In vivo imaging of human anatomy in temporal lobe epilepsy.

Temporal lobe epilepsy is the most important cause of medically intractable seizures. Complex partial seizures, the main clinical manifestation of temporal lobe epilepsy, arise primarily from the mesial temporal structures, the amygdala, and the hippocampus [1 , 2) . This form of epilepsy is also the most readily treatable with surgery: in most series, recovery is reported in 60-85% of cases [3). The pathologic entities associated with temporal lobe epilepsy are varied and include tumors, vascular malformations, heterotopias, and hippocampal sclerosis [ 4-6). Hippocampal or mesial temporal sclerosis is by far the most common pathologic finding, occurring in approximately 65% of cases [5, 6) . In those cases without evidence of alien tissue, hippocampal sclerosis is thus the overwhelmingly predominant pathology; furthermore, its location coincides with the electrophysiologically defined origin of most complex partial seizures [1 ). Finally, there is a high correlation between the presence of hippocampal sclerosis in the excised surgical specimen and the likelihood that the patient will benefit from the surgical procedure [5). Unfortunately, in many cases of temporal lobe epilepsy, the routine diagnostic studies may not clearly indicate the side of the disease. Clinical manifestations may be ambiguous with respect to lateralization, and electroencephalographic discharges may often appear bilaterally. Accordingly, it is clear that any method of preoperative identification of hippocampal sclerosis would be of significant clinical value. Because previous reports of MR detection of hippocampal sclerosis have been controversial [7 -13), the articles by Bronen et al. [14) and Ashtari et al. [15) in this issue of the AJNR are of special importance. Both studies make use of substantial advances in MR technology or in quantitative computational evaluation . Both provide strong positive evidence for MR detection of hippocampal sclerosis and the atrophy associated with it. They support the earlier observations of