MR volumetry of the entorhinal, perirhinal, and temporopolar cortices in drug-refractory temporal lobe epilepsy

BACKGROUND AND PURPOSE: The occurrence of damage in the entorhinal, perirhi nal, and temporopolar cortices in unilateral drug-refractory temporal lobe epilepsy (TLE) was investigated with quantitative MR imaging. METHODS: Volumes of the entorhinal, perirhinal, and temporopolar cortices w ere measured in 27 patients with unilateral drug-refractory TLE, 10 patient s with extratemporal partial epilepsy, and 20 healthy control subjects. All patients with TLE were evaluated for epilepsy surgery and underwent operat ions. RESULTS: In left TLE, the mean volume of the ipsilateral entorhinal cortex was reduced by 17% (P < .001 compared with control subjects) and that of th e ipsilateral temporopolar cortex by 17% (P < .05). In right TLE, the mean ipsilateral entorhinal volume was reduced by 13% (P less than or equal to . 01), but only in patients with hippocampal atrophy. Asymmetry ratios also i ndicated ipsilateral cortical atrophy. When each patient was analyzed indiv idually, the volume of the ipsilateral hippocampus was reduced (greater tha n or equal to 2 SD from the mean of controls) in 63% and that of the entorh inal cortex in 52% of patients with TLE. Furthermore, ipsilateral entorhina l (left: r = 0.625, P < .001; right: r = 0.524, P less than or equal to 01) , perirhinal (left: r = 0.471, P < .05), and temporopolar (right: r = 0.556 , P < .01) volumes correlated with ipsilateral hippocampal volumes. There w as no association, however, with clinically or pathologically identified ca uses of epilepsy, duration of epilepsy, or age at onset of epilepsy. Mean c ortical volumes were unaffected in extratemporal partial epilepsy. CONCLUSION: Subpopulations of patients with unilateral TLE have ipsilateral damage in the entorhinal and temporopolar cortices. The damage is associat ed with hippocampal damage.