Intermittent claudication is a predictable pattern of lower leg pain caused by inadequate blood flow to exercising muscle.
The pain of intermittent claudication has three characteristics:
- It is a cramping pain in the calves that is brought on by exertion
- It is relieved by rest
- It is reproducible; that is, it almost always occurs after having walked the same distance, for example. (However, the pain may occur earlier if walking uphill or more quickly.)
Intermittent claudication is caused by arterial insufficiency (inadequate blood supply), primarily due to atherosclerosis. Atherosclerosis is a condition that involves fatty build-up and narrowing of the arteries, which thus occludes or limits blood flow through them; the narrowed areas may be localized or extensive. Cigarette smoking is the most important risk factor for vascular disease bar none. Others include high blood pressure, high cholesterol, diabetes mellitus and a family history of atherosclerosis.
Pain brought on by walking is less serious than pain taking place during sleep or while at rest; these are indications of disease progression, and warrant more aggressive therapy. Patients with these symptoms are classified as “pre-gangrenous”, meaning that deterioration could lead to gangrene, a condition where so little blood reaches the affected tissue that damage is irreversible and tissue death results, requiring amputation. This occurs in 5% of untreated atherosclerotic patients within 5 years.
Inadequate blood flow to the lower extremities may result in deformed toenails, hair loss, skin thinning, and ulcers or infections on the feet or ankles. Small cuts and wounds on the lower legs may heal very slowly; thus foot care is an important part of treatment.
Pain in the lower legs can be caused by arthritis of the spine, herniated vertebral disk, and other diseases of the spine which can pinch the nerves that supply the legs. Muscle cramps can also cause leg pain, but do not exhibit the same three characteristics listed above.
Conventional medicine uses Doppler studies (a specialized ultrasound test) and transcutaneous oxygen pressure measurements to evaluate blood flow. Angiography may be performed to determine the best treatment; this is a method used to visualize the blood vessels using dye injection and X-ray. This test shows the extent of vessel narrowing.
Conservative treatment is indicated in patients who experience symptoms only upon exertion. In these cases, stopping smoking is critical. Blood pressure, lipids and blood sugar (in diabetics) should be lowered and monitored closely. “Blood thinning” drugs (anti-platelet drugs) have not proven helpful in this group of patients, but exercise has.