Factors associated with hearing preservation after Gamma Knife surgery for vestibular schwannomas in patients who retain serviceable hearing

Clinical article

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Gamma Knife surgery (GKS) has been a safe and effective treatment for small- to medium-sized vestibular schwannomas (VSs) over relatively long-term outcomes. However, even with recent radiosurgical techniques, hearing results following GKS remain unsatisfactory. The purpose of this study was to evaluate the hearing preservation rate as well as factors related to hearing preservation in patients with VSs and serviceable hearing who were treated with GKS.


Among patients with Gardner-Robertson (GR) Class I or II serviceable hearing and VSs treated with GKS between 1991 and 2009, 117 were evaluable via periodic MR imaging and audiometry.


The median age at the time of GKS was 52 years. Four patients (3%) had undergone prior surgery. Fifty-six patients (48%) had GR Class I hearing and 61 (52%) had GR Class II hearing at the time of GKS. The median tumor volume was 1.9 cm3. The median maximum and tumor margin radiation doses were 24 and 12 Gy, respectively. The median follow-up periods for MR imaging and audiometry were 74 and 38 months, respectively. The overall tumor control rate was 97.5%. Actuarial 3-, 5-, and 8-year hearing preservation rates were 55%, 43%, and 34%, respectively. On multivariate analysis, GR hearing class at the time of GKS and the mean cochlear dose affected hearing preservation significantly. In a limited number of patients who were treated using the most recent dose planning techniques and who had GR Class I hearing before treatment, the 3- and 5-year hearing preservation rates increased to 80% and 70%, respectively.


For the majority of patients with small- to medium-sized VSs, GKS was an effective and reasonable alternative to resection with satisfactory long-term tumor control. Factors related to hearing preservation included a GR Class I hearing pre-GKS and a lower mean cochlear radiation dose. To retain serviceable hearing, it is important to apply GKS treatment while patients retain GR Class I hearing.

Abbreviations used in this paper: D95 = radiation dose that includes 95% of the planning target volume; GKS = Gamma Knife surgery; GR = Gardner-Robertson; PTA = pure tone average; SRS = stereotactic radiosurgery; VS = vestibular schwannoma.

Article Information

Address correspondence to: Toshinori Hasegawa, M.D., Department of Neurosurgery, Komaki City Hospital, Gamma Knife Center, 1-20 Jobushi, Komaki, Aichi Prefecture, 485-8520, Japan. email: h-toshi@komakihp.gr.jp.

Please include this information when citing this paper: published online August 26, 2011; DOI: 10.3171/2011.7.JNS11749.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    After delineation of the cochlea on heavy T2-weighted MR images, the maximum and mean cochlear doses were shown by volume calculation of the cochlea (white square) using GammaPlan.

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    The distance from the meatal fundus to the tumor end (white square) was obtained by drawing a line (arrow) with GammaPlan.

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    Kaplan-Meier curve demonstrating the tumor expansion rate.

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    Graph showing the time courses for the median PTAs on the tumor side and the normal side. GKRS = Gamma Knife radiosurgery; N = number of patients; Y = year(s).

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    Graph showing the time courses for the differences between the pre- and post-GKS PTAs on the tumor side and the normal side.

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    Kaplan-Meier curve demonstrating the hearing preservation rates plotted against time.

  • View in gallery

    Kaplan-Meier curves demonstrating the hearing preservation rates depending on the GR classification (Class I vs II, upper) and the mean cochlear dose (< 6 vs ≥ 6 Gy, lower).



Arthurs BJFairbanks RKDemakas JJLamoreaux WTGiddings NAMackay AR: A review of treatment modalities for vestibular schwannoma. Neurosurg Rev 34:2652792011


Battaglia AMastrodimos BCueva R: Comparison of growth patterns of acoustic neuromas with and without radiosurgery. Otol Neurotol 27:7057122006


Bhandare NJackson AEisbruch APan CCFlickinger JCAntonelli P: Radiation therapy and hearing loss. Int J Radiat Oncol Biol Phys 76:3 SupplS50S572010


Bloch OSughrue MEKaur RKane AJRutkowski MJKaur G: Factors associated with preservation of facial nerve function after surgical resection of vestibular schwannoma. J Neurooncol 102:2812862011


Chopra RKondziolka DNiranjan ALunsford LDFlickinger JC: Long-term follow-up of acoustic schwannoma radiosurgery with marginal tumor doses of 12 to 13 Gy. Int J Radiat Oncol Biol Phys 68:8458512007


Emami BLyman JBrown ACoia LGoitein MMunzenrider JE: Tolerance of normal tissue to therapeutic irradiation. Int J Radiat Oncol Biol Phys 21:1091221991


Flickinger JCKondziolka DNiranjan AMaitz AVoynov GLunsford LD: Acoustic neuroma radiosurgery with marginal tumor doses of 12 to 13 Gy. Int J Radiat Oncol Biol Phys 60:2252302004


Foote RLCoffey RJSwanson JWHarner SGBeatty CWKline RW: Stereotactic radiosurgery using the gamma knife for acoustic neuromas. Int J Radiat Oncol Biol Phys 32:115311601995


Franzin ASpatola GSerra CPicozzi PMedone MMilani D: Evaluation of hearing function after Gamma Knife surgery of vestibular schwannomas. Neurosurg Focus 27:6E32009


Gardner GRobertson JH: Hearing preservation in unilateral acoustic neuroma surgery. Ann Otol Rhinol Laryngol 97:55661988


