The asymmetric mamillary body: association with medial temporal lobe disease demonstrated with MR.

PURPOSE To determine whether mamillary body atrophy is caused by deafferentation of the mamillary body in patients with mesial temporal sclerosis. METHODS We studied 36 patients with thin-section MR to assess mamillary body symmetry. These patients included 10 control subjects without seizures and 26 patients with a history of seizures. Thin-section T1 scans were available for all cases. The patients with epilepsy underwent axial and coronal T2 scans as well. RESULTS In five of eight cases with prior medial temporal lobe resection for intractable epilepsy, there was evidence of unilateral mamillary body atrophy ipsilateral to the resection. Similar findings were evident in three of six patients with MR findings of mesial temporal sclerosis without surgery. Two patients with medial temporal stroke or tumor also had ipsilateral mamillary body atrophy. CONCLUSION These findings provide support for the proposed mechanism of mamillary body atrophy caused by prior medial temporal lobe injury.