Diagnostic Yield and Safety of Brain Biopsy for Suspected Primary Central Nervous System Angiitis

Background and purpose: The utility and safety of brain biopsy for suspected primary angiitis of the central nervous system (PACNS) are uncertain. Factors predictive of a positive biopsy have not been well described. Our aim was to evaluate the diagnostic yield and safety of brain biopsy in suspected PACNS and determine whether any prebiopsy variables are associated with a positive biopsy.

Methods: This is a retrospective study of consecutive patients who underwent diagnostic brain biopsy for PACNS at a single institution. The relationship between biopsy yield and patient demographics, surgical technique, laboratory testing, neuroimaging, biopsy characteristics, and prebiopsy immunosuppressive therapy were examined.

Results: PACNS was confirmed in 9 of 79 patients (11%). Biopsy identified alternative diagnoses in 24 patients (30%), with cerebral amyloid angiopathy (8 patients), encephalitis (5 patients), demyelination (3 patients), and CNS lymphoma (3 patients) most commonly found. There was no correlation between a positive biopsy and cerebrospinal fluid results, neuroimaging, surgical technique, biopsy characteristics, or preoperative immunosuppressive therapy. Smaller biopsies (P=0.02) and closed procedures (P=0.013) were less likely to yield a diagnosis. Postoperative complications occurred in 13 patients (16%), 3 (4%) of which were serious.

Conclusions: Brain biopsy leads to pathological confirmation of vasculitis in a minority of suspected PACNS cases but alternative diagnoses are often identified. Importantly, rare but meaningful complications may occur.