Primary central nervous system vasculitis (PCNSV) is a rare and poorly understood syndrome. We describe the clinical findings in 8 patients who appear to have a distinct subset of PCNSV. We identified 101 consecutive patients with PCNSV who were seen between January 1, 1983, and December 31, 2003. The diagnosis was based on conventional angiography in 70 patients and on central nervous system biopsy in 31 patients. Six of the 31 patients also had angiograms showing changes of vasculitis. Thus, 76 patients of the cohort had abnormal angiograms. Eight of the 101 patients had normal angiograms ("angiography-negative") but had brain biopsies that showed vasculitis. We compared the clinical and laboratory findings and outcomes of the 8 patients with angiography-negative PCNSV with those of the 76 patients with PCNSV whose angiograms showed evidence of vasculitis ("angiography-positive"). In comparison with the 76 patients with angiography-positive PCNSV, the 8 patients with angiography-negative PCNSV more commonly had 1) a cognitive disorder (87.5% vs. 43.4%; p =.024); 2) cerebrospinal fluid abnormalities (a protein level >or=700 mg/L or a white blood cell count >or=10 x 10(6)/L) (100% vs. 35.5%; p =.034); and 3) meningeal or parenchymal enhancing lesions on magnetic resonance imaging (75.0% vs. 23.9%; p =.007). Other differences between the 2 groups were observed but were not significantly different. All patients with angiography-negative PCNSV responded to treatment and none died. Angiography-negative PCNSV appears to be a distinct subtype of cerebral vasculitis with small vessel involvement beyond the resolution of conventional angiography and is associated with a favorable outcome.
