Bilateral hippocampal granule cell dispersion: autopsy study of 3 infants.

Recent morphologic studies of Ammon's horn sclerosis (AHS) have recorded granule cell dispersion (GCD) in a significant proportion of temporal lobes surgically resected for temporal lobe epilepsy (TLE). We report the first post-mortem descriptions of GCD in three unrelated infants. GCD was bilateral in all three and there were also migrational defects, heterotopias or polymicrogyria. Only one child, a 2.5-year-old boy, presented with a severe seizural disorder and exhibited bilateral AHS. But in the two younger children, deceased at 12 weeks and 5 months, respectively, no seizures were observed and hippocampal neuronal populations were intact. To date, GCD has only been reported in association with epilepsy and has not been observed bilaterally or in neurologically normal individuals. The present observations bring into question the hypothesis that GCD is causally related to seizure activity in early life, suggesting an opposing view that it is an independent developmental disorder.