Recent advances in radiosurgery for cerebral arteriovenous malformations: The University of Tokyo experience

Stereotactic radiosurgery has been widely applied to treat cerebral arteriovenous malformations (AVMs), and various relevant studies have been reported to date. Recently, however, a lot of new facts were clarified by our up-to-date long-term follow-up study after stereotactic radiosurgery using a gamma knife. The risk of hemorrhage from AVMs was reduced by 54% even during the latency period after radiosurgery and further 78% after obliteration. However, a small risk of hemorrhage still remained after obliteration. Therefore, angiographic obliteration, which was one the treatment goals, does not necessarily mean an ultimate cure of AVMs. Such a risk was significantly related to the continuous enhancement on computerized tomographic or magnetic resonance imaging. Advancement in imaging technique provided by these three-dimensional imaging realized significantly less frequent complication. Integration of diffusion - tensor tractography into treatment planning of radiosurgery enabled clear visualization of the corticospinal tract during the treatment planning, and the tolerable dose of the corticospinal tract was clarified to be 25 Gy. Thus, safer and more effective treatment can be achieved with recent advances in stereotactic radiosurgery to treat cerebral AVMs.