Spondylocostal dysostosis (Jarcho-Levine syndrome) associated with occult spinal dysraphism: Report of two cases.

Spondylocostal dysostosis, also known as Jarcho-Levine syndrome, is a rare disorder characterized by multiple vertebral and rib anomalies at birth. The association of occult spinal dysraphic lesions with this entity is rare. Two patients with spondylocostal dysostosis and occult spinal dysraphic lesions, one with type I split cord malformation and another with spinal dermal sinus are being reported. A 7-month-old female child who was operated at birth for imperforate anus was noted to have a dimple at the low back with altered skin color around the dimple. Examination revealed the right lower extremity was slightly thinner than the left. Plain radiographs showed features of spondylocostal dysostosis with scoliosis. Magnetic resonance imaging (MRI) showed a type I split cord malformation at the lumbosacral junction with low-lying conus and terminal syringomyelia. Patient underwent excision of the bony spur uneventfully. A 14-month-old male child was noted to have a small swelling in the low back along with deformity of the right lower chest since birth. Plain radiographs revealed features of spondylocostal dysostosis. MRI showed a spinal dermal sinus at the lumbosacral junction with a low-lying conus. The patient underwent excision of the spinal dermal sinus and untethering of the cord uneventfully. Although rare, spondylocostal dysostosis can be associated with occult spinal dysraphic lesions like type I split cord malformations or spinal dermal sinus. Physicians should be aware about the possibility of children with spondylocostal dysostosis harboring occult spinal dysraphic lesions so that these patients receive appropriate treatment.

Introduction

Spondylocostal dysostosis, also known as Jarcho-Levine syndrome, is a rare disorder characterized by multiple vertebral and rib anomalies at birth.[1] It was originally described by Jarcho and Levine in 1938.[2] A variety of congenital malformations have been described in this syndrome.[34567] In this study, two cases of spondylocostal dysostosis with associated occult spinal dysraphism with tethered cord are being reported.

Case Reports

Case 1

A 7-month-old female child, the first born of non-consanguineous parents, was found to have imperforate anus at birth and was operated for the same shortly after birth. The child was found to have a dimple with altered skin color around the dimple in the low back since birth. The child was referred for neurosurgical consultation at the age of 7 months for evaluation of associated spinal dysraphism. Examination revealed a moderately nourished child who had a deflected gluteal cleft and a dimple in the low lumbar region with surrounding discoloration of the skin. The right lower limb was slightly thinner than the left lower limb. No other neurological deficits could be made out. Plain radiographs revealed scoliosis of the lumbar spine with hemivertebrae of L4 and L5, spina bifida of S1, and absent last two sacral segments [Figure 1]. In addition, there were also rib anomalies characteristic of spondylocostal dysostosis in the form of absent ribs in the mid-thoracic region with a fusion of the ribs posteriorly on the affected side [Figure 1]. Magnetic resonance imaging (MRI) of the spine revealed a low-lying cord with a terminal syrinx along with features of type I split cord malformation at the level of L5–S1 [Figures 2–4]. Axial images revealed the right hemicord to be slightly thinner than the left hemicord [Figure 4]. In view of the above radiological features, a diagnosis of spondylocostal dysostosis with associated type I split cord malformation was made. During surgery, laminectomy of L5 and S1 was done. During laminectomy, the diastematomyelic spur was found attached to the posterior elements and was removed [Figure 5]. Postoperative period was uneventful. There were no respiratory complications during or after surgery. The child was followed for 9 months thereafter without any fresh neurological deficits.

