Pediatric idiopathic scoliosis
Scoliosis is a coronal curvature of the spine measuring > 10°. This article focuses on idiopathic scoliosis, which is a diagnosis of exclusion. The differential diagnosis is vast (see table below); however, the majority of scoliosis cases – about 80% – are idiopathic. The age at onset is used to define/group idiopathic scoliosis:
- Infantile (0-3 years old)
- Juvenile (4-10 years old)
- Adolescent (11-17 years old)
- Adult (?18 years)
Infantile Idiopathic Scoliosis (IIS)
- Male:Female = 3:2
- Incidence: 0.5%
- Associated conditions include plagiocephaly, hip dysplasia, congenital heart disease, and mental retardation
- Increased incidence of neural axis abnormalities (ie, Chiari malformation, syringomyelia, brain stem tumor, etc)
- Majority of curves resolve spontaneously and are self-limiting; curves developing within first year of life have greatest likelihood of resolving
Juvenile Idiopathic Scoliosis (JIS)
- Male:Female = 1.6:1 if < 6 years old and 1:2.7 if > 6 years old at presentation1
- Incidence: 10.5%
- Often progressive with potential for severe trunk deformity
- More likely to progress and require surgical intervention
- Curves ?30° nearly always progress if left untreated
- Rate of progression
- 1-3°/year before age 10
- 4.5-11°/year after age 101
Adolescent Idiopathic Scoliosis (AIS)
- Equal male to female ratio for smaller curves
- Male:Female = 1:8 for progressive curves requiring treatment
- Most common form of idiopathic scoliosis; incidence: 89%2
- About 2% of adolescents have a scoliotic deformity ?10°; only 5% of those progress to > 30°
- Three-dimensional deformity including coronal plane, sagittal plane, and torsional malalignment of the spinal column
- Curve location (based on apex of curve)
- Cervical: C2-C6
- Cervicothoracic: C7-T1
- Thoracic: T2-T11
- Thoracolumbar: T12-L1
- Lumbar: L2-L4
- Major curve: Largest measured curve based on the Cobb angle
- Minor curve: Lesser magnitude curves; compensatory curves to balance the spine over the pelvis
- Structural vs. non-structural curves: Defined based on curve magnitude on side-bending AP radiographs3
- Structural: ? to 25°
- Non-structural: < 25°
- Lenke et al incorporated sagittal plane alignment into curve classification;3 structural criteria for minor curves include:
- Proximal thoracic kyphosis (T2-T5) ?20°
- Main thoracic kyphosis (T10-L2) ?20°
- Thoracolumbar/lumbar kyphosis (T10-L2) ?20°
- Normal+ sagittal alignment:
- Thoracic kyphosis averaging 30-35° (T5-T12)
- Lumbar lordosis averaging 50-60° (T12-S1)
- Scoliosis is associated with decreased thoracic kyphosis
- Right-sided thoracic curve the most common deformity for AIS
- Left-sided thoracic curve more common in IIS
- “Hump” on back is caused by rib prominence due to rotational deformity of vertebrae and rib cage
Lenke Classification System for Scoliosis
Curve types in the Lenke Classification System3
Criteria for each curve type in the Lenke Classification System3
King-Moe Classification System
- Unknown etiology, hence the term “idiopathic”
- However, many theories exist:
- Genetic: Increased incidence of scoliosis in families of affected individuals.
