Gamma Knife Radiosurgery for Large Vestibular Schwannomas: A Canadian Experience

Zeiler, Frederick A.; Bigder, Mark; Kaufmann, Anthony M.; McDonald, Patrick J.; Fewer, Derek; Butler, James; Schroeder, G.; West, Michaline

doi:10.1017/s0317167100014281

Cited by 26 publications

(23 citation statements)

References 19 publications

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“…Although radiosurgery has been reported to produce similar facial nerve outcomes for Koos grade 3 tumors (mean volume 9 cm 3 ), its role in the context of large vestibular schwannomas remains controversial and it may be indicated only in patients with minimal symptoms of brainstem compression, surgical contraindications, or significant residual tumor mass despite attempted debulking. 4,15,25,41,43,44,47,50 A proposal to stage large vestibular schwannomas between 2 surgeries has been shown to improve facial nerve outcome and morbidity. 30 Staging the tumor resection was decided intraoperatively if there was cerebellar or The extent of resection is another important factor, with several studies demonstrating significantly lower rates of recurrence with complete or near-complete resections compared with subtotal or partial debulking.…”

Section: Discussionmentioning

confidence: 99%

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

Hoshide

Faulkner

Teo³

et al. 2018

Neurosurgical Focus

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OBJECTIVEThere are numerous treatment strategies in the management for large vestibular schwannomas, including resection only, staged resections, resections followed by radiosurgery, and radiosurgery only. Recent evidence has pointed toward maximal resection as being the optimum strategy to prevent tumor recurrence; however, durable tumor control through aggressive resection has been shown to occur at the expense of facial nerve function and to risk other approach-related complications. Through a retrospective analysis of their single-institution series of keyhole neurosurgical approaches for large vestibular schwannomas, the authors aim to report and justify key techniques to maximize tumor resection and reduce surgical morbidity.METHODSA retrospective chart review was performed at the Centre for Minimally Invasive Neurosurgery. All patients who had undergone a keyhole retrosigmoid approach for the resection of large vestibular schwannomas, defined as having a tumor diameter of ≥ 3.0 cm, were included in this review. Patient demographics, preoperative cranial nerve status, perioperative data, and postoperative follow-up were obtained. A review of the literature for resections of large vestibular schwannomas was also performed. The authors’ institutional data were compared with the historical data from the literature.RESULTSBetween 2004 and 2017, 45 patients met the inclusion criteria for this retrospective chart review. When compared with findings in a historical cohort in the literature, the authors’ minimally invasive, keyhole retrosigmoid technique for the resection of large vestibular schwannomas achieved higher rates of gross-total or near-total resection (100% vs 83%). Moreover, these results compare favorably with the literature in facial nerve preservation (House-Brackmann I–II) at follow-up after gross-total resections (81% vs 47%, p < 0.001) and near-total resections (88% vs 75%, p = 0.028). There were no approach-related complications in this series.CONCLUSIONSIt is the experience of the senior author that complete or near-complete resection of large vestibular schwannomas can be successfully achieved via a keyhole approach. In this series of 45 large vestibular schwannomas, a greater extent of resection was achieved while demonstrating high rates of facial nerve preservation and low approach-related and postoperative complications compared with the literature.

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Section: Discussionmentioning

confidence: 99%

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

Hoshide

Faulkner

Teo³

et al. 2018

Neurosurgical Focus

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“…Prior to CK, the median maximal diameter and reported volume for solid and cystic tumors were 3.3 cm and 9.2 cm 3 , compared to 3.3 cm and 8.9 cm 3 , respectively ( Table 1). SRS was delivered in three equal fractions (N=29) over the course of 3 days, to a median prescription dose of 18 Gy (range [18][19][20][21][22][23][24][25] prescribed to median 80% (range 71-M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 90) isodose line (radiobiologically equivalent to a 11.3-Gy single dose, using the linear-quadratic model and α/β ratio of 3 as previously described). 28,36 The cystic tumor of greatest volume was treated with 5 fractions given its still large residual complexity with multiple cystic components after resection.…”

