Cystic Vestibular Schwannomas and Post–Gamma Knife Radiosurgery-Induced Necrosis of Vestibular Schwannomas: Report of Two Cases and Review of Literature

AbstractCystic vestibular schwannomas (VS) form a rare subgroup that differs from the solid variant clinically and radiologically. Certain unique features reported in cystic VS are larger size, presentation with atypical initial symptoms such as dysgeusia, vertigo, facial pain and gait unsteadiness, short duration of symptoms, rapid progression of symptoms or sudden deterioration and frequent involvement of facial nerve. Gamma Knife radiosurgery (GKRS) is a safe and effective treatment for VS, achieving tumor control and resulting in a very low morbidity rate. Here, we described two cases of cystic vestibular schwannomas prior to GKRS and their radiological appearances post-GKRS.

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Long-term outcomes of Gamma Knife radiosurgery in patients with vestibular schwannomas

Journal of Neurosurgery ◽

10.3171/2009.12.jns091339 ◽

2011 ◽

Vol 114 (2) ◽

pp. 432-440 ◽

Cited By ~ 51

Author(s):

Erin S. Murphy ◽

Gene H. Barnett ◽

Michael A. Vogelbaum ◽

Gennady Neyman ◽

Glen H. J. Stevens ◽

...

Keyword(s):

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Tumor Diameter ◽

Long Term Effects ◽

Median Dose ◽

The Mean

Object The authors sought to determine the long-term tumor control and side effects of Gamma Knife radiosurgery (GKRS) in patients with vestibular schwannomas (VS). Methods One hundred seventeen patients with VS underwent GKRS between January 1997 and February 2003. At the time of analysis, at least 5 years had passed since GKRS in all patients. The mean patient age was 60.9 years. The mean maximal tumor diameter was 1.77 ± 0.71 cm. The mean tumor volume was 1.95 ± 2.42 ml. Eighty-two percent of lesions received 1300 cGy and 14% received 1200 cGy. The median dose homogeneity ratio was 1.97 and the median dose conformality ratio was 1.78. Follow-up included MR imaging or CT scanning approximately every 6–12 months. Rates of progression to surgery were calculated using the Kaplan-Meier method. Results Of the 117 patients in whom data were analyzed, 103 had follow-up MR or CT images and 14 patients were lost to follow-up. Fifty-three percent of patients had stable tumors and 37.9% had a radiographically documented response. Imaging-documented tumor progression was present in 8 patients (7.8%), but in 3 of these the lesion eventually stabilized. Only 5 patients required a neurosurgical intervention. The estimated 1-, 3-, and 5-year rates of progression to surgery were 1, 4.6, and 8.9%, respectively. One patient (1%) developed trigeminal neuropathy, 4 patients (5%) developed permanent facial neuropathy, 3 patients (4%) reported vertigo, and 7 patients (18%) had new gait imbalance following GKRS. Conclusions Gamma Knife radiosurgery results in excellent local control rates with minimal toxicity for patients with VS. The authors recommend standardized follow-up to gain a better understanding of the long-term effects of GKRS.

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Gamma Knife radiosurgery for treatment of growing vestibular schwannomas in patients with neurofibromatosis Type 2: a matched cohort study with sporadic vestibular schwannomas

Journal of Neurosurgery ◽

10.3171/2016.9.jns161463 ◽

2018 ◽

Vol 128 (1) ◽

pp. 49-59 ◽

Cited By ~ 11

Author(s):

Ivo J. Kruyt ◽

Jeroen B. Verheul ◽

Patrick E. J. Hanssens ◽

Henricus P. M. Kunst

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Gamma Knife Radiosurgery ◽

Neurofibromatosis Type ◽

Hearing Preservation ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Nerve Function

