Claudication is derived from the Latin word for “limping, lame”; strictly speaking, the term should be used only for symptoms in the lower extremities. The pain is a deep-seated ache usually in the calf muscle, which gradually progresses until the patient is compelled to stop walking. Patients occasionally describe “cramping” or “tiredness” in the muscle. Typically, symptoms are relieved after 5 minutes of inactivity. Claudication is distinguished from other types of pain in the extremities in that some exertion is always required before it appears; it is reproducible; it does not occur at rest; and it is relieved by cessation of walking. Relief of symptoms is not dependent upon sitting or other positional change. The distance a patient can walk varies with the rate of walking, the level of incline, and the degree of arterial obstruction. The average patient with involvement of a single arterial segment can walk 90–180 meters on a level terrain at a moderate pace before pain appears. The presence of additional lesions may reduce the walking tolerance to a few meters. The degree of claudication is traditionally expressed in terms of city blocks, a poorly defined and variable unit that should be defined to clarify walking distance.
Regardless of which arterial segment is involved, claudication involves the calf muscles due to their high workload with normal walking. Gluteal pain is added by lesions in or proximal to the hypogastric arteries; impotence often accompanies these symptoms. Occasionally, patients describe transient numbness of the extremity accompanying the pain and fatigue of claudication as nerves become ischemic as well as muscles.
The two conditions that most often mimic claudication are osteoarthritis of the hip or knee, and spinal stenosis. Osteoarthritis can be differentiated from claudication because pain occurs predominantly in joints; the amount of exercise required to elicit symptoms varies. Neurospinal compression symptoms are produced by impinging on the spinal canal or nerve root; therefore, standing as well as walking causes symptoms, and symptoms may occur while sitting. Neurospinal pain may follow a dermatomal distribution, which can be identified.
There are uncommon conditions that can mimic symptoms of arterial insufficiency such as coarctation of the aorta, chronic compartment syndrome, popliteal artery entrapment, and vasculitis, although age at presentation and associated findings may aid in diagnosing these unusual conditions.
The correct diagnosis should be easily established by determining the location of pain (calf), the quality of the pain, the length of time required for relief of symptoms, the reproducibility of symptoms, the distance walked before symptoms begin, and the type of rest or position required for symptom relief.
Ischemic Rest Pain
It appears at bed rest (hence the name) and may prevent sleep. Because gravity aids the delivery of arterial blood, classically, the patient with rest pain can obtain relief by simply hanging the leg over the side of the bed. This simple maneuver will not relieve pain caused by peripheral neuropathy, the most common cause of foot pain at rest. If the foot is constantly kept dependent to relieve pain, the leg and foot may be swollen, causing some confusion in diagnosis. Ischemic neuritis pain is resistant to opioids for relief.
Rest pain may be preceded by claudication but may occur de novo in diabetics with distal tibial disease, embolic occlusion of the distal tibial arteries, and patients whose walking is limited by other conditions (eg, angina pectoris). Differentiating ischemic rest pain from neuropathy in diabetics may be difficult and require vascular testing.
Nonhealing Wounds or Ulcers
Patients with severe lower extremity arterial insufficiency often develop ulcers or wounds on the feet even from seemingly trivial trauma. These lesions are most commonly located on the distal foot and toes, but on occasion they can be in the upper foot and ankle. Typically, the wounds are excruciatingly painful, deep, and devoid of any evidence of healing such as contraction or formation of granulation tissue. Frank gangrene eventually affects these ulcerations.
Inability to attain or maintain an erection may be produced by lesions that obstruct blood flow through both hypogastric arteries, and is commonly found in association with narrowing of the terminal aorta or common iliac arteries. Vasculogenic erectile dysfunction is less common than that due to most other causes.
Although the patient may report numbness in the extremity, sensory abnormalities are generally absent on examination. If decreased sensation is found in the foot, peripheral neuropathy should be suspected.