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  • Combined Treatment Approach to Cerebral Arterial-Venous Malformation: Stereotactic Radiosurgery to Partially Onyx-embolized AVM. Important Safety Lessons

    Final Number:

    Andrew A Kanner MD; Ido Strauss; Benjamin W. Corn; Natan Shtraus BS; Vladimir Frolov MD; Shimon Maimon MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2014 Annual Meeting

    Introduction: Treatment of arterio-venous malformations (AVM) of the brain can be challenging due to the complexity of, size, morphology and location (e.g., proximity to the normal cerebral vascular circulation). Recent improvements in catheter techniques and embolization materials, in particular Onyx (liquid Ethylene vinyl alcohol copolymer), have increased the success rate of total and near-total obliteration. However, the use of Onyx causes distortion of the MRI and CT images, which must be considered in any radiation treatment planning predicated on CT and MRI images. These distortions impact on the actual delivered dose to the nidus and make heterogeneity correction necessary (Shtraus N.J Neurooncol 2010).

    Methods: We have reviewed 45 consecutive patients, who underwent combined treatment in our institution between May-2007 and November-2012.

    Results: 27 were women, with a median age of 32 years (6-70). The median time from diagnosis to SRS was 24 months (1-141). At least 18 (40.0%) patients had one episode of hemorrhage prior to treatment. Spezler/Martin grade prior to the embolization were 2-5. Patients underwent a median 2 (1-6) embolization procedures. The embolization material used in total was median 1 cc (0.5-12.0) per patient. The radiosurgical treatment dose to the margin of the angiography-based nidus: median dose of 1884cGy (1402-2751) with a median max dose of 2538cGy (1893-3044). The median treatment volume was 0.7cc (0.1-7.3). Follow up period median 32.9 months (6.5-81.2). We confirmed so far 20 (44.4%) complete closures. In 7 (15.5%) additional patients a significant flow reduction was noted. In 2 (4.4%) patients with follow up of 55.0 and 51.1 months the nidus is without significant change. Two patients (4.4%) bleed in the follow-up period, making surgical intervention necessary. Three patients (6.6%) developed brain edema, 2 transient and one persistent. The latter occurred in the only case that a heterogeneity correction was not performed.

    Conclusions: To the best of our knowledge this study cohort comprises the largest combined experience in the literature. The use of onyx reduces the treatment volume significantly. Importantly we implemented the heterogeneity correction to avoid increased radiation exposure to normal surrounding brain tissue. The combined approach appears to be safe provided that the above mentioned corrections are implemented.

    Patient Care: Implementing heterogeneity correction in this approach will increase safety of the procedure

    Learning Objectives: Implementing heterogeneity correction in the radiosurgical planning for onyx embolized AVM

    References: Shtraus al J Neurooncol (2010) 98:271–276

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