Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Rete MCA anomaly, also known as twiglike MCA, is extremely rare, exclusively unilateral, and thought to be due to the persistence of the fetal arterial network that usually coalesces into a definitive MCA. This vascular lesion appears to be related to a higher incidence of aneurysms and vulnerability to both hemorrhagic and ischemic strokes. It is important to be acquainted with the radiologic features of rete MCA anomaly to avoid misdiagnosis and futile treatments. DSA reveals plexiform vascular structures (white arrow) instead of a definitive left M1 segment. The caliber and flow of the distal MCA (yellow arrows) are maintained. There is no evidence of atheromatous plaques or focal stenosis in other cerebral arteries. The white asterisk indicates a treated anterior communicating artery aneurysm.