Chronic Exertional Compartment Syndrome

Chronic exertional compartment syndrome is an rare, exercise-induced compression of nerves, blood vessels, and muscle inside a closed space (compartment) within the body. This leads to tissue death from lack of oxygenation; the blood vessels being compressed by the raised pressure within the compartment. Compartment syndrome most often involves the forearm and lower leg.

Anyone can develop chronic exertional compartment syndrome, but it's more common in athletes who participate in sports that involve repetitive movements, such as running, fast walking, biking, swimming and cross-country skiing. Chronic exertional compartment syndrome is sometimes called chronic compartment syndrome or exercise-induced compartment syndrome.

Conservative treatments typically don't help with chronic exertional compartment syndrome. However, surgery is usually successful, allowing you — whether you're a recreational or serious athlete — to return to your sport.

Symptoms and signs

There are classically 5 "Ps" associated with compartment syndrome — pain out of proportion to what is expected, paresthesia, pallor, paralysis, pulselessness; sometimes a 6th P, for polar/poikilothermia (failure to thermoregulate) is added. Of these, only the first two are reliable in the diagnosis of compartment syndrome. Paresthesia, however, is a late symptom.

• Pain is often reported early and almost universally. The description is usually of severe, deep, constant, and poorly localized pain, sometimes described as out of proportion with the injury. The pain is aggravated by stretching the muscle group within the compartment and is not relieved by analgesia up to and including morphine.
• Paresthesia (altered sensation e.g. "pins & needles") in the cutaneous nerves of the affected compartment is another typical sign.
• Paralysis of the limb is usually a late finding. The compartment may also feel very tense and firm (pressure). Some find that their feet and even legs fall asleep. This is because compartment syndrome prevents adequate blood flow to the rest of the leg.
• Note that a lack of pulse rarely occurs in patients, as pressures that cause compartment syndrome are often well below arterial pressures and pulse is only affected if the relevant artery is contained within the affected compartment.
• Tense and swollen shiny skin, sometimes with obvious bruising of the skin.
• Congestion of the digits with prolonged capillary refill time.

Causes

Because the connective tissue (fascia) that defines the compartment does not stretch, swelling of the muscles within the compartment, can cause the pressure to rise greatly. 

When compartment syndrome is caused by repetitive use of the muscles, as in a cyclist, it is known as chronic compartment syndrome (CCS). This is usually not an emergency, but the loss of circulation can cause temporary or permanent damage to nearby nerves and muscles.

Pathophysiology

Any condition that results in an increase in compartment contents or reduction in a compartment’s volume can lead to the development of an acute compartment syndrome. When pressure is elevated, capillary blood flow is compromised. Edema of the soft tissue within the compartment further raises the intra-compartment pressure, which compromises venous and lymphatic drainage of the injured area. Pressure, if further increased in a reinforcing vicious circle, can compromise arteriole perfusion, leading to further tissue ischemia.

The normal mean interstitial tissue pressure is near zero in non-contracting muscle. If this pressure becomes elevated to 30 mmHg or more, small vessels in the tissue become compressed, which leads to reduced nutrient blood flow, ischemia and pain. Of particular importance is the difference between compartment pressure and diastolic blood pressure; where diastolic blood pressure exceeds compartment pressure by less than 30 mmHg it is considered an emergency.

Untreated compartment syndrome-mediated ischemia of the muscles and nerves leads to eventual irreversible damage and death of the tissues within the compartment.

Diagnosis

Compartment syndrome is a clinical diagnosis. However, it can be tested for by gauging the pressure within the muscle compartments. If the pressure is sufficiently high, a fasciotomy will be required to relieve the pressure. Various recommendations of the intracompartmental pressure are used with some sources quoting >30 mmHg as an indication for fasciotomy while others suggest a <30 mmHg difference between intracompartmental pressure and diastolic blood pressure. This latter measure may be more sensible in the light of recent advances inpermissive hypotension, which allow patients to be kept hypotensive in resuscitation. It is now relatively easy to measure compartment and subcutaneous pressures using the pressure transducer modules (with a simple intravenous catheter and needle) that are attached to most modern anaesthetic machines.

Treatment

Chronic compartment syndrome in the lower leg can be treated conservatively or surgically. Conservative treatment includes rest, anti-inflammatories, and manual decompression. Elevation of the affected limb in patients with compartment syndrome is contraindicated, as this leads to decreased vascular perfusion of the affected region. Ideally, the affected limb should be positioned at the level of the heart. The use of devices that apply external pressure to the area, such as splints, casts, and tight wound dressings, should be avoided. In cases where symptoms persist, the condition should be treated by a surgical procedure, subcutaneous fasciotomy or open fasciotomy. Left untreated, chronic compartment syndrome can develop into the acute syndrome. A possible complication of surgical intervention for chronic compartment syndrome can be chronic venous insufficiency.

Hyperbaric oxygen therapy has been suggested by case reports but not proven in controlled randomized trials to be an adjunctive therapy for crush injury, compartment syndrome, and other acute traumatic ischemias by improving wound healing and reducing repetitive surgery.

Complications

Failure to relieve the pressure can result in necrosis of tissue in that compartment, since capillary perfusion will fall leading to increasinghypoxia of those tissues. This can cause Volkmann's contracture in affected limbs.

If left untreated, acute compartment syndrome can lead to more severe conditions including rhabdomyolysis and kidney failure potentially leading to death.


Reprinted from the Wikipedia article on Compartment Syndrome.