SURGICAL-TREATMENT OF TEMPORAL-LOBE EPILEPSY - CLINICAL, RADIOLOGICAL, AND HISTOPATHOLOGICAL FINDINGS IN 178 PATIENTS

The surgical treatment of pharmacoresistant temporal lobe epilepsy is increasing rapidly. The correlation of preoperative MRI, histopatholog ical findings, and postoperative seizure control is reported for 178 p atients with chronic medically intractable temporal lobe epilepsy who were operated on between November 1987 and January 1993. Histopatholog ically there were distinct structural abnormalities in 97.2% of the su rgical specimens. Signal abnormalities on MRI were present in 98.7% of patients with neoplastic lesions (n = 79), 76.6% of patients with non -neoplastic focal lesions (n = 55), and 69.2% of patients with Ammon's horn sclerosis (n = 39). Overall, structural abnormalities were detec ted by MRI in 82.7% of all patients. The mean postoperative follow up period was three years. Some 92% of the patients benefited from surger y: 103 patients (61.7%) were seizure free, 26 (15.5%) had no more than two seizures a year, and 24 (14.4%) showed a reduction of seizure fre quency of at least 75%. Fourteen patients (8.4%) had a <75% reduction of seizure frequency. The percentage of patients who were completely f ree of seizures after operation was 68.5% for patients with neoplastic lesions, 66.7% for Ammon's horn sclerosis, and 54.0% for patients wit h non-neoplastic focal lesions. By contrast, none of the patients in w hom histopathological findings were normal became seizure free postope ratively. The data show that the presence of focal lesions or Ammon's horn sclerosis as determined by histopathological examination is assoc iated with improved postoperative seizure control compared with patien ts without. specific pathological findings. Brain MRI was very sensiti ve in detecting neoplasms; however, its sensitivity and specificity we re limited with respect to non-neoplastic focal lesions and Ammon's ho rn sclerosis. Improvement of imaging techniques may provide a more pre cise definition of structural lesions in these cases and facilitate li mited surgical resections of the epileptogenic area rather than standa rdised anatomical resections.