Part I : Infect Ious and Inflammatory Condit Ions

Isolated angiitis of the central nervous system (CNS) is a rare condition with an incidence estimated at less than 1:2 000 000 (Moore, 1999). It was defined, in 1959, as an idiopathic vasculitis restricted to small leptomeningeal and parenchymal arteries and veins, without apparent systemic involvement (Cravioto and Feigin, 1959). Almost 50 years later, the affliction remains poorly recognized, and its pathogenesis mysterious, despite the growing pool of knowledge on processes responsible for CNS inflammation. The term “primary angiitis” is sometimes preferred to “isolated angiitis” because complete autopsies are rarely performed and minor abnormalities are occasionally observed in systemic organs of patients who died from so-called isolated CNS angiitis (Johnson et al., 1994). In numerous patients with no histological proof of vascular inflammation, the descriptive term “angiopathy” is more appropriate than “angiitis,” but the latter term has often been overused in the recent literature. Although stroke most often reveals the disease, it appears as the initial manifestation in only a minority of patients. Because of the protean clinical symptoms and blurred diagnostic criteria, identification is a difficult challenge for all clinicians.