Intermittent Claudication

Intermittent Claudication, is a predictable pattern of lower leg pain caused by inadequate blood flow to exercising muscle.

Causes and Development

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.

Signs and Symptoms

The pain of intermittent claudication may be dull and aching, or sharp and crampy; or it may feel like plain old muscle fatigue.  Blockages may cause pain in the thighs or buttocks.  If the blockage is lower in the legs, pain may affect the calves or feet.  Just like angina, such pain is the warning cry of oxygen-starved muscles during exertion.  If you find that the distance you can walk without pain is growing shorter, it's probable that the condition is getting worse.

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.)

Pain in the lower legs can also 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.

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.

Diagnosis and Tests

Pain brought on by walking is less serious than pain occurring 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.

In more advanced cases, the pain may also come on at rest, especially during the night.  It may be relieved by sitting up or dangling the feet over the side of the bed so gravity can bolster the blood supply.  In other cases, narrowed leg arteries produce no pain.  For example, a person who doesn't walk far enough or fast enough to bring on discomfort may remain unaware of a problem.  Someone who suffers decreased sensation in the legs or feet from a condition such as diabetes may also feel no pain.

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.

Treatment and Prevention

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.

Small cuts and wounds on the lower legs may heal very slowly; thus foot care is an important part of treatment.