Bulbar watershed ischemic stroke: the comma-shaped sign-a case series.

Watershed infarcts can involve the brainstem, with lesions distributed across the terminal supply from the vertebral and cerebellar arteries. Brain imaging can highlight a comma-shaped lesion at the edge of vertebral and posteroinferior cerebellar artery vascularization territory. Such peculiar MRI lesion shape might suggest a watershed hypoperfusion etiology and direct workup towards causes of hemodynamic impairment, including postural hypotension, cardiac failure, or vertebral artery origin occlusion.