eMedicine Specialties > Radiology > Pediatrics

Scoliosis, Idiopathic

Author: Prabhakar Rajiah, MD, MBBS, FRCR, Registrar, Department of Radiology, Central Manchester and Manchester Children's University Hospitals, UK
Contributor Information and Disclosures

Updated: Mar 26, 2009

Introduction

Background

Scoliosis is the presence of 1 or more lateral rotatory curves of the spine in the coronal plane. Although defined as a side-to-side deformity, it is a 3-dimensional (3D) rotational deformity. Many causes of scoliosis are known; however, 80% of them are idiopathic. Idiopathic scoliosis is a diagnosis of exclusion.

• Indications for radiography include alterations in normal spinal alignment on physical examination, evaluation of spinal curvature progression, and follow-up of treatment.
• For a scoliosis survey, the preferred method is a posteroanterior radiograph with the patient in the upright position.
• For those patients who are being assessed or are being clinically treated for scoliosis, other images include right and left lateral bending images, lateral vertical beam image, and a posteroanterior image of the left wrist and the hand for bone age.
• Radiographic analysis should identify the presence, direction, location, and apex of the curvature.
• Skeletal maturity determination is important because mild to moderate scoliotic curves do not progress after cessation of growth.

Pathophysiology

Development and biomechanics of scoliosis

The development of scoliosis can be explained biomechanically on the basis of the Heuter-Volkmann law, which states that pressure on epiphysis retards the rate of growth and that tension increases the rate of growth. Hence, the leading edge of the deformity grows more rapidly than trailing edge, increasing the rate of progression.

In scoliosis, the essential deformity is lordosis, with the spinous process deviated to the concavity of the lateral curve. As the rotation progresses, the load on the epiphysis on the side of body that is more anterior increases, resulting in a lateral deformity. Thus, scoliosis is a deformity of lordosis, rotation, and lateral wedging of the vertebrae.²

Types of scoliosis

Scoliosis is broadly divided into 2 types: postural and structural. Idiopathic scoliosis is a type of the structural form.

Postural scoliosis

Postural scoliosis is a flexible deformity due to faulty positioning and is confirmed by spontaneous correction when the patient bends toward the convexity of the curve. No associated rotational deformity or wedging is observed. Although postural scoliosis is transient, it can become fixed and structural if it is habitual and chronic.

Common causes of postural scoliosis are habitual faulty posture, a shortened lower limb, disk prolapse, pain, and hysterical etiologies.

Structural scoliosis

Structural scoliosis is a rigid deformity that cannot be actively corrected by a change of posture.

Structural scoliosis has various causes, as follows:

• Idiopathic causes
• Congenital causes
  • Failure of formation - Wedge vertebra, hemivertebra
  • Failure of segmentation - Fused vertebra, fused ribs, unilateral fused bar
  • Combination of both failures
• Mesodermal causes
  • Neurofibromatosis (NF)
  • Osteogenesis imperfecta
  • Mucopolysaccharidosis
  • Marfan syndrome
• Neuromuscular causes
  • Spinal dysraphism
  • Myelomeningocele
  • Syringomyelia
  • Diastematomyelia
  • Tethered cord
  • Arnold-Chiari malformations
  • Muscular dystrophy
  • Poliomyelitis
  • Friedreich ataxia
  • Cerebral palsy
  • Arthrogryposis multiplex congenita
  • Motor neuron disease
  • Congenital hypotonia
• Radiation therapy
• Skeletal dysplasias
  • Spondyloepiphyseal dysplasia
  • Diastrophic dwarfism
  • Metatrophic dwarfism
  • Chondrodysplasia congenita
• Infections
  • Pyogenic osteomyelitis
  • Tuberculosis
  • Brucellosis
• Tumors
  • Osteoid osteoma
  • Osteoblastoma
  • Meningiomas
  • Neurofibromas
  • Astrocytomas
  • Ependymomas
  • Metastasis
• Miscellaneous causes
  • Congenital heart disease
  • Coarctation of the aorta
  • Cyanotic heart disease
  • Congenital torticollis
  • Ocular torticollis
  • Spondylolisthesis
  • Malignant hyperpyrexia
  • Familial dysautonomia
  • Metabolic bone disease
  • Endocrine bone disease

Idiopathic scoliosis

Idiopathic scoliosis is the most common type of scoliosis, accounting for 80% of cases. It occurs in 3 forms: infantile, juvenile, and adolescent.

