Anterior temporal abnormality in temporal lobe epilepsy - A quantitative MRI and histopathologic study

Objective: To examine the nature and frequency of anterior temporal lobe (A T) abnormalities that occur in intractable temporal lobe epilepsy (TLE). Me thods: We reviewed the MR scans and clinical histories of 50 consecutive pa tients with intractable TLE. Histopathology was available in 42 surgically treated cases. Results: MRI demonstrated loss of the gray-white matter diff erentiation and decreased T1- and increased Ta-weighted signal in the ipsil ateral AT in 58% of the 50 patients. This appearance was observed in 64% of the 36 patients with hippocampal sclerosis (HS) but was also seen in patie nts without HS. These changes were associated with temporal lobe atrophy, a higher hippocampal T2 relaxation time, and a history of febrile convulsion s. Pathologic examination showed that the MRI appearances were not caused b y dysplasia, degenerative abnormalities, or inflammatory change. Histologic quantitation showed increased glial cell nuclei counts in the intractable TLE cases compared with controls. There was no difference in glial cell num bers between cases with AT abnormality and those without this appearance. P resence or absence of changes was not predictive of preoperative neuropsych ology, postoperative change in neuropsychology, or seizure outcome after su rgery. Conclusions: These frequently seen ipsilateral changes are not cause d by gliosis and may reflect a nonspecific increase in water content in the temporal lobe. This may be due to myelin abnormalities or some other as ye t unidentified pathologic factor.