Gamma Knife radiosurgery for larger-volume vestibular schwannomas

Clinical article

Restricted access


Stereotactic radiosurgery (SRS) is an important management option for patients with small- and medium-sized vestibular schwannomas. To assess the potential role of SRS in larger tumors, the authors reviewed their recent experience.


Between 1994 and 2008, 65 patients with vestibular schwannomas between 3 and 4 cm in one extracanalicular maximum diameter (median tumor volume 9 ml) underwent Gamma Knife surgery. Seventeen patients (26%) had previously undergone resection.


The median follow-up duration was 36 months (range 1–146 months). At the first planned imaging follow-up at 6 months, 5 tumors (8%) were slightly expanded, 53 (82%) were stable in size, and 7 (11%) were smaller. Two patients (3%) underwent resection within 6 months due to progressive symptoms. Two years later, with 63 tumors overall after the 2 post-SRS resections, 16 tumors (25%) had a volume reduction of more than 50%, 22 (35%) tumors had a volume reduction of 10–50%, 18 (29%) were stable in volume (volume change < 10%), and 7 (11%) had larger volumes (5 of the 7 patients underwent resection and 1 of the 7 underwent repeat SRS). Eighteen (82%) of 22 patients with serviceable hearing before SRS still had serviceable hearing after SRS more than 2 years later. Three patients (5%) developed symptomatic hydrocephalus and underwent placement of a ventriculoperitoneal shunt. In 4 patients (6%) trigeminal sensory dysfunction developed, and in 1 patient (2%) mild facial weakness (House-Brackmann Grade II) developed after SRS. In univariate analysis, patients who had a previous resection (p = 0.010), those with a tumor volume exceeding 10 ml (p = 0.05), and those with Koos Grade 4 tumors (p = 0.02) had less likelihood of tumor control after SRS.


Although microsurgical resection remains the primary management choice in patients with low comorbidities, most vestibular schwannomas with a maximum diameter less than 4 cm and without significant mass effect can be managed satisfactorily with Gamma Knife radiosurgery.

Abbreviations used in this paper: ARE = adverse radiation effect; ICP = intracranial pressure; SRS = stereotactic radiosurgery.

Article Information

Address correspondence to: Douglas Kondziolka, M.D., University of Pittsburgh, Suite B-400, UPMC Presbyterian, 200 Lothrop Street, Pittsburgh, Pennsylvania 15213. email:

Please include this information when citing this paper: published online August 27, 2010; DOI: 10.3171/2010.8.JNS10674.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Axial MR images obtained in a 71-year-old man with Grade II hearing and facial numbness who underwent SRS for a vestibular schwannoma. A: Image obtained at the time of the initial radiosurgical procedure. B: Image obtained 6 months after radiosurgery showing loss of central contrast enhancement C: Image obtained 3 years after radiosurgery demonstrating a significant reduction in tumor volume.

  • View in gallery

    Upper: Kaplan-Meier curves comparing tumor control rates after SRS for tumor volume either ≥ 10 or < 10 ml. The smaller-volume tumors were significantly associated with better tumor control rate (p = 0.05). Lower: Kaplan-Meier curves comparing tumor control rate after SRS for patients with and without facial weakness. Patients with no facial weakness were significantly associated with a better tumor control rate (p = 0.05).

  • View in gallery

    Upper: Kaplan-Meier curves comparing tumor control rate after SRS for patients with and without a history of resection. No previous resection was significantly associated with better tumor control rate (p = 0.01). Lower: Kaplan-Meier curves comparing tumor control rate after SRS for Koos Grade 3 versus Grade 4 tumors. Koos Grade 3 tumors were significantly associated with better tumor control rate (p = 0.02).


