てんかんの画像診断

Neuroimaging in the Diagnosis of Epilepsy

Point

・てんかん外科にかかわる画像診断には，MRIを中心とした形態画像と，脳機能を反映する機能画像がある．

・てんかん外科の対象となる器質病変は，MRIでも微細な所見しか認めないものもあり，診断には熟練を要する．

・外科治療の対象となる病変（機能異常部位）は，MRIで認められる器質病変のみでないことも多く，機能画像やその他のモダリティを含め，総合的に判断する必要がある．

　Neuroimaging is commonly used for presurgical evaluation in epilepsy surgery. Neuroimaging for epilepsy includes structural and functional neuroimaging. Lesions detected by structural neuroimaging are crucial to determine the indication of epilepsy surgery, as well as to predict seizure outcomes, as patients with MRI-visible lesions are likely to have better seizure outcomes. However, MRI lesions sometimes show very faint findings; therefore, the diagnosis of structural neuroimaging requires sophisticated skills. Moreover, the epilepsy focus should not only involve the MRI-visible lesion, but also the surrounding tissue with abnormal neuronal function. The MRI-lesion, which is almost the same as that epileptogenic lesion, is a part of the epileptogenic zone. Surgical strategy should be conducted by comprehensive evaluation including neuroimaging in addition to other modalities.