Kałuza J, Gruszka E
Klinika Chirurgii Polsko-Amerykańskiego, Collegium Medicum, Uniwersytetu Jagiellońskiego w Krakowie.
Przegl Lek. 1998;55(4):155-8.
The abnormal closure of the neural tube results in defects of the nervous system development, which are referred to as dysraphism. Considering successive steps of the development of the human foetus, it can be estimated that spinal cord malformations arise from pathologies of early foetal development between 17th and 28th day gestational age. This time period comprises a development of the neural plate and subsequently neural tube. The development is completed with a closure of a posterior aperture of the neural tube (caudal neuropore). Congenital malformations are often caused by defective closure of the caudal neuropore. The neural plate develops about 17th day gestational age, the cerebral vesicle appears about 21st day and the neural tube forms between 17th and 20th day. The rostral neuropore closes on the day 25th as does the caudal neuropore on the day 28th. The embryo is 2.5 mm long at the time. Noxious factors acting during that period can affect normal closure of the caudal neuropore and distort the process of spinal cord canalization. The resultant defect is called spina bifida. This is the most severe form of dysraphism-rachischisis. Meninges are also affected in this defect. They cannot cover the neural canal and on the margins of the lesion are replaced by epithelium. In milder types of the defect lack of a complete bony framework is concealed by soft tissues, forming a sac of variable size over the lesion. Spina bifida can be subdivided according to the sac structure: meningocoele, meningocysticoele, meningomyelocoele, meningomyelocystocoele. Central canal pathologies constitute another form of spinal cord malformations presenting as hydromyelia. Abnormal closure of the neural tube may affect development of the vertebral column and spinal cord along their entire length or only at a certain portion. Malformations are seen most frequently in the lumbo-sacral and then cervical regions.
神经管的异常闭合会导致神经系统发育缺陷，即神经管闭合不全。考虑到人类胎儿发育的连续步骤，可以估计脊髓畸形源于孕龄第17至28天早期胎儿发育的病理状况。这个时间段包括神经板的发育以及随后神经管的形成。随着神经管后孔（尾侧神经孔）的闭合，发育完成。先天性畸形通常由尾侧神经孔的闭合缺陷引起。神经板在孕龄约第17天发育，脑泡在约第21天出现，神经管在第17至20天形成。头侧神经孔在第25天闭合，尾侧神经孔在第28天闭合。此时胚胎长2.5毫米。在此期间起作用的有害因素会影响尾侧神经孔的正常闭合，并扭曲脊髓管道化过程。由此产生的缺陷称为脊柱裂。这是神经管闭合不全最严重的形式——脊柱裂。在这种缺陷中，脑膜也会受到影响。它们无法覆盖神经管，在病变边缘被上皮组织取代。在较轻类型的缺陷中，软组织掩盖了缺乏完整骨框架的情况，在病变上方形成大小不一的囊。脊柱裂可根据囊的结构分为：脊膜膨出、脊膜囊肿膨出、脊髓脊膜膨出、脊髓脊膜囊肿膨出。中央管病变构成脊髓畸形的另一种形式，表现为脊髓积水。神经管的异常闭合可能会影响脊柱和脊髓的整个长度或仅某一部分的发育。畸形最常出现在腰骶部，其次是颈部。
