What does mild levocurvature (abnormal curvature of the spine to the left) on X-ray indicate?

Mild Levocurvature on X-ray: Clinical Significance and Management

Mild levocurvature (leftward spinal curvature) on X-ray is a red flag that requires immediate orthopedic referral and MRI evaluation, as left thoracic curves are atypical for idiopathic scoliosis and may indicate underlying neural axis abnormalities. 1, 2

Understanding the Clinical Significance

Levocurvature refers to a leftward (convex to the left) spinal curvature, which is the opposite of the typical rightward thoracic curve seen in most idiopathic scoliosis cases. 1 The term "mild" typically indicates a Cobb angle between 10-20 degrees, which is the threshold for diagnosing scoliosis. 3

Why Left Thoracic Curves Are Concerning

• Left thoracic curves are atypical patterns that suggest potential neural abnormalities rather than typical idiopathic scoliosis. 1, 2
• Up to 2-4% of adolescent idiopathic scoliosis patients have neural axis abnormalities including Chiari I malformation, cord syrinx, cord tethering, or intraspinal tumors. 1
• Left thoracic curve pattern is one of the established risk factors requiring MRI evaluation before any treatment decisions. 4, 5

Immediate Action Required

Do not adopt a "watch and wait" approach with left thoracic curves—immediate specialist referral is warranted. 2

Mandatory Workup Steps

1. Refer immediately to orthopedic specialist for evaluation of this atypical curve pattern. 2
2. Obtain MRI of the complete spine without IV contrast to rule out neural axis abnormalities before making any treatment decisions. 4, 5
3. Perform thorough neurological examination looking for focal deficits, though normal exam does not exclude intraspinal pathology. 1

Additional Red Flags to Assess

Beyond the left thoracic curve itself, evaluate for these concerning features that further increase suspicion for secondary causes: 1, 2

• Rapid curve progression (>1 degree per month)
• Short segment curve (involving only 4-6 vertebral levels)
• Absence of apical segment lordosis (hyperkyphosis at curve apex)
• Male gender (idiopathic scoliosis with large curves is 10:1 female predominant)
• Functionally disruptive pain
• Cutaneous stigmata (hemangioma, hairy patches, nevi suggesting spinal dysraphism)

Management Algorithm Based on Curve Magnitude

If Cobb Angle <20 Degrees (Truly Mild)

• Complete MRI evaluation first to exclude neural pathology. 4, 5
• If MRI is normal and curve <20 degrees in skeletally immature patient, progression risk is <30%. 4
• Monitor with repeat radiographs every 12 months for Risser stages 0-3, or every 18 months for Risser stages 4-5. 4, 2

If Cobb Angle 20-26 Degrees

• Refer for bracing consideration after neural axis abnormalities are excluded. 2
• Progression likelihood exceeds 70% in skeletally immature individuals with curves >20 degrees. 4, 5

If Cobb Angle >26 Degrees

• Bracing and specialist management required. 2
• Surgical consultation if curve approaches 40-50 degrees, particularly with remaining growth potential. 2, 5

Common Pitfalls to Avoid

Never assume a normal neurological examination rules out intraspinal abnormalities—physical exam accuracy is only 62% for detecting these lesions. 4 The most consistent mistake is treating left thoracic curves as typical idiopathic scoliosis without obtaining MRI. 1, 2

Do not delay imaging while "watching" a left thoracic curve progress, as curves can advance silently during growth periods, and underlying neural pathology may worsen. 2

Distinguishing from Normal Variation

While mild spinal curvatures (3-10 degrees) are observed in up to 51% of young adults and may represent normal variation, 6 a left thoracic curve pattern is not part of normal variation and requires investigation regardless of magnitude. 1, 2 The leftward direction itself is the concerning feature, not just the degree of curvature.

Skeletal Maturity Considerations

• Skeletally immature patients require more aggressive monitoring as progression risk is highest during rapid growth periods. 3, 7
• Assess skeletal maturity using Risser grading (iliac apophysis ossification) and Tanner staging (pubertal development). 7
• Even after skeletal maturity, thoracic curves >50 degrees may progress at approximately 1 degree per year. 4, 5