Embolization of spinal intramedullary arteriovenous malformations using the liquid embolic agent, Onyx: a single-center experience in a series of 17 patients

Object. The aim of this study was to analyze the endovascular treatment results of using the Onyx liquid embolic system for spinal intramedullary arteriovenous malformations (AVMs). Methods. The clinical and radiological records of 17 patients with symptomatic spinal intramedullary AVMs treated exclusively by embolization with Onyx between 1999 and 2003 were retrospectively reviewed. There were 12 females and five males in the patient series (mean age 29 years). Four of these AVMs were located in the cervical spine, eight in the thoracic spine, and five in the lumbar spine. The clinical presentation of these AVMs included upper motor neuron signs and symptoms, and hemorrhage was the initial presentation in 12 patients. Neurological and functional evaluation was performed before and after treatment with Onyx in all patients. Results. Thirteen patients underwent a single endovascular treatment and four patients underwent two endovascular treatments (average 1.23 sessions per patient). Intraprocedural complications occurred on two occasions without neurological consequences. The mean follow-up duration was 24.3 months. Angiographic outcomes included total AVM obliteration in six patients (37.5%), subtotal obliteration in five patients (31.25%), and partial obliteration in five patients (31.25%). Improvement in neurological and/or functional status was noted in 14 patients, resulting in an 82% rate of overall good clinical outcome. Conclusions. Embolization using the Onyx system is a promising treatment method for spinal vascular malformations, even for challenging intramedullary AVMs. Larger studies with longer follow-up durations will further enhance our knowledge on the safety and efficacy of this relatively new liquid embolic agent.