Staged embolization with staged gamma knife radiosurgery to treat a large AVM.

Treatment of arteriovenous malformations (AVMs) is complicated because of many factors including increasing size, eloquent location, and risk of unacceptable neurological deficits. Each of the treatment modalities, microsurgery, embolization, and stereotactic radiosurgery (SRS), has its pros and cons. Surgery and embolization are limited by location, size, and afferent and efferent vessel anatomy. Stereotactic radiosurgery is limited by size and location, with increasing volume of the AVM resulting in decreasing the therapeutic dose. Many articles address the concern of high dose radiation not being able to be used in SRS over a large volume.1-5 Embolization is an endovascular treatment that often precedes surgical excision or stereotactic radiosurgery for the treatment of AVMs.6-8 This type of combination is typically utilized for larger AVMs (>3 cm3) in order to reduce the overall size needed to be treated through microsurgical removal or SRS.6,7,9,10 Staged gamma knife radiosurgery (GKRS) provides another method of treating larger AVMs and is based on the idea of safe re-treatment; however, unlike re-treatment which occurs approximately three years after the first treatment, staged SRS is multiple treatments over shorter period of time (~3 to 8 months).11-14 We present a case showing successful obliteration of a large AVM in a 12-year-old male through the use of embolization to initially reduce nidus size followed by staged gamma knife radiosurgery. To the author’s knowledge successful obliteration of a large AVM by combining staged embolization with stagedvolume GKRS has not previously been described.