Disorders of pulmonary function, sleep, and the upper airway in Charcot-Marie-Tooth disease

Charcot-Marie Tooth disease (CMT) encompasses several inherited peripheral motor-sensory neuropathies and is one of the most common inherited neuromuscular diseases. Charcot-Marie-Tooth disease can be associated with several disorders that may be encountered by the pulmonary physician, including restrictive pulmonary impairment, sleep apnea, restless legs, and vocal cord dysfunction. Restrictive pulmonary impairment has been described in association with phrenic nerve dysfunction, diaphragm dysfunction, or thoracic cage abnormalities. Central sleep apnea may be associated with diaphragm dysfunction and hypercapnia, whereas obstructive sleep apnea has been reported as possibly due to a pharyngeal neuropathy. Restless legs and periodic limb movement during sleep are found in a large proportion of patients with CMT2, a type of CMT associated with prominent axonal atrophy. Vocal cord dysfunction, possibly due to laryngeal nerve involvement, is found in association with several CMT types and can often mimic asthma. There may be special therapeutic considerations for the treatment of those conditions in individuals with CMT. For instance, bi-level positive airway pressure may be more appropriate than continuous positive airway pressure (CPAP) for the treatment of sleep apnea in the individual with concomitant restrictive pulmonary impairment. The prominence of peripheral neuropathy as a cause of the restless legs syndrome in CMT may justify treatment with neuropathic medications as opposed to the more commonly recommended dopaminergic agents. The risk of progression to bilateral vocal cord dysfunction in CMT and the risk of aspiration with laryngeal neuropathy may limit the therapeutic options available for vocal cord paralysis.