The infantile form is seen in patients as old as 3 years, and it is more common in boys than in girls. It usually involves the thoracic region with convexity to the left side. Faulty positioning of the infant in cot is one of the theories of formation. This type is uncommon in America and more common in Europe and Asia. It is associated with skull and pelvic abnormalities. Although infantile scoliosis often spontaneously resolves, some cases can progress, especially in the first 18 months during the growth spurt of infancy.

The juvenile form occurs between 4 and 9 years of age. Most cases involve the dorsolumbar region with convexity to the left side. This type is usually progressive. Some of these cases are either slowly progressing infantile scoliosis that is diagnosed late or adolescent scoliosis that is diagnosed early.

The adolescent form is seen between 10 years of age and maturity. This is the most common type of idiopathic scoliosis, accounting for 80% of all cases. It is more common in female adolescents (95%) than in male adolescents. Most cases involve the thoracic region with convexity to the right side; the apex of the curve commonly at the level of T7 or T8. This form can occur in the lumbar vertebrae, which is commonly concave to the right side. Theoretically, most of these curves originate in juveniles and later manifest in adolescents.

In the simple Dickson classification, idiopathic scoliosis is divided into early-onset ( <5 y) and late-onset (>5 y) types.

The exact etiology of idiopathic scoliosis is not yet known. Many theories of formation have been proffered, implying the disease is likely to be multifactorial. Contributing factors are growth asymmetry, hormonal factors, abnormal equilibrium system in the brainstem, genetic factors, and soft tissue abnormalities.^3,4

Autosomal dominant inheritance is proposed, but multifactorial inheritance is most likely. Type I fibers in the erector spinae muscle on the concave side of scoliotic curve may be involved in idiopathic scoliosis. These fibers, which are resistant to fatigue, play an important role in sustained tonic activities, and a decrease in these fibers may be an etiologic factor.

Frequency

United States

The prevalence of idiopathic adolescent scoliosis is approximately 4.5%. The overall prevalence is 3-5%, for curves less than 20° and 0.5% for curves more than 20°. The prevalence of scoliosis more than 25° is 1.5 cases per 1000 population. Scoliosis is most common in tall and heavy people.

International

The prevalence of idiopathic scoliosis requiring treatment is 0.1-0.3%. Adolescent scoliosis is widely distributed all over the world. The prevalence of curves more than 10° is 2.5 cases per 100 population. The prevalence of curves more than 20° is 1 case in 2500.

The prevalence of scoliosis is 11% in first-degree relatives of patients with diagnosed scoliosis, 2.4% in second-degree relatives, and 1.4% in third-degree relatives.

Infantile scoliosis is uncommon in America and more common in Europe and Asia.

Mortality/Morbidity

The mortality rate in patients with scoliosis is twice than that of healthy population. The mean age at death is 45-60 years.

• Scoliosis produces cosmetic deformity, disability, pain, and severe restriction of the patient's capacity to work.
• Cardiovascular compromise occurs in severe scoliosis (curves >60°). One third of patients with curves of 60-100° and one half of those with curves of more than 100° have cardiac complications. Cardiac involvement is more common with thoracic curves than with curves in other locations.
• Respiratory failure, cor pulmonale, restrictive lung disease, and right-sided heart failure are common cardiopulmonary complications. The risk of cardiovascular complications is highest in individuals with early-onset, large-curve scoliosis. The risk is low in late-onset scoliosis, even if the curve is severe.

Race

Infantile scoliosis is uncommon in America and more common in Europe and Asia.

Sex

The overall female-to-male ratio is 1.25:1. With curves of 6-10°, the ratio is almost 1:1, but with curves more than 20°, the ratio is 5.4:1.

• The infantile type is most common in boys, but the adolescent type is more frequent in female adolescents (95 %).
• Progression of the curve is more common in female individuals than in male individuals. The disease progresses in approximately 15.4% of female patients with scoliosis of more than 10°, compared with the general rate of 6.8%.
• The prevalence of scoliosis in daughters of mothers with scoliosis is 15-27%.

