What is the most likely etiology of a 17-year-old girl's mild spinal curvature, given her medical history of asthma managed with budesonide (corticosteroid) and albuterol (bronchodilator) via inhaler, family history of cerebral palsy, and active lifestyle?

Etiology of Spinal Curvature in This Patient

The most likely etiology of this 17-year-old girl's mild spinal curvature is idiopathic, specifically adolescent idiopathic scoliosis (AIS). 1, 2

Clinical Reasoning

This patient's presentation is classic for adolescent idiopathic scoliosis based on several key factors:

• Age and demographics: She is 17 years old, which falls squarely within the typical age range for AIS (10-18 years), and AIS represents the most frequent spinal deformity in this age group 3, 4

• Incidental discovery: The curvature was found incidentally on chest x-ray, which is consistent with mild scoliosis that typically produces no symptoms and is often discovered during routine examinations 4

• Active lifestyle: She plays tennis competitively, indicating no functional impairment, which is typical for mild curves that have not progressed to severe deformity 4

• Absence of red flags: There are no neurological symptoms, no history of trauma, no signs of neuromuscular disease affecting her directly, and no congenital abnormalities mentioned 5, 2

Why Other Etiologies Are Unlikely

Neuromuscular causes are excluded because:

• Her brother's cerebral palsy is not relevant to her condition—neuromuscular scoliosis requires the patient themselves to have a neuromuscular disorder (cerebral palsy, muscular dystrophy, spinal muscular atrophy) 5
• She has normal motor function and plays competitive sports 4

Congenital scoliosis is ruled out because:

• Congenital scoliosis results from vertebral malformations present at birth and typically presents earlier in childhood 1, 2
• It would have been evident on the chest x-ray as structural vertebral anomalies 2

Degenerative causes are inappropriate for this age group:

• Degenerative scoliosis occurs in adults, typically over age 50, due to disc degeneration and facet joint arthritis 5

Traumatic etiology is excluded by:

• No history of spinal trauma mentioned 5
• Active participation in sports without limitation 4

Important Consideration Regarding Budesonide Use

While this patient uses inhaled corticosteroids (budesonide) for asthma management, low-to-medium dose ICS at guideline-recommended doses show no clinically significant effects on bone mineral density or skeletal development that would cause scoliosis 5, 6. The evidence demonstrates that:

• Budesonide at therapeutic doses does not cause structural spinal deformities 5, 7
• Any growth velocity effects are small, nonprogressive, and reversible, not associated with scoliosis development 5
• ICS effects are fundamentally different from oral corticosteroids and do not cause the skeletal complications seen with systemic steroids 6

Next Steps in Management

For this patient with mild curvature discovered incidentally:

• Obtain standing PA and lateral spine radiographs to measure the Cobb angle and assess skeletal maturity using the Risser index 1, 2

• If curve is <20 degrees: Observation with clinical examination every 6-12 months is appropriate, as curves under 20 degrees have less than 30% risk of progression 1, 2

• If curve is 20-25 degrees: Monitor more closely (every 6 months) given her likely near-skeletal maturity at age 17, though progression risk decreases significantly as she approaches Risser stage 5 1, 3

• Assess skeletal maturity: At age 17, she is likely Risser stage 4-5, meaning skeletal maturity is near or achieved, which dramatically reduces progression risk 1, 2