What Causes Exercise-Induced Compartment Syndrome?
Exercise-induced compartment syndrome is due to a pressure build-up within the muscles of the leg. Muscles are enclosed within a tight tissue called a fascia. This fascia wraps around and contains the muscle. Normally, the fascia has enough extra room within to allow the muscle to function without problem.When activity levels are increased, blood flow to a muscle increases, and the size of the muscle increases. In most people, the fascia allows sufficient room to accommodate this increase in muscle size during exercise. However, in patients with exercise-induced compartment syndrome, the fascia is too tight, and it constricts the muscle during activity.
Why Does Muscle Constriction Cause Pain in Exercise-Induced Compartment Syndrome?
As the muscle expands and becomes constricted by the fascia, the blood flow to the muscle is interrupted. The lack of blood flow causes ischemia -- the same phenomenon as a heart-attack. When blood flow to a muscle is interrupted, pain can occur. When this occurs in the heart muscle, chest pain is the result; when it occurs in the leg, leg pain is the result.Before you begin to worry, ischemia of the heart and exercise-induced compartment syndrome are very different! The cause of these problems is different, but the end result causes a similar problem. Furthermore, relief of exercise induced compartment syndrome is usually very easy -- simply stop exertion of the muscle.
What Are the Symptoms of Exercise-Induced Compartment Syndrome?
The most common symptom is pain during with activity that is quickly relieved with rest. Patients may notice a tingling or numbness in the leg or foot due to lack of blood flow to the nerves. Often when the symptoms are present, the area over the muscles of the front of the leg feels very tight.Diagnosis is made by measuring the pressure within the muscles of the leg. Usually a pressure measurement is made at rest, and then the patient does some activity (such as a quick run) until the pain is present. A repeat measurement is then made and the pressure change is compared. Normally, the pressure difference from rest and activity is small. Patients with exercise-induced compartment syndrome will have a dramatic increase in pressure readings when the symptoms are present after exercise.
What Other Conditions Can Causes these Symptoms?
Several other conditions need to be considered. Exercise-induced compartment syndrome is uncommon, and it is much more likely that shin pain is being caused by one of the following conditions:- Medial tibial stress syndrome (shin splints)
- Stress fractures
What Is the Treatment?
A period of rest may be attempted, as well as avoiding any activities that causes the symptoms. However, if the diagnosis of exercise-induced compartment syndrome is clear, and the symptoms persist, then surgery may be needed. The surgery involves the release of the tight fascia, called a fasciotomy. An incision is made over the affected area, and then the surgeon cuts the tight tissue that surrounds the muscle. The major risk of this surgery is cutting a small nerve that provides sensation to the top of the foot. Usually the surgeon can identify the nerve and avoid it, but it is still possible to damage the nerve. Patients who sustain an injury to this nerve will have an area of permanent numbness over the top of the foot.
Sources:
Fraipont MJ and Adamson GJ "Chronic Exertional Compartment Syndrome" J. Am. Acad. Ortho. Surg., July/August 2003; 11: 268 - 276.
