Low bone mineral density in spinal muscular atrophy

Area of Science:

• Pediatric Endocrinology
• Neuromuscular Disorders
• Bone Metabolism

Background:

• Pathological fractures are frequent complications in pediatric neuromuscular disorders.
• Dual-energy x-ray absorptiometry (DXA) is the standard for bone mineral density (BMD) measurement in pediatric populations.
• Limited data exist on BMD in pediatric neuromuscular diseases, excluding Duchenne muscular dystrophy.

Purpose of the Study:

• To evaluate bone mineral density (BMD) in children with various neuromuscular disorders.
• To compare BMD across different pediatric neuromuscular conditions.
• To identify specific neuromuscular diseases associated with lower BMD.

Main Methods:

• Retrospective analysis of 84 DXA scans from 79 pediatric patients (4 months–18 years) over 23 months.
• BMD measurements focused on the L1-4 spine region.
• Osteopenia classification based on Z-scores: mild (0 to -1.5), moderate (-1.5 to -2.5), and severe (> -2.5).

Main Results:

• Spinal muscular atrophy (SMA) patients showed the lowest mean BMD (Z-score: -2.25 ± 0.31).
• Duchenne muscular dystrophy patients had a mean BMD Z-score of -1.72 ± 0.1.
• Nonambulatory SMA patients exhibited significantly lower BMD compared to ambulatory SMA patients (P < 0.05).

Conclusions:

• Osteopenia is prevalent in children diagnosed with neuromuscular disorders.
• Patients with spinal muscular atrophy (SMA) demonstrate the lowest bone mineral density among the studied groups.
• These findings underscore the importance of BMD monitoring in pediatric neuromuscular care.