CIM Case: Left Thoracic Scoliosis - Atypical Pattern

Clinical Scenario

Patient: 7-year-old male Presentation: Progressive left thoracic scoliosis noticed by parents over 6 months, no back pain Relevant history: Full-term delivery, normal developmental milestones, no previous spinal problems, no family history of scoliosis or neurological conditions Examination findings:

• Left thoracic scoliosis visible on forward bend test
• Left rib hump (Adams test positive)
• Subtle left-hand weakness (grip strength reduced)
• Bilateral lower limb hyperreflexia (3+)
• No clonus, upgoing plantars
• No café-au-lait spots or axillary freckling
• No midline skin abnormalities
• Cobb angle 35° on X-ray

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Investigations Provided

Laboratory Results

Imaging

Image 1: Standing PA and Lateral Whole Spine Radiographs

Radiological features:

• Left thoracic curve, Cobb angle 35° (T5-T11)
• Apex at T8
• Right thoracolumbar compensatory curve
• No congenital vertebral anomalies
• Risser 0 (no iliac apophysis ossification)
• Open triradiate cartilages
• No widened interpedicular distance

Image 2: MRI Whole Spine with Brainstem (if obtained)

MRI findings (expected investigation):

• Syringomyelia from C5 to T8
• Syrinx cavity 6mm diameter
• Chiari I malformation with 8mm tonsillar descent
• No tumour
• No tethered cord

Questions & Model Answers

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Key Teaching Points

Pattern Recognition

This pattern suggests Atypical Scoliosis with Underlying Cause:

• Left thoracic curve (90% of AIS is right thoracic)
• Male patient (AIS is predominantly female)
• Juvenile onset (<10 years)
• Neurological signs (any weakness, hyperreflexia)
• Rapid progression

Comparison - Typical vs Atypical Scoliosis:

Critical Management Points

1. MRI is MANDATORY - before any treatment decision
2. Treat the cause FIRST - Chiari decompression before scoliosis surgery
3. Syringomyelia is most common cause - found in 60% of atypical scoliosis
4. 50% of curves stabilise after decompression - wait and watch
5. Higher surgical risk - if scoliosis surgery needed
6. MDT approach essential - orthopaedic spine + neurosurgery

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Common Examiner Follow-ups

Q: "What is the natural history of an untreated syrinx with scoliosis?"

Untreated syringomyelia with scoliosis:

• Scoliosis will likely progress
• Neurological deterioration is expected
• Upper limb weakness (hands) progresses
• Sensory loss develops (cape distribution)
• Eventually affects lower limbs
• Scoliosis surgery without treating syrinx has high complication rate

Therefore, treatment of the underlying cause is essential.

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Q: "What are the indications for Chiari decompression?"

Asymptomatic incidental Chiari without syrinx can be observed.

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Q: "What if MRI shows no abnormality in this patient?"

If MRI is normal in a patient with atypical scoliosis features:

• Consider the scoliosis may still be idiopathic (some left curves are)
• Rule out other causes: neuromuscular, congenital
• Follow closely for neurological changes
• May need repeat MRI if progression unusual
• Manage as idiopathic if no cause found after thorough workup

However, in THIS patient with neurological signs (hand weakness, hyperreflexia), a normal MRI would be unusual and warrant reconsideration of the clinical findings.

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Related Topics

• Adolescent Idiopathic Scoliosis
• Chiari Malformation
• Syringomyelia
• Tethered Cord Syndrome
• Congenital Scoliosis
• Neurofibromatosis and Spine