OBJECTIVENeurofibromatosis Type 2 (NF2) is a tumor syndrome characterized by an autosomal dominant pattern of inheritance. The hallmark of NF2 is the development of bilateral vestibular schwannomas (VSs), generally by 30 years of age. One of the first-line treatment options for small to medium-large VSs is radiosurgery. Although radiosurgery shows excellent results in sporadic VS, its use in NF2-related VS is still a topic of dispute. The aim of this study was to evaluate long-term tumor control, hearing preservation rates, and factors influencing outcome of optimally dosed, contemporary Gamma Knife radiosurgery (GKRS) for growing VSs in patients with NF2 and compare the findings to data obtained in patients with sporadic VS also treated by means of GKRS.METHODSThe authors performed a retrospective analysis of 47 growing VSs in 34 NF2 patients who underwent GKRS treatment performed with either the Model C or Perfexion Leksell Gamma Knife, with a median margin dose of 11 Gy. Actuarial tumor control rates were estimated using the Kaplan-Meier method. For patient- and treatment-related factors, a Cox proportional hazards model was used to identify predictors of outcome. Trigeminal, facial, and vestibulocochlear nerve function were assessed before and after treatment. NF2-related VS patients were matched 1:1 with sporadic VS patients who were treated in the same institute, and the same indications for treatment, definitions, and dosimetry were used in order to compare outcomes.RESULTSActuarial tumor control rates in NF2 patients after 1, 3, 5, and 8 years were 98%, 89%, 87%, and 87%, respectively. Phenotype and tumor volume had significant hazard rates of 0.086 and 22.99, respectively, showing that Feiling-Gardner phenotype and a tumor volume not exceeding 6 cm3 both were associated with significantly better outcome. Actuarial rates of serviceable hearing preservation after 1, 3, 5, and 7 years were 95%, 82%, 59%, and 33%, respectively. None of the patients experienced worsening of trigeminal nerve function. Facial nerve function worsened in 1 patient (2.5%). No significant differences in tumor control, hearing preservation, or complications were found in comparing the results of GKRS for NF2-related VS versus GKRS for sporadic VS.CONCLUSIONSWith modern GKRS, the use of low margin doses for treating growing VSs in patients with NF2 demonstrates good long-term tumor control rates. Feiling-Gardner phenotype and tumor volume smaller than 6 cm3 seem to be independently associated with prolonged progression-free survival, highlighting the clinical importance of phenotype assessment before GKRS treatment. In addition, no significant differences in tumor control rates or complications were found in the matched-control cohort analysis comparing GKRS for VS in patients with NF2 and GKRS for sporadic VS. These results show that GKRS is a valid treatment option for NF2-related VS, in addition to being a good option for sporadic VS, particularly in patients with the Feiling-Gardner phenotype and/or tumors that are small to medium in size. Larger tumors in patients with the Wishart phenotype appear to respond poorly to radiosurgery, and other treatment modalities should therefore be considered in such cases.

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Tumor control and hearing preservation after Gamma Knife radiosurgery for vestibular schwannomas in neurofibromatosis type 2

Journal of Neuro-Oncology ◽

10.1007/s11060-010-0181-1 ◽

2010 ◽

Vol 98 (2) ◽

pp. 265-270 ◽

Cited By ~ 21

Author(s):

Manish Singh Sharma ◽

Rakesh Singh ◽

Shashank S. Kale ◽

Deepak Agrawal ◽

Bhawani Shankar Sharma ◽

...

Keyword(s):

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Neurofibromatosis Type ◽

Hearing Preservation ◽

Neurofibromatosis Type 2 ◽

Vestibular Schwannomas ◽

Tumor Control

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Pretreatment ADC predicts tumor control after Gamma Knife radiosurgery in solid vestibular schwannomas

Acta Neurochirurgica ◽

10.1007/s00701-021-04738-x ◽

2021 ◽

Author(s):

Pranay Soni ◽

Tamia Potter ◽

Matthew Poturalski ◽

Christopher Karakasis ◽

Hamid Borghei-Razavi ◽

...

