The value of respiratory muscle testing in a child with congenital muscular dystrophy

Area of Science:

• Neurology
• Pulmonology
• Genetics

Background:

• Noninvasive respiratory muscle tests like vital capacity are standard but may miss specific muscle dysfunctions.
• Congenital muscular dystrophies (CMDs) can present with complex phenotypes affecting respiratory function.
• Early and accurate diagnosis of respiratory compromise is vital for managing neuromuscular disorders.

Observation:

• A 12-year-old boy with suspected CMD exhibited preserved expiratory muscle strength but impaired diaphragmatic function.
• Clinical features included diffuse muscle atrophy, finger hyperlaxity, and proximal contractures.
• Invasive, non-volitional testing was key to identifying the diaphragmatic dysfunction.

Findings:

• The patient was diagnosed with Ullrich CMD due to the specific respiratory findings and clinical phenotype.
• Fibroblast analysis showed intracellular collagen 6 (COL6) retention, and MRI confirmed COL6 myopathy.
• Genetic testing identified a COL6A2 gene mutation (c.954+2T>C).

Implications:

• Diaphragmatic dysfunction diagnosis led to a sleep study revealing hypoxemia, necessitating nocturnal noninvasive ventilation.
• This case underscores the importance of invasive respiratory muscle assessment for accurate CMD diagnosis.
• Targeted respiratory management based on invasive testing significantly improved clinical care and patient outcomes.