title: Delayed microsurgery for vestibular schwannoma after gamma knife radiosurgery.
abstract: Stereotactic radiosurgery for vestibular schwannomas (VSs) has become popular during the last decade with promising clinical results after long-term follow-up. However, on rare occasions, some cases have needed traditional microsurgery to remove the tumor several months or years after radiosurgery. We present a retrospective analysis of data acquired during a 16-year period in delayed microsurgery of seven patients with VSs who underwent gamma knife surgery (GKS). A total of 444 with VS underwent GKS between March 1993 and December 2008, and 7 (1.57%) underwent delayed microsurgery at a median of 26 months (range from 3 months to 6 years) after GKS. The mean size of the tumor during GKS was 10.4 ml (range 2.3-23.5 ml). These seven patients were younger, and female predominant. The indications of microsurgery included adverse radiation effect with peri-focal edema, tumor enlargement, and cyst enlargement. Although the perifocal edema could lead to more difficulty in surgery than in typically performed operations for schwannoma, subtotal resection was achieved in all patients. There was no surgery-related morbidity or mortality. The histology showed benign tumor in five patients, malignant peripheral nerve sheath tumor in one, and necrotic tissue in one. The need of microsurgery for further treatment of VS after radiosurgery is rare, but can be a challenge to neurosurgeons in terms of surgical indication, timing, and techniques. The authors concluded the incidence of delayed microsurgery was 1.57% in a series of 444 patients over a 16-year period. We concluded some experience from operative indications, timing, approach, and outcome.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, 17F, No. 201, Shih-Pai Road, Sec. 2, Peitou, Taipei, 11217, Taiwan, ROC. yfnaughty@gmail.com
authors.forename: Cheng-Chia
authors.initials: CC
authors.lastname: Lee
authors.forename: Yu-Shu
authors.initials: YS
authors.lastname: Yen
authors.forename: David Hung-Chi
authors.initials: DH
authors.lastname: Pan
authors.forename: Wen-Yuh
authors.initials: WY
authors.lastname: Chung
authors.forename: Hsin-Mei
authors.initials: HM
authors.lastname: Wu
authors.forename: Wan-Yuo
authors.initials: WY
authors.lastname: Guo
authors.forename: Ming-Te
authors.initials: MT
authors.lastname: Chen
authors.forename: Kang-Du
authors.initials: KD
authors.lastname: Liu
authors.forename: Yang-Hsin
authors.initials: YH
authors.lastname: Shih
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D019394:Ki-67 Antigen / Q000378:metabolism; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology* / Q000601:surgery*; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D009418:S100 Proteins / Q000378:metabolism; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D019394:Ki-67 Antigen; D009418:S100 Proteins
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