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

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.

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.

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.

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.