Compartment syndrome is increased tissue pressure within a closed fascial space, resulting in tissue ischemia. The earliest symptom is pain out of proportion to the severity of injury. Diagnosis is by measuring compartmental pressure. Treatment is fasciotomy.

Compartment syndrome is a self-perpetuating cascade of events. It begins with the tissue edema that normally occurs after injury (eg, because of soft-tissue swelling or a hematoma). If edema develops within a closed fascial compartment, typically in the anterior or posterior compartments of the leg, there is little room for tissue expansion, so interstitial (compartmental) pressure increases. As compartmental pressure exceeds about 20 mm Hg, cellular perfusion slows and may ultimately stop. (NOTE: Because 20 mm Hg is much lower than arterial pressure, cellular perfusion can stop long before pulses disappear.) Resultant tissue ischemia further worsens edema in a vicious circle. As ischemia progresses, muscles necrose, sometimes leading to rhabdomyolysis and infections; these complications can cause loss of limb and, if untreated, death. If arteries are injured, arterial pressure can drop below even mildly elevated compartmental pressures, causing or worsening compartment syndrome.

Etiology

Common causes include fractures and severe contusions. Rare causes include snakebites, severe exertion, drug overdose (heroin, cocaine), casts, tight bandages, and other rigid circumferential devices that limit swelling and thus increase compartmental pressure. Prolonged pressure on a muscle during coma may cause rhabdomyolysis.

Symptoms and Signs

Compartment syndrome usually occurs in the anterior lower leg. The earliest symptom is worsening pain. It is typically out of proportion to the severity of the apparent injury and is exacerbated by passive stretching of the muscles within the compartment (eg, for the anterior leg compartment, by passive toe flexion, which stretches the toe extensor muscles). Pain, one of the 5 P's of tissue ischemia, is followed by the other 4: paresthesias, paralysis, pallor, and pulselessness. Compartments may feel tense when palpated.

Diagnosis

• Measurement of compartmental pressure

Diagnosis must be made and treatment started before pallor or pulselessness develop, indicating necrosis. Diagnosis is by measuring compartmental pressure (normal ≤ 20 mm Hg), usually with a commercially available wick catheter.

Treatment

• Often fasciotomy

Pressures of 20 to 40 mm Hg can sometimes be treated conservatively with analgesics, elevation, and splinting; casts, if present, are removed or bivalved. Pressures > 40 mm Hg usually require immediate fasciotomy to relieve pressure. If necrosis occurs, amputation may be needed.

Last full review/revision October 2007 by James R. Roberts, MD