The systemic vasculitides are a spectrum of diseases with the shared features of vascular inflammation, vascular necrosis, and varying degrees of target organ ischemia. The clinical manifestations of these disorders are highly varied and depend on the nature, intensity, and distribution of the inflammatory process. The vasculitides are classified broadly as primary or secondary. The primary vasculitides are those unassociated with systemic diseases, and in only rare instances have been associated with specific etiologic agents (eg, hepatitis B and C, a specific drug). The pathogenesis of most of these disorders is not well understood but is generally believed to be immunologically mediated. Successful therapy of the systemic vasculitides represents a balance between opposing forces, namely, suppressing the undesired inflammatory response while sparing the host complications of immunosuppression and drug toxicity (Figure 1).

Regardless of the vasculitic syndrome involved or its specific drug therapy, a series of therapeutic principles belie a successful clinical outcome. First and foremost is the prerequisite of an accurate diagnosis. Obstacles to prompt and accurate diagnosis include the general lack of highly sensitive and specific noninvasive diagnostic tests and the low specificity and test efficiency of invasive studies such as biopsy and angiography. Numerous conditions including systemic infections, malignancies, infiltrative and inflammatory disease states, and noninflammatory vascular diseases such as thrombosis, emboli, and spasm, may mimic vasculitis.

A second principle of therapy is the urgency of diagnosis. Acute and possibly irreversible renal failure, respiratory failure, bowel infarction, stroke, and other complications of ischemia are all possible consequences of a delay in diagnosis. Third, successful treatment of vasculitis requires an accurate determination of disease activity. Certain disorders are associated with highly efficient surrogate markers of disease activity such as the erythrocyte sedimentation rate (ESR) in giant cell arteritis, whereas in other diseases, similar markers are less reliable (i.e., Takayasu arteritis). Unfortunately, in the treatment of neurologic complications of vasculitis, end-organ damage of brain and peripheral nerves are slow to clinically improve even when the vasculitic response is totally suppressed. Recognition of these limitations may help avoid confusion of irreversible target organ damage with treatment-resistant disease activity.

This review first focuses on the therapeutic modalities employed for systemic vasculitis, highlighting principles of their usage as well as mechanisms of action and toxicities. Additionally, the major vasculitic syndromes are briefly discussed, outlining unique principles of therapy, with particular emphasis on neurologic complications. Finally, a number of general principles important in the chronic treatment of vasculitis are discussed.