Early onset idiopathic scoliosis (EOIS)

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Paediatric Idiopathic scoliosis

General

• Comprised of (old classification)
• Infantile Idiopathic Scoliosis
• Children ages 3 years or less
• More common in boys
• usually left thoracic
• More common in Europe but rare in the USA
• Associated with plagiocephaly, developmental delay, congenital heart disease, and developmental hip dysplasia;
• Juvenile Idiopathic Scoliosis
• Children between ages 4 and 10
• Represents a gradual transition from the characteristics of infantile idiopathic scoliosis to those of adolescent idiopathic scoliosis.
• More common in girls
• Less common than adolescent idiopathic scoliosis,
• right thoracic and double major curve types

Numbers

• Rare (1% in the United States, ~5% in Europe)
• 4-15% of all idiopathic scoliosis cases

• It is typically a left-sided curve

• Which develops after birth, but is not present at birth

Pathophysiology

• Unknown

• the T1-L5 spinal segment grows fastest in the 1st five years of life

• the height of the thoracic spine increases by 2 times between birth and skeletal maturity

• Theory
• Result of intrauterine moulding
• the counter to this suggestion is the fact that EOIS is rarely seen at birth.
• Result of ‘body moulding’ from the positioning of the child.
• If the infant lies in the lateral decubitus position a curve will develop;
• This is supported by the observation of plagiocephaly in this group.

Clinical features

• Early-onset scoliosis (before age 5) who develop severe curves (90°) with cor pulmonale and right ventricular failure, resulting in premature death.

Clinical assessment

Deformity assessment

• Check patient’s spinal shape from the back and the sides.

• Record general imbalance and compensations for:
• Coronal balance: plumb line
• Sagittal balance: ability to stand upright
• Compensation: pelvic retroversion, knee flexion, etc

• Check shoulder, trunk, and pelvic asymmetry:
• Shoulder-height difference
• Shoulder angle
• Axillary angle
• Scapular angle
• Iliac crest line
• Gluteal-fold asymmetry
• Knee and ankle joint position

• Specific for EOIS
• Pulmonary function tests
• Concomitant respiratory problems
• Nutrition percutaneous endoscopic gastrostomy (PEG)
• Seizures
• Ventriculoperitoneal (VP) shunts
• Baclofen pumps
• Check for stigma of different syndromes
• Arachnodactyly, hyperlaxity and pectus excavatum in Marfan syndrome
• Café au lait spots for neurofibromatosis, etc

• Flexibility:
• Check deformity in standing and prone positions
• Apply traction in neuromuscular patients

Radiological assessment

Scoliosis is a curve in the coronal plane of >10 degrees.

• Intra-interobserver error of 3-5°

• In EOIS if Cobb angle > 20 degrees associated with progression

Measurements specific for EOIS

• Fulcrum Bending Radiograph (FBR)
• Purpose:
• The FBR was developed to assess the flexibility of the thoracic spine,
• identify any structural changes,
• Determine the selection of fusion levels in AIS patients.
• Fulcrum-Bending flexibility (%) = (Preoperative Angle – Fulcrum Bending Angle) / Preoperative Angle × 100

• Fulcrum Bending Correction Index (FBCI)
• Purpose:
• A preferred method to assess the correction rate because it takes into account the curve’s flexibility.
• It helps compare curve correction and instrumentation systems between different patient series.
• Fulcrum Bending Correction Index (%) (FBCI) = Correction Rate / Fulcrum-Bending Flexibility × 100
• Correction rate (%) = (Preoperative Angle – Postoperative Angle) / Preoperative Angle × 100
• An FBCI close to 100% suggests that the instrumentation has fully utilised the flexibility revealed by the FBR.

