Sleep patterns in nonambulatory boys with Duchenne muscular dystrophy

Sleep patterns and respiratory function during sleep were studied in five nonambulatory boys with Duchenne muscular dystrophy to clarify why patients with this disease awaken frequently at night. It was hypothesized that hypoxemia during sleep due to severe restrictive lung disease might cause nighttime arousals. Each boy underwent electroencephalography, electro-oculography and electromyography. Also determined were arterial oxyhemoglobin saturation, airflow from the nose and mouth, chest and abdominal excursions, and carbon dioxide tension of exhaled breaths. All five subjects had pulmonary function abnormalities consistent with severe restrictive lung disease and respiratory muscle weakness but none had evidence of respiratory failure or cor pulmonale. The boys awakened three times more frequently than age-matched published norms and experienced sleep stage shifts twice as often as normal children. Rapid-eye movement (REM) sleep as a proportion of total sleep was significantly reduced; sleep stage I was increased compared to normal values. No subject developed oxyhemoglobin desaturation during sleep. End-tidal CO2 tensions rose during sleep stages I, II and V (REM) in association with reduced chest wall excursion, suggesting transient episodes of mild hypoventilation which were not associated with arousals. Sleep fragmentation, frequent arousals and REM sleep deprivation occur in some boys with Duchenne muscular dystrophy but are not associated with significant disorders in breathing during sleep.