Basilar artery free-floating thrombus.

A 53-year-old female presented with vertigo and vomiting, which worsened 12 hours later with right facial numbness and ataxia. CT scans were normal, but CTA revealed occlusion of the right vertebral artery and a filling defect in the basilar artery, indicative of a free-floating thrombus, with the characteristic "donut sign." Thrombectomy was performed to remove the thrombus; however, the patient deteriorated rapidly with severe vomiting and loss of consciousness. Repeat angiography revealed complete basilar artery occlusion, leading to a second thrombectomy. Post-procedure imaging showed recanalization of the vertebral and basilar arteries, with reperfusion of the posterior inferior cerebellar artery (PICA) and anterior inferior cerebellar artery. MRI revealed a high DWI signal in the right medulla and cerebellum. Ten days later, the patient was discharged with persistent dysphagia, dysarthria, and right-sided sensory deficits. This case highlights the rare occurrence of a free-floating thrombus in the basilar artery, which may mimic Wallenberg syndrome. It underscores the importance of considering thrombus migration and suggests that early removal of residual thrombus may prevent recurrent embolism. Further research is needed to refine treatment strategies.