Overview of neuromuscular disorders affecting respiratory function.

A great many neuromuscular disorders affect respiratory function. This article focuses on neuropathic and myopathic disorders that weaken the diaphragm and respiratory muscles. This discussion gives a general overview and attempts to update the reader on recent pathophysiological insights and developments in therapy. Among the disorders discussed, amyotrophic lateral sclerosis, poliomyelitis, postpolio syndrome, Kennedy syndrome, and spinal muscular atrophy are motor neuron diseases. Brachial plexitis and isolated unilateral or bilateral phrenic neuropathies can also weaken the diaphragm significantly. Peripheral neuropathies affecting respiration are primarily acute disorders such as Guillain-Barré syndrome, porphyria, and critical illness neuropathy, but chronic diseases such as chronic inflammatory demyelinating polyneuropathy (CIDP) and Charcot-Marie-Tooth disease (CMT) can also cause respiratory insufficiency. Disorders of neuromuscular transmission such as Lambert-Eaton syndrome, botulism, and myasthenia gravis often affect respiration. Many muscle diseases also affect pulmonary function, including polymyositis/dermatomyositis, muscular dystrophy, hereditary channel disorders, mitochondrial encephalomyopathies, acid maltase deficiency, and congenital myopathy.