Age

• Scoliosis is characterized by progression with age. The rate of progression depends on the cause and the patient's rate of growth, with the incidence of progression of 5-79%. Progression is marked during accelerated growth in infancy and adolescence. Approximately 60% of rapidly growing curves can worsen.
• Progression usually stops when maturity is attained, particularly if the curve is less than 30°. Curves of more than 30° can grow at the rate of 1° per year after maturity.
• The infantile type affects infants and children as old as 3 years. The juvenile type affects children aged 4-9 years. The adolescent type occurs between 10 years and adulthood, and the adult form occurs between ages 20 and 50 years. In the Dickson classification, scoliosis is identified as early onset ( <5 y) or late onset (>5 y).

Anatomy

Anatomy of the spine

A normal spine has a typical curvature of lordosis in the cervical and lumbar regions and kyphosis in the thoracic and sacral region. A straight line can be drawn through the cervicothoracic, thoracolumbar, and lumbosacral junctions.

Development of the spine

The spinal curvature varies in different stages of life. At birth, the spine has a single curve, which is concave anteriorly. In infants, the cervical lordosis is established when they start to keep their head in erect position. The lumbar lordosis develops in the second year, when the child develops the ability to stand erect.

The spine continues to grow mainly by means of the proliferation of the cartilage in the superior and inferior aspects of the primary ossification center in the vertebral body. The annular cartilages develop independent of the primary ossification center and do not contribute to longitudinal growth. This center fuses with the body only after it is completely developed. By puberty, the normal adult curve is established, with the cervical and lumbar lordoses and the thoracic and sacral kyphoses.

Presentation

Clinical findings

On clinical evaluation, patients with scoliosis have a lateral bending of the spine that cannot be corrected by a change of posture. On bending forward, the prominence of the posterior ribs on the convex side of curve becomes most obvious. The spine deviates from the midline in all the 3 planes. The displacement is lateral in the frontal plane, with lordosis in the sagittal plane and rotation of the vertebrae about their own axis toward the convex side of the curve.

Idiopathic scoliosis does not produce symptoms such as pain and disability. An asymmetrical spine is the only finding. The ribs and scapula are prominent on 1 side, with a raised shoulder or hip protrusion on the other side. The deformity is most obvious when the curve is high, especially in the thoracic position. In combined thoracolumbar curves, the visible deformity is lessened as a result of balancing of the curves, but shortening of the trunk is visible.

On occasion, the clinical and imaging features are not typical of idiopathic scoliosis. Comprehensive clinical and neurologic examination and imaging are indicated in these atypical cases.

Scoliosis is atypical if the patient is male or has a left-sided thoracic curve, rapid progression of the curve, neurologic deficits, headache, neck ache, backache, and/or foot deformity.

Complications

Pulmonary function can be affected in severe scoliosis. The deformity affects expansion of the lungs, resulting in a restrictive defect apparent on pulmonary function tests. Although dyspnea is not common in children, it can occur in adults, depending on the severity of scoliosis.

Cardiac anomalies can be associated with idiopathic scoliosis. Idiopathic scoliosis is seen in 1-5% of patients with congenital heart disease; the incidence is highest in those with cyanotic heart disease.

Progression

Progression is indicated when the curve grows more than 5° per year. Scoliosis progresses with age at variable rate of 5-79%. The rate depends on the cause and the patient's rate of growth. Progression is marked during accelerated growth in infancy and adolescence, and 60% of rapidly growing curves can worsen.

The vertebrae continue to grow on the convex side and inhibited on the concave side. Curves less than 30 ° do not progress after maturity. Curves of 30-50° progress if they are rotated more than 25°, at the rate of 1° per year. Curves more than 50-75° progress regardless of maturity.

Other problems to consider

Neuromuscular curve

This is usually a long curve and C shaped.

Neurofibromatosis

Neurofibromatosis usually involves a short, sharply angulated curve. The 2 most common types of NF are type I (NF-I) and type II (NF-II). NF-I, or von Recklinghausen disease, is characterized by peripheral neurofibromas, plexiform neurofibromas, café au lait spots, Lisch nodules in the iris, optic-nerve gliomas, bone dysplasias, and scoliosis. NF-II is characterized by bilateral acoustic neuromas, meningiomas, schwannomas, and posterior subcapsular cataracts. The defect in type I is on chromosome 17, and in type II, the defect is on chromosome 22.