Keyword(s):

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Vestibular Schwannomas ◽

Tumor Control

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Safety and Efficacy of Gamma Knife Radiosurgery for the Management of Koos Grade 4 Vestibular Schwannomas

Neurosurgery ◽

10.1227/neu.0000000000001154 ◽

2015 ◽

Vol 78 (4) ◽

pp. 521-530 ◽

Cited By ~ 15

Author(s):

Christian Iorio-Morin ◽

Fahd AlSubaie ◽

David Mathieu

Keyword(s):

Gamma Knife ◽

Tumor Size ◽

Gamma Knife Radiosurgery ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Inclusion Criteria ◽

Shunt Insertion ◽

Safety And Efficacy ◽

Nerve Preservation

Abstract BACKGROUND: Gamma Knife radiosurgery (GKRS) is commonly used in treating small vestibular schwannomas; however, its use for larger vestibular schwannomas is still controversial. OBJECTIVE: To assess the long-term safety and efficacy of treating eligible Koos grade 4 vestibular schwannomas with GKRS. METHODS: We conducted a single-center, retrospective evaluation of patient undergoing GKRS for Koos grade 4 vestibular schwannomas. We evaluated clinical, imaging, and treatment characteristics and assessed treatment outcome. Inclusion criteria were tumor size of ≥4 cm3 and follow-up of at least 6 months. Patients with neurofibromatosis type 2 were excluded. Primary outcomes measured were tumor control rate, hearing and facial function preservation rate, and complications. All possible factors were analyzed to assess clinical significance. RESULTS: Sixty-eight patients met inclusion criteria. Median follow-up was 47 months (range, 6-125 months). Baseline hearing was serviceable in 60%. Median tumor volume at radiosurgery was 7.4 cm3 (range, 4-19 cm3). The median marginal dose used was 12 Gy at the 50% isodose line. Actuarial tumor control rates were 95% and 92% at 2 and 10 years, respectively. Actuarial serviceable hearing preservation rates were 89% and 49% at 2 and 5 years, respectively. Facial nerve preservation was 100%. Clinical complications included balance disturbance (11%), facial pain (10%), facial numbness (5%), and tinnitus (10%). Most complications were mild and transient. Hydrocephalus occurred in 3 patients, requiring ventriculoperitoneal shunt insertion. Larger tumor size was significantly associated with persisting symptoms post-treatment. CONCLUSION: Patients with Koos grade 4 vestibular schwannomas and minimal symptoms can be treated safely and effectively with GKRS.

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Low-Dose Gamma Knife Radiosurgery for Vestibular Schwannomas: Tumor Control and Cranial Nerve Function Preservation After 11 Gy

Journal of Neurological Surgery Part B Skull Base ◽

10.1055/s-0036-1584231 ◽

2016 ◽

Vol 78 (01) ◽

pp. 002-010 ◽

Cited By ~ 1

Author(s):

Rohan Lall ◽

Rishi Lall ◽

Allan III ◽

Amit Ayer ◽

Samir Sejpal ◽

...

Keyword(s):

Gamma Knife ◽

Cranial Nerve ◽

Low Dose ◽

Gamma Knife Radiosurgery ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Nerve Function ◽

Cranial Nerve Function ◽

Function Preservation

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Gamma Knife radiosurgery for larger-volume vestibular schwannomas

Journal of Neurosurgery ◽

10.3171/2010.8.jns10674 ◽

2011 ◽

Vol 114 (3) ◽

pp. 801-807 ◽

Cited By ~ 40

Author(s):

Huai-che Yang ◽

Hideyuki Kano ◽

Nasir Raza Awan ◽

L. Dade Lunsford ◽

Ajay Niranjan ◽

...

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Univariate Analysis ◽

Gamma Knife Radiosurgery ◽

Volume Reduction ◽

Vestibular Schwannomas ◽

Maximum Diameter ◽

Tumor Control ◽

Recent Experience

Object 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. Methods 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. Results 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. Conclusions 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.

