Rossi A, Cama A, Piatelli G, Ravegnani M, Biancheri R, Tortori-Donati P
Department of Pediatric Neuroradiology, G Gaslini Children's Research Hospital, Genoa, Italy.
J Neuroradiol. 2004 Jan;31(1):3-24. doi: 10.1016/s0150-9861(04)96875-7.
Spinal cord development occurs through the three consecutive periods of gastrulation (weeks 2-3), primary neurulation (weeks 3-4), and secondary neurulation (weeks 5-6). Spinal cord malformations derive from defects in these early embryonic stages, and are collectively called spinal dysraphisms. Spinal dysraphisms may be categorized clinically into open and closed, based on whether the abnormal nervous tissue is exposed to the environment or covered by skin. Open spinal dysraphisms include myelomeningocele and other rare abnormalities such as myelocele, hemimyelomeningocele, and hemimyelocele, and are always associated with a Chiari II malformation. Closed spinal dysraphisms are further divided into two subsets based on whether a subcutaneous mass is present in the low back. Closed spinal dysraphisms with mass comprise lipomyelocele, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise simple dysraphic states (tight filum terminale, filar and intradural lipomas, persistent terminal ventricle, and dermal sinuses) and complex dysraphic states. The latter category involves abnormal notochordal development, either in the form of failed midline integration (ranging from complete dorsal enteric fistula to neurenteric cysts and diastematomyelia) or of segmental agenesis (caudal agenesis and spinal segmental dysgenesis). Magnetic resonance imaging is the imaging modality of choice for evaluation of this complex group of disorders.
脊髓发育通过原肠胚形成（第2 - 3周）、原发性神经管形成（第3 - 4周）和继发性神经管形成（第5 - 6周）这三个连续阶段进行。脊髓畸形源于这些早期胚胎阶段的缺陷，统称为脊柱裂。脊柱裂在临床上可根据异常神经组织是否暴露于外界或被皮肤覆盖分为开放性和闭合性。开放性脊柱裂包括脊髓脊膜膨出和其他罕见异常，如脊髓膨出、半脊髓脊膜膨出和半脊髓膨出，且总是与Chiari II畸形相关。闭合性脊柱裂根据下腰部是否存在皮下肿块进一步分为两个亚组。有肿块的闭合性脊柱裂包括脂肪脊髓膨出、脂肪脊髓脊膜膨出、脊膜膨出和脊髓囊肿膨出。无肿块的闭合性脊柱裂包括单纯性脊柱裂状态（终丝紧张、终丝和硬膜内脂肪瘤、持续性终室和皮样窦）和复杂性脊柱裂状态。后一类涉及异常的脊索发育，表现为中线融合失败（从完全性背侧肠瘘到神经肠囊肿和脊髓纵裂）或节段性发育不全（尾部发育不全和脊柱节段发育异常）。磁共振成像（MRI）是评估这一复杂疾病组的首选影像学检查方法。
