Sixteen of 48 children undergoing temporal lobectomy for temporal lobe epilepsy at the Hospital for Sick Children, Toronto, Ontario, were found to have tumors (12 patients), vascular malformations (3), and arachnoid cyst (1). Nine of these patients had concomitant mesial temporal sclerosis. In 11 of 18 operations (61%), it was necessary to extend the original cortical excision because of persistent epileptiform activity. The duration of seizures in the 16 patients varied between 1 and 13 years (average 6 yrs). Memory was impaired in 31% of patients, 39% had behavior problems, and 39% had deteriorating school performance.

Temporal lobectomy was performed on the right side in 8 cases and on the left side in 8. Four patients had an increased neurological deficit postoperatively and all had contralateral superior quadrantanopic defects. Of 15 patients followed for more than 1 year, 9 are seizure free (only 4 on medication), and 7 had more than 50% reduction in seizure frequency. [1]

COMMENT. The authors emphasize that simple excision of the tumor may not eradicate the seizures. The common occurrence of mesial temporal sclerosis in association with mass lesions requires extension of the resection to include removal of the hippocampus as well as the cortex adjacent to the tumor. It is suggested that hippocampal changes are secondary to repetitive seizure activity.

The late detection of cerebral gliomas as a cause of childhood epilepsy has been noted by other investigators. Diagnosis of supratentorial tumors was delayed for an average of 2 years after the initial seizure and 8 of 31 patients continued to have seizures for periods between 3 and 8 years before a tumor was demonstrated in a study of 291 cases at the Mayo Clinic. Seizures occurred in 17% of the total group — in 25% of patients with supratentorial tumors and in 12% of those with infratentorial tumors. They were the initial symptoms in 15% of patients with supratentorial tumors. Seizures were more common in patients with slowly growing astrocytomas, grades 1 and 2, than in those with more rapidly expanding astrocytomas, grades 3 or 4. [2]

The MRI should permit earlier diagnosis of the temporal lobe glioma as a cause of childhood epilepsy. MRI is superior in defining the extent of gliomas grade 1 and 11 that may be poorly delineated by CT, and MRI should be a complementary examination in suspected tumor cases [3]. The prompt surgical excision of the tumor before seizures become medically unresponsive may prevent the development of the mesial temporal sclerosis and dual pathology stressed in the present report.