Embolization of high flow arteriovenous malformations: experience with use of superabsorbent polymer microspheres.

Purpose: To determine efficacy, safety, and requirements for adjunctive embolization or surgery in the treatment of symptomatic arteriovenous malformations (AVMs) with superabsorbent polymer microsphere (SAP-MS) particles.
Materials and Methods: SAP-MS particles (sodium acrylate and vinyl alcohol copolymer) are nonbiodegradable spheres with a precisely calibrated diameter. SAP-MS particles swell by absorbing fluids and become soft and deformable. Twenty-five patients (16 men, nine women; mean age, 32 y; range 12-66 y) with symptomatic facial (n = 5), upper- (n = 8) and lower- (n = 12) extremity AVMs were treated primarily (n = 23) or preoperatively (n = 2) by transarterial embolization (TAE) treatment with use of SAP-MS particles. Direct puncture embolization (DPE; n = 4) and/or surgical intervention (n = 5; ie, skin graft, resection, or amputation) were required. Surgical specimens from the resected (n = 2) and the amputated (n = 2) patients were evaluated histologically. Follow-up study, including clinical findings and imaging studies, was performed at intervals ranging from 3 months to 1 year. Clinical outcome was evaluated retrospectively, depending on the subjective improvement of symptoms and signs, according to the medical records.
Results: Seventy-two TAEs (range, 1-11; mean, 2.8) and 12 DPEs (range, 1-3; mean, 2.4) were performed during the mean follow-up period of 38 months (range, 7-110 mo). Twenty patients (80%) experienced symptom improvement by embolotherapy alone (n = 17) or in combination with surgery (n = 3). One lip and two finger AVMs were totally removed by surgical excision or amputation after TAE treatment. In diffuse upper- (n = 1) and lower- (n = 1) extremity AVMs, the symptoms were uncontrolled. No nerve injury or skin necrosis was observed after TAE treatment with SAP-MS particles. Mucosal necrosis was induced by DPE with ethanol in one patient. Histologically, SAP-MS particles penetrated intralesional vessels and conformed to the vessel lumen, resulting in tight vessel occlusion. Minimal perivascular reaction was observed.
Conclusion: SAP-MS particles were used safely in TAE treatment of AVM. TAE treatment with use of SAP-MS particles was suitable for certain symptomatic AVMs, but diffuse AVMs remain a challenge and a combination of alternative methods will be necessary for further strategy.