Central nervous system (CNS) involvement can occur in large, medium, or small-sized vessel vasculitides. It is present in less than 10p. cent of systemic vasculitides. Clinical symptoms are heterogeneous and reflect the various mechanisms involved: vasculitis, blood hypertension, thrombosis and embolism. The symptoms can be present initially, at the time of relapse or occur as a treatment side effect. A primary angiitis of the CNS can also be observed. This granulomatous vasculitis is rare and isolated. Its diagnosis is difficult. The prognosis has improved but the disease remains severe. Diagnosis can be made by histology but is suggested by the association of clinical symptoms and brain imaging. Cognitive modifications, sometimes severe can also be observed but can improve with treatment. Prognosis of CNS manifestations is severe. It counts for one point in the Five Factor Score (FFS) which has been validated in some systemic vasculitides. The death rate is 12p. cent when the score is 0 and 50 percent for 2 points. Patients should be treated with a combination of steroids and cyclophosphamide which improves CNS vasculitis outcome.