Early Onset Scoliosis
The Race Against Pulmonary Insufficiency
C-EOS Classification
Critical Must-Knows
- Thoracic Insufficiency Syndrome (TIS): The inability of the thorax to support normal respiration.
- Mehta Angle (RVAD): The key predictor of progression in infantile scoliosis.
- MRI: Mandatory for all EOS cases (Neural axis abnormalities in 20-40%).
- C-EOS Classification: Etiology, Cobb, Kyphosis, Progression.
- Treatment: Delay fusion! Use Casting, Bracing, or Growing Rods.
Examiner's Pearls
- "Look for cutaneous stigmata (hairy patch, dimple) - Intraspinal pathology
- "Assess flexibility (Bending films)
- "Neurology is mandatory (Abdominal reflexes)
- "Plagiocephaly is often associated with Infantile Scoliosis
The MRI Rule
Mandatory MRI
Standard of Care. 20-40% of EOS patients have neural axis abnormalities (Chiari/Syrinx) even with normal neuro exam.
Mehta Angle (RVAD)
Greater than 20° = Progressive. less than 20° = Resolving. Key predictor for Infantile Scoliosis.
Lung Danger
Avoid Early Fusion. Fusing more than 4 thoracic segments before age 8 stunts lung development → Thoracic Insufficiency Syndrome.
Infantile (0-3) vs Juvenile (4-10) vs Adolescent (10+)
| Feature | Infantile | Juvenile | Adolescent (AIS) |
|---|---|---|---|
| Male | Female | Female | |
| Left Thoracic | Right Thoracic | Right Thoracic | |
| High (MRI mandatory) | High (MRI mandatory) | Low (MRI if red flags) | |
| Resolves (80%) or Severe | Often Progresses | Variable |
Goals of Management
Memory Hook:LSG (Life Support Growth).
C-EOS Etiology Categories
Memory Hook:CNSI (Central Nervous System Injury? No, just the list).
Risk of Progression (Infantile)
Memory Hook:RPC (Rapid Progression Criteria).
Overview/Epidemiology
Early Onset Scoliosis is a time-based definition (Age less than 10). It encompasses a heterogeneous group of diagnoses.
- Pulmonary Impact: The primary concern is Thoracic Insufficiency Syndrome (TIS).
- Alveoli multiply rapidly until age 8.
- Severe deformity restricts lung volume, leading to restrictive lung disease to Pulmonary Hypertension to Cor Pulmonale to Early Death.
- Epidemiology:
- Infantile Idiopathic: Rare (1% of all scoliosis). Male > Female. Left-sided curves are typical.
- Juvenile Idiopathic: Female > Male. Right-sided curves (like AIS). Malignant progression is common.
Pathophysiology and Mechanisms
The Mehta Angle (Rib-Vertebral Angle Difference - RVAD) This is the angle between the rib neck and the vertebral body.
- Measured at the apical vertebra.
- Calculation: RVAD = Angle on Concave side - Angle on Convex side.
- Significance:
- Less than 20 degrees: 80% chance of spontaneous resolution. (Resolving).
- Greater than 20 degrees: 80% chance of progression. (Progressive).
Rib Head Phases (Mehta)
- Phase 1: Prominent gap between rib head and vertebral body.
- Phase 2: Rib head overlaps the vertebral body. Indicates progression.
Classification Systems
C-EOS Classification (2014)
1. Etiology (CNSI):
- Congenital, Neuromuscular, Syndromic, Idiopathic.
2. Cobb Angle:
- Current magnitude of the major curve.
3. Kyphosis:
- Hyperkyphosis (greater than 50) is a major negative predictor for pulmonary function.
4. Progression Modifier:
- P0: Stable (less than 10 deg/year).
- P1: Progressive (greater than 10 deg/year).
- P2: Malignant (greater than 20 deg/year).
Clinical Assessment
History:
- Birth Hx: Prematurity? NICU admission?
- Development: Walking age? Milestones? (Neuromuscular).
- Family Hx: Neurofibromatosis? Marfan?
Physical Exam:
- Skin: Café-au-lait spots (NF1), Hairy patch (Spinal dysraphism), Laxity (Ehlers-Danlos).
- Neurology: Full exam. Abdominal reflexes are critical for Syringomyelia.
- Spine: Assess flexibility. Can you correct it with traction/bending?
