Scoliotic deformity and asymptomatic cervical syrinx in a 9 year old with caudal regression syndrome

Abstract

We report late presentation of caudal regression syndrome in a 9 year old presenting with a scoliotic deformity. She in addition had an asymptomatic cervical syrinx and vitiligo. We discuss the reasons for this unusual constellation of symptomatology present in our case.

Introduction

Caudal regression syndrome (CRS) is a rare disorder of distal spinal segments affecting the development of the spinal cord, with attendant sequelae. Intelligence is preserved. The exact etiology is elusive, though maternal diabetes, genetic factors, and hypoperfusion might play roles. We report late presentation of CRS in a 9 year old with scoliotic deformity with an asymptomatic cervical syrinx, in absence of any systemic abnormality.

Case Report

A 9-year-old girl was referred in view of a lateral deformity of dorso lumbar spine to explore the possibility of an underlying skeletal dysplasia. There was no history of trauma, associated weakness of any part of body, bowel and bladder involvement or protruding mass over the spine. Child was born of third degree consanguious mating at full term by normal vaginal delivery at home. According to mother there was no obvious skin pointer to a neural tube defect at birth. She was of normal intelligence with Intelligence Quotient (IQ) of 105 on Developmental Assessment Scales for Indian Infants (DASII) score.

Clinical examination revealed short stature with short trunk, the height being less than 3^rd centile with upper to lower segment ratio 0.9. There was a visible lateral curvature of thoracic spine to left. Her neurological examination and bladder bowel tone were normal. Examination revealed multiple hypo pigmented patches over the left ear lobule, left angle of mouth, and mid dorsum of right leg.

The radiograph revealed scoliotic deformity of dorso lumbar spine with convexity towards left side. Additional finding was evidence of dysgenesis at lumbo sacral region with abnormal orientation of sacrum [Figure 1]. Magnetic Resonance Imaging (MRI) spine revealed butterfly vertebrae at D10 level, the first three sacral segments were hypoplastic, distal sacrum and coccyx were absent. Fusion defects were present in L1-L2 and L3-L4 vertebrae. A syrinx was present in cervico-thoracic region opposite C5-T1 vertebrae [Figure 2]. The underlying spinal cord was completely normal.

Figure 1.

X-ray showing lumbosacral dysgenesis with abnormal orientation of sacrum

Figure 2.

Saggital neuroimaging shows rudimentary disc at L1-L2, L3-L4, visualization of only S1 and S2 segments and non-visualization of distal sacral segments and coccyx

Discussion

CRS is a rare congenital malformation characterized by varying degrees of developmental failure first described by Duhmel in 1964 to explain the spectrum of sacrococcygeal malformations.[1] The developmental defects include the lower extremities, the lumbar spine, the coccygeal and thoracic vertebrae, and corresponding segments of spinal cord.

CRS is rare affecting 0.1 to 0.25 per 10,000 pregnancies.[2] A male to female ratio of 2.7:1 has been reported.[3] However, upto 22% cases of CRS are associated with diabetes mellitus in the mother, diabetic women being 200 times to 400 times more likely to have a child with CRS.[2,4,5] Child's mother was a non-diabetic.

There are two groups of CRS. Group 1 has blunt spinal cord termination above L1, and is the most severely affected. The sacrum usually ends at S1 and may even be completely absent. Group 2 has less severe dysgenesis with low-lying tapered spinal cord and tethered cord, which may be caused by tight filum, lipoma, etc., Thus, the best diagnostic clue for CRS is dysgenetic lumbosacral vertebrae and abnormal distal spinal cord. The latter may explain or at least aggravate the scoliosis that was the only clinical sign in this child. The sacral dysgenesis below S2 suggests this is a group 2 case, therefore an associated tethering mechanism should be suspected. Alternatively, probably the scoliosis may be explained by vertebral anomalies at D10, L1-2 and L3-4 instead of a tethering mechanism, It is unlikely that a child with spinal cord tethering associated with a CRS would merely present with a scoliosis. On the other hand, it is even more unlikely to presume there would be a scoliosis without an associated tethering mechanism, unless the scoliosis is related to the malaligned dysgenetic vertebra as seen in our case. The exact etiology of CRS at embryonic level is thought to result from defect in induction of caudal elements in the embryo before the 4^th week of gestation. The insult occurs at midposterior axis mesoderm, causing the absence of the development of the mesoblastic caudal bud. The proximity and interdependence of developing caudal neurons, spinal, hindgut and mesonephric elements involved in closure of the neural tube result, in the constellation of neural, distal vertebral, anorectal, renal, and genital abnormalities. The attenuation of bone morphogenetic protein signaling at the posterior primitive streak of embryos leads to the caudal dysmorphogenesis including the cloaca and fusion of both hind limbs. Genetic tissue lineage studies indicate the presence of coordinated organogenesis. Hedgehog-responding cells derived from peri-cloacal mesenchyme contribute to the urogenital/reproductive organs. These findings indicate the existence of developmental programs for the coordinated organogenesis of urogenital/reproductive tissues based on growth factor function and crosstalk.[6] Interestingly, structures that are developmentally separate from these caudal elements such as the brain, proximal spine and spinal cord, are generally spared by CRS. The consequences of the disruption after the maturation of spinal cord's caudal portion ensue after the 4^th week of gestation are different. This results in motor deficits and neurologic impairment, varying from incontinence of urine and feces to complete neurologic loss.[7] Understandably, most children affected by CRS- except the very mild cases-would have some problem with genito-urinary and/or anorectal anatomy and function while our case was surprisingly asymptomatic till 7 years of age. Short trunk, late onset scoliosis and absence of anomaly of any other system are the unusual manifestations of our case.

The presence of an asymptomatic cervical syrinx in association with CRS in our case is also intriguing. The overall radiological incidence of syringomyelia in patients with distal spinal abnormalities has varied from 19% to 22.5% in asymptomatic group to 48.5% in symptomatic group.[8] If one were to consider the most accepted theories concerning the pathogenesis of syringomyelia in children with CRS, Chiari II malformation, hydrocephalus and tethered cord favour the formation of a cavitating lesion of the spinal cord. Syringomyelia does not seem to be present at birth or in early infancy. In fact, a sizeable spina bifida population, screened with cranial and spinal ultrasound in infancy, showed the absence of syringomyelia. The syrinx may start after the 1^st year of life, and remain asymptomatic for a variable amount of time.[9] In our child the syrinx was completely asymptomatic. It was interesting to note the presence of segmental vitiligo in our patient with CRS, which might be a chance assoction.

This patient was managed by using a Milwauki brace for her scoliotic deformity. Neurosurgical consultation taken advocated stringent follow-up, but decided against prophylactic untethering in absence of neurological symptoms. Segmental vitiligo was managed conservatively and showed improvement in follow up period. This also emphasizes the multidisciplinary care these children require.

Given the fact that genetic and environmental causes may produce a very similar phenotype, a sharp division between syndrome and “association” is nearly impossible and makes counselling for recurrence risk challenging. The term “caudal regression” is probably incorrect since more than caudal structures are involved and nothing regressed that was previously present.