What causes compartment syndrome?

Muscles, nerves, and blood vessels are enclosed by firm tissue called fascia. When bleeding or swelling occurs inside that limited space, pressure can increase because the fascia cannot expand easily. The rising pressure can reduce blood flow and impair nerve and muscle function.

Acute compartment syndrome may follow a fracture, crush injury, severe bruise, tight cast or dressing, or restored blood flow after a blocked vessel. Exertional compartment syndrome is a different pattern in which exercise-related swelling causes recurring pressure and pain that settles with rest.

After a significant limb injury, escalating pain should be assessed rather than treated by repeatedly tightening a support or waiting for swelling to settle. A clinician checks pain with gentle muscle stretch, sensation, movement, circulation, and the injured area. Pressure testing or urgent surgical assessment may be needed when the diagnosis is uncertain.

Go to emergency care for severe or rapidly increasing pain that seems out of proportion to the injury, a tense swollen limb, new numbness or tingling, difficulty moving the foot or hand, or skin that becomes unusually pale or cool. Do not delay for pain medicine to take effect; early review is needed when this condition is suspected.

Ask what injury or pressure source is suspected, how circulation and nerve function will be monitored, and whether a cast or dressing needs adjustment. If symptoms occur with exercise, ask how activity should be modified and what testing can distinguish exertional symptoms from an acute emergency.