Chapter 89: Rhabdomyolysis

INTRODUCTION AND EPIDEMIOLOGY

Rhabdomyolysis is the destruction of skeletal muscle, caused by any mechanism that results in injury to myocytes and their membranes. Direct muscle injury and genetic and biochemical factors can predispose to rhabdomyolysis. Acute necrosis of skeletal muscle fibers and the leakage of cellular contents into the circulation result in myoglobinuria.

Several classification systems have been developed to characterize the numerous causes of rhabdomyolysis. None of these systems is universally recognized, and each has its limitations.

Table 89-1 lists commonly recognized conditions associated with rhabdomyolysis. In general, the most common causes of rhabdomyolysis in adults appear to be alcohol and drugs of abuse, followed by medications, muscle diseases, trauma, neuroleptic malignant syndrome, seizures, immobility, infection, strenuous physical activity, and heat-related illness.^1,2 A host of drugs and toxins have been identified that are associated with or causative of rhabdomyolysis.³ Multiple causes are present in more than half of patients.¹ In children, rhabdomyolysis is less common and is thought to be more benign.³ In one study of children, the most common causes of nonrecurrent rhabdomyolysis were trauma, viral myositis, and connective tissue disease.⁴ For adults and children, inherited metabolic disorders should be suspected with recurrent episodes of rhabdomyolysis, especially if associated with exercise intolerance.

Patients in coma are at risk for rhabdomyolysis from unrelieved pressure on gravity-dependent body parts. Alcohol consumption can result in rhabdomyolysis secondary to coma-induced muscle compression and a direct toxic effect. Nutritional compromise, hypokalemia, hypomagnesemia, and hypophosphatemia, all common in alcoholics, increase the risk of rhabdomyolysis. Alcohol and drugs are thought to play a role in most cases of rhabdomyolysis in adults.¹ Drugs of abuse are commonly implicated in acute rhabdomyolysis, and many commonly prescribed medications have been associated as well.² Statin-related myopathies include myalgias with or without elevation of creatine kinase ...