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Magnetic resonance imaging characteristics and the prediction of outcome of vestibular schwannomas following Gamma Knife radiosurgery

Journal of Neurosurgery ◽

10.3171/2016.9.jns161510 ◽

2017 ◽

Vol 127 (6) ◽

pp. 1384-1391 ◽

Cited By ~ 6

Author(s):

Chih-Chun Wu ◽

Wan-Yuo Guo ◽

Wen-Yuh Chung ◽

Hisu-Mei Wu ◽

Chung-Jung Lin ◽

...

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Gamma Knife Radiosurgery ◽

Reduction Ratio ◽

Volume Reduction ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Mri Features ◽

Before And After

OBJECTIVEGamma Knife surgery (GKS) is a promising treatment modality for patients with vestibular schwannomas (VSs), but a small percentage of patients have persistent postradiosurgical tumor growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term tumor control after GKS.METHODSThe authors performed a retrospective study of all patients with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 patients who had a minimum of 24 months of clinical and radiological assessment after radiosurgery were included in this study. Those who underwent a craniotomy with tumor removal before and after GKS were excluded. Study patients comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4–82.3 years). Tumor volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole tumor by serial MRI before and after GKS.RESULTSThe median follow-up period was 60.8 months (range 24–128.9 months), and the median treated tumor volume was 3.54 cm3 (0.1–16.2 cm3). At last follow-up, imaging studies indicated that 150 tumors (80.2%) showed decreased tumor volume, 20 (10.7%) had stabilized, and 17 (9.1%) continued to grow following radiosurgery. The postradiosurgical outcome was not significantly correlated with pretreatment volumes or postradiosurgical enhancing patterns. Tumors that showed regression within the initial 12 months following radiosurgery were more likely to have a larger volume reduction ratio at last follow-up than those that did not (volume reduction ratio 55% vs 23.6%, respectively; p < 0.001). Compared with solid VSs, cystic VSs were more likely to regress or stabilize in the initial postradiosurgical 6–12-month period and during extended follow-up. Cystic VSs exhibited a greater volume reduction ratio at last follow-up (cystic vs solid: 67.6% ± 24.1% vs 31.8% ± 51.9%; p < 0.001). The mean preradiosurgical maximum ADC (ADCmax) values of all VSs were significantly higher for those with tumor regression or stabilization at last follow-up compared with those with progression (2.391 vs 1.826 × 10−3 mm2/sec; p = 0.010).CONCLUSIONSLoss of central enhancement after radiosurgery was a common phenomenon, but it did not correlate with tumor volume outcome. Preradiosurgical MRI features including cystic components and ADCmax values can be helpful as predictors of treatment outcome.

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Gamma Knife radiosurgery for large vestibular schwannomas greater than 3 cm in diameter

Journal of Neurosurgery ◽

10.3171/2016.12.jns161530 ◽

2018 ◽

Vol 128 (5) ◽

pp. 1380-1387 ◽

Cited By ~ 13

Author(s):

Cheng-Wei Huang ◽

Hsien-Tang Tu ◽

Chun-Yi Chuang ◽

Cheng-Siu Chang ◽

Hsi-Hsien Chou ◽

...

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Gamma Knife Radiosurgery ◽

Pure Tone Audiometry ◽

Volume Reduction ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Recent Experience ◽

Single Dimension

OBJECTIVEStereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs.METHODSBetween 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm3, underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm3 (range 10.3–24.5 cm3). The median tumor margin dose was 11 Gy (range 10–12 Gy).RESULTSThe median follow-up duration was 48 months (range 6–156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%–50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB.The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0.99–100.00). A tumor volume ≥ 15 cm3 was a significant factor predictive of GKRS failure (p = 0.005). No difference in outcome was observed based on indication for GKRS (p = 0.0761).CONCLUSIONSAlthough microsurgical resection remains the primary management choice in patients with VSs, most VSs that are defined as having both a single dimension > 3 cm and a volume > 10 cm3 and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm3 is a significant factor predicting poor tumor control following GKRS.

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