Inflammation of blood vessels within the central nervous system. Etiologies include autoimmune disorders (see also LUPUS ERYTHEMATOSUS, SYSTEMIC; POLYARTERITIS NODOSA; WEGENER'S GRANULOMATOSIS), infections, exposure to radiation or toxins, and other conditions. Autoimmune or idiopathic vasculitides limited to the central nervous system are referred to as primary CNS vasculitides. CNS vasculitides associated with a systemic process or known pathogens are referred to as secondary CNS vasculitides. Clinical manifestations are highly variable but include headaches; SEIZURES; behavioral alterations; INTRACRANIAL HEMORRHAGES; transient ischemic attacks (ISCHEMIC ATTACK, TRANSIENT); and BRAIN INFARCTION. (From Adams et al., Principles of Neurology, 6th ed, pp856-61).