Management of Complex Arteriovenous Malformations Using a Novel Combination Therapeutic Algorithm.

Importance: Current therapeutic options for patients with extracranial head and neck arteriovenous malformations are limited. Surgical intervention, such as sclerotherapy or resection, often result in rapid recurrence and progression of disease.

Objective: To assess the efficacy and tolerability of sirolimus as an adjuvant therapy for endovascular embolization in the management of complicated extracranial head and neck arteriovenous malformations.

Design, Setting, and Participants: This case series examined 6 patients with extracranial head and neck arteriovenous malformations treated from January 1, 2013, to December 31, 2017, at a multidisciplinary vascular anomalies clinic within Stanford Hospital and Clinics.

Intervention: Initiation of sirolimus at least 1 month prior to endovascular embolization, targeting a trough level of 10 to 15 ng/mL throughout the course of the endovascular embolization series and continued for at least 1 month after the series.

Main Outcomes and Measures: Clinical manifestations; disease progression and overall response to treatment were assessed via clinical evaluation and radiographic imaging.

Results: All 6 patients (4 male and 2 female patients; mean age, 24.5 years [range, 9-44 years]) responded favorably to the combination of sirolimus therapy followed by endovascular embolization, and 4 patients exhibited a near-complete response. The median duration of follow-up was 19 months (range, 6-40 months). One patient discontinued sirolimus soon after embolization and experienced regrowth of the arteriovenous malformation after 1 year. Sirolimus was resumed, which has stabilized his disease for more than 2 years. Mild adverse effects were noted in 4 patients. The combination therapy was well tolerated in all patients. One patient developed skin ulceration after embolization and required surgical debridement. Another patient developed pulmonary microthrombi after embolization with cyanoacrylate glue that resolved with a brief course of anti-inflammatory therapy.

Conclusions and Relevance: Although further prospective trials are needed, this report suggests the benefit of a mammalian target of rapamycin inhibitor as an adjuvant therapy for surgical embolization of complex, extracranial head and neck arteriovenous malformations. The optimal dosing and therapeutic duration of sirolimus treatment before and after embolization remain to be determined.