The following is a summary of “Cerebral Amyloid Angiopathy–Related Inflammation and Biopsy-Positive Primary Angiitis of the CNS: A Comparative Study,” published in the June 2024 issue of Neurology by Grangeon, et al.
Cerebral amyloid angiopathy-related inflammation (CAA-RI) and biopsy-positive primary angiitis of the CNS (BP-PACNS), though difficult to distinguish due to similar symptoms and imaging, are being studied to see if they have different relapse rates.
Researchers conducted a retrospective study to compare how CAA-RI and BP-PACNS appear in imaging and clinical data and how often relapses occur in each disease.
They retrospectively enrolled patients with CAA-RI and BP-PACNS from two multicenter cohorts. Patients with CAA-RI either had positive biopsies or met probable clinical radiologic criteria. Patients with BP-PACNS had confirmed CNS angiitis histopathologically, excluding secondary causes. Brain MRIs were interpreted by a neuroradiologist unaware of CAA-RI or BP-PACNS diagnoses. Clinicoradiologic features using logistic regression models. Relapse rates were compared using a Fine-Gray subdistribution hazard model, considering death a competing risk.
The results included 104 patients with CAA-RI (mean age 73 years, 48% female) and 52 with BP-PACNS (mean age 45 years, 48% female). Patients with CAA-RI more often had characteristic MRI findings such as white matter hyperintense lesions (93% vs. 51%, P<0.001), acute subarachnoid hemorrhage (15% vs. 2%, P=0.02), cortical superficial siderosis (27% vs. 4%, P<0.001), ≥1 lobar microbleed (94% vs. 26%, P<0.001), past intracerebral hemorrhage (17% vs. 4%, P=0.04), ≥21 visible centrum semiovale perivascular spaces (34% vs. 4%, P<0.01), and leptomeningeal enhancement (70% vs. 27%, P<0.001). Patients with BP-PACNS more frequently reported headaches (56% vs. 31%, P<0.01), motor deficits (56% vs. 36%, P=0.02), and nonischemic parenchymal gadolinium enhancement (82% vs. 16%, P<0.001). Acute ischemic lesions occurred in 18% of CAA-RI and 22% of patients with BP-PACNS (P=0.57). Specific MRI features with high specificity for CAA-RI included acute subarachnoid hemorrhage (98%), cortical superficial siderosis (96%), past intracerebral hemorrhage (96%), and ≥21 visible centrum semiovale perivascular spaces (96%). The probable CAA-RI criteria showed 71% sensitivity (95% CI 44%–90%) and 91% specificity (95% CI 79%–98%) for differentiating BP-CAA-RI from BP-PACNS. CAA-RI had a lower relapse rate within the first 2 years post-remission than BP-PACNS (hazard ratio 0.46, 95% CI 0.22–0.96, P=0.04).
Investigators found CAA-RI showed distinct hemorrhagic and perivascular space features, with promising diagnostic criteria but a potential need for biopsy; relapses were lower in CAA-RI within two years.