Mechanical thrombectomy for top of basilar artery occlusion and delayed distal thrombus migration involving the artery of Percheron: illustrative case.

backgroundMechanical thrombectomy (MT) for acute basilar artery occlusion (BAO) has become the standard of treatment. Indications for MT in cases of BAO are determined by the degree of activities of daily living before onset, clinical severity, extent of baseline ischemia, and time from onset. OBSERVATIONS: A 43-year-old woman was treated by endovascular intervention for BAO with delayed occlusion of the artery of Percheron (AOP) due to presumed distal thrombus migration. After a fluctuating mild clinical course of more than 60 hours, the patient was finally transferred to the author's institution, presenting with severely impaired consciousness (Glasgow Coma Scale score of 7). The radiological assessment suggested initial BAO followed by distal thrombus migration, resulting in an acute AOP occlusion. Emergency MT was performed because the onset of severe symptoms had worsened within the last 16 hours. Endovascular intervention resulted in complete vascular reperfusion with an abrupt return of consciousness and a modified Rankin Scale score of 2 four months after transfer. LESSONS: Understanding the anatomical and hemodynamic relationships between the BA and AOP is important for the effective treatment of acute BAO. In particular, ischemic changes in the posterior circulation can be reversible despite prolonged symptom duration. https://thejns.org/doi/10.3171/CASE25171.