[Radiosurgery and fractionated stereotactic radiotherapy of vestibular schwannoma].

Management of vestibular schwannoma (VS) should always be interdisciplinary and results better than the natural course. Particularly in small VS, either microsurgical resection or radiosurgery (RS) can be employed. RS is a special method (initially only possible stereotactically) for delivering high-precision radiation from many directions to the target point (the isocenter) in a single high dose. With the development of three different systems-Gamma Knife (Elekta, Stockholm, Sweden), special linear accelerators, and CyberKnife (Accuray, Sunnyvale, CA, USA)-the options were extended to 1-5 fractions for RS and multisession RS (msRS), and to up to 6 weeks of conventional fractionation as stereotactic radiotherapy (SRT). Whereas RS uses high ablative single doses, SRT is based on the well-known radiobiological effects of multiple fractions comprising lower single doses up to a required much higher total dose. Evaluation showed that RS and SRT achieve similarly high rates of tumor control of around 90% and low rates of side effects (1-7%). Therefore, SRT is unnecessary for small but clearly progressing VS, which has made RS a very comfortable, effective treatment option. In addition to SRT, larger VS can be treated comparably effectively with CyberKnife-based msRS. Since modern MRI frequently discovers small VS as "incidental findings", the initial biding strategy (wait and scan) is of particular importance. Only with increasing symptoms and detectable tumor growth is the treatment indication established, at which time the decision for surgery and RS/SRT should be taken interdisciplinary under consideration of the patient's wishes.