Treatment Outcomes and Dose Rate Effects Following Gamma Knife Stereotactic Radiosurgery for Vestibular Schwannomas

Smith, Deborah R.; Saadatmand, Heva J.; Wu, Cheng‐Chia; Black, Paul; Wuu, Yen-Ruh; Lesser, Jonathan B.; Horan, Maryellen; Isaacson, Steven R.; Wang, Tony J. C.; Sisti, Michael B.

doi:10.1093/neuros/nyz229

Cited by 41 publications

(40 citation statements)

References 64 publications

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“…When it comes to SRS, the tumor control rate is comparable to conventional microsurgery 21 . It was able to maintain serviceable hearing at four years in 72.2% of the total patient in a study 22 . However, in a study that observed for a longer time, only 23% of the patient's hearing was preserved following ten years of treatment 23 .…”

Section: Discussionmentioning

confidence: 89%

Machine learning approach for prediction of hearing preservation in vestibular schwannoma surgery

Cha

Shin

Kim

et al. 2020

Sci Rep

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in vestibular schwannoma patients with functional hearing status, surgical resection while preserving the hearing is feasible. Hearing levels, tumor size, and location of the tumor have been known to be candidates of predictors. We used a machine learning approach to predict hearing outcomes in vestibular schwannoma patients who underwent hearing preservation surgery: middle cranial fossa, or retrosigmoid approach. After reviewing the medical records of 52 patients with a pathologically confirmed vestibular schwannoma, we included 50 patient's records in the study. Hearing preservation was regarded as positive if the postoperative hearing was within serviceable hearing (50/50 rule). The categorical variable included the surgical approach, and the continuous variable covered audiometric and vestibular function tests, and the largest diameter of the tumor. Four different algorithms were lined up for comparison of accuracy: support vector machine(SVM), gradient boosting machine(GBM), deep neural network(DNN), and diffuse random forest(DRF). The average accuracy of predicting hearing preservation ranged from 62% (SVM) to 90% (DNN). The current study is the first to incorporate machine learning methodology into a prediction of successful hearing preservation surgery. Although a larger population may be needed for better generalization, this study could aid the surgeon's decision to perform a hearing preservation approach for vestibular schwannoma surgery.Vestibular schwannomas (VSs), or acoustic neuromas are benign tumors arising from the cochleovestibular nerve, which grows slowly 1 . It accounts for 6-8% of all intracranial tumors and is the most common cerebellopontine angle tumor 2 . Recently, with the help of better access to magnetic resonance imaging, the incidence has been increased, and the tumor size at the time of diagnosis has decreased 3,4 . With more early detection rates, more patients are asymptomatic when diagnosed. In these patients, the following management options may all be feasible: watchful waiting, surgery, or stereotactic radiosurgery(SRS). However, there are no clear guidelines or consensus on the optimal management of small VSs, and the optimal treatment is still under debate 5,6 . Treatment options differ individually and are dependent upon the physician's experience, the size and growth rate of the tumor, age, patient's preference, and hearing status. If the tumor is too big, or hearing is below serviceable hearing, hearing preservation is not essential in treatment 7 . Nevertheless, in small to medium-sized tumors with serviceable hearing, hearing preservation surgeries can be offered. Currently, middle cranial fossa approach(MCFA) and retrosigmoid approach(RSA) are the two most commonly used approaches to remove VSs.The selection between the two approaches depends on the size and location of the