Neuropathological findings in resective surgery for medically-intractable epilepsy. A study of 195 cases.

This report concerns the histopathological findings in 195 consecutive surgical specimens of patients with chronic pharmacoresistant epilepsy. Six pathological groups were identified corresponding to 63 tumors, 51 developmental lesions, 39 Ammon's horn sclerosis, 27 non specific changes, 11 glial or gliomesodermal scars and 4 Rasmussen's encephalitis. In 14 patients, 2 distinct abnormalitites were observed with Ammon's horn sclerosis as on part of the dual pathology. All tumors were of low histopathological grade and included 30 dysembryoplastic neuroepithelial tumors, 17 gangliogliomas, 5 subependymal giant cell astrocytomas of tuberous sclerosis, 4 pleomorphic xanthoastrocytomas, 3 astroblastomas, 3 astrocytomas and 1 oligodendroglioma. Developmental lesions included 22 hamartomas, 12 focal dysplasias, 5 microdysgenesis, 1 modular cortical heterotopia, 1 arachnoid cyst and .10 cavernomas. These findings emphasize two pathological features. Firstly. well-defined changes were present in all specimens. Secondly, the most common lesions were respectively tumors and developmental abnormalities.