Clinical features of rhabdomyolysis

Rhabdomyolysis is a complication of poisoning that occurs in patients with an altered conscious state, hyperthermia or, less commonly, as a direct effect of a toxin (eg myotoxicity due to some snake venoms). More commonly sustained pressure on muscle compartments can lead to breakdown and necrosis of skeletal muscle. Muscle necrosis causes leakage of intracellular elements (eg myoglobin) into the circulation and can lead to kidney injury.

Rhabdomyolysis is characterised by myoglobinuria, muscle pain and tenderness, muscle swelling and loss of function. Other complications of rhabdomyolysis include potentially life-threatening hyperkalaemia and hypocalcaemia, which are often transient.

In patients with rhabdomyolysis, compartment syndrome can occur due to injury of discrete muscle groups, especially in weight-bearing areas such as the deltoid and gluteal muscles. Following the primary injury, pressure increases within a muscular compartment, leading to further muscle necrosis. A high index of suspicion is needed to diagnose compartment syndrome in patients with confirmed rhabdomyolysis.