- 11.1% incidence in first-degree relatives2
- In monozygotic twins, frequency of scoliosis in both twins when one is affected is 73%-92%
- In dizygotic twins, frequency of scoliosis in both twins when one is affected is 36%-63%5,6
- Specific responsible genes remain unknown
- Tissue deficiencies: Conditions affecting the structural architecture of the spine (bone, muscle, ligament, disc) often associated with scoliosis, including fibrous dysplasia, Duchenne muscular dystrophy, and Marfan syndrome
- Osteopenia also suggested as a cause
- Lower bone mineral density of vertebral bodies in girls with scoliosis aged 12-14 years compared to matched controls7-9
- Vertebral growth abnormalities: Onset and progression of scoliosis related to adolescent growth spurts, giving rise to theories suggesting abnormalities in vertebral growth as an etiology
- Disparate growth rates between right and left sides of the spine leading to asymmetry10-15
- Altered growth with increased length of anterior column results in relative thoracic lordosis; subsequently, spine rotates and buckles its apical segments laterally to effectively shorten anterior column and maintain global sagittal balance 16
- Increased levels of growth hormones found during growth spurts also linked to development of scoliosis;17,18 however, no definitive relationship has been established
- Asymmetric growth and wedging of spine occurs as disease progresses following the Heuter-Volkmann principle; compression of spine at the concavity results in reduced growth
- Central nervous system: Greater asymmetry of cerebral cortices, abnormalities in equilibrium/vestibular function, and syringomyelia noted, but no causal relationship established 19-23
- Melatonin deficiency and elevated calmodulin levels also postulated, again with no clear relationship
- Incidence of back pain among patients with scoliosis is similar to that in the general population
- Early-onset idiopathic scoliosis more likely to be progressive
- Rib-vertebra-angle-difference (RVAD) of more than 20° associated with high likelihood of progression for IIS24
- In JIS, curve apex at T8, T9, or T10 indicates an 80% chance that spinal fusion will be needed by age 151
- Curve progression is greatest during peak skeletal growth
- Thoracic curves with apex above T12 more likely to progress than lumbar curves; curves with greater magnitude more likely to progress25-28
- Curves may progress after skeletal maturity:
- Thoracic curves < 30° tend not to progress
- Thoracic curves between 50° and 75° progress at 1° per year
- Lumbar curves > 30 ° tend to progress29,30
- Severe curves may lead to cardiopulmonary compromise and increased mortality rate31,32
- Often presents after routine school screening examination
- Obtain a focused history
- Neurological history: Positive findings suggest a non-idiopathic cause
- Symptoms include weakness, sensory loss, ataxia, radiating pain, paresthesias, numbness, persistent headaches, visual disturbances, bowel/bladder incontinence
- Back pain: Severe back pain suggestive of a non-idiopathic etiology
- For example, scoliosis with associated osteoid osteoma commonly presents with significant back pain
- Family history: Three times more likely to occur if a parent is affected; seven times more likely if sibling is affected33
- Surgical history: May also rule out idiopathic scoliosis if associated congenital condition identified
- Growth history: Recent growth useful in predicting curve progression; breast development and menses may serve as key landmarks in history for females
- Evaluate pubertal development: Tanner staging may be performed
- Evaluate body/trunk asymmetry
- Shoulder height, scapular positioning, waist crease symmetry, pelvic tilt, truncal shift
- Adam’s forward bend test evaluates rotational deformity of spine
- Neurologic exam
- Gait, motor, sensory, and reflex examination for all four extremities and abdomen
- Evaluate limb lengths; discrepancies may cause compensatory curvature of spine
- Cutaneous examination: Skin lesions may indicate associated diseases, such as:
- Café au lait spots and axillary freckles: Neurofibromatosis
- Hairy patch or skin dimpling in lumbosacral area: Spina bifida, diastemetomyelia
- Skin/joint laxity: Marfan syndrome, Ehlers-Danlos, other connective tissue disorders
Imaging and Diagnostic Studies
- Standing PA spine X-ray: Entire spine from T1 to pelvis on one cassette
- Lateral spine X-ray: Usually obtained after diagnosis is confirmed unless back pain or sagittal deformity noted on physical exam
- Lateral bending X-ray: Used to assess structural vs. non-structural curves for surgical treatment; typically performed supine, but may also be done standing or over a bolster
- Stagnara oblique view: Taken perpendicular to the rib prominence; provides more accurate view of large curves34
- MRI, CT, and bone scans may be used in select patients with associated neurologic findings, atypical curves, and/or severe back pain suspicious for an associated condition (eg, spondyloysis, tumor, infection)
- Examine radiographs for soft tissue abnormalities, congenital bone abnormalities (eg, hemivertebrae, bar formation, spina bifida), bone lucency (may suggest tumor or infection), and curvature
- Cobb method used to measure magnitude of each curve
Cobb's angle evaluates curves in scoliosis based on an AP radiograph of the spine (image from xray2000, www.e-radiography.net)
- Compare most recent X-rays to X-rays from the original and previous visits for analysis of curve progression
- Vertebral rotation may be assessed on radiographs through asymmetry of pedicles and/or shift of spinous processes:
- Cobb method
- Nash-Moe method
- Perdriolle method35
- Stokes’ method
- Assess growth potential radiographically:
- Risser sign
- Triradiate cartilage closure
- Greulich and Pyle method
- Sauvegrain et al method36
- Tanner-Whitehouse-III RUS scores and digital skeletal age maturity scoring system correlate highly with curve acceleration phase for girls with idiopathic scoliosis37,38
- Upper motor neuron
- Cerebral palsy
- Spinocerebellar degeneration
- Friedreich disease
- Charcot-Marie-Tooth disease
- Roussy-Levy disease
- Spinal cord tumor
- Spinal cord trauma
- Lower motor neuron
- Other viral myelitides
- Spinal muscular atrophy
- Werdig-Hoffmann disease
- Kugelberg-Welander disease
- Myelomeningocele (paralytic)
- Dysautonomia (Riley-Day syndrome)
- Muscular dystrophy
- Duchenne (pseudohypertrophic)
- Fibertype disproportion
- Congenital hypotonia
- Myotonia dystrophica
- Failure of formation
- Wedge vertebra
- Failure of segmentation
- Unilateral bar
- Bilateral (fusion)
Associated with Neural Tissue Defect
- Spinal dysraphism
- Marfan syndrome
- Ehlers-Danlos syndrome
- Fracture or dislocation
- Spondyloepiphyseal dysplasia
- Diastrophic dwarfism
- Juvenile osteoporosis
- Osteogenesis imperfecta
Related to Lumbosacral Area
- Curves < 25° monitored every 4 to 12 months with clinical and radiographic exams
- IIS with RVAD < 20° should be followed every 4-6 months.
