Embolization with particles in thoracic intramedullary arteriovenous malformations: long-term angiographic and clinical results. To evaluate the long-term results of endovascular treatment with particles in the management of thoracic intramedullary arteriovenous malformations (AVMs), the authors retrospectively reviewed the angiographic and clinical findings in 35 patients. Follow-up was 1-15 years (mean, 6 years) in 28 patients and 6-10 months (mean, 7 months) in seven. A total of 158 embolization procedures were performed in 35 patients. Revascularization occurred frequently, necessitating multiple endovascular sessions. Long-term clinical evaluation showed clinical improvement, compared with the initial status before treatment, in 63% of the patients. Clinical aggravation due to embolization was observed in seven patients (20%) after 12 of the 158 endovascular sessions (8%). These results are better than those reported after surgery and indicate that embolization with particles is an efficient and safe tool in the treatment of thoracic intramedullary AVMs. 