The MRIs of 13 members of two families with febrile convulsions (FC) and 10 members without FC were compared with 23 control subjects in a study at the Universities of Magdeburg and Bonn, Germany. One member of each family with febrile convulsions had developed temporal lobe epilepsy (TLE) and both TLE patients showed left-sided hippocampal sclerosis. All subjects with febrile convulsions and without subsequent epilepsy and six unaffected relatives showed asymmetric hippocampal volumes, the left smaller than right. The pattern and left-sided involvement of hippocampal sclerosis in TLE patients was similar to that in their relatives without epilepsy. Additional subcortical heterotopias were found in one FC patient. 
COMMENT. Patients with familial febrile convulsions may have a subtle, inherited form of pre-existing hippocampal malformation that predisposes to and is not a consequence of febrile convulsions. The hippocampal malformation may facilitate the development of hippocampal sclerosis in patients with temporal lobe epilepsy and antecedent febrile convulsions. A dominant mode of inheritance is suggested. These findings are interesting and provocative but not entirely supported by previous reports.
In an editorial, Sloviter RS and Pedley TA comment that other large series of surgical resections for TLE had not found a predilection for the left side in patients with hippocampal sclerosis . Bilateral hippocampal abnormalities and dual pathologies, focal cortical dysplasia occurring with mesial temporal sclerosis, were reported in patients with TLE treated at the University of Alabama (see Ped Neur Briefs April 1998;12:26). Routine MRIs may miss subtle abnormalities, and special techniques are necessary to uncover hippocampal structural anomalies.