Neurology India, Vol. 58, No. 2, March-April, 2010, pp. 334-335
Segmental spinal dysgenesis: A rare malformation of the spinal cord
Shivani Pahwa, Ajay Garg, NK Mishra
Department of Neuroradiology, Neurosciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110 029, India
Correspondence Address: Ajay Garg, Department of Neuroradiology, Neurosciences Center, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110 029, India, firstname.lastname@example.org
Date of Acceptance: 20-Sep-2009
Code Number: ni10091
A 2-year-old male child and a 3-year-old female child presented with spastic paraparesis and dribbling incontinence of urine since birth. On examination, spastic rigidity of the lower limbs and bilateral talipes equinovarus deformity were present in both. In addition, kyphoscoliotic deformity of the lumbar spine was seen in the boy.
Magnetic resonance imaging (MRI) of the male child revealed an abnormal disjointed lumbosacral spinal cord within the spinal canal. The upper segment of the spinal cord ended in a bulbous tip at the level of L1 vertebra [[Figure - 1]a and b], with focal hydromyelia extending from D10 to L1 level [[Figure - 1]b and c]. A bulky lower disjointed segment was seen in the sacral spinal canal, with thin strands of tissue connecting the two segments [[Figure - 1]b and d]. MRI in the female child showed that the upper segment was interrupted at the level of D6 vertebra and a bulky, thickened lower cord segment was seen caudally at L1 level [Figure - 2]. In between the two segments, the spinal cord was altogether indiscernible.
The clinico-radiologic definition of SSD includes segmental agenesis or dysgenesis of the spine, segmental abnormality of the underlying spinal cord and nerve roots, congenital paraplegia or paraparesis and congenital lower limb deformities.  The spinal segments caudal to the dysgenetic segment are always normal. segmental spinal dysgenesis (SSD) and caudal regression syndrome (CRS) represent two facets of a single spectrum of segmental malformation of the spine and spinal cord.  Embryonic chordamesodermal derangement of an intermediate segment along the longitudinal embryonal axis results in SSD, whereas derangement of the most caudal segment results in CRS.  Clinically, the patient with SSD presents with varying degrees of motor weakness, neurogenic bladder, associated deformities of the lower limbs and renal and cardiac anomalies. ,
MRI is the imaging standard for the evaluation of SSD.  Characteristic findings are a normal upper spinal cord that abruptly changes in caliber resulting in a wedge shape, a markedly thinned out or indiscernible middle cord segment devoid of nerve roots and a bulky, low-lying, thickened cord caudally. 
It is important to separate SSD from CRS or other forms of dysraphism as SSD is unlikely to benefit significantly from detethering procedures because the neurologic disturbance is related to the congenital hypoplasia of a segment of the cord rather than to cord tethering. , Surgery is indicated when significant compression of the spinal cord is demonstrated on radiological examination.  The neurosurgeons and neuroradiologists should be aware of this condition, which has distinct clinical and neuroradiologic features, and should differentiate this from CRS as the prognosis and management for these patients is different from those with CRS.
We thank Miss Ally Chuan Xiang, from King′s College London School of Medicine, 2 nd Floor, Henriette Raphael House, Guy′s Campus, London Bridge, London, SE1 1UL, UK, for her English editing.
Copyright 2010 - Neurology India
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