A SPINAL DEFORMITY

This patient has a abnormality in spinal alignment in the coronal plane – a scoliosis. The spine has normal curves in the sagittal plane that provide stability and balance. The cervical and lumbar spines are convex anteriorly, termed lordosis. The thoracic and sacral spines are convex posteriorly, termed kyphosis. These normal curves can be exaggerated, e.g. in congenital deformities such as achondroplasia where there is almost always a significant lumbar lordosis. Having found a scoliosis, the next question is whether it is postural (common) or structural (rare). A postural scoliosis may be caused by pain or be secondary to a leg-length discrepancy and these conditions should be ruled out first. Leg-length discrepancy is usually easily managed with a shoe raise. Provided both are absent, a postural scoliosis will disappear when the child bends forwards to try to touch her toes and no further intervention is required. In a structural scoliosis, the curvature persists in the forwardbending test and there is rotation of the vertebral bodies towards the convexity of the curve, causing a ‘rib hump’. Most cases of structural scoliosis are idiopathic but some are related to an underlying condition and these need exclusion.

Differential diagnosis of a structural scoliosis

• Idiopathic

• Neuromuscular, e.g. cerebral palsy or Duchenne muscular dystrophy

• Congenital structural abnormalities of the vertebrae, e.g. hemivertebrae – there is a high risk of associated spinal cord defects, e.g. spinal dysraphism and other congenital abnormalities, especially genitourinary

• Syndromic, e.g. neurofibromatosis and Marfan syndrome

Therefore, children with a structural scoliosis need a thorough neurological evaluation before concluding that the scoliosis is idiopathic. Treatment assumes that a progressive scoliosis will cause unacceptable deformities, an increased risk of early joint disease and cardiorespiratory compromise. In idiopathic structural scoliosis, the risk of progression depends upon sex, age, pubertal status and the degree of curvature. Premenarchal girls are at highest risk. All patients with, or at risk of, structural scoliosis should be monitored regularly. Bracing and surgical correction are the two treatment options. Surgery is recommended earlier in those with neuromuscular or congenital scoliosis.

KEY POINTS

• Scoliosis is often picked up incidentally and most are postural.

• Patients found to have a structural scoliosis must have a thorough neurological evaluation although most cases are idiopathic.

• A structural scoliosis in a premenarchal girl is the most likely to progress.