  • 1

    Chung WYLiu KDShiau CYWu HMWang LWGuo WY: Gamma knife surgery for vestibular schwannoma: 10-year experience of 195 cases. J Neurosurg 102:Suppl87962005

  • 2

    Cohen RJ: Acoustic neuroma: summary of the NIH consensus. Md Med J 41:112811301992

  • 3

    Combs SEThilmann CDebus JSchulz-Ertner D: Long-term outcome of stereotactic radiosurgery (SRS) in patients with acoustic neuromas. Int J Radiat Oncol Biol Phys 64:134113472006

  • 4

    Flickinger JCKondziolka DNiranjan ALunsford LD: Results of acoustic neuroma radiosurgery: an analysis of 5 years' experience using current methods. J Neurosurg 94:162001

  • 5

    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

  • 6

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

  • 7

    Godefroy WPvan der Mey AGde Bruine FTHoekstra ERMalessy MJ: Surgery for large vestibular schwannoma: residual tumor and outcome. Otol Neurotol 30:6296342009

  • 8

    Gormley WBSekhar LNWright DCKamerer DSchessel D: Acoustic neuromas: results of current surgical management. Neurosurgery 41:50601997

  • 9

    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

  • 10

    House JWBrackmann DE: Facial nerve grading system. Otolaryngol Head Neck Surg 93:1461471985

  • 11

    Inoue HK: Low-dose radiosurgery for large vestibular schwannomas: long-term results of functional preservation. J Neurosurg 102:Suppl1111132005

  • 12

    Jung SKang SSKim TSKim HJJeong SKKim SC: Current surgical results of retrosigmoid approach in extralarge vestibular schwannomas. Surg Neurol 53:3703782000

  • 13

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

  • 14

    Kondziolka DLunsford LDFlickinger JC: Acoustic neuroma radiosurgery. Origins, contemporary use and future expectations. Neurochirurgie 50:4274352004

  • 15

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

  • 16

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

  • 17

    Lanman THBrackmann DEHitselberger WESubin B: Report of 190 consecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach. J Neurosurg 90:6176231999

  • 18

    Leksell L: A note on the treatment of acoustic tumours. Acta Chir Scand 137:7637651971

  • 19

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

  • 20

    McElveen JT JrBelmonte RGFukushima TBullard DE: A review of facial nerve outcome in 100 consecutive cases of acoustic tumor surgery. Laryngoscope 110:166716722000

  • 21

    Park CKJung HWKim JESon YJPaek SHKim DG: Therapeutic strategy for large vestibular schwannomas. J Neurooncol 77:1671712006

  • 22

    Pollock BELunsford LDFlickinger JCClyde BLKondziolka D: Vestibular schwannoma management. Part I. Failed microsurgery and the role of delayed stereotactic radiosurgery. J Neurosurg 89:9449481998

  • 23

    Pollock BELunsford LDKondziolka DSekula RSubach BRFoote RL: Vestibular schwannoma management. Part II. Failed radiosurgery and the role of delayed microsurgery. J Neurosurg 89:9499551998

  • 24

    Régis JPellet WDelsanti CDufour HRoche PHThomassin JM: Functional outcome after gamma knife surgery or microsurgery for vestibular schwannomas. J Neurosurg 97:109111002002

  • 25

    Samii MGerganov VSamii A: Improved preservation of hearing and facial nerve function in vestibular schwannoma surgery via the retrosigmoid approach in a series of 200 patients. J Neurosurg 105:5275352006

  • 26

    Samii MMatthies C: Management of 1000 vestibular schwannomas (acoustic neuromas): hearing function in 1000 tumor resections. Neurosurgery 40:2482621997

  • 27

    Samii MMatthies C: Management of 1000 vestibular schwannomas (acoustic neuromas): the facial nerve—preservation and restitution of function. Neurosurgery 40:6846951997

  • 28

    Schulder MSreepada GSKwartler JACho ES: Microsurgical removal of a vestibular schwannoma after stereotactic radiosurgery: surgical and pathologic findings. Am J Otol 20:3643681999

  • 29

    Wanibuchi MFukushima TMcElveen JT JrFriedman AH: Hearing preservation in surgery for large vestibular schwannomas. Clinical article. J Neurosurg 111:8458542009

  • 30

    Yamakami IUchino YKobayashi EYamaura AOka N: Removal of large acoustic neurinomas (vestibular schwannomas) by the retrosigmoid approach with no mortality and minimal morbidity. J Neurol Neurosurg Psychiatry 75:4534582004




All Time Past Year Past 30 Days
Abstract Views 279 279 99
Full Text Views 178 178 3
PDF Downloads 124 124 1
EPUB Downloads 0 0 0


Google Scholar