Recurrence of Cerebral Amyloid Angiopathy-Related Inflammation: A Report of Two Cases from the iCAβ International Network.

Background: Cerebral amyloid angiopathy-related inflammation (CAA-ri) represents the most readily responsive form of CAA, if diagnosed and treated early. Although CAA-ri typically presents with a monophasic pattern, recurrences have been occasionally reported.

Objectives: To describe the evolution of the clinical and neuroradiological features of CAA-ri recurrence.

Methods: From the 60 CAA-ri cases recruited through the iCAβ International Network, we identified those patients who experienced a CAA-ri recurrence at more than 12 months after the first inflammatory event. Neuroradiological evidence of cerebral inflammation (vasogenic edema) and sulcal superficial siderosis or multiple areas of cortical/subcortical microhemorrhages (MHs) were evaluated based upon fluid-attenuated inversion recovery and T2 *-weighted gradient echo or susceptibility weighted imaging, respectively. In one patient, the deposition of amyloid-β was evaluated using 11C-Pittsburgh Compound B-positron emission tomography (PiB-PET).

Results: Of the 60 cases, two were identified as having experienced a late CAA-ri recurrence, at two and seven years after the first presentation, respectively. At recurrence, the inflammatory lesions colocalized with the appearance of new MHs and were observed in brain areas different from those where the first onset occurred. PiB-PET four months after remission showed particularly low amyloid-β deposition in the left frontal lobe, while no change was observed in the area of the inflammatory relapse.

Conclusions: Our observations highlight the importance of not underestimating any new neurological symptoms in patients who have already experienced an episode of CAA-ri. Although the frequency of CAA-ri recurrences is rare, in cases of suspected relapse, a prompt clinical and radiological follow-up should be considered in order to obtain a timely diagnosis and treatment, having a potential strong impact on patients' clinical outcome.