What are the clinical features of rhabdomyolysis?
The clinical features of rhabdomyolysis are variable depending on the underlying cause and extent of the muscle injury.
Patients usually complain of myalgias and may have associated muscle weakness.
Blood pressure in rhabdomyolysis is usually maintained secondary to vasoconstriction, in part because of the sequestration of nitric oxide by free myoglobin.
Affected muscles may be tender, sometimes with marked stiffness and swelling.
The large muscles of the leg and lower back are most commonly involved. Sometimes muscle swelling within a myofascial compartment may compress blood vessels, limiting local blood supply, leading to further muscle ischemia.
This is known as compartment syndrome and requires urgent surgical intervention (fasciotomy) to prevent ongoing ischemic muscle damage.
The measurement of intramuscular pressures can be used to help guide decisions regarding the need for surgical intervention.
Note that less severe rhabdomyolysis may be asymptomatic and may be detected only on routine laboratory testing.