Quantitative MRI in temporal lobe epilepsy - Evidence for fornix atrophy

Objective: To investigate whether the fornix and mamillary bodies, being pa rt of the limbic system, are abnormal in patients with mesial temporal lobe epilepsy (MTLE). Background: The limbic system comprises the hippocampal f ormation, fornix, mamillary bodies, thalamus, and other integrated structur es. This system is implicated in complex functions, including memory and em otion, and in diseases such as MTLE. Methods: The authors performed volumet ric measurements of hippocampus, amygdala, fornix, and mamillary bodies in 50 patients with MTLE and compared the results with normal controls and pat ients with extratemporal lobe epilepsy. Results: Control (n = 17) measureme nts of the amygdala, hippocampus, and for nix revealed larger volumes of th e right hemisphere structures (p < 0.001). Normalized fornix volumes reveal ed atrophy in 86% of studies concordant with hippocampal atrophy in all cas es but one. Similarly, the mean hippocampal and fornix volumes for the grou p discriminated the epileptogenic temporal lobe (p < 0.001). Limbic volumes were normal in all patients with extratemporal lobe epilepsy. Conclusions: quantitative MRI findings support the concept that MTLE is not a process l imited to the hippocampus but also involves other interrelated limbic syste m structures, in particular, the fornix.