Control of temporal lobe epilepsy following en bloc resection of low-grade tumors

Thirty-one patients with a mean age of 18.9 years (range 3 to 53 years) who underwent temporal lobe surgery for tumor-related epilepsy over a 14-year period are presented. All had suffered chronic drug-resistant temporal lobe seizures (mean age at onset 6.9 years, range 0 to 30 years; mean duration of condition 11.9 years, range 3 to 39 years). Preoperative interictal scalp electroencephalography tracings indicated unilateral localized epileptic foci in 90% of patients, and computerized tomography scans showed abnormalities within the temporal lobe in 87%. All patients underwent en bloc temporal lobectomy. No patient received adjuvant radiotherapy or chemotherapy. Review of the histological material showed dysembryoplastic neuroepithelial tumor in 27 (87%) of the specimens and microscopic evidence of incomplete removal of tumor in 22 (71%). At long-term follow-up evaluation (mean duration 5.8 years, range 1 to 14 years), 81% of patients were completely free of seizures (Engel grade I) and 10% were almost seizure free (Engel grade II) with no deaths reported in either early or late follow-up review. Only one patient in the series failed to benefit from the surgery. Four patients suffered permanent neurological deficit causing a mild disability. Psychological assessment showed no significant fall in verbal or performance intelligent quotient for the group, but a mild memory impairment was evident in 32%. Behavioral and social aspects improved in nearly all (94%) cases. Relief of seizures could not be predicted by intraoperative electrocorticography, and outcome was independent of the completeness of tumor resection. Postoperative electroencephalographic findings identified epileptiform potentials in 65% of patients, which were associated with a worse seizure-control outcome grade.