Figure 1

Plain radiographs (a) anteroposterior view and, (b) lateral view showing absent ribs in the mid thoracic region, posterior fusion of the ribs, multiple vertebral abnormalities with scoliosis

Figure 2

Magnetic resonance imaging lumbosacral spine, T1-weighted sequences showing a low-lying conus with terminal syrinx

Figure 4

Magnetic resonance imaging, axial T2-weighted sequences showing features of type I split cord malformation

Figure 5

Intra-operative photograph showing the bony spur (white arrow) attached to the posterior elements of the spine, black arrow heads point to the undivided spinal cord, the white arrow heads point to the hemicords, the probe is in the defect between the hemicords

Magnetic resonance imaging lumbosacral spine, T2-weighted sequences showing a low-lying conus with terminal syrinx along with a bony spur at the level of L5–S1

Case 2

A 14-month-old male child, 2nd child born of non-consanguineous parents, was brought for neurosurgical consultation for a swelling in the low back along with deformity of the chest since birth. On examination, the child was neurologically intact but had a small, skin-covered swelling in the lumbar region [Figure 6]. There was no cry impulse. There was deformity of the chest on the right side. Plain radiographs of the chest and spine revealed features of spondylocostal dysostosis in the form of absence of fifth and sixth ribs on the right side with multiple hemivertebrae in the mid-thoracic region. Scoliosis with convexity to the right side was also evident [Figure 7]. Computed tomography of the thorax revealed features of spondylocostal dysostosis [Figure 8]. MRI of the whole spine revealed a low-lying cord extending up to S1 level with a terminal syrinx and a spinal dermal sinus extending intraspinally [Figures 9 and 10]. In view of the above clinical and radiological findings, a diagnosis of spondylocostal dysostosis with tethered cord due to spinal dermal sinus was made. During surgery, the spinal dermal sinus tract was traced to end in the spinal cord just above the termination of the conus [Figure 11]. The sinus tract was excised. There was also a thickened filum terminale [Figure 12] which was also sectioned. Postoperatively, there was no change in the neurological status of the child. When examined 1-year later, the child had no neurological deficits but had mild scoliosis which had not worsened in the interim.

Figure 6

Clinical photograph of case number 2 revealing a swelling in the lumbar region with deformity of the right lower chest

Figure 7

Plain radiographs (a) anteroposterior and, (b) lateral views revealing absence of fifth and sixth ribs on the right side with multiple hemivertebrae in the mid-thoracic region. Scoliosis with convexity to the right side is also evident

Figure 8

Computed tomography of thorax revealing features of spondylocostal dysostosis

Figure 9

Magnetic resonance imaging sagittal sequences: Left panel: T2- weighted sequence showing conus extending up to the lumbosacral junction; right panel: T1-weighted sequence showing a spinal dermal sinus (arrow)

Figure 10

Magnetic resonance imaging T2-weighted axial sequence showing a spinal dermal sinus extending intraspinally

Figure 11

Intra-operative photograph showing a low-lying conus (black arrow heads) and a spinal dermal sinus extending intradurally (white arrow)

Figure 12

Intra-operative photograph after excision of the spinal dermal sinus showing the thickened filum terminale (arrow)

Discussion

Spondylocostal dysostosis and spondylothoracic dysostosis are rare forms of segmental costovertebral malformations.[89] Both are subtypes of Jarcho-Levine syndrome, a hereditary condition manifested by the vertebral body and related rib malformations.[8] This condition was first described by Jarcho and Levine in 1938 and is characterized by short neck and short-trunk dwarfism resulting from multiple vertebral and rib anomalies.[2] The vertebral abnormalities in this syndrome consists of hemivertebrae, butterfly vertebrae, and unsegmented hypoplastic vertebrae.[10] Involvement of the thoracic and lumbar spine results in scoliosis and involvement of the cervical spine results in short neck.[8] The number and shape of the ribs can vary with fusion of the ribs near their costovertebral ends.[810]“Fan-like” or “crab-like” rib cage anomalies due to posterior fusion and anterior flaring of the ribs are common.[3] The severity of the vertebral and rib abnormalities will determine the presence and degree of kyphosis, scoliosis, and pectus deformities.[8] In 1978, Solomon et al. divided Jarcho-Levine syndrome into two types: Spondylothoracic dysostosis and spondylocostal dysostosis.[11] Spondylothoracic dysostosis is a severe form of the disease with an autosomal dominant pattern of inheritance and is associated with severe chest abnormalities and a high mortality rate early in life.[11] Spondylocostal dysostosis is inherited as either autosomal dominant or recessive and is more common than spondylothoracic dysostosis and is much more compatible with longer life span.[811] Some cases of spondylocostal dysostosis have been found to be caused by the gene DDL3 mapped to 19p13.1–q13.3 region.[12] Spondylothoracic dysostosis has a mortality rate of around 45% while spondylocostal dysostosis usually, has a better prognosis due to the asymmetry of the thorax resulting in a less-restrictive thorax.[13] Mortier et al. noted that the location of the vertebral anomalies correlated with other abnormalities.[14] However, this finding was not replicated in other studies on spondylocostal dysostosis.[15]

