Sleep abnormalities associated with neuromuscular disease: pathophysiology and evaluation

The development of respiratory failure is common in patients with neuromuscular disorders that involve the respiratory muscles. However, the high incidence of sleep-related breathing problems in this population is less well known. In patients with neuromuscular disease, nocturnal breathing abnormalities frequently precede respiratory failure during wakefulness by months or even years. These nocturnal breathing problems are caused by multiple factors, including diaphragm and upper airway muscle weakness, scoliosis, obesity, and central respiratory control problems. Advances in the understanding of the links between sleep-disordered breathing and the development of daytime dysfunction and respiratory failure has revolutionized the management of these individuals. Mask positive pressure therapy is now available to improve both quality of life and longevity for these individuals. The lack of correlation between daytime testing and the severity of nocturnal breathing abnormalities makes it difficult to predict the presence of sleep-disordered breathing. Further, patients may not always be aware of symptoms associated with sleep-disordered breathing, even if specifically questioned. However, simple bedside measurements of vital capacity and inspiratory muscle strength can provide useful guides for when nocturnal respiratory monitoring is indicated.