The importance of alcohol-induced muscle disease

Alcohol-induced muscle disease (AIMD) is a composite term to describe any muscle pathology (molecular, biochemical, structural or physiological) resulting from either acute or chronic alcohol ingestion or a combination thereof. The chronic form of AIMD is arguably the most prevalent skeletal muscle disorder in the Western Hemisphere affecting more than 2000 subjects per 100,000 population and is thus much more common than hereditary disorders such as Becker or Duchenne muscular dystrophy. Paradoxically, most texts on skeletal myopathies or scientific meetings covering muscle disease have generally ignored chronic alcoholic myopathy. The chronic form of AIMDs affects 40-60% of alcoholics and is more common than other alcohol-induced diseases, for example, cirrhosis (15-20% of chronic alcoholics), peripheral neuropathy (15-20%), intestinal disease (30-50%) or cardiomyopathy (15-35%). In this article, we summarise the pathological features of alcoholic muscle disease, particularly biochemical changes related to protein metabolism and some of the putative underlying mechanisms. However, the intervening steps between the exposure of muscle to ethanol and the initiation of the cascade of responses leading to muscle weakness and loss of muscle bulk remain essentially unknown. We argue that alcoholic myopathy represents: (a) a model system in which both the causal agent and the target organ is known; (b) a myopathy involving free-radical mediated pathology to the whole body which may also target skeletal muscle and (c) a reversible myopathy, unlike many hereditary muscle diseases. A clearer understanding of the mechanisms responsible for alcoholic myopathy is important since some of the underlying pathways may be common to other myopathies.