Abstract:

Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are major causes of intractable epilepsy in children. The probable pathogenesis of FCD and HMG is the abnormal migration and differentiation of neurons. The aim of the present study was to clarify the abnormal cytoarchitecture, based on neuronal immaturation. Tissue samples were obtained from 16 FCD and seven HME patients, aged between 2 months and 12 years, who had been diagnosed as typical FCD and HME, following surgical treatment for intractable epilepsy. Paraffin-embedded sections were stained with the antibodies of three layer-markers that are usually present only during the fetal period, namely SATB2 (expressed in the upper layer of the normal fetal neocortex), FOXP1 (expressed in the 5th layer), and TBR1 (expressed in the 6th layer). In FCD, SATB2-positive (+) cells located in the middle and deep regions of FCD Ia and Ib, but only in the superficial region of FCD IIa and IIb. FOXP1+ cells diffusely located in the neocortex, especially the upper layer of FCD IIa and IIb. TBR1+ cells mainly located in the middle and deep regions, and also white matter. In FCD IIb, TBR1+ cells were in the superficial region. In HME, SATB2+ and FOXP1+ cells were found diffusely. TBR1+ cells were in the middle and deep regions. On the basis of continued expression of fetal cortical layer-specific markers in FCD and HME brains, the abnormal neocortical formation in both is likely to be the result of disrupted neuronal migration and dysmaturation. The expression pattern is different between FCD and HME.

日本語要旨:

難治性てんかんの原因となる皮質異形性と片側巨脳症はともに神経細胞の遊送障害が成因である。外科切除標本を用いて層特異的に発現する3つのタンパク質を免疫組織化学的に検討した。その結果皮質異形性において3つのパターンに分類でき、また片側巨脳症においては層をまたいで瀰漫性に染色されるなど、それぞれが異なった染色パターンを示し、その成因が異なることが強く示唆された。