Acute ischemic stroke in a twig-like middle cerebral artery: A case report and review of etiology and thrombectomy risks.

Background: Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a rare congenital vascular anomaly characterized by the absence or hypoplasia of the M1 segment, replaced by a network of small tortuous collateral arteries. Although Ap/T-MCA predominantly presents with intracerebral hemorrhage from rupture of fragile vessels, acute ischemic stroke can occur, presenting with diagnostic and therapeutic challenges. Case Description: A 79-year-old woman presented with acute right hemiplegia and aphasia. Initial imaging suggested left M1 segment occlusion of the MCA, prompting emergency thrombolysis and mechanical thrombectomy (MT). Intraoperative angiography revealed a reticulated vascular network replacing the normal M1, consistent with Ap/T-MCA. Subsequently, subarachnoid hemorrhage due to vascular injury developed, along with cerebral infarctions in the anterior cerebral artery (ACA) territory and the frontal lobe of the MCA territory. Postprocedural cardiac evaluations identified no cardioembolic source. The stroke may have resulted from thrombosis within the Ap/T-MCA network or from a thrombus at the terminal segment of the internal carotid artery or the network entrance that migrated to the ACA. Conclusion: This case report highlights challenges in diagnosing and managing acute ischemic stroke with Ap/T-MCA. Because complex vascular anatomy may suggest M1 occlusion on non-invasive imaging, MT may lead to interventions with high hemorrhagic risk. Caution is warranted when apparent M1 occlusion coexists with a complex network typical of Ap/T-MCA. Understanding the angiographic features and recognizing the potential risks of MT are essential to optimizing outcomes. Further studies are required to establish appropriate management strategies for acute stroke in this rare vascular anomaly.