Rhabdomyolysis is the rapid breakdown (lysis) of skeletal muscle tissue (rhabdomyo) due to injury to muscle tissue. The muscle damage may be caused by physical (e.g. crush injury), chemical, or biological factors. The destruction of the muscle leads to the release of the breakdown products of damaged muscle cells into the bloodstream; some of these, such as myoglobin (a protein), are harmful to the kidney and may lead to acute kidney failure. Treatment is with intravenous fluids, and dialysis or hemofiltration if necessary.

Rhabdomyolysis and its complications are major problems in people who are injured in disasters such as earthquakes and bombing. The disease and its mechanisms were first elucidated in the Blitz of London in 1941.

Signs and symptoms

Most cases of rhabdomyolysis develop as a result of muscle injury or strain, or other external causes (such as medication or intoxication). However, the cause is not always directly evident. Pain, tenderness, weakness and edema (swelling) of the affected muscles may be present. If the swelling is very rapid (such as after being released from a collapsed building), low blood pressure and shock may be present due to depletion of fluid from the bloodstream. Other symptoms are nonspecific and result either from the consequences of the breakdown in muscle tissue, or from the condition that caused the muscle breakdown.

Swelling of the damaged muscle occasionally leads to compartment syndrome, the compression by swollen muscle of surrounding tissues in the same fascial compartment (such as nerves and blood vessels), leading to damage or loss of function in the part of the body supplied by these structures. Symptoms of this complication include decreased blood supply, decrease in sensation, or pain in the affected limb.

Release of the components of muscle tissue into the bloodstream leads to disturbances in electrolytes, causing nausea, vomiting, confusion, coma and cardiac arrhythmias (abnormal heart rate and rhythm). Furthermore, damage to the kidneys may lead to dark (tea-colored) urine or a marked decrease (oliguria) or absence (anuria) of urine production, usually about 12–24 hours after the initial muscle damage. Finally, disruptions in blood clotting may lead to the development of a state called disseminated intravascular coagulation.

Causes

Physical causes

Recognized physical causes for rhabdomyolysis are:

• Traumatic compression of muscles: crush syndrome (e.g. in earthquakes), car accident, confinement in a fixed position (e.g. after a stroke, due to drunkenness or in prolonged surgery), physical torture or abuse
• Obstruction of blood supply to muscles: arterial thrombosis (blood clots forming locally) or embolism (clots or other debris from elsewhere in the body), clamping of an artery during surgery, generally reduced blood supply in shock or sepsis (due to any cause)
• Excessive muscle strain or activity: extreme physical exercise (particularly when poorly hydrated), delirium tremens (alcohol withdrawal), tetanus, prolonged seizures or status epilepticus
• Electrical: lightning, high-voltage electric shock, including electroshock weapon injuries