Gerosa MMesiano NLonghi MDe Simone AForoni RVerlicchi A: Gamma Knife surgery in vestibular schwannomas: impact on the anterior and posterior labyrinth. J Neurosurg 113:Suppl1281352010


Hasegawa TFujitani SKatsumata SKida YYoshimoto MKoike J: Stereotactic radiosurgery for vestibular schwannomas: analysis of 317 patients followed more than 5 years. Neurosurgery 57:2572652005


Hasegawa TKida YKobayashi TYoshimoto MMori YYoshida J: Long-term outcomes in patients with vestibular schwannomas treated using gamma knife surgery: 10-year follow up. J Neurosurg 102:10162005


Kano HKondziolka DKhan AFlickinger JCLunsford LD: Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma. Clinical article. J Neurosurg 111:8638732009


Kim CHChung KWKong DSNam DHPark KKim JH: Prognostic factors of hearing preservation after gamma knife radiosurgery for vestibular schwannoma. J Clin Neurosci 17:2142182010


Kondziolka DLunsford LDMcLaughlin MRFlickinger JC: Long-term outcomes after radiosurgery for acoustic neuromas. N Engl J Med 339:142614331998


Kondziolka DNathoo NFlickinger JCNiranjan AMaitz AHLunsford LD: Long-term results after radiosurgery for benign intracranial tumors. Neurosurgery 53:8158222003


Koos WTDay JDMatula CLevy DI: Neurotopographic considerations in the microsurgical treatment of small acoustic neurinomas. J Neurosurg 88:5065121998


Lobato-Polo JKondziolka DZorro OKano HFlickinger JCLunsford LD: Gamma knife radiosurgery in younger patients with vestibular schwannomas. Neurosurgery 65:2943012009


Lunsford LDNiranjan AFlickinger JCMaitz AKondziolka D: Radiosurgery of vestibular schwannomas: summary of experience in 829 cases. J Neurosurg 102:Suppl1951992005


Massager NNissim ODelbrouck CDevriendt DDavid PDesmedt F: Role of intracanalicular volumetric and dosimetric parameters on hearing preservation after vestibular schwannoma radiosurgery. Int J Radiat Oncol Biol Phys 64:133113402006


Norén GGreitz DHirsch ALax I: Gamma knife surgery in acoustic tumours. Acta Neurochir Suppl (Wien) 58:1041071993


Paek SHChung HTJeong SSPark CKKim CYKim JE: Hearing preservation after gamma knife stereotactic radiosurgery of vestibular schwannoma. Cancer 104:5805902005


Pan CCEisbruch ALee JSSnorrason RMTen Haken RKKileny PR: Prospective study of inner ear radiation dose and hearing loss in head-and-neck cancer patients. Int J Radiat Oncol Biol Phys 61:139314022005


Petit JHHudes RSChen TTEisenberg HMSimard JMChin LS: Reduced-dose radiosurgery for vestibular schwannomas. Neurosurgery 49:129913072001


Pollock BEDriscoll CLFoote RLLink MJGorman DABauch CD: Patient outcomes after vestibular schwannoma management: a prospective comparison of microsurgical resection and stereotactic radiosurgery. Neurosurgery 59:77852006


Prasad DSteiner MSteiner L: Gamma surgery for vestibular schwannoma. J Neurosurg 92:7457592000


Régis JCarron RPark MCSoumare ODelsanti CThomassin JM: Wait-and-see strategy compared with proactive Gamma Knife surgery in patients with intracanalicular vestibular schwannomas. J Neurosurg 113:Suppl1051112010


Régis JRoche PHDelsanti CThomassin JMOuaknine MGabert K: Modern management of vestibular schwannomas. Prog Neurol Surg 20:1291412007


Smouha EEYoo MMohr KDavis RP: Conservative management of acoustic neuroma: a meta-analysis and proposed treatment algorithm. Laryngoscope 115:4504542005


Sughrue MEYang IAranda DLobo KPitts LHCheung SW: The natural history of untreated sporadic vestibular schwannomas: a comprehensive review of hearing outcomes. Clinical article. J Neurosurg 112:1631672010


Tamura MCarron RYomo SArkha YMuraciolle XPorcheron D: Hearing preservation after gamma knife radiosurgery for vestibular schwannomas presenting with highlevel hearing. Neurosurgery 64:2892962009


Timmer FCHanssens PEvan Haren AEMulder JJCremers CWBeynon AJ: Gamma knife radiosurgery for vestibular schwannomas: results of hearing preservation in relation to the cochlear radiation dose. Laryngoscope 119:107610812009


Whitmore RGUrban CChurch ERuckenstein MStein SCLee JY: Decision analysis of treatment options for vestibular schwannoma. Clinical article. J Neurosurg 114:4004132011


Wowra BMuacevic AJess-Hempen AHempel JMMüller-Schunk STonn JC: Outpatient gamma knife surgery for vestibular schwannoma: definition of the therapeutic profile based on a 10-year experience. J Neurosurg 102:Suppl1141182005


Yamakami IUchino YKobayashi EYamaura A: Conservative management, gamma-knife radiosurgery, and microsurgery for acoustic neurinomas: a systematic review of outcome and risk of three therapeutic options. Neurol Res 25:6826902003


Yang IAranda DHan SJChennupati SSughrue MECheung SW: Hearing preservation after stereotactic radiosurgery for vestibular schwannoma: a systematic review. J Clin Neurosci 16:7427472009


Yoshimoto Y: Systematic review of the natural history of vestibular schwannoma. J Neurosurg 103:59632005


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