Neurological manifestation of vasculitis: update on immunopathogenic mechanisms and clinical features.

Study of the vasculitides illustrates a spectrum of interactions from physiological to pathological between the immune system and the blood-vessel wall. Endothelial cells demonstrably recruit leukocytes by both antigen-specific and antigen-nonspecific mechanisms in the systemic vasculitides. A cascade of cytokine and factors can initiate, perpetuate, and regulate the close interactions of leukocytes and the endothelium. Specific types of leukocytes (neutrophils, T lymphocytes, eosinophils) predominate in the vascular infiltrates of specific diseases. Other mural cells potentially initiate the inflammatory process; this may be particularly important in the central nervous system where regulatory systems may diminish a primary role of the endothelium in vascular inflammation. Neurological abnormalities are a prominent feature of some vasculitides and rare in others. In polyarteritis nodosa, Wegener's granulomatosis, and lymphomatoid granulomatosis neurological features may be prominent and early. The cutaneous vasculitides, hypersensitivity vasculitis, are seldom associated with neurological abnormalities. Isolated angiitis of the central nervous system is notable because it invariably targets the central nervous system and because it must be distinguished from other causes of central nervous system vasculitis, including infections and toxins. In this article we review some of the recent information adding to our knowledge of the immunopathogenic and clinical features in the vasculitides affecting the nervous system.