Stereotactic radiosurgery for intramedullary spinal arteriovenous malformations

• Spinal cord AVMs can present with recurrent hemorrhage or progressive ischemia.
• Their size and location sometimes make embolization and/or microsurgical resection difficult.
• We report 37 patients treated between 1997-2014 with CyberKnife stereotactic radiosurgery.
• CyberKnife radiosurgery safely obliterates or significantly shrinks most intramedullary AVMs.

Spinal cord arteriovenous malformations (AVM) are rare lesions associated with recurrent hemorrhage and progressive ischemia. Occasionally a favorable location, size or vascular anatomy may allow management with endovascular embolization and/or microsurgical resection. For most, however, there is no good treatment option. Between 1997 and 2014, we treated 37 patients (19 females, 18 males, median age 30 years) at our institution diagnosed with intramedullary spinal cord AVM (19 cervical, 12 thoracic, and six conus medullaris) with CyberKnife (Accuray, Sunnyvale, CA, USA) stereotactic radiosurgery. A history of hemorrhage was present in 50% of patients. The mean AVM volume of 2.3 cc was treated with a mean marginal dose of 20.5 Gy in a median of two sessions. Clinical and MRI follow-up were carried out annually, and spinal angiography was repeated at 3 years. We report an overall obliteration rate of 19% without any post-treatment hemorrhagic events. In those AVM that did not undergo obliteration, significant volume reduction was noted at 3 years. Although the treatment paradigm for spinal cord AVM continues to evolve, radiosurgical treatment is capable of safely obliterating or significantly shrinking most intramedullary spinal cord AVM.