側頭葉てんかんの海馬萎縮と臨床像の検討 ―MRIを用いた海馬萎縮の簡易評価―

側頭葉てんかん患者39例の海馬萎縮をMRIを用いて評価し,臨床像との関連を検討した｡MRIの冠状断short SE像で海馬の幅を計測し,萎縮側海馬の村側海馬に対する比(a)を求め,海馬萎縮(+)群;a<0.8,11例,境界群;0.8≦a<0.9,13例,海馬萎縮(-)群;a≧0.9,15例の3群に分けた｡海馬萎縮(+)群で罹病期間が長い傾向があった｡また,発作間歇期脳波の焦点側は海馬委縮(+)群の11例中9例で萎縮側と一致した。しかし,発病年齢,MRI撮影時年齢,発作頻度,全般化発作の有無,抗てんかん薬総服用量,知能障害,精神症状,生下時仮死の有無については3群間で差が認められなかった｡この結果から,側頭葉てんかんにおける海馬萎縮は,生下時や全身けいれん発作時の低酸素状態によるものではなく,脳局所の反復するてんかん性発射と関連する可能性が示唆され,海馬萎縮の機序を考えるうえで興味深く思われた。

We studied hippocampal atrophy in 39 patients with temporal lobe epilepsy using MRI. The ratio (a) of the width of the hippocampus on the atrophic side to that on the contralateral side was measured in coronal sections of the short SE in MRI. According to this ratio, the patients were divided into three groups : 11 with hippocampal atrophy (a<0.8), 13 with borderline atrophy (0.8≦a≦0.9), and 15 with no hippocampal atrophy (a≧0.8). In the patients of the group with hippocampal atrophy, the clinical history of epilepsy tended to be long, and the site of hippocampal atrophy was consistent with that of interictal spike foci on the electroencephalogram in 9 out of 11 patients. However, there was no difference between the three groups, with regard to age at onset, age when MRI was conducted, frequency of seizures, generalized seizures, the types and doses of antiepileptic drugs used, history of neonatal asphyxia, intelligence and epilpetic psychosis. These results suggest that hippocampal atrophy in temporal lobe epilepsy may be related to repetition of epileptic dischargges in a localized part of the brain.