MURAGAKI Yoshihiro    Department   School of Medicine(Tokyo Women's Medical University Hospital), School of Medicine    Position   Visiting Professor
Language	English
Category	Chapter contribution
Title	Do We Really Still Need an Open Surgery for Treatment of Patients with Vestibular Schwannomas?
Book title	Gamma Knife Neurosurgery in the Management of Intracranial Disorders
ISBN	9783709113752
Editor	Mikhail Chernov,Motohiro Hayashi,Jeremy Ganz,Kintomo Takakura
Edition, Volume, Page	116,pp.25-36
Publisher	Springer
Publication place (City and country)	Wien,Austria
Author and coauthor	HAYASHI Motohiro, CHERNOV Mikhail, Samuel M. Lipski, TAMURA Noriko, Shoji Yomo, MATSUOKA Ayako, TSUZUKI Syunsuke, IZAWA Masahiro, OKADA Yoshikazu, MURAGAKI Yoshihiro, ISEKI Hiroshi, Pavel Ivanov, Jean Regis, TAKAKURA Kintomo
Publication date	2013/03
Summary	Abstract BACKGROUND: Gamma Knife surgery (GKS) should be considered a standard treatment option for small and medium-sized vestibular schwannomas (VSs). It results in a tumor control rate similar to that seen with microsurgery and provides better preservation of facial nerve function and hearing. METHODS: From December 2002 to April 2011, a total of 260 patients with VS underwent GKS using Leksell Gamma Knife model 4C with an automatic positioning system. There were 30 Koos stage I tumors, 112 stage II, 100 stage III, and 18 stage IV. All patients were treated with the use of high-resolution magnetic resonance imaging; creation of the highly precise conformal and selective multi-isocenter dose planning with small collimators, carefully sparing adjacent cranial nerves of any excessive irradiation; and creation of a wide 80 % isodose area within the tumor while applying a low marginal dose (mean 11.9 Gy) at the 50 % isodose line. RESULTS: Among 182 patients who were followed for more than 3 years after treatment, the tumor control and shrinkage rates were 98.4 % and 76.4 %, respectively. Volume reduction of >50 % was marked in 54.9 % of VSs. Preservation of facial nerve function and hearing at the pretreatment level was noted in 97.8 % and 87.9 %, respectively. There was marked improvement of facial nerve function and hearing after GKS in 2.2 % and 3.8 %, respectively. There was no major morbidity. CONCLUSION: Due to contemporary technological and methodological achievements GKS can be focused not only on growth control but on shrinking the VS, with possible reversal of the neurological deficit.