Asymmetric distribution of cerebral microbleeds in patient with infarction and atrophy: A case report

Cerebral microbleeds (CMBs) are commonly associated with cerebral small vessel disease (CSVD) and cerebral amyloid angiopathy (CAA) and usually present bilaterally. Unilateral distribution is rare and challenges current understanding of disease pathophysiology. We report the case of an asymmetric distribution of cerebral microbleeds. A 69-year-old hypertensive woman presented with acute right-sided hemiparesis and aphasia. Magnetic resonance imaging revealed an acute left frontal infarction, multiple lobar CMBs exclusively in the left hemisphere, and progressive left hemispheric atrophy without significant large-vessel stenosis. Although CAA and CAA-related inflammation (CAA-ri) were considered, definitive diagnosis was precluded by absent histopathological confirmation and incomplete imaging criteria. The case was considered within the spectrum of cerebral small vessel disease, acknowledging the diagnostic uncertainty. The patient was managed conservatively with antithrombotic therapy and strict blood pressure control, with no recurrent ischemic or hemorrhagic events. During 3-year follow-up, no recurrent ischemic or hemorrhagic events occurred; however, progressive cognitive function declined (MMSE: 20→16→6) and mild unilateral cerebral atrophy developed, suggesting ongoing small-vessel-related pathology. This case highlights the diagnostic challenges posed by asymmetric CMB distribution and underscores the importance of careful longitudinal clinical and imaging follow-up in patients with atypical CSVD presentations.