DIAGNOSIS OF CEREBRAL AMYLOID ANGIOPATHY - SENSITIVITY AND SPECIFICITY OF CORTICAL BIOPSY

Background and Purpose Examination of cortical tissue obtained surgica lly is an important tool for diagnosis of cerebral amyloid angiopathy (CAA) during life. Analysis of a single sample of cortical tissue, how ever, might lead to conclusions that are either falsely positive (beca use of the high frequency of CAA in the healthy elderly) or falsely ne gative (because of the patchy distribution of CAA pathology). We there fore attempted to estimate the sensitivity and specificity of cortical biopsy for diagnosis of CAA as the cause of intracerebral hemorrhage. Methods To simulate biopsy in CAA, we took biopsy-sized cortical samp les from postmortem brains with known extents of CAA: either CAA-relat ed hemorrhage or mild to severe CAA without hemorrhage. Samples were s tained with the use of methods routinely available in surgical patholo gy laboratories and blindly examined for vascular amyloid and amyloid- related vasculopathic changes. Results The presence of vascular amyloi d was a sensitive marker for CAA-related hemorrhage occurring In all 2 8 specimens from brains with hemorrhage. Conversely, the appearance of fibrinoid necrosis in amyloid-laden vessels was relatively specific f or CAA-related hemorrhage. This Ending occurred in 13 of the 28 specim ens (46%) from brains with hemorrhage but in none of 27 sections from brains with mild CAA and in only 4 of 42 specimens with moderate to se vere CAA without hemorrhage. Conclusions These data help to define cri teria for the diagnosis of CAA-related hemorrhage from surgical specim ens.