 

 

• Rib phase
• technique
• convex rib head position with respect to the apical vertebrae
• findings
• phase 1 - no rib overlap
• is associated with resolution in 84– 98% of cases.
• phase 2 - rib overlap with the apical vertebrae
• Associated with progression in 84– 97% of cases.
• high risk for curve progression

• RVAD (rib vertebrae angle difference, Mehta angle)
• Technique
• measure angle between the endplate and rib (line between midpoint of rib head and neck)
• RVAD = difference of 2 rib-vertebral angles
• Findings
• > 20° is linked to high rate of progression
• < 20° is associated with spontaneous recovery

Associated with other conditions

• talipes equinovarus,

• developmental dysplasia of the hips,

• Torticollis

• Inguinal hernia

• thoracic insufficiency syndrome
• characterized by
• decreased thoracic growth + lung volume --> pulmonary hypertension + cor pulmonale
• pulmonary function impairment associated with curves > 60°
• cardiopulmonary issues associated with curves > 90°

• Some 22% of patients with presumed EOIS with curves less than 20° have an underlying neural axis anomaly (i.e. they were not truly idiopathic).
• 80% of patients with a neural axis anomaly required neurosurgical intervention.

Classification

Resolving phase(85%)

• Tx
• observed with advice to sleep in the prone position.

Progressive phase (15%)

• with progression likely in those with
• a rib-vertebral angle difference > 20°
• increasing rib phase (overlap of rib head and apical vertebral body).

• Tx
Conservative

• Observe (repeated x-rays)
• Indication
• Curves < 20°

• Bracing
• Indications
• Progressive curves.
• Curves in the 25-50° range.
• Aim
• designed to prevent curve progression, not correct the curve
• relative contraindication to bracing is thoracic hypokyphosis
• Buy time so that the spine can fully grow before fixation and fusion
• Technique
• frequent radiographs to observe for curve progression
• with serial derotational (plaster) casting followed by orthotic treatment with a Milwaukee brace.
• Serial plaster casts such as those popularized by Cotrel and used to good effect by Mehta (elongation de-rotation flexion, or EDF casts) can be moulded to control small, progressive curves.
• 16-23h/day until skeletal growth completed or surgery indicated
• Rigid braces are of little use, due to the rapid growth rate of the child,
• Boston brace

Surgery
• Indication
• Large curves (> 50° Cobb angle)
• Curves that continue to progress despite orthotic treatment require surgery.
• Surgical decision making is complex in view of the wide age range of patients presenting in juvenile idiopathic scoliosis.
• As older so some might benefit from complete fusion with the danger of crankshafting
• The dilemma
• is that early spinal fusion → prevent thoracic growth → thoracic insufficiency syndrome → respiratory failure → reduced life expectancy.
• Aim
• Control the curve, while maintaining growth.
• Techniques
• Dual rod growing system.
• Indication
• early juvenile scoliosis patients
• Here, the curve is instrumented proximally and distally (usually two levels at each end), but the centre of the curve is left undisturbed.
• Rods are used on each side to connect the proximal and distal instrumentation.
• thoracic height that is most important in deciding between using growth rods vs final fusion.
• Traditional rods
• had to be lengthened every four to six months to allow growth, and this necessitated repeated surgical procedures.
• Complications such as wound infection or rod breakage were encountered in all of these cases eventually, due to repeated extension of instrumentation through the same scar.
• Intrinsic magnetic motor rods
• That allows telescoping has recently entered clinical use and offers the possibility of repeated lengthening using an external magnet in the outpatient clinic, obviating the need for repeated surgery.

• Selectively inhibit growth on the curve convexity.
• This technique is still somewhat experimental and not widely adopted.
• In extreme cases, a combined anterior and posterior fusion procedure is an option but will consequently limit development of the thorax, lungs, and normal trunk height.
A single-stage posterior fusion procedure
• Concerns
• effect of treatment on remaining growth
• potential for development of crankshaft phenomenon
• Not good option for infantile but for older juvenile idiopathic scoliosis might be an option
Combined anterior and posterior fusion with posterior instrumentation
• Indication
• For older patients.

Natural history

• 90% of cases will resolve spontaneously.
• Juvenile idiopathic scoliosis
• 70% of curves progress and require some forms of treatment (bracing or surgery).

• Factors that increases the risk of progression
• Double curves are more likely to progress than single curves
• RVAD angle < 20°, 85– 90% curve will spontaneously resolve
• Phase 2 rib phase
• Girls with a right- sided curve have a much poorer prognosis than those with left- sided curves.

• Progressive EOIS is associated with
• Thoracic insufficiency syndrome --> a reduction in life expectancy
• It is likely that the historical descriptions of this group of patients included many who had an underlying cause for their scoliosis