Practice Essentials
The term scoliosis is derived from the Greek word skolios ("twisted") and refers to a sideward (right or left) curve in the spine. Scoliosis is not a simple curve to one side but, in fact, is a more complex three-dimensional deformity that often develops in childhood.
The term infantile scoliosis is used specifically to describe scoliosis that occurs in children younger than 3 years. [1] Other terms for scoliosis also depend on the age of onset, such as juvenile scoliosis (4-9 years) and adolescent scoliosis (10-18 years). These terms, however, are now being replaced by the broader terms early-onset scoliosis and late-onset scoliosis, depending on whether the scoliosis occurs before or after the age of 10 years. [2]
In 80% of cases of scoliosis, there is no obvious cause; this is termed idiopathic scoliosis. In the remaining 20% of cases, a definite cause can be found. These cases are divided into the following two types:
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Nonstructural (functional) scoliosis
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Structural scoliosis, which could be part of a well-recognized syndrome (syndromic scoliosis) or could involve congenital spinal column abnormalities (congenital scoliosis), neurologic disorders, or genetic conditions
Evidence in the literature from two major centers in the United Kingdom suggests that the association of neural axis anomalies with early-onset idiopathic scoliosis is only 11.1%.
The syndromes that can produce structural scoliosis are VATER syndrome (vertebral anomalies, anorectal anomalies, tracheoesophageal fistula, and renal anomalies), VACTERL syndrome (vertebral anomalies, anorectal anomalies, tracheoesophageal fistula, renal and vascular anomalies, and cardiac and limb defects), Jarcho-Levin syndrome, Klippel-Feil syndrome, Alagille syndrome, Wildervank syndrome, Goldenhar syndrome, Marfan syndrome, and MURCS association (müllerian, renal, cervicothoracic, and somite abnormalities).
The congenital anomalies of the vertebral spinal column include defects of segmentation (block vertebra, unilateral bar) and defects of formation (hemivertebra—fully segmented, semisegmented, incarcerated and nonsegmented, wedge vertebra).
The neurologic deficits in structural scoliosis may be secondary to the spinal deformity or may be associated with vertebral anomalies (spinal dysraphism—diastematomyelia, myelocele, myelomeningocele, meningocele).
A higher incidence of idiopathic scoliosis has been reported in families of children with congenital scoliosis. Spondylocostal dysostosis (Jarcho-Levin syndrome) has a genetic etiology. [3, 4, 5, 6] Research is ongoing to identify any scoliosis-related genes. [3, 4]
Infantile scoliosis usually is detected during the first year of life either by the parents or by the pediatrician during routine examination of the infant. Usually, a single long thoracic curve to the left is present; less often, a thoracic and lumbar double curve is noted.
There are three management options for infantile scoliosis: observation, orthosis, and operation (see Treatment). The decision when to use each of these is based on the rib-vertebral angle difference (RVAD). The RVAD is a useful guide in distinguishing between resolving and progressive idiopathic infantile scoliosis.
Anatomy
The spine is made up of 33 individual vertebrae that form a column. The spine is divided into the following five regions, starting from the top:
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Cervical spine (C1-C7)
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Thoracic spine (T1-T12)
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Lumbar spine (L1-L5)
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Sacrum (S1-S5)
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Coccyx (Co1-Co4)
In adults, the sacrum and the coccyx are fused.
The spine provides a protective function for the spinal cord, bears and distributes the weight of the body, provides an area for attachment of ligaments and muscles, and is the site for production of red blood cells. Together, all the vertebrae form a flexible structure providing mobility for the body to bend forward or sideward.
Each vertebra has a cushionlike fibrous structure called a disk, which acts like a shock absorber during movements of the spine. The disk is made up of a soft, jellylike central nucleus pulposus surrounded by a ring of fibrous tissue called an anulus, which is actually a strong ligament between two adjacent vertebrae.
