Congenital scoliosis is the curvature due to imbalance of growth of the spine caused by the presence of vertebral defects. Most of these defects develop during the first 6 weeks of embryological life.
Classification of Congenital Scoliosis
Failure of formation
- Partial failure of formation (wedge vertebra)
- Complete failure of formation (hemivertebra)
Failure of segmentation
- Unilateral failure of segmentation (unilateral unsegmented bar)
- Bilateral failure of segmentation (block vertebra)
In addition to this regions of the spine involved are also mentioned in the classification like the cervicothoracic spine, thoracic spine, thoracolumbar spine, and lumbosacral spine.
The deformity produced by a failure of formation is much more difficult to predict than that caused by failure of segmentation.
The patient is evaluated as per routine spinal evaluation first. In addition, specific findings should be looked for in congenital scoliosis
Problems in Congenital Scoliosis
The five major problems in congenital scoliosis are
- Trunk deformation
- Trunk decompensation
- Truncal shortening
- Altered neurology
- Other congenital anomalies
The major target site for deformation in congenital scoliosis is the vertebral bone itself.
Trunk deformation arises out of growth imbalance on the two sides of the spine. The reason for this growth imbalance is structural –
- Presence of wedge or hemivertebrae on one side of the spine
- Presence of an unsegmented bony bar with or without contralateral hemivertebrae.
Unilateral unsegmented bar with a convex hemivertebra produces most progressive curve followed by unilateral unsegmented bar and a double convex hemivertebra. Thoracolumbar curves have maximum progression, followed by lower thoracic and upper thoracic regions. The least severe scoliosis is caused by a block vertebra.
The site of the bony anomaly is important as lower thoracic and thoracolumbar curves have a larger propensity to increase. Upper thoracic or cervical scoliosis has a high visibility and becomes a cosmetic problem much earlier.
Hence it is important to identify the structural defect responsible for the spinal deformity.
A solitary hemivertebra located strategically may give rise to truncal decompensation. This happens at the junctional zones e.g. the lumbosacral junction (patient has oblique take off), the thoracolumbar or cervicothoracic junction.
Large rigid curves may show poor compensation above or below the curve.
Trunk balance is an important aspect to be considered in treatment planning.
Due to reduced growth potential truncal shortening may be visible. Secondarily due to early spinal fusion the truncal height may be reduced. However, a short straight trunk is better than a deformed one. We have currently no means available to increase truncal height and this remains a research area
Congenital scoliosis is characterised by a high incidence of intraspinal problems ranging upto 30% in some series. These comprise pathologies like those of diastematomyelia, fibrous splitting of the cord, low filum terminale, cord or root tethering etc. These may be responsible for altered neurological signs prior to treatment. They also have important implications for surgical treatment e.g. distraction instrumentation. This may demand rectification of the intraspinal pathology prior or along with the definitive surgical treatmen
Other congenital anomalies
The VATER association and presence of other anomalies e.g. cardiac or genitourinary may have a bearing on treatment and all congenital scolioses need to be evaluated for presence of other congenital problems.
Diastematomyelia, tethered cord, spinal cord tumor, kyphosis, arnold chiari malformation and syringomyelia in spine are frequent associated abnormalities. Apart from this congenital heart defects, pulmonary dysfunction,cor pulmonale and back pain can be associated.
The patient presents with deformity of the back. Subtle deformities may not be seen unless patient is evaluated for some other reason.
In addition to the routine spinal evaluation, some specific physical findings should be sought in patients with congenital scoliosis.
- Hair patches, lipomata, dimples, and scars may indicate an underlying vertebral defect and should be looked for.
- A complete neurological evaluation should be done.
- Clubfoot, calf atrophy, absent reflexes, and limb atrophy could be signs of neurological involvement or associated anomalies
Age, remaining growth, presence of other congenital defects and neurological status are important in clinical examination. A thorough clinical and radiological evaluation should include analysis of the type and site of vertebral anomaly, trunk balance, presence of laminar defects and signs of occult dysraphism etc.
Imaging in Congenital Scoliosis
Anteroposterior and lateral radiographs are the basic imaging studies required for this. Sserial radiographic investigation would tell about the progression of the curve.The radiograph also let us know if the curve is due to failure of segmentation or a failure of formation.
Growth potential of the curves should be estimated to better determine the possibility of curve progression.
Myelography or MRI should be considered if diastematomyelia or a neurological abnormality is suspected. Some authors recommend urological evaluation of all patients with congenital scoliosis with ultrasound.
Treatment of Congenital Scoliosis
The treatment options when faced with a patient of congenital scoliosis are either non operative or operative.
Nonoperative treatment has a limited role in congenital scoliosis.
- Small curves
- Initially to determine progression
- Long, flexible curves
- Curves correctable on traction or on side bending
- Curves with a mixture of anomalous and nonanomalous vertebrae.
- Curve < 40° with flexibility of 50%
- Where better trunk balance can be obtained by bracing
- Post operative management of curves where localised apical fusion is carried out.
Nonprogressive curves require regular observation with six monthly xrays. 75% of congenital curves are progressive and only 5% to 10% can be treated with bracing. Therefore bracing has limited role in congenital scoliosis
Surgery remains the main treatment in congenital scoliosis.
Operative management is indicated for congenital scoliosis in the following situations
- Progressive increase in deformity
- Trunk decompensation
- Neural deficit
Following operative procedures are used in treatment of congenital scoliosis
- Posterior fusion without instrumentation
- Posterior fusion with instrumentation
- Combined anterior and posterior fusion
- Combined anterior and posterior convex hemiepiphysiodesis
- Hemivertebra excision
- Instrumentation without fusion
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