Mechanical thrombectomy for tandem internal carotid artery-middle cerebral artery occlusion in a patient with a persistent hypoglossal artery: illustrative case.

backgroundMechanical thrombectomy (MT) is the established treatment for acute ischemic stroke due to large-vessel occlusion. However, rare cerebrovascular anomalies, such as a persistent hypoglossal artery (PHA), present unique challenges that require procedural modifications. OBSERVATIONS: The authors present the case of a woman in her 80s who developed sudden-onset impaired consciousness and left hemiparesis, with a National Institutes of Health Stroke Scale (NIHSS) score of 20. Imaging revealed a tandem occlusion of the right internal carotid artery (ICA) and middle cerebral artery (MCA). Notably, perfusion imaging demonstrated an extensive penumbra not only in the right MCA territory, but also in bilateral posterior cerebral artery territories, despite an anterior circulation occlusion. Angiography revealed a functionally significant PHA originating from the right ICA and supplying the entire posterior circulation. Successful recanalization was achieved with a modified Thrombolysis in Cerebral Infarction grade of 2b. The patient experienced significant neurological improvement, with an NIHSS score of 2 at the final follow-up. LESSONS: This case highlights that a PHA may function as a critical collateral pathway. Recognition of atypical perfusion patterns and preprocedural identification of vascular anomalies are essential for safe and effective MT. https://thejns.org/doi/10.3171/CASE25961.