Asymptomatic “twig-like” middle cerebral artery embryological anomaly

Introduction. Anomalies of the middle cerebral artery (MCA) are very rare. ?Rete MCA,? ?twig-like MCA? (T-MCA), ?aplastic MCA,? ?unfused MCA,? and others are all synonyms for unilateral embryological anomaly of the M1 segment of the MCA, where, due to an unknown cause, fusion of primordial arteries of the M1 segment did not happen. As a result, the M1 segment of the affected side consists of a mesh of small arteries from which arise normal perforators and cortical branches. Moyamoya disease, moyamoya-like syndrome, atherosclerotic steno-occlusive disease, vasculitis, and dissection of the MCA should be considered in differential diagnosis. Case outline. We present a 60-year-old female patient with twig-like left MCA, incidentally diagnosed due to persistent headaches six days prior to admission. Non-contrast computed tomography head examination was without peculiarities. Computed tomography angiography showed a network of small vessels in place of the left M1 segment, bridging internal carotid artery terminus with branches of the MCA bifurcation and giving rise to lenticulostriate arteries. Fourteen months later, on physical examination, the patient was in good general condition, without a neurological deficit, with occasional episodes of headache no stronger than 3?4/10 on the visual analogue scale. Conclusion. We report a patient with extremely rare variation of the M1 segment of the left MCA, incidentally diagnosed due to headaches.