Vestibular schwannoma: Microsurgical dissection or the gamma knife? Results of surgery following stereotactic irradiation for acoustic neuromas. Slattery WH, Brackmann DE American Journal of Otology 1995: 16(3); 315–321

Object. The authors conducted a study to determine the optimal radiation dose for vestibular schwannoma (VS) and to examine the histopathology in cases of treatment failure for better understanding of the effects of irradiation. Methods. A retrospective study was performed of 195 patients with VS; there were 113 female and 82 male patients whose mean age was 51 years (range 11–82 years). Seventy-two patients (37%) had undergone partial or total excision of their tumor prior to gamma knife surgery (GKS). The mean tumor volume was 4.1 cm3 (range 0.04–23.1 cm3). Multiisocenter dose planning placed a prescription dose of 11 to 18.2 Gy on the 50 to 94% isodose located at the tumor margin. Clinical and magnetic resonance (MR) imaging follow-up evaluations were performed every 6 months. A loss of central enhancement was demonstrated on MR imaging in 69.5% of the patients. At the latest MR imaging assessment decreased or stable tumor volume was demonstrated in 93.6% of the patients. During a median follow-up period of 31 months resection was avoided in 96.8% of cases. Uncontrolled tumor swelling was noted in five patients at 3.5, 17, 24, 33, and 62 months after GKS, respectively. Twelve of 20 patients retained serviceable hearing. Two patients experienced a temporary facial palsy. Two patients developed a new trigeminal neuralgia. There was no treatment-related death. Histopathological examination of specimens in three cases (one at 62 months after GKS) revealed a long-lasting radiation effect on vessels inside the tumor. Conclusions. Radiosurgery had a long-term radiation effect on VSs for up to 5 years. A margin 12-Gy dose with homogeneous distribution is effective in preventing tumor progression, while posing no serious threat to normal cranial nerve function.

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Tufts Medical Center Experience with Long Term Follow up of Vestibular Schwannoma Treated with Gamma Knife Stereotactic Radiosurgery: Novel Finding of Delayed Pseudoprogression

Advances in Radiation Oncology ◽

10.1016/j.adro.2021.100687 ◽

2021 ◽

pp. 100687

Author(s):

Justin Wage ◽

John Mignano ◽

Julian Wu

Keyword(s):

Stereotactic Radiosurgery ◽

Gamma Knife ◽

Vestibular Schwannoma ◽

Medical Center ◽

Long Term Follow Up ◽

Gamma Knife Stereotactic Radiosurgery

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Fractionated gamma knife for vestibular schwannoma

Otolaryngology ◽

10.1016/j.otohns.2009.06.245 ◽

2009 ◽

Vol 141 (3) ◽

pp. P80-P80

Author(s):

Nitin Bhatia ◽

Sheri Dewan ◽

Brian Duff ◽

Georg Noren

Keyword(s):

Gamma Knife ◽

Vestibular Schwannoma

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Microsurgery for vestibular schwannoma after Gamma Knife surgery: challenges and treatment strategies

Journal of Neurosurgery ◽

10.3171/2014.8.gks141312 ◽

2014 ◽

Vol 121 (Suppl_2) ◽

pp. 150-159 ◽

Cited By ~ 10

Author(s):

Cheng-Chia Lee ◽

Hsiu-Mei Wu ◽

Wen-Yuh Chung ◽

Ching-Jen Chen ◽

David Hung-Chi Pan ◽

...

Keyword(s):

Gamma Knife ◽

Vestibular Schwannoma ◽

Radiation Effects ◽

Tumor Resection ◽

Treatment Strategies ◽

Gamma Knife Surgery ◽

Neurological Outcomes ◽

Radiological Changes ◽

Cyst Development

ObjectResection of vestibular schwannoma (VS) after Gamma Knife surgery (GKS) is infrequently performed. The goals of this study were to analyze and discuss the neurological outcomes and technical challenges of VS resection and to explore strategies for treating tumors that progress after GKS.MethodsIn total, 708 patients with VS underwent GKS between 1993 and 2012 at Taipei Veterans General Hospital. The post-GKS clinical courses, neurological presentations, and radiological changes in these patients were analyzed. Six hundred patients with imaging follow-up of at least 1 year after GKS treatment were included in this study.ResultsThirteen patients (2.2%) underwent microsurgery on average 36.8 months (range 3–107 months) after GKS. The indications for the surgery included symptomatic adverse radiation effects (in 4 patients), tumor progression (in 6), and cyst development (in 3). No morbidity or death as a result of the surgery was observed. At the last follow-up evaluation, all patients, except 1 patient with a malignant tumor, had stable or near-normal facial function.ConclusionsFor the few VS cases that require resection after radiosurgery, maximal tumor resection can be achieved with modern skull-based techniques and refined neuromonitoring without affecting facial nerve function.

