Patients with neuromuscular disorders or high spinal cord disease are at risk of development of serious sleep-breathing disorders. In particular, patients with weakness or paresis of the diaphragm have the highest risk of respiratory compromise during REM sleep, a stage in which the only functional respiratory muscle is the diaphragm. Fortunately, most patients will respond favorably to application of positive airway pressure, but the diagnosis of respiratory compromise during sleep needs to be ascertained. Noninvasive ventilation has improved the quality of life and increased survival in many forms of neuromuscular disorders. Patients with symptomatic neuromuscular disorders or high spinal cord disease should be considered candidates for evaluation with polysomnography.
| || |
• Patients who have neuromuscular disorders are at high risk for development of sleep-related respiratory disorders and respiratory failure.
| || |
• The single most important laboratory test in patients with hypersomnolence and nocturnal sleep disturbances is polysomnographic recording. Capnography monitoring should be used.
| || |
• Patients with chronic neuromuscular disease should be routinely assessed for sleep-disordered breathing and sleep complaints because these are treatable complications in an otherwise progressive disease process.
Historical note and terminology
Clinicians and investigators began to be aware of sleep disorders and sleep-related respiratory compromise in patients with neuromuscular diseases after Sarnoff and colleagues directed attention to hypoventilation in poliomyelitis patients and after Benaim and Worster-Drought described alveolar hypoventilation in myotonic dystrophy (76; 08). Similarly, since the description of “Ondine's curse” in brainstem and high cervical cord lesions (79), the role of spinal cord dysfunction in the genesis of sleep disturbances secondary to respiratory dysrhythmias has become apparent. Since the advent of clinical polysomnography, sleep-disordered breathing has been quantified, and the beneficial effects of noninvasive positive breathing treatments have been observed in patients with neuromuscular and spinal cord disorders. Other sleep alterations, such as periodic limb movement disorders in patients with spinal cord disease, have also been uncovered with the widespread use of polysomnography. Culebras and colleagues reported abundant inclusion bodies within the cytoplasm of thalamic neurons in 6 patients with myotonic dystrophy, 4 of whom had mental defect (26). The authors hypothesized that cytoplasmic bodies represented a structural alteration of thalamic neurons likely related to progressive dementia, behavioral changes, slow dominant posterior EEG rhythms, and hypersomnia, thus suggesting a central form of hypersomnia.
Sleep-related abnormalities due to neuromuscular and chest wall disorders are now classified in the International Classification of Sleep Disorders under “Sleep-related hypoventilation/hypoxemia due to medical conditions” in the large category of Sleep Related Breathing Disorders (02).