Granular cell dispersion and bilamination: two distinct histopathological patterns in epileptic hippocampi?

Cytoarchitectural modifications of the dentate gyrus are among the most obvious abnormalities observed in the hippocampal sclerosis associated with refractory epilepsy. Here, we examined the morphological changes of granular cells (dispersion, bilamination and cell loss) in sclerotic hippocampi from nine TLE patients, comparing abnormal and preserved areas. A total of 2,577 granular cells were analyzed with respect to four different histopathological patterns: areas with bilamination (n = 936), areas with dispersion (n = 905), areas with neuronal loss (n = 279), and preserved areas (n = 457). Quantitative parameters included somatic perimeter (P), area (A) and form factor (ff). Although different patterns were often observed in the same patient, highly significant differences were observed (p < 0.0001) when patterns were compared to one another. Since granular cell dispersion and bilamination have different morphological aspects in sclerotic hippocampi from TLE patients, we suggest that these patterns should be considered separately. Future studies are needed to determine the frequency with which these patterns occur in the general population and whether each one can interfere with seizure susceptibility.