- Patients during peak height velocity require monitoring every 4-6 months
- Curves > 50° at skeletal maturity should be monitored every 5 years
- Serial casting may be performed for those with IIS or JIS
- Goal of bracing: Maintain or slow progression of current deformity
- Growing children/adolescents with curves 25°-45°
- Growing patients with curves < 25° but with a markedly significant increase in curve magnitude from previous measurements
- Bracing for 23 hours/day has been recommended until completion of growth
- Several brace types available, including:
- Milwaukee brace
- Boston brace
- Wilmington brace
- Charleston brace
- Skepticism exists regarding the effectiveness of part-time bracing39-43
- For curves 36°-45°, 83% of the curves treated with Charleston brace had curve progression, versus 43% treated with Boston brace.
- Recommended that Charleston brace be reserved for single lumbar or thoracolumbar curves less than 35°44
- Goals of surgery: Obtain curve correction, restore spinal balance, prevent future progression
- Indications (guidelines and not absolute indications):
- Thoracic curves > 45° in the skeletally immature
- Thoracic curves > 50° in the skeletally mature with symptoms and/or progression
- Posterior instrumentation and fusion
- Originally popularized by Harrington
- Most commonly employed technique
- Can be performed with hooks, screws, and/or sublaminar wires with rigid rod fixation
- Anterior instrumentation and fusion
- Generally limited to deformities with a single curve
- Saves fusion segments
- Can minimize or prevent crankshaft phenomenon
- Need an access surgeon
- May have negative effects on pulmonary function
- Combined anterior and posterior fusion
- Large rigid curves (ie, > 75° curves with bend correction < 50°)
- Those at risk for crankshaft deformity
- Less common with use of periapical releases and osteotomies
- Instrumentation without fusion
- Used in younger children with large progressive curves despite cast and/or brace treatment
- Instrumentation placed subcutaneously or subfascially spanning the deformity; sequential distraction performed every 6 to 12 months until growth and correction optimized, followed by definitive instrumentation and fusion
- Thorough neurologic evaluation
- Wounds monitored for signs of infection
- Assess patients for post-operative ileus and be vigilant for SMA syndrome
- Routine clinical and radiographic evaluation of spinal alignment, hardware positioning, and arthrodesis
- Physical therapy for mobilization and conditioning
- Bracing more effective than observation in preventing progression of scoliosis; may not have negative impact on patients' quality of life45-47
- Patient satisfaction after surgical correction of AIS is often evaluated using Scoliosis Research Society-22 (SRS-22) domain scores
- At 2 years, there is a statistically significant change in all the SRS domain scores, with improvement from preoperative status
- However, there is low to moderate association between the change in SRS-22 scores and patient satisfaction with treatment
- May be due to a ceiling effect in “satisfaction” domain or lack of responsiveness of the SRS-22 to measure clinically relevant changes in activity, pain, and mental health 2 years after correction of scoliosis in adolescent population 48
Complications from Bracing
- Skin break down
- Non-compliance and curve progression
Complications from Surgery
- Intra-operative issues:
- Blood loss
- Neurologic injury
- Direct trauma
- Vascular Injury
- Post-operative issues:
- Neurological deterioration
- Delayed issues:
- Failed Instrumentation
- Loss of curve correction
- Adjacent level degeneration
- Adjacent level deformity
- Back pain
Pearls and Pitfalls
- Idiopathic scoliosis is a diagnosis of exclusion; other pathologies must be ruled out
- Early screening and referral followed by prompt treatment can minimize long-term physical and psycho-social sequelae
- Compliance with brace treatment is a major issue and must be addressed frequently and often with the family
- Save motion segments when possible
- Use osteotomies and releases to improve correction and limit hardware fatigue
- Use neurophysiologic monitoring to minimize peri-operative neurologic injury
- Maintain mean arterial pressure at 80 mm Hg during curve correction and instrumentation to minimize ischemic injury
- Restoration and maintenance of sagittal alignment critical for long-term success
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