Section: Radiosurgery Treatment Planmentioning

confidence: 99%

“…37 Compilation of the relevant literatures on the outcome of VS of at least Koos Grade III treated by radiosurgery, the overall progression free survival rates range from 82-100% at long-term follow-up (Table 4). 12,29,30,33,[37][38][39][40][41] The available evidence suggested that large VSs are potentially amenable to primary SRS therapy, but there may still be poor tumor control in the largest of tumors. We confirmed this relationship when further stratifying our cohort by volume, with tumors < 15 cm 3 associating with better control rates.…”

Section: Tumor Control: Radiosurgery As An Optionmentioning

confidence: 99%

“…From the available evidence, approximately 85-88% of treatment naïve large VS have been controlled with SRS. 12,29,39 When looking at reports on strictly adjuvant SRS, Pan et al found a control rate of up to 100% for both preceding intracapsular decompression and radical extracapsular resection. 40 In another report, van de Langenberg et al found a control rate of 90% and a clinical control rate of 92% in 50 cases.…”

Section: Tumor Control: Radiosurgery As An Optionmentioning

confidence: 99%

“…15,16 Thus, partial resections with SRS has become a promising strategy to minimize complications, while providing high tumor control in 82-93% of cases at five years follow-up. 12,[17][18][19][20][21][22] However, there remains a cohort of patients with large VS who are relatively asymptomatic or with minimal symptoms despite brainstem compression, those who are non-ideal surgical candidates, or those with very large residual tumors despite attempted surgical debulking. The aim of this study is to therefore evaluate the outcome of this group of patients after SRS.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Outcome of Hypofractionated Stereotactic Radiosurgery for Large Vestibular Schwannomas

Teo

Zhang

et al. 2016

World Neurosurgery

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Prediction of transient tumor enlargement using MRI tumor texture after radiosurgery on vestibular schwannoma

et al. 2020

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Purpose: Vestibular schwannomas (VSs) are uncommon benign brain tumors, generally treated using Gamma Knife radiosurgery (GKRS). However, due to the possible adverse effect of transient tumor enlargement (TTE), large VS tumors are often surgically removed instead of treated radiosurgically. Since microsurgery is highly invasive and results in a significant increased risk of complications, GKRS is generally preferred. Therefore, prediction of TTE for large VS tumors can improve overall VS treatment and enable physicians to select the most optimal treatment strategy on an individual basis. Currently, there are no clinical factors known to be predictive for TTE. In this research, we aim at predicting TTE following GKRS using texture features extracted from MRI scans. Methods: We analyzed clinical data of patients with VSs treated at our Gamma Knife center. The data was collected prospectively and included patient-and treatment-related characteristics and MRI scans obtained at day of treatment and at follow-up visits, 6, 12, 24 and 36 months after treatment. The correlations of the patient-and treatment-related characteristics to TTE were investigated using statistical tests. From the treatment scans, we extracted the following MRI image features: first-order statistics, Minkowski functionals (MFs), and three-dimensional gray-level co-occurrence matrices (GLCMs). These features were applied in a machine learning environment for classification of TTE, using support vector machines. Results: In a clinical data set, containing 61 patients presenting obvious non-TTE and 38 patients presenting obvious TTE, we determined that patient-and treatment-related characteristics do not show any correlation to TTE. Furthermore, first-order statistical MRI features and MFs did not significantly show prognostic values using support vector machine classification. However, utilizing a set of 4 GLCM features, we achieved a sensitivity of 0.82 and a specificity of 0.69, showing their prognostic value of TTE. Moreover, these results increased for larger tumor volumes obtaining a sensitivity of 0.77 and a specificity of 0.89 for tumors larger than 6 cm 3 . Conclusions: The results found in this research clearly show that MRI tumor texture provides information that can be employed for predicting TTE. This can form a basis for individual VS treatment selection, further improving overall treatment results. Particularly in patients with large VSs, where the phenomenon of TTE is most relevant and our predictive model performs best, these findings can be implemented in a clinical workflow such that for each patient, the most optimal treatment strategy can be determined.

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Gamma Knife Radiosurgery for Large Vestibular Schwannomas: A Canadian Experience

Cited by 26 publications

References 19 publications

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

The Outcome of Hypofractionated Stereotactic Radiosurgery for Large Vestibular Schwannomas

Prediction of transient tumor enlargement using MRI tumor texture after radiosurgery on vestibular schwannoma

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