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Extremity pain can have many causes. This chapter provides a
comprehensive differential diagnosis of such pain. The reader should
consult the individual chapters dealing with particular pain syndromes
to find specific treatment options.
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Acute Arterial
Insufficiency
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The pain of acute arterial insufficiency is characterized by
its sudden onset. Emboli lodge at artery branch points, which are
also more likely to be affected by atherosclerosis. Emboli may occlude more
than one vessel at a branch point and thereby limit collateral flow.
Muscle necrosis and irreversible changes may occur if blood flow
is not reestablished within 4 to 6 hours.1
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The five cardinal features of arterial insufficiency (the five “Ps”)
consist of pain, pallor, paresthesias, paralysis, and pulselessness.
The pain is well localized to an extremity and severe. It may be attenuated
by good collateral circulation; that is, occlusion of a brachial
artery may not produce as dramatic a clinical picture as occlusion
of a common femoral artery or popliteal artery. Nerve endings and
muscle tissue are extremely sensitive to hypoxia, and acute obstruction
soon leads to anesthesia and paralysis in an affected extremity.2
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Pulses usually, but not always, are absent distal to the site
of obstruction. Therefore, pain and associated signs and symptoms
of ischemia in the presence of detectable pulses warrant further investigation.2 Conversely,
pulses may be unusually strong proximal to the site of the occlusion.
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Acute ischemia in an extremity also is accompanied by a change
in the skin temperature distal to the site of occlusion. The extremity
appears pale, and the veins may seem to be empty. Palpation along
the course of the artery may reveal tenderness over the site of
occlusion. The muscles begin to feel hard and inelastic as the ischemia
progresses.2 Muscular fatigue and weakness are
apparent.
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Chronic Arterial
Insufficiency
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Chronic arterial insufficiency can produce a wide variety of
painful symptoms. Affected patients can have numbness, coldness,
tingling, or total paresis. The degree of insufficiency determines the
type of pain in the lower extremity (intermittent claudication or
rest pain). Atherosclerosis is the most common cause of chronic
lower limb ischemia. Hypertension, diabetes mellitus, hypercholesterolemia,
and cigarette smoking increase the incidence and severity of atheroma
formation.3 Thromboangiitis obliterans (Buerger’s
disease), popliteal artery entrapment, and cystic adventitial disease
can also cause lower limb ischemia.
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Claudication refers to cramping pain that occurs when blood flow
cannot be increased to a muscle mass in response to the increased
metabolic demands of exercise. Blood flow is adequate in the extremity
at rest. Claudication has several diagnostic features: (1) it is
always relieved by rest after exercise, (2) it is produced by a
consistent amount of exercise, and (3) it is always experienced
in a functional muscle group.4
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Ischemic rest pain occurs when blood flow in ...