Kamiya Kouhei, Sato Noriko, Saito Yuko, Nakata Yasuhiro, Ito Kimiteru, Shigemoto Yoko, Ota Miho, Sasaki Masayuki, Ohtomo Kuni
Department of Radiology, National Center Hospital of Neurology and Psychiatry, 4-1-1, Ogawahigashi-chyo, Kodaira, Tokyo 187-8551, Japan.
Department of Radiology, National Center Hospital of Neurology and Psychiatry, 4-1-1, Ogawahigashi-chyo, Kodaira, Tokyo 187-8551, Japan.
J Neuroradiol. 2014 Jul;41(3):202-10. doi: 10.1016/j.neurad.2013.08.005. Epub 2013 Oct 1.
In infants with hemimegalencephaly, asymmetrical white-matter intensities suggestive of advanced myelination are observed as well as aberrant midsagittal fibers (AMFs) specific to hemimegalencephaly. Also noted are otherwise unreported abnormally enlarged periventricular fibers (APVFs) running anteroposteriorly along the caudate nucleus. This study investigated the degree of myelination and presence of aberrant fibers in hemimegalencephaly through a retrospective review of MRI scans in relation to histopathological findings.
MRI scans of 24 infants with hemimegalencephaly (13 boys and 11 girls, 1-9 months old) were evaluated, focusing on the presence and signal intensities of AMFs and APVFs. White-matter signal intensities on T1- and T2-weighted imaging of the cerebral hemisphere were also evaluated and compared with the timetable for normal myelination. Surgical specimens were pathologically examined with Klüver-Barrera staining in four patients.
AMFs and APVFs were observed in 18 and nine patients, respectively, while 22 patients had accelerated myelination of the megalencephalic hemisphere that tended to extend along fiber pathways including AMFs and APVFs. In six cases, accelerated myelination even extended into the contralateral hemisphere via the corpus callosum or AMFs. Histopathological analysis identified hypermyelination with disarrayed myelinated fibers corresponding to MRI findings.
Accelerated myelination is frequently observed in patients with hemimegalencephaly and tends to extend along fiber pathways, including aberrant or abnormal fibers, as seen in 75% of hemimegalencephaly patients. Accelerated myelination may reflect propagation pathways of abnormal brain activity in such patients.
在半侧巨脑症婴儿中，可观察到提示髓鞘形成提前的不对称白质信号强度，以及半侧巨脑症特有的异常矢状中纤维（AMF）。还注意到有沿尾状核前后走行的未被其他报道的异常增粗的脑室周围纤维（APVF）。本研究通过回顾性分析与组织病理学结果相关的MRI扫描，调查半侧巨脑症中髓鞘形成程度及异常纤维的存在情况。
对24例半侧巨脑症婴儿（13例男孩和11例女孩，年龄1 - 9个月）的MRI扫描进行评估，重点关注AMF和APVF的存在及信号强度。还评估了大脑半球T1加权和T2加权成像上的白质信号强度，并与正常髓鞘形成时间表进行比较。对4例患者的手术标本进行了Klüver - Barrera染色的病理检查。
分别在18例和9例患者中观察到AMF和APVF，22例患者的巨脑半球存在髓鞘形成加速，且倾向于沿包括AMF和APVF在内的纤维束延伸。在6例病例中，加速的髓鞘形成甚至通过胼胝体或AMF延伸至对侧半球。组织病理学分析发现髓鞘形成过度，且有与MRI表现相对应的排列紊乱的有髓纤维。
半侧巨脑症患者中经常观察到髓鞘形成加速，且倾向于沿纤维束延伸，包括异常纤维，75%的半侧巨脑症患者均有此现象。髓鞘形成加速可能反映了此类患者异常脑活动的传播途径。