Congenital heart disease

Congenital heart disease can be associated with scoliosis (1-5%). Unlike idiopathic scoliosis, scoliosis with this involvement is most common in male individuals and usually convex to the right side (3:1). It is more common and severe with cyanotic heart disease than with acyanotic heart disease. The incidence of congenital heart disease with aortic coarctation is high. The spine and skull can be thick and dense as a result of hypoxia due to cardiac failure.

Scoliosis in the elderly

This is a type of scoliosis seen in men older than 60 years. Scoliosis in the elderly has no particular cause, though it is believed to be secondary to severe degenerative disease. Unlike the curve in idiopathic scoliosis, the curve in elderly scoliosis is short, segmental, and without any lateral wedging or abnormalities of the neural arch.

Management of scoliosis

The management of scoliosis depends on the maturity of the skeleton and on the degree of curvature. With curves of less than 25° in an immature skeleton or less than 30° in a mature skeleton, management is conservative and includes regular follow-up and radiography. Curves less than 25° require management when they are rapidly progressive, especially in preadolescents. With curves of 25-50°, orthotic devices (eg, braces) are used to restore the curvature to acceptable levels and to prevent progression.^5,6 However, such devices are not used if the patient has respiratory or neurologic compromise.

Spontaneous improvement occurs in approximately 3% of patients, especially when the curve is less than 10°.

Aims of surgery are to prevent curve progression, to maintain balance, to reduce pain, to preserve respiratory and neurologic function, to facilitate nursing care, to improve cosmetic appearances (eg, of the large rib bump), to address failure of bracing, and to treat curves of greater than 40-50° in a growing child.

Prognosis

The prognosis depends on the age of the patient, the onset of menarche, the degree of spinal curvature, the number of vertebrae involved, the location of the curve, the rotational deformity, the maturation of the bone (as assessed by using the Risser index), the patient's family history, and the associated anomalies.

Preferred Examination

Clinical examination

Clinical examination should include neurologic examination to assess the deformity. A scoliometer is placed over the spinous process at the apex to measure the angle of trunk rotation (ATR). The measurement is significant if it is more than 5°.

Imaging examination

Radiography is the mainstay in assessment of scoliosis. It is used to confirm the clinical diagnosis of scoliosis, to exclude underlying causes (eg, segmentation abnormalities), to assess the curves and their severity, to monitor progression, to assess skeletal maturity, and to determine a patient's suitability for surgery. This study is also useful in diagnosing postoperative complications and in follow-up.

Limitations of Techniques

The main limitation of radiography is the radiation dose. The risk of carcinogenesis is increased because of the repeated examinations done to monitor curve progression. This risk can be reduced with the judicious use of radiography and proper protection techniques.

Radiography is less sensitive than bone scanning and MRI because tumors or infections are apparent only after 50% of the bone is destroyed. Radiographs cannot be used to assess abnormalities of the spinal cord.

CT scanning is not routinely indicated, but it is a good method for assessing rotation and segmentation abnormalities. Radiography can provide all of the information needed. MRI is not cost-effective, and it is not a good screening tool because its yield in depicting important clinical abnormalities that change management is minimal.

Differential Diagnoses

Other Problems to Be Considered

Neuromuscular curve
Neurofibromatosis
Congenital heart disease
Scoliosis in the elderly

• Search for CME/CE on This Topic »

• Idiopathic Scoliosis (Orthopedic Surgery)
• Infantile Scoliosis (Orthopedic Surgery)
• Spinal Orthotics (Physical Medicine and Rehabilitation)
• Scheuermann Disease (Physical Medicine and Rehabilitation)

• Interferon Gamma-1b May Not Improve Survival in Idiopathic Pulmonary Fibrosis
• Surgery for Degenerative Lumbar Scoliosis Often Effective: Review
• Obstructive Sleep Apnea Is Common in Idiopathic Pulmonary Fibrosis

• Scoliosis in Pediatric Patients: Comorbid Disorders and Screening
• Which of the Following Statements About Adolescent Suicide Is True?
• Hyper IgE Syndrome: An Update on Clinical Aspects and the Role of Signal Transducer and Activator of Transcription 3

• Spinal Disorders Resource Center