DEVELOPMENTAL ABNORMALITIES OF THE MEDIAL TEMPORAL-LOBE IN PATIENTS WITH TEMPORAL-LOBE EPILEPSY

PURPOSE: To evaluate MR temporal lobe malformations and their frequenc y in patients with temporal lobe epilepsy. METHODS: Two hundred twenty -two consecutive adult patients with temporal lobe epilepsy of varying severity were investigated with 1.0-T or 1.5-T MR units using three-d imensional T1-weighted acquisition protocol. RESULTS: Sixteen patients (7.2%) presented with malformations of the temporal lobe. Four patter ns of malformations were encountered: (a) heterotopia (n = 1), lining the temporal horn of the lateral ventricle; (b) focal neocortical dysg enesis (n = 6), which consisted of cortical thickening, poor gray/whit e matter demarcation, abnormal gyration (n = 5), or limited schizencep haly (n = 1); (c) hippocampal malformations (n = 5), which presented a s abnormal hippocampal formation associated with a cyst (n = 2), isola ted malformation of the subiculum (n = 1), or bilateral hippocampal ma lformation (n = 2) consisting of an abnormal shape and a misplaced fim bria; (d) complex malformations of the temporal lobe, combining catego ries a, b, and c (n = 4). The age at onset, severity of the disease, a nd occurrence of generalized tonicoclonic seizures were not significan tly different between patients with malformations and the entire popul ation of patients with temporal lobe epilepsy. CONCLUSION: MR analysis of temporal lobe malformations allowed a precise determination of the extent of the malformations and the presence or absence of associated hippocampal disease, all of which are of great help in the preoperati ve evaluation of patients with intractable epilepsy.