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Results of Outpatient Gamma Knife Radiosurgery for Primary Therapy of Acoustic Neuromas

Gamma Knife Radiosurgery ◽

10.1007/978-3-7091-0583-2_8 ◽

2004 ◽

pp. 75-78 ◽

Cited By ~ 8

Author(s):

Alexander Muacevic ◽

A. Jess-Hempen ◽

J. C. Tonn ◽

B. Wowra

Keyword(s):

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Primary Therapy ◽

Acoustic Neuromas

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Gamma Knife Radiosurgery does not alter the copy number aberration profile in sporadic vestibular schwannoma

Journal of Neuro-Oncology ◽

10.1007/s11060-020-03631-4 ◽

2020 ◽

Vol 149 (3) ◽

pp. 373-381

Author(s):

Aril Løge Håvik ◽

Ove Bruland ◽

Dhanushan Dhayalan ◽

Morten Lund-Johansen ◽

Per-Morten Knappskog

Keyword(s):

Radiation Exposure ◽

Gamma Knife ◽

Vestibular Schwannoma ◽

Copy Number ◽

Statistical Tests ◽

Gamma Knife Radiosurgery ◽

Copy Number Aberration ◽

Recurrent Event ◽

Chromosome 22 ◽

Increased Risk

Abstract Introduction Ionizing radiation is a known etiologic factor in tumorigenesis and its role in inducing malignancy in the treatment of vestibular schwannoma has been debated. The purpose of this study was to identify a copy number aberration (CNA) profile or specific CNAs associated with radiation exposure which could either implicate an increased risk of malignancy or elucidate a mechanism of treatment resistance. Methods 55 sporadic VS, including 18 treated with Gamma Knife Radiosurgery (GKRS), were subjected to DNA whole-genome microarray and/or whole-exome sequencing. CNAs were called and statistical tests were performed to identify any association with radiation exposure. Hierarchical clustering was used to identify CNA profiles associated with radiation exposure. Results A median of 7 (0–58) CNAs were identified across the 55 VS. Chromosome 22 aberration was the only recurrent event. A median aberrant cell fraction of 0.59 (0.25–0.94) was observed, indicating several genetic clones in VS. No CNA or CNA profile was associated with GKRS. Conclusion GKRS is not associated with an increase in CNAs or alteration of the CNA profile in VS, lending support to its low risk. This also implies that there is no major issue with GKRS treatment failure being due to CNAs. In agreement with previous studies, chromosome 22 aberration is the only recurrent CNA. VS consist of several genetic clones, addressing the need for further studies on the composition of cells in this tumor.

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Clinical experience of 300 vestibular schwannoma treated by gamma knife radiosurgery using a 12-Gy margin dose

Surgical Neurology ◽

10.1016/j.surneu.2008.10.021 ◽

2009 ◽

Vol 71 (1) ◽

pp. 136-137

Author(s):

N. Massager ◽

S. Lonneville ◽

C. Delbrouck ◽

L. Abeloos ◽

D. Devriendt ◽

...

Keyword(s):

Gamma Knife ◽

Clinical Experience ◽

Vestibular Schwannoma ◽

Gamma Knife Radiosurgery

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Hearing preservation in patients with vestibular schwannoma treated with Gamma Knife surgery

Journal of Neurosurgery ◽

10.3171/2012.10.jns12880 ◽

2013 ◽

Vol 118 (3) ◽

pp. 571-578 ◽

Cited By ~ 40

Author(s):

Andrew M. Baschnagel ◽

Peter Y. Chen ◽

Dennis Bojrab ◽

Daniel Pieper ◽

Jack Kartush ◽

...

Keyword(s):

Hearing Loss ◽

Gamma Knife ◽

Vestibular Schwannoma ◽

Hearing Preservation ◽

Gamma Knife Surgery ◽

Speech Discrimination ◽

Before And After ◽

Nerve Dysfunction ◽

Preservation Rate

Object Hearing loss after Gamma Knife surgery (GKS) in patients with vestibular schwannoma has been associated with radiation dose to the cochlea. The purpose of this study was to evaluate serviceable hearing preservation in patients with VS who were treated with GKS and to determine if serviceable hearing loss can be correlated with the dose to the cochlea. Methods Forty patients with vestibular schwannoma with serviceable hearing were treated using GKS with a median marginal dose of 12.5 Gy (range 12.5–13 Gy) to the 50% isodose volume. Audiometry was performed prospectively before and after GKS at 1, 3, and 6 months, and then every 6 months thereafter. Hearing preservation was based on pure tone average (PTA) and speech discrimination (SD). Serviceable hearing was defined as PTA less than 50 dB and SD greater than 50%. Results The median cochlear maximum and mean doses were 6.9 Gy (range 1.6–16 Gy) and 2.7 Gy (range 0.7–5.0 Gy), respectively. With a median audiological follow-up of 35 months (range 6–58 months), the 1-, 2-, and 3-year actuarial rates of maintaining serviceable hearing were 93%, 77%, and 74%, respectively. No patient who received a mean cochlear dose less than 2 Gy experienced serviceable hearing loss (p = 0.035). Patients who received a mean cochlear dose less than 3 Gy had a 2-year hearing preservation rate of 91% compared with 59% in those who received a mean cochlear dose of 3 Gy or greater (p = 0.029). Those who had more than 25% of their cochlea receiving 3 Gy or greater had a higher rate of hearing loss (p = 0.030). There was no statistically significant correlation between serviceable hearing loss and age, tumor size, pre-GKS PTA, pre-GKS SD, pre-GKS Gardner-Robertson class, maximum cochlear dose, or the percentage of cochlear volume receiving 5 Gy. On multivariate analysis there was a trend toward significance for serviceable hearing loss with a mean cochlear dose of 3 Gy or greater (p = 0.074). Local control was 100% at 24 months. No patient developed facial or trigeminal nerve dysfunction. Conclusions With a median mean cochlear dose of 2.7 Gy, the majority of patients with serviceable hearing retained serviceable hearing 3 years after GKS. A mean cochlear dose less than 3 Gy was associated with higher serviceable hearing preservation.

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