- Chest: Pectus deformities? Rib hump?
Investigations
Imaging:
- Whole Spine X-ray (PA and Lateral): Measure Cobb, Kyphosis.
- Bending Films / Traction Films: Assess flexibility.
- Mehta Angle (RVAD): Calculate on apical vertebra.
MRI (Whole Spine):
- Mandatory for all patients.
- Look for: Chiari Malformation, Syrinx, Tethered Cord, Diastematomyelia, Intraspinal tumors.
Genetic Testing:
- Consider if syndromic features present (Microarray).
Management Algorithm
1. Serial Casting (Mehta/Cotrel)
- Indication: Idiopathic Infantile, Progressive, Flexible.
- Goal: Cure? (Possible if started young less than 2 years) or Delay surgery.
- Technique: Under GA, traction and derotation, plaster jacket applied. Changed every 2-3 months.
2. Bracing (TLSO)
- Indication: Juvenile cases, older children, or maintenance after casting.
- Efficacy: Less effective than casting for true infantile curves.
Surgical Techniques
Magnetically Controlled Growing Rods
Concept: Implant proximal and distal anchors (screws/hooks) spanning the deformity. Connect with a rod that has a magnetic actuator. Procedure:
- Limited exposure at top and bottom.
- Sub-muscular passage of rods.
- Lengthening: Done in clinic using an external magnet every 3 months. Pros: No repeated surgeries for lengthening. Cons: Metal artifacts on MRI. Actuator failure.
Deep Dive: Surgical Pearls
1. The Law of Diminishing Returns With traditional growing rods, every time you go in to lengthen (every 6 months), the spine gets stiffer (auto-fusion). By the time you do the final fusion, the spine may already be fused in a less-than-perfect position. MCGR helps avoid this "Law of Diminishing Returns" by avoiding open surgery.
2. Crankshaft Phenomenon If you fuse the posterior elements (or they auto-fuse) but the anterior vertebral body growth plates remain open, the spine will twist and rotate as it grows anteriorly.
- Prevention: In young children (less than 10), definitive fusion often requires Anterior and Posterior fusion to stop all growth centers.
3. Hemiepiphysiodesis For a congenital hemivertebra:
- You can fuse the convex side (epiphysiodesis). The concave side continues to grow, potentially correcting the curve over time.
- Or: Resect the hemivertebra entirely (more aggressive, better correction).
Complications
| Complication | Rate | Prevention/Management |
|---|---|---|
| Infection | High (Repeat surgeries) | Sub-muscular placement. MCGR reduces rate. |
| Rod Fracture | Common | Dual rods better than Single rods. Diameter increase. |
| Anchor Pull-out | Common | Hooks usually safer than screws in osteoporotic/small bone. |
| PJK (Proximal Kyphosis) | Common | Don't stop at the apex of kyphosis. |
| Auto-fusion | Inevitable | Delay open surgery as long as possible. |
Postoperative Care
- Bracing: Most growing rod patients wear a brace post-op to protect the anchors.
- Physio: Essential to maintain flexibility (auto-fusion prevention).
- Follow-up: Lengthening schedule (MCGR: Clinic every 3 months. TGR: Surgery every 6 months).
Outcomes/Prognosis
- Pulmonary: The main goal is survival. Early fusion (less than age 5) results in severe TIS and death. Delaying fusion until age 10-12 significantly improves pulmonary volume.
- Deformity: complete correction is rarely the goal. "Control" is the goal.
- Final Fusion: Usually performed at skeletal maturity (Age 12-14 females, 14-16 males) to lock in the correction.
Evidence Base
- Defined the Rib-Vertebral Angle Difference (RVAD)
- RVAD greater than 20 degrees predicts progression
- Early casting can cure infantile scoliosis
- Dual Growing Rods vs Single Rods
- Dual rods provide better stability and correction
- Lower rate of implant failure
- MCGR (Magnet rods) vs TGR (Traditional)
- MCGR reduces number of surgeries
- Similar complication profile (minus the planned surgeries)
- Significant psychological benefit
- Described Thoracic Insufficiency Syndrome (TIS)
- Introduced VEPTR device
- Lung volume is the priority, not the Cobb angle
- Effect of early fusion on lung function
- Fusion of greater than 4 thoracic segments before age 8 leads to diminished Pulmonary Function Tests (PFTs)
- Spine height less than 22cm is predictive of TIS
Viva Scenarios
Practice these scenarios to excel in your viva examination
The Infantile Diagnosis
"18-month-old boy. Left thoracic curve 35 degrees. Parents are worried."
