Infratentorial Cerebral Microbleeds in Patients with Cerebral Amyloid Angiopathy

Abstract

Cerebral microbleeds (CMBs) observed in hypertension-related arteriolosclerosis tend to occur in the supratentorial deep gray matter, whereas those in cerebral amyloid angiopathy (CAA) typically show a supratentorial lobar distribution. Recently, superficial spontaneous cerebellar intracerebral hemorrhage has been shown to be associated with strictly lobar CMBs. Few data exist on infratentorial CMBs in CAA. The purpose of this study was to describe the incidence, number, and characteristics of infratentorial CMBs in patients with CAA. We performed a retrospective analysis of data derived from a prospectively recruited cohort of patients with possible or probable CAA according to the Boston criteria. A total of 115 patients with CAA (59% with CMBs) were analyzed. Eighteen percent of all patients with CAA had at least 1 infratentorial CMB. For patients with CMBs, presence and median CMB number were as follows: brainstem, 8% and 1; deep cerebellum, 4% and 1; superficial cerebellum, 10% and 1.5. Brainstem or deep cerebellum CMB was associated with the presence of and with higher numbers of supratentorial deep gray matter CMBs (P < .001 for both) and with hypertension (P = .048), whereas superficial cerebellar CMB was associated with the presence of and with higher numbers of supratentorial lobar CMBs (P < .001 for both). Based on our study, superficial cerebellar CMBs (in low numbers when present) seem to be a CAA-related phenomenon observed in a minority of patients who have CAA with a relatively high supratentorial lobar CMB load.