Rhabdomyolysis is the acute destruction of striated muscle tissue. It is a serious and potentially fatal condition and is a leading cause of renal failure. It accounts for 5% to 7% of all cases of acute renal failure requiring dialysis in the United States each year. There are about 25,000 cases of rhabdomyolysis (rhabdo) reported every year in the US.
Rhabdo is both an acquired and inherited disease and occurs in patients in all age groups.
In adults, a common etiology of acquired rhabdo is related to drug use, both legal and illegal. The use of lipid lowering statins used as monotherapy is associated with a hospitalization rate of .44%. Ingestion of phenylalkyamine derivatives and large amounts of caffeine have also been reported in association with rhabdomyolysis.
The most common abuse drugs associated with the development of rhabdomyolysis are cocaine and heroine. It is estimated that 20% of cocaine overdoses are complicated by rhabdo. Other abuse drugs that can cause rhabdo are amphetamines and alcohol.
In children, the most common acquired cause of rhabdo is trauma. Other causes include strenuous exercise, non ketotic hyperosmolar coma, viral myositis, dystonia and very rarely malignant hyperthermia. It is now recognized that genetic conditions may predispose to acute muscle breakdown also.
The risk of exertional rhabdomyolysis is thought to be increased in the setting of prolonged heat exposure, sickle cell disease or trait, and the use of dietary supplements such as ephedra. The sport most associated with rhabdo is ultra-long distance running.
Acute exertional rhabdomyolysis is common in military recruits undergoing basic training and is reported in 2% to 40% of trainees in the first 5-6 days. Generally, in this group of otherwise young, healthy individuals the myoglobinuria resolves within 2 to 3 days of cessation of strenuous exercise with muscle pain resolving within one week.
Acute exertional rhabdo is also not uncommon in the prison population and in professional firefighters. Worse outcomes including renal failure requiring dialysis and death typically occur in the setting of heatstroke.
Whatever the cause, rhabdomyolysis represents a final common pathway of cell destruction with the release of the intracellular contents of striated muscle into the general circulation.
The key cellular event in the initiation of rhabdomyolysis is the opening of stretch-activated channels in the cell sarcolemma from mechanical shear forces.