Volumetric evidence of bilateral damage in unilateral mesial temporal lobe epilepsy

Purpose: We sought to analyze the contralateral volumes of the temporal pole, posterior segment of the temporal lobe, amygdala, hippocampus, and parahippocampal gyrus in patients with temporal lobe epilepsy (TLE) due to histologically proven mesial temporal lobe sclerosis (MTLS), seizure free for >= 4 years of postsurgical follow-up. Methods: Forty-six (23 male) TLE patients, operated on between 1996 and 2001, with histopathologic diagnosis of MTLS, and a postsurgical follow-up of >= 4 years, had their temporal lobe structures manually segmented, measured, and compared with those of 23 normal volunteers, paired as groups for sex, age, and handedness. Results: The mean volumes of the contralateral temporal pole, hippocampus, and parahippocampal gyrus in TLE patients were significantly lower than those in controls. Conclusions: MRI volumetric data show that the damage in TLE due to MTS may be more widespread and bilateral, even in patients with unilateral TLE by clinical and neurophysiological criteria. Our results are relevant to the discussion of epileptogenic mechanisms in TLE.