Developmentally, the spine of the fetus is C-shaped, with concavity in the front (kyphotic) of the thoracic region; this is called the primary curve. Two secondary curves develop after birth, with concavity occurring anteriorly (lordosis); one of the secondary curves develops in the cervical region as the infant starts to hold up the neck, and the second curve develops in the lumbar region when the child starts to walk. Normally, there are no sideward (scoliosis) curves, so that the spine looks straight when viewed from behind or from the front.
Pathophysiology
Most of the curves in the spine develop during the first year of life, and strong correlation has been found between the nursing posture of the infant and development of the curve. It is less common in the United States than in Europe, where babies are nursed in the supine position. Infants have a natural tendency to turn toward the right side, and because of plasticity of the infant's axial skeleton, this can lead to development of plagiocephaly, bat ear on the right side, and curvature of the spine toward the left side. [7]
Etiology
Although the exact cause of idiopathic infantile scoliosis is not known, hypotheses have been proposed on the basis of epidemiologic evidence [3, 4, 5, 7, 8] :
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One theory holds that the mechanical factors during intrauterine life are responsible for the higher incidence of plagiocephaly, developmental dysplasia of the hip, and scoliosis on the same side of the body
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A second hypothesis suggests multifactorial causes, including predisposing genetic factors that are either facilitated or inhibited by external factors such as defective motor development or collagen disorders, joint laxity, and nursing posture of the infant
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Other associations include older mothers from poorer families, breech presentation, and premature and male low-birth-weight babies
Epidemiology
Infantile scoliosis is a rare condition, accounting for fewer than 1% of cases of idiopathic scoliosis in North America; in Europe, the rate is 4%.
Males account for 60% of the cases of early-onset scoliosis; 90% of the cases of early-onset scoliosis resolve spontaneously, but the other 10% progress to a severe and disabling condition. Females constitute 90% of late-onset cases and need close monitoring to allow intervention at appropriate times.
A study of infantile, juvenile, and adolescent idiopathic scoliosis in a large integrated healthcare system in Southern California reported incidence figures of 3.9/100,000, 28.6/100,000, and 393/100,000, respectively. [9] This study found idiopathic scoliosis to be more than twice as common in females as in males in all age groups. Asian and non-Hispanic white patients had the highest odds ratio for the condition. Initial curve magnitude was significantly greater in females as compared with males and in white, Black, and mixed-race patients as compared with Hispanic patients. Underweight patients had a 50% increased odds ratio for idiopathic scoliosis as compared with normal-weight patients.
Prognosis
More favorable outcomes have been associated with male sex, a left-side curve, a low initial curve measurement, an RVAD of less than 20° in the initial radiograph (see Workup), and the onset of scoliosis in the first year of life.
A study by Gomez et al evaluated 68 patients in the Children's Spine Study Group and Growing Spine Study Group registries who underwent cast treatment for idiopathic scoliosis and were followed for a minimum of 1 year. [10] The prognosis was best for those patients who underwent casting at an earlier age, had smaller major curves, and showed a greater percent major curve correction in initial casting.
A retrospective study by Negrini et al assessed the medium-term results of bracing for conservative treatment of early-onset scoliosis, noting that the repeated general anesthesia required for casting has been questioned for the possibility of brain damage. [11] Patients who had idiopathic infantile scoliosis (IIS) were compared with patients who had secondary infantile scoliosis (SIS), and those with IIS were found to respond better than those with SIS.
In a study of the outcomes of brace treatment in 29 patients with infantile idiopathic sclerosis, Babaee et al found bracing to be successful in more than two thirds of cases, preventing surgery before the age of 10 years. [12]
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RVAD (rib-vertebral angle difference) measurement at apical vertebra: RVAD = b - a (concave - convex side).
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Preoperative scoliogram showing Cobb angle.
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Postoperative scoliogram after correction with pediatric Isola system.
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Preoperative and postoperative radiographs show increase in space available for lung (SAL) after correction of scoliosis by VEPTR (vertical expandable prosthetic titanium rib).
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Preoperative and postoperative radiographs show increase in space available for lung (SAL) after correction of scoliosis by VEPTR (vertical expandable prosthetic titanium rib).
