NEUROPATHOLOGICAL FINDINGS IN 224 PATIENTS WITH TEMPORAL-LOBE EPILEPSY

During the period between 1976 and 1990, 247 patients with pharmaco-re sistant complex partial seizures and a documented unilateral epileptog enic area in the mediobasal temporal lobe underwent a selective amygda lo-hippocampectomy procedure at our institution. Biopsy specimens from 224 patients (91% of the total) were available for a retrospective hi stopathological and immunohistochemical review. The tissue specimens o f 23 patients without evidence for a macroscopic lesion have been used for neurochemical studies and could not be evaluated histopathologica lly. The most common temporal lobe pathology were neoplasms in 126 pat ients, i. e. 56%. Tumor entities observed included 23 astrocytomas (18 % of all tumors), 17 gangliogliomas (13%), 15 oligodendrogliomas (12%) , 15 cases of glioblastoma multiforme (12%), 13 pilocytic astrocytomas (10%), 12 oligo-astrocytomas (10%), 11 anaplastic astrocytomas (9%) a nd 20 tumors of various other histologies. In 23 specimens (10%), smal l foci of oligodendroglia-like clear cells were found. The frequent as sociation of these foci with low-grade gliomas or neural hamartomas ra ises the possibility that these structures may serve as precursor lesi on for neuroepithelial tumors of the temporal lobe. In 98 cases, patho logical changes of non-neoplastic origin were encountered. The most co mmon diagnoses in this group included hippocampal gliosis/sclerosis (4 9 cases, 22%) and vascular malformations (20 cases, 9%). Hamartomas, i .e. focal accumulations of dysplastic neuro-glial cells were diagnosed in 14 patients (6%). In only four cases have we not been able to dete ct any microscopic pathology. These results indicate that a high propo rtion of pharmaco-therapy-resistent complex-partial seizures are cause d by neoplasms of the temporal lobe, some of which appear to be striki ngly overrepresented in this group of patients.