Neurological complications of vasculitis.

The vasculitides are a group of disorders that include the polyarteritis nodosa group of systemic necrotizing vasculitides, hypersensitivity vasculitis, Wegener's granulomatosis, lymphomatoid granulomatosis, giant cell arteritis, Behçet's disease, and isolated angiitis of the central nervous system. Classification is based on clinical, angiographic, and histological features. The frequency and distribution of neurological involvement vary with the underlying disorder and may provide the initial symptoms. Polyarteritis nodosa and Wegener's granulomatosis may affect both the central and peripheral nervous systems, whereas isolated angiitis of the central nervous system and Behçet's disease affect the central nervous system alone. Neurological dysfunction occurs in 80% of patients with polyarteritis nodosa and fewer than 10% of patients with hypersensitivity vasculitis. The mechanism of neurological dysfunction in the vasculitides is tissue ischemia. The clinical effects of ischemia vary, and symptoms may be transient or prolonged. Mononeuritis multiplex, polyneuropathy, and stroke are frequent complications, but encephalopathies, cranial neuropathies, and brachial plexopathies are seen as well. The occurrence of symptoms late in the course of a disease suggests ischemia resulting from healed, scarred vessels as well as from those that are acutely inflamed; this is the case in Takayasu's arteritis and possibly also in polyarteritis nodosa. Treatment is based on identifying and removing the sensitizing agent when possible. Wegener's granulomatosis requires therapy with cyclophosphamide; temporal arteritis, with corticosteroids. In other vasculitides a balance must be reached between the progression of the disease and the side effects of immunosuppression.