Dissociation between diffusion MR tractography density and strength in epilepsy patients with hippocampal sclerosis.

Mesial temporal lobe epilepsy (MTLE) is hypothesized to involve derangement of long-range limbic connectivity, but in vivo evidence is lacking. We used diffusion tractography to investigate the relationship between hippocampal atrophy and connectivity in MTLE patients with hippocampal sclerosis (HS). Atrophy was correlated with relatively decreased connectivity density but increased connectivity strength, suggesting that HS is accompanied by relatively sparse but strong connections as measured by diffusion anisotropy.