Compartment syndrome of the upper arm.

The physical signs of a compartment syndrome of the upper arm are swelling and tenderness, possibly accompanied by functional impairment of all the nerves of the brachial plexus. The most common cause is exposure of the upper limb over a prolonged period to compression by the body-weight against a solid underground. The resulting tissue lesion leads to rhabdomyolysis. Laboratory investigations show an orthotolidin-positive urine reaction (Hemastix), pigmented granular casts in the urinary sediment, together with a markedly elevated level of serum creatine phosphokinase (CPK). The treatment of choice consists of immediate open fasciotomy. The history is given of two patients, in whom a prolonged period of recumbency due to coma caused the development of an upper-arm compartment syndrome. An explanation is offered to account for the rarity of this phenomenon compared to the more frequently encountered compartment syndrome of the lower leg.