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Idiopathic Scoliosis

Introduction

  • Scoliosis is a sideways curvature of the spine
  • Scoliosis is a descriptive term and not a diagnosis
  • For some reason, the vertebral bodies of a person with scoliosis do no line up appropriately and result in a curvature of the spine
  • This appears grossly on exam as a spine with an "S" or a "C" shape rather than a straight line
  • Some of the bones in a scoliotic spine also may have rotated slightly, making the person's waist or shoulders appear uneven 

Pathogenesis

  • Everyone's spine has natural curves
  • These curves round our shoulders and make our lower back curve slightly inward
  • During growth and development these curves should be maintained, but no side to side curve should be present
  • Conditions known to cause spinal deformity 
    • Idiopathic
      • No specific cause
      • 80% of cases
      • Sub-classified according to when onset occurred
        • Infantile
        • Juvenile
        • Adolescent
        • Adult 
    • Congenital spinal column abnormalities
    • Neurological disorders
    • Genetic conditions 

Aetiology

  • Theories on AIS's aetiology include mechanical, hormonal, metabolic, neuromuscular, growth and genetic abnormalities
  • Given the strong epidemiological data demonstrating familial clustering, AIS is thought to be a complex genetic disorder, with one or more genes interacting with the environment to result in spinal deformity
  • Growth hormone
    • The relationship of growth to curve progression makes growth hormone an obvious candidate
    • Several studies have found an increase in the level of growth hormone or somatomedians in adolescent girls
    • Sporadic cases of a rapid increase in scoliotic curvature have been reported in patients undergoing growth-hormone therapy
  • Some research suggests that primary neurological pathologies might cause a functional asymmetry in balance and consequently result in scoliosis
  • Syringomyelia associated with a Chiari type I malformation at the foramen magnum has a substantially increased prevalence in patients with AIS
  • Collagen and elastic fibres are principal elements in the supporting structures of the spinal column and have been the focus of many studies dealing with the pathophysiology of AIS
  • Although changes have been identified within the musculature, extracellular matrix of spinal ligaments and the intervertebral disc, it is not possible to differentiate whether these are primary, i.e., causing scoliosis, or secondary, i.e., resulting from the spinal deformity
  • Growth asymmetry has been put forward as an aetiology of AIS, although this has not been supported definitively by research studies

Risk factors

  • Genetic predisposition is thought to be the biggest risk factor, although the exact genes involved have not been determined
  • The 3 main risk factors of curve progression are
    • Female gender : Risk of curve progression 10 times higher than males
    • Future growth potential
    • Curve magnitude at the time of diagnosis

Prevention

  • Due to the elusive nature of the cause of most cases of scoliosis, preventative measures have not been established

Natural History

  • According to the National Scoliosis Foundation, an estimated 6 million people have scoliosis in the United States alone
  • Congenital scoliosis
    • A fixed spinal curvature that is present at birth
    • Usually is due to a deformity in the bony structure of 1 or more vertebrae
    • Affects girls more often than boys (60% to 40%)
    • Affects approximately 1 in 10 000 Americans
  • Adolescent idiopathic scoliosis (AIS)
    • Accounts for an estimated 80% of idiopathic scoliosis cases
    • Affects 2% to 4% of all adolescents
    • Detected most commonly in children between the ages of 10 and 16 years
  • Neuromuscular and traumatic scoliosis account for only a small fraction of cases

Clinical Presentation

  • Mild cases usually do not cause physical restrictions or complaints from patients
  • Mild and moderate cases are often more problematic from a social standpoint in appearance-conscious adolescents
  • Progression of the curvature can result in more severe symptoms
  • Severe cases of scoliosis suffer from
    • Diminishing lung capacity
    • Putting pressure on the heart
    • Restricting physical activities
  • The more serious symptoms are only seen with severe curvature which results in compression of the thoracic cavity
  • Signs of scoliosis are usually picked up on routine screening at school or at yearly well-child visits
  • Physical exam could reveal
    • Overt curvature of the spine
    • Shoulder blade asymmetry
    • Waistline asymmetry
    • Trunk shift
  • The Adam's Forward Bend Test looks for the rotational aspect of the scoliosis in the upper part of the back (rib prominence) or in the lower part of your back (flank or waist prominence)

Differential Diagnosis

Even though most cases are idiopathic, it is important to look for an underlying cause such as

  • Congenital vertebral anomalies
  • Tethered cord
  • Spina bifida
  • Associated genetic conditions

Psychosocial impact of disease

  • Even mild cases of scoliosis may have a negative psychosocial impact, due to the disfiguring nature of the disease
  • This is especially relevant since the majority of cases develop in adolescent girls
  • Obvious spinal curvature and uneven shoulders and hips can be very uncomfortable for self-conscious adolescents at a time when physical appearance is extremely important

Imaging and Diagnostic Studies

  • Scoliosis must be confirmed by X-Ray to assess the severity of the curvature
  • The preferred initial images for assessing a suspected case of scoliosis are the PA standing and lateral standing views which include the entire length of the spine
  • The curve of the spine is then measured in degrees to determine the severity of the curvature
    • The standard method for assessing the curvature quantitatively is measurement of the Cobb angle
    • The Cobb angle is the angle between two lines, drawn perpendicular to the upper endplate of the uppermost vertebrae involved and the lower endplate of the lowest vertebrae involved
    • Although the Cobb angle does have some inter- and intra-observer variability, it is a reliable indicator of curve severity

Laboratory evidence

  • There is no laboratory test to diagnose scoliosis
  • However, various tests may be used to diagnose associated genetic and metabolic conditions

Treatment

  • Observation indicated for
    • Small curves when the patient is still growing (adolescent scoliosis)
    • For moderate size curves (<40-45°) when done growing
  • Bracing
    • Indicated for curves between 25-45° in growing children
    • The brace cannot correct curves
    • The goal of bracing is to prevent further progression
  • Surgical treatment
    • Reserved for curves that are >50° for adolescent patients and adults
    • The goals of surgical treatment are to obtain curve correction and to prevent curve progression
    • This is generally achieved by placing metal implants onto the spine, attached to rods which correct the spine curvature and hold it in the corrected position

Outcome

  • No definite evidence has shown that physical therapy or bracing
    • Reduces the risk of curve progression
    • Corrects the existing deformity
    • Decreases the need for surgery
  • Surgery has been shown to decrease deformity and prevent progression
  • Long term outcomes of recently developed surgical techniques still need to be examined

Complications

  • The main complication of bracing is psychological stress
  • Surgical complications
    • Intra-operative problems
      • Blood loss
      • Anesthesia reactions
    • Immediate postoperative complications
      • Pneumothorax
      • Pleural effusion
      • Pneumonia
      • Post-operative ileus
      • Infection
    • Late problems
      • Pseudarthrosis
      • Instrumentation failure
      • Loss of correction
      • Extension of a curve beyond the corrected area
      • Neurologic complications
  • I did not have access to many of the journals that included articles related to this question and therefore I was unable to find any article that explicitly stated the odds of potential complications

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