Archives of neurology
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Primary angiitis of the central nervous system (PACNS) is a rare form of vasculitis of unknown cause. The mean age of onset is 50 years, and men are affected twice as often as women. Headache and encephalopathy are the most frequent initial symptoms. ⋯ The differential diagnosis of PACNS is broad and includes reversal cerebral vasoconstriction. In contrast to patients with PACNS, patients with reversal cerebral vasoconstriction are more often young women who experience a thunderclap headache and have a normal cerebrospinal fluid analysis. Patients with biopsy-proven PACNS are treated with cyclophosphamide and prednisone.