Diagnostic test results in primary CNS vasculitis

Background: Primary CNS vasculitis (PCNSV) can be diagnosed using cerebral angiography or histopathology combined with clinical features. The original diagnostic criteria, which weigh each test equally, have not been validated. Limited sensitivity and specificity for biopsy and angiography are recognized. We systematically reviewed results of diagnostic tests performed in patients with an ultimate diagnosis of PCNSV. Methods: We searched the OVID Medline database and bibliographies for original cases of PCNSV. We recorded demographics, diagnostic tests used, and assessed agreement between angiography and biopsy when both tests were performed. We also recorded MRI and CSF results. Results: We found 701 original cases with PCNSV diagnosed with angiography or pathology. A total of 269 patients (38.4%) had both cerebral angiography and histopathologic testing (biopsy/postmortem). Classic angiographic features of vasculitis were associated with pathologic confirmation in just 32 patients (4.6%). Seventy-four patients (10.6%) with any abnormality on angiography had a normal biopsy, and 99 patients (14.1%) with abnormal biopsies had normal angiography. Brain MRI was abnormal in 505/541 patients (93.3%) and CSF was abnormal in 360/484 patients (74.4%). Increasing use of angiography and decreasing histopathologic testing were found over time. Conclusions: Cerebral angiography and pathologic tissue examination were undertaken in a minority of published cases with a diagnosis of PCNSV. When both diagnostic tests were performed, disagreement between them was more than 5 times more likely than agreement. Diagnostic criteria for PCNSV may require revision to classify the clinical, pathologic, and radiologic features of this condition more accurately.