Clinical, genetic, and MR characteristics of 68 patients with familial mesial temporal lobe epilepsy (MTLE) were analysed at the University of Campinas-UNICAMP, Brazil. Hippocampal atrophy (HA) was identified by MRI in 48 (57%) of 84 patients examined. HA was present in 46% of 13 patients with seizure remission, in 51% of 16 patients whose seizures were well controlled by AEDs, and in all 16 patients with refractory MTLE. HA was also found in some patients without MTLE: in 30% of 10 patients with febrile seizures alone, 60% of 10 with generalized tonic-clonic epilepsy, and in 1 of 4 with a single partial seizure. Familial MTLE is a heterogeneous syndrome with a genetic component in etiology. 
COMMENT. In this series of patients with familial mesial temporal lobe epilepsy, 57% had MRI evidence of mesial temporal sclerosis. Hippocampal atrophy is found not only in patients with refractory epilepsy but also in patients with a favorable outcome. Genetically determined mechanisms may have a role in hippocampal damage in familial cases of MTLE. In contrast to most patients with temporal lobe epilepsy, a history of febrile seizures is uncommon in patients with familial TLE.