Cerebral Amyloid Angiopathy Related Inflammation With Prominent Meningeal Involvement. A Report of 2 Cases

Abstract

Cerebral amyloid angiopathy related inflammation (CAA-RI) is a rare form of CAA characterized by subacute encephalitic symptoms (cognitive decline, seizures, focal deficits) associated with extensive and confluent white matter lesions co-localizing with lobar microbleeds on brain MRI. We report two cases of unusual CAA-RI mimicking meningoencephalitis but without typical brain lesions on FLAIR and T2^* sequences. These 2 cases may extend the clinical spectrum of CAA-RI by suggesting the possible occurrence of quite purely meningeal forms of CAA-RI.

Keywords: cerebral amyloid angiopathy (CAA); cerebral amyloid angiopathy-related inflammation (CAA-RI); meningeal inflammation; subarachnoid hemorrhage; xanthochromia.

Figure 1

Baseline brain MRI in patients 1 and 2, performed during the first month of the disease. (A) Diffusion weighted sequences showing multiple deep and cortical acute microinfarcts in both patients (arrows). (B) FLAIR sequences showing no or minimal brain parenchymal lesions but high intensity signal in cortical sulci in patients 1 and 2 (arrows). (C) T2* sequences showing doubtful sulcal hypointensities in patient 1 and 5 microbleeds in patient 2 (arrows).

Figure 2

Meningeal biopsy in patient 1. Meningeal tissue section showing Aβ amyloid deposits in the wall of small meningeal arteries (brown staining) and a lymphocytic perivascular infiltrate (dark blue cells).

Figure 3

Follow-up brain MRI in the 2 patients. T2* sequences at 1 year after the onset, in patient 1 and patient 2 showing increasing load of superficial microbleeds and hemosiderosis.