Noninvasive diagnosis for CAA-related inflammation validated
medwireNews: Researchers have validated clinical and imaging criteria that can help to identify patients with cerebral amyloid angiopathy-related inflammation (CAA-ri).
The criteria were 82% sensitive and up to 97% specific for possible or probable CAA-ri, report Steven Greenberg (Massachusetts General Hospital and Harvard Medical School, Boston, USA) and co-workers.
“Pending further validation studies, the modified probable CAA-ri criteria seem sufficiently specific to be incorporated into clinical practice for identifying patients who can be treated without the requirement of an invasive brain biopsy”, they write in JAMA Neurology.
They suggest that clinicians go ahead and prescribe immunosuppressive therapy to patients identified by these criteria, adding: “A reasonable follow-up approach would be to consider brain biopsy in empirically treated patients who fail to respond to corticosteroid therapy within 3 weeks.”
The researchers modified the originally proposed criteria in line with their clinical experience, including expanding the duration of clinical symptoms (eg, headache, decreased consciousness, focal neurological deficits) to include chronic symptoms. They refined the imaging criteria to count superficial siderosis as a bleeding manifestation, to mandate white matter hyperintensity (WMH) extension to the immediate subcortical white matter and to regard asymmetrical WMH patterns as probable CAA-ri and other patterns as possible CAA-ri.
The criteria also included age of at least 40 years and the absence of other possible causes, such as neoplasms or infections.
The researchers conducted a retrospective, but blinded, assessment of 17 patients with pathologically confirmed CAA-ri, finding that 82% met the criteria for both possible and probable CAA-ri.
The corresponding rates were 5% and 0% among 21 patients with noninflammatory CAA with lobar intracerebral haemorrhage (ICH), and 69% and 6% among 16 patients with noninflammatory CAA without lobar ICH.
This gave a sensitivity of 82% for probable or possible CAA-ri and respective specificities of 97% and 68%.
The researchers note that not mandating an asymmetrical WMH pattern reduced specificity without increasing sensitivity. “Because extensive WMH per se is common in noninflammatory and inflammatory CAA, the specificity of any proposed criteria depends on defining the particular patterns of WMH that are most characteristic of CAA-ri”, they write.
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