Musculoskeletal ImagingScoliosis
a lateral curvature of the
spine from the normally straight vertical condition. In the great majority of cases scoliosis is of unknown cause (idiopathic) and is first observed during childhood. In other instances causative factors may include
congenital architectural imbalance or asymmetry of growth; damage from
neoplasm,
trauma, or infection; irradiation; reflexive splinting due to nerve irritation; bone dysplasias; or asymmetric neuromuscular control. Scoliosis should be characterized as structural (curvature not completely corrected with lateral bending) or nonstructural (flexible, with correction to linear alignment with lateral bending). Evaluation of the skeletal maturity is a helpful clinical tool as most mild or moderate spinal curvatures will no longer progress after the cessation of growth.
Routine posteroanterior radiographs may be obtained serially to help monitor progression of the curvature. Specialized imaging techniques such as scintigraphy and ultrasonography are also helpful in certain situations; myelography and MR imaging may be of limited value in cases of idiopathic scoliosis.
Congenital scoliosis
is the result of a
congenital anomaly of the
spine. Wedge vertebra or hemivertebra, supernumerary hemivertebra, failure of segmentation (unilateral block vertebra, pediculate bar, neural arch fusion) or a combination of these lesions may be causative.
Idiopathic scoliosis
may be classified into infantile, juvenile and adolescent groups. Although
resolution occurs in approximately 75% of cases of infantile scoliosis, juvenile scoliosis almost invariably progresses with growth. Spinal curvatures of more than 25 may be treated with thoracolumbar orthotic braces or surgery (spinal fusion). Complications of spinal fusion include breakage of wires or rods, loosening and migration of hooks, spondylolysis, pseudarthrosis, dislocation above the fusion site after
trauma to the long lever arm of the ankylosed
spine, gastric volvulus, aortic
aneurysm and retroperitoneal
fibrosis.
Neuromuscular scoliosis
may result from asymmetric innervation or unbalanced muscular function, most commonly
cerebral palsy. Abnormal curvatures may also occur after traumatic paraplegia or quadriplegia, spinal muscular atrophy, Friedreich's ataxia, familial dysautonomia, hypertrophic
interstitial polyneuritis and peroneal muscular atrophy. Although pelvic obliquity is characteristic, in some cases neuromuscular scoliosis may be indistinguishable from idiopathic scoliosis.
The scoliosis associated with neurofibromatosis has classically been described as one with sharp angulation and associated kyphosis. Paravertebral soft tissue mass, deformed transverse processes, enlarged vertebral foramina, marked rotation of the spinal curvature, and a coarsened and sclerotic trabecular pattern are common.
Degenerative lumbar scoliosis
is seen in some elderly persons; its course may be slow or rapid Other causes of scoliosis are tumours in the
vertebrae or adjacent ribs, radiation therapy for treatment of
malignant tumours, bone dysplasias and Marfan's syndrome.
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