LONGITUDINAL VARIATION IN CELL-DENSITY AND MOSSY FIBER REORGANIZATIONIN THE DENTATE GYRUS FROM TEMPORAL-LOBE EPILEPTIC PATIENTS

Variation in cell loss and messy fiber reorganization was examined alo ng the longitudinal axis of the dentate gyrus from temporal lobe epile ptic (TLE) patients. Previous evidence has indicated that the anterior hippocampus is prone to seizure activity. We compared granule and hil ar cell number in addition to Timm stain density of the molecular laye r and hilus in more anterior and more posterior specimens of hippocamp us obtained from patients surgically treated for intractable epilepsy by the removal of the anterior half of the hippocampus. Granule cells/ mm in the more anterior specimen were less than or equal to those in t he more posterior specimen locations in 77% of the patients, while the re was no significant difference in hilar neuron density between the t wo blocks. These results demonstrate a significantly greater pathology in the granule cell layer in more anterior specimens and no differenc e in pathology for hilar neurons. Molecular layer Timm stain density w as significantly greater in the more anterior specimen of 71% of the p atients. The molecular layer Timm stain density ratio was inversely re lated to hilar cell density in more anterior specimens, whereas in mor e posterior specimens there was no significant relationship with hilar cell density. Our observations show that although differences exist a mong TLE patients for these neuroanatomic measures, pathology was grea ter in more anterior specimens. The latter result is consistent with t he conclusion that seizure activity may originate in the anterior regi on of the hippocampus in a majority of patients.