Estimation of Treatment Benefit in Patients with Cerebral Arteriovenous Malformations

Background: Cerebral arteriovenous malformations (AVMs) are vascular lesions that may be associated with a significant morbidity and mortality. There is still today no consensus regarding treatment of unruptured AVMs. Using known data from the literature, and data from our own institution concerning stereotactic radiotherapy, our aim was to construct an equation that may be used to evaluate the benefit of intervention vs. conservative treatment in unruptured AVMs. Methods: Assuming an annual bleeding risk of 4% and previously reported mortality (29%) and morbidity (16%) rates after a bleeding from an AVM, an equation was constructed. This equation would estimate the time until the combined mortality and morbidity associated with conservative treatment would equal the mortality and morbidity of stereotactic radiotherapy. Results: Using stereotactic radiotherapy this treatment would benefit over conservative treatment in excess of 8.12 years. The risk of bleeding was the most important factor influencing the benefit of intervention vs. conservative treatment. Conclusions: We argue that that it may be possible to estimate the benefit of intervention vs. conservative treatment in an unruptured AVM. This may be achieved using our proposed equation and data specific to each center performing treatment for AVMs.