Abstracts

To investigate if hippocampal histopathology can be predictive of epilepsy surgery outcome when correlated with presurgical MRI findings. The surgical outcomes of 40 adults (ages 17-57) with refractory mesial temporal epilepsy were retrspectively analyzed and correlated with presurgical high resolution MRI of the temporal lobes and surgical histopathology specimens. All patients underwent resection of the hippocampus and amygdala between 11/96 and 1/03. Patients with lesions such as tumors, vascular malformations or dysplasias were not included. Post-surgical follow-up times ranged from 1 to 8 years (mean 4.9 years). 24 were female and 16 were male. 10/40 (75%) of patients are currently seizure free or have simple partial seizures. 34/40 (85%) had clear mesial temporal sclerosis (MTS) on high resolution MRI scan with 12/40 having right MTS and 28 having left MTS. 38/40 (95%) had gliosis and mild to severe neuronal loss in the hippocampus on histopathology. 2/40 did not have pathology results available. Of the 6 patients who had normal MRI scans, 3 continued to have refractory complex partial or convulsive seizures, 1 has rare complex partial seizures and 2 are seizure free. Of the 10 patients who continued to have seizures after surgery, 3 had normal MRI scans, and 5 had histopathology consistent with only [quot]mild[quot] gliosis. In the other 5 patients the histopathology results were not graded. Although gliosis and neuronal loss in the hippocampus on histopathology does not guarantee seizure freedom after epilepsy surgery, the combination of hippocampal sclerosis on MRI plus hippocampal gliosis and neuronal loss on histopathology appear to be excellent predictive factors of post-surgical seizure freedom. In contrast, normal MRI findings and only minimal pathologic changes suggest a poor surgical outcome.