Spondylocostal Dysostosis and Spinal Dysraphism

Association of neural tube defects with spondylocostal dysostosis has been known for some time.[13469161718] Duru et al. reported three patients with spondylocostal dysostosis, two of whom had neural tube defects.[4] Rodriguez et al. reported a preterm girl born at 35 weeks with spondylocostal dysostosis, thoracolumbar meningomyelocele and imperforate anus who died shortly after birth.[19] Nadkarni et al. reported two patients with spondylocostal dysostosis associated with lipomyelomeningocele.[6]

However, the association of split cord malformation with spondylocostal dysostosis has been reported only on five occasions. Etus et al. reported a 7-year-old girl with spondylocostal dysostosis and type I split cord malformation.[16] Reyes et al. reported the autopsy findings of two patients with spondylocostal dysostosis and one of these patients had diastematomyelia.[20] Giacoia and Say reported a child with multiple congenital abnormalities with spina bifida cystica and diastematomyelia.[17] However, whether the split cord malformation was type I or type II was not mentioned. Elier and Morton reported the occurrence of diastematomyelia in association with spondylocostal dysostosis in the offspring of a lysergic acid diethylamide user.[21] Recently, Kansal et al. reported the occurrence of type I split cord malformation in a child with spondylocostal dysostosis.[18] It is interesting to note that in all the patients in whom the type of split cord malformation was reported, the malformation was of type I split cord. The case reported by us is the sixth case of split cord malformation in association with spondylocostal dysostosis.

It is interesting to note that till date, there has been no report of tethered cord due to a spinal dermal sinus in association with spondylocostal dysostosis. Our case 2 is the first such report in the literature.

Pathogenesis of spondylocostal dysostosis and associated occult spinal dysraphism

The vertebral anomalies observed in this syndrome are believed to be secondary to a developmental disturbance between the 4th and 8th weeks of gestation.[8] At that time, multiple centers of chondrification form about the notochord to form a complete cartilaginous pro-vertebra. Failure of these chondrification centers to develop or unite can result in hemivertebrae or butterfly vertebrae. The anomalous rib development is believed to be secondary to anomalous vertebral development.[22] Association of type I split cord malformation with spondylocostal dysostosis can be explained as follows: According to the unified theory of embryogenesis of split cord malformations,[23] split cord malformations arise as a result of formation of an accessory neurenteric canal that results in the formation of an endomesenchymal tract that bisects both the developing notochord as well as the neural plate. It is therefore conceivable, that this endomesenchymal tract is associated with notochord abnormalities that lead to vertebral body and rib anomalies of spondylocostal dysostosis.

Association of spondylocostal dysostosis with spinal dermal sinus might be because of the defective disjunction of the neuroectoderm from the ectoderm that takes place in the setting of the defective vertebral development.

Conclusions

Spondylocostal dysostosis is a rare form of vertebral malformation. Occasionally, this may be associated with occult spinal dysraphic lesions like type I split cord malformations or spinal dermal sinus tracts. Physicians should be aware of this rare combination of congenital abnormalities so as to provide appropriate care for these patients.