 -- Surgery for intractable temporal lobe epilepsy may cause a decline in verbal recall memory in about a third of patients, but the opportunity to end seizures may be worth the risk, investigators here said.
In a multicenter study of 138 patients who did not respond to multiple anti-epileptic drugs, resection of the epileptogenic focus allowed more than three-quarters of them to remain seizure-free for up to five years, reported John T. Langfitt, Ph.D., of the University of Rochester, and colleagues.
But the surgery also caused post-operative reduction in memory performance in a little more than one-third of patients, and 18% still had seizures after surgery, the researchers reported in the June 5 issue of Neurology.
When patients had the misfortune to suffer both a memory loss and failed surgery, the result was significant decline in their health-related quality of life, the authors found.
But clinicians and patients should also understand that the risk that a patient will lose some verbal memory performance has to be weighed against the risk of cognitive decline associated with uncontrolled seizures, wrote Gregory D. Cascino, M.D., chairman of the division of epilepsy in the department of neurology at the Mayo Clinic in Rochester, Minn., in an accompanying editorial.
"The postoperative memory deficit is usually material-specific and not a global amnestic syndrome and may not interfere with the individual's quality of life with an excellent seizure outcome," he wrote.
"Ultimately," said Dr. Cascino, "the patient should be considered for surgical treatment, even if at risk for verbal memory loss, earlier rather than later in the presence of an intractable seizure disorder because rendering the individual seizure free is required to be a participating and productive member of society. "
In the Multicenter Study of Epilepsy Surgery, Dr. Langfitt and colleagues evaluated seizure control, memory change, and health-related quality of life in 138 patients.
All patients had monthly consciousness-impairing seizures for at least the previous two years, despite trials of two or more anti-seizure medications. They had all been evaluated for resective surgery using a common protocol, including intracarotid amobarbital testing to determine hemispheric speech dominance.
Before surgery patients also completed the Quality of Life in Epilepsy Inventory-89, a survey of health-related quality of life that consists of the Short Form 36 questionnaire plus a 53-item epilepsy-targeted supplement. In addition, patients had baseline neuropsychological testing, including the California Verbal Learning Test, a 16-item, multi-trial list-learning test often used to evaluate verbal memory both before and after temporal lobe surgery.
The patients then underwent temporal lobe resection and were followed up with quarterly telephone calls asking for information from their diaries about seizure occurrence. They also were given the Quality of Life in Epilepsy Inventory-89 annually, and were retested with the neuropsychological battery at the two- and five-year intervals.
In all, 113 patients (82%) had complete remission of seizures at the two-and/or five-year follow-up intervals. The authors found that regardless of memory outcome, the health-related quality of life was improved in these patients.
Among the 18% of patients who were not in remission at either interval, they said, there was no change over baseline in their health-related quality of life, provided that their memory function had not declined after surgery.
But in the 11 patients (8%) who had both a memory decline and no remission of seizures, there was a significant decline in health-related quality of life, the researchers said.
"These 11 patients had baseline characteristics predictive of poor seizure or memory outcome," the authors wrote. "Declines were most apparent on health-related quality of life subscales assessing memory, role limitations, and limitations in work, driving, and social activities."
In his editorial, Dr. Cascino suggested that candidates for temporal lobe resection of an epileptogenic focus be evaluated for "preoperative memory, employment or educational activities, the pathology underlying the epileptogenic zone, the lateralization of the temporal lobe, and MRI findings."
Dr. Langfitt and colleagues noted that their study was limited by loss to follow-up of younger, male, nonwhite, and less well-educated patients, especially because many were not compliant with the neuropsychological follow-up assessments.
"Selective loss-to-follow-up may lead to biased estimates of the incidence and predictors of cognitive changes after surgery," they wrote.