Primary angiitis of the central nervous system in adults and children.

Primary angiitis of the central nervous system (PACNS) is a rare disease, although it is increasingly recognized both in adults and children. Little is known about pathogenesis, but efforts at classification into subtypes are being made, and the distinction of PACNS from reversible cerebral vasoconstriction syndrome has been a major advance. The prognosis for improvement, or at least stabilization, of neurologic function is good with prompt and aggressive treatment, but the diagnosis continues to be challenging. Refinement of treatment strategies is needed. Multicenter collaboration may be crucial to make additional progress via randomized trials.