Compartment syndrome involves the compression of nerves and blood vessels within an enclosed space. This leads to impaired blood flow and muscle and nerve damage.
Thick layers of tissue called fascia separate groups of muscles in the arms and legs from each other. Inside each layer of fascia is a confined space, called a compartment, that includes the muscle tissue, nerves, and blood vessels. (They are surrounded by the fascia much like wires surrounded by insulation.)
Unlike a balloon, fascia do not expand, so any swelling in a compartment will lead to increasing pressure in that compartment, which will compress the muscles, blood vessels, and nerves. If this pressure is high enough, blood flow to the compartment will be blocked, which can lead to permanent injury to the muscle and nerves. If the pressure lasts long enough, the limb may die and need to be amputated.
Swelling leading to compartment syndrome is associated with high-energy trauma, such as from a car accident or crush injury, or surgery. Compartment syndrome may also occur due to tight bandages or casts; with significant swelling, pressure will build up and can cause compartment syndrome. Chronic compartment syndrome can be caused by repetitive activities like running that increase the pressure in a compartment only during that activity.
Compartment syndrome is most common in the lower leg and forearm, although it can also occur in the hand, foot, thigh and upper arm.
The hallmark symptom of compartment syndrome is severe pain that does not respond to elevation or pain medication. In more advanced cases, there may be decreased sensation, weakness, and paleness of the skin.
Exams and Tests
Typically, severe pain will occur when a muscle running through a compartment is passively moved. For example, when the doctor moves the toes up and down, a patient with compartment syndrome in the foot or lower leg will experience severe pain. The skin overlying the compartment will be tensely swollen and shiny. There will also be pain when the compartment is squeezed.
The test that will absolutely diagnose this condition involves directly measuring the pressure in the compartment by inserting a needle attached to a pressure meter into the compartment. When the compartment pressure is greater than 45 mmHg or when the pressure is within 30 mmHg of the diastolic blood pressure (the lower number of the blood pressure), then the diagnosis is made. When chronic compartment syndrome is suspected, this test must be performed immediately after the activity that causes pain.
Treatment for both acute and chronic compartment syndrome is usually surgery. Long incisions are made in the fascia to release the pressure building inside. The wounds are generally left open (covered with a sterile dressing) and closed during a second surgery, usually 48-72 hours later. Skin grafts may be required to close the wound.
If a cast or bandage is causing the problem, the dressing should be loosened or cut down to relieve the pressure.
If the diagnosis of compartment syndrome is made promptly and surgical release performed, the outlook is excellent for recovery of the muscles and nerves inside the compartment. However, the overall prognosis will be determined by the injury leading to the syndrome.
If there is a delay in diagnosis, there can be permanent nerve injury and loss of muscle function. This is more common when injured person is unconscious or heavily sedated and incapable of complaining. Permanent nerve injury can occur after 12-24 hours of compression.
Complications include permanent injury to nerves and muscles that can dramatically impair function. (See Volkmann's ischemia.)
In more severe cases, limbs may need to be amputated because all the muscles in the compartment have died from lack of oxygen.
When to Contact a Medical Professional
If you have suffered an injury and have severe swelling and/or pain that does not improve with pain medications, contact your health care provider to be evaluated for compartment syndrome.
While there is probably no way to prevent compartment syndrome, being very aware of this condition and early diagnosis and treatment will help to prevent many of the complications. People placed in casts need to be made aware of the risk of swelling and need to see their health care provider or go to the emergency room if they have increasing pain under the cast despite elevation and pain medicine.
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