This is likely Infantile Idiopathic Scoliosis (Male, Left curve). However, I must rule out red flags. **MRI is mandatory** to exclude syrinx/Chiari. I would measure the **Mehta Angle (RVAD)**. If RVAD is greater than 20 degrees, the curve is progressive. Management: **Serial Casting** (Mehta casts) under anaesthesia is the gold standard to attempt cure or delay. Bracing is less effective.
Congenital Hemivertebra
"3-year-old. L1 Hemivertebra noticed on X-ray. Fully segmented. Curve is 30 degrees."
A fully segmented hemivertebra has a high progression potential (approx 5-10 deg/year). It will not resolve. Observation is only to document progression, but early intervention is often better. Options: **Hemiepiphysiodesis** (stop growth on convex side) or **Resection** (excision of hemivertebra) with short fusion. Given the lumbar location, compensatory curves can be severe. I would lean towards resection if healthy.
The Failing Rods
"8-year-old with SMA (SMA Type 2). Has growing rods. Now has proximal hook pull-out and skin breakdown."
This is a salvage situation. Neuromuscular EOS is difficult due to poor bone quality. Infection must be ruled out (swabs/washout). If infected: Remove hardware. If aseptic: Revision usually requires extending fixation (perhaps to ribs or pelvis) or changing anchors. In SMA, the goal is often sitting balance. If the spine is stiff enough, and lungs are adequate, one might consider definitive fusion now (age 8 is borderline, but better than chronic infection).
MCQ Practice Points
Prognosis MCQ
Q: What is the most reliable predictor of progression in infantile idiopathic scoliosis? A: The Mehta Angle (Rib-Vertebral Angle Difference - RVAD). Greater than 20 degrees = Progression.
Anatomy MCQ
Q: At what age does the multiplication of alveoli (lung development) plateau? A: Age 8. (This is why fusion before age 8 is so dangerous for lung function).
Diagnosis MCQ
Q: What is the rate of neural axis abnormalities in "idiopathic" early onset scoliosis? A: 20-40%. (Hence MRI is mandatory for all).
Epidemiology MCQ
Q: What is the typical pattern of Infantile Idiopathic Scoliosis? A: Male gender, Left-sided Thoracic curve. (Opposite of Adolescent Idiopathic).
Complication MCQ
Q: What is the Crankshaft Phenomenon? A: Rotational deformity progression after posterior fusion, due to continued anterior growth.
Australian Context
- Centers: EOS is managed in major tertiary Paediatric Spine centers (e.g., SCH, RCH, QCH).
- Access: MCGR (Magnet rods) are funded in Australia but are expensive.
- Regional: Patients from regional areas require coordinated care for casting/lengthening schedules.
EARLY ONSET SCOLIOSIS
High-Yield Exam Summary
DEFINITIONS
- •Age less than 10
- •Infantile (0-3)
- •Juvenile (4-10)
- •Congenital / NM / Syndromic / Idiopathic
RED FLAGS
- •Left curve (check MRI)
- •Hairy Patch
- •Pain (Osteoid Osteoma)
- •Neuro Deficit
KEY NUMBERS
- •Mehta greater than 20 deg (Progressive)
- •RVAD less than 20 deg (Resolving)
- •Alveoli age 8
- •MRI 40% abnormal
MANAGEMENT
- •Cast (Mehta)
- •Brace (maintenance)
- •Grow (Rods/VEPTR)
- •Fuse (Final)
Deep Dive: EDP (Early Derotation Plastering)
The Mehta Technique Min Mehta revolutionized the treatment of infantile scoliosis.
- Principle: The spine grows rapidly in the first 2 years. If you can hold it straight, the growth will correct the deformity (Hueter-Volkmann law).
- Technique:
- General Anaesthesia.
- Risser Table (Traction frame).
- Derotation: Correct the rotation, not just the lateral bend. Mold over the apical rib hump.
- Window: Cut a large anterior "mushroom" window for belly breathing (infants are diaphragmatic breathers).
- Result: Can result in a permanent cure for idiopathic curves if started early.