In the late non-ambulatory stage of Duchenne muscular dystrophy, which feature is most characteristic?

• A. No cardiac involvement
• B. Severe respiratory decline requiring full-time ventilation
• C. Unchanged lifespan
• D. Progressive cardiac involvement

Answer: (B)

In Duchenne muscular dystrophy, as the disease advances to the late non-ambulatory stage, weakness of the respiratory muscles becomes the dominant issue. The diaphragm and intercostal muscles weaken, leading to hypoventilation, impaired cough, nocturnal desaturation, and a higher risk of pneumonia. This progressive respiratory failure often requires ventilatory support, sometimes full-time, and it largely defines the care needs and prognosis in this stage. Cardiac involvement does occur as part of the disease, so saying there is no cardiac involvement isn’t accurate, and lifespan typically shortens with disease progression. While cardiac deterioration progresses, the feature most characteristic of the late non-ambulatory phase is the severe respiratory decline needing ventilation.