By late middle age 5% of men and women will have developed peripheral arterial disease and within 5 years 25% of these will develop pain at rest, ulceration, and gangrene (critical limb ischemia).1 Physicians who practice in the specialty of pain medicine need to be familiar with the causes and treatment of pain due to peripheral vascular disease because it has a high prevalence. Appropriate therapy and management can significantly improve the quality of life for patients. Pain medicine physicians, by encouraging secondary or tertiary preventive therapy, have the opportunity to improve the life expectancy of their patients with symptomatic peripheral vascular disease of whom more than 50% have disease of the coronary and/or carotid arteries. This chapter will outline the disease conditions and treatments for pain associated with peripheral vascular disease.2
The ischemic pain of peripheral vascular disease can be approximated by sustained tourniquet inflation on an extremity. In experimental studies, as time passes, tissue oxygenation levels fall, metabolic byproducts accumulate, reactive cellular agents are released, nociceptive signals entering the central nervous system (CNS) increase, and patients report increasing intensity of pain. The affective descriptors for this pain differ and are more difficult to tolerate than pain produced by other experimental modalities. Patients with peripheral vascular disease experience this type of pain without the ability to restore blood flow by releasing the tourniquet. Effective management of this pain can restore quality of life for these patients.
Arterial insufficiency is most commonly the result of occlusive diseases with atheroma formation (arteriosclerosis obliterans), but less commonly occurs in thromboangiitis obliterans (Buerger disease), Raynaud syndrome, diabetic arteritis, and arteritis associated with collagen disease. Other diseases with vascular-related causes such as migraine and cluster headache are discussed elsewhere (see Chapter 3).
ATHEROMA AND ITS CONSEQUENCES: ARTERIOSCLEROSIS
The role of lipids was suggested with the early appearance of fatty streaks in young soldiers during emergency surgery and at autopsy in the 1970s. The role of lipids distinguishes arteriosclerosis from other arterial disease. Primary and secondary prevention strategies are available to reduce the incidence and/or aggressively treat the known risk factors of hypercholesterolemia, hypertension, cigarette smoking, and poor control of diabetes. As the disease progresses, plaque formation tends to occur at bifurcations in large and medium-sized arteries where turbulence, alteration of laminar flow, and shear stress may provoke an endothelial and/or vascular smooth muscle response. Arteriosclerosis is a dynamic process that involves vascular and inflammatory tissue responses with decreased release of nitric oxide (NO) and other protective secretions, increased release of cytokines by inflammatory cells responding to exposed matrix, and release of growth factors from the endothelium, as well as platelet activation. Arteries may respond initially to this process with an increase in size, but arterial remodeling may not be sustained in the face of ongoing plaque accumulation. Although a full ...