Segmental Spinal Dysgenesis–“Redefined”

Abstract

Study Design Retrospective single institutional observational study. Purpose Segmental spinal dysgenesis (SSD), a complex spinal dysraphic state caused by notochord malformation disorders, is named after its morphological presentation where a spine segment is dysgenetic, malformed or absent. This study’s objective was to examine and reassess SSD imaging findings and correlate them with an embryological explanation. Overview of Literature Scott and his colleagues defined SSD as segmental agenesis or dysgenesis of the lumbar or thoracolumbar vertebrae and underlying spinal cord. Tortori-Donati and his colleagues defined it as a morphologic continuum ranging from hypoplasia to an absent spinal cord segment. Methods Fifteen children, whose imaging findings and clinical features were consistent with SSD, were included in the study. Magnetic resonance imaging (MRI) was performed per institutional spine protocol. Results Five children (33.3%) presented with a high-ending bulbous cord with no caudal segment, six (40%) presented with a dorsal or lumbar segmental dysgenetic cord with a low-lying, bulky caudal cord but without significant spinal canal narrowing, and four (26.6%) presented with segmental caudal dysgenesis with severe kyphoscoliosis, gibbus deformity, and spinal canal narrowing with a normal distal segment (normal or low-lying). Conclusions SSD is a complex spinal anomaly in children requiring clinical-radiological assessment followed by multidisciplinary management based on the extent and severity of the dysgenetic cord and the type of SSD. MRI plays a crucial role in both diagnosing and classifying SSD prior to surgical treatment to prevent further impairment.

Segmental spinal dysgenesis with open spinal dysraphism and Chiari II features, case report

“…SSD refers to a complex closed spinal dysraphism associated with certain diagnostic criteria, including congenital paraparesis/paraplegia with lower extremity abnormalities, congenital kyphoscoliosis, or kyphosis with or without vertebral anomalies, absent or malformed segments of the spinal cord and underlying nerve roots, and visualization of the spinal cord segment distal to the interrupted cord [1 , 2] . Previous studies have described cervicodorsal junction involvement in a few cases [3 , 4] .…”

“…Recently, Chellathurai et al [4] categorized SSD as follows: Type I SSD associated with mild kyphosis and a thickened spinal cord that ends abruptly with a low-lying caudal cord segment and sparing of the spinal canal and Type II SSD associated with severe kyphoscoliosis, gibbus deformity, spinal cord thinning at the gibbus apex, and severe spinal canal sparing.…”

“…Magnetic resonance imaging (MRI) plays a pivotal role to diagnose this entity for early management plan [3] . The correlation between the embryology and imaging features of this entity has been described thoroughly most recently [4] . However, the association between SSD and Chiari II features remains unreported.…”

Segmental Spinal Dysgenesis

“…(2) more than one segment vertebral abnormality which may include kyphosis or kyphoscoliosis; (3) the absence or malformation of a portion of the spinal cord, along with associated nerve roots anywhere from the cervical spine to the sacrum; and (4) the presence of spinal cord distal to the affected region of cord. 3 Dysraphic conditions such as SSD have been attributed to a mishap in the development of the early neural tube that results in a nonclosure. 2,4,5 The diversity of accompanying malformations in other organs is thought to be the result of a singular event in embryogenesis that simultaneously disrupts all 3 embryonic germ layers.…”

“… 1 SSD was originally defined as agenesis or dysgenesis localized to the lumbar or thoracolumbar regions of the spine, 2 but the definition was later expanded to congenital spinal dysraphism that must include (1) paraparesis/paraplegia, including lower limb aberrations; (2) more than one segment vertebral abnormality which may include kyphosis or kyphoscoliosis; (3) the absence or malformation of a portion of the spinal cord, along with associated nerve roots anywhere from the cervical spine to the sacrum; and (4) the presence of spinal cord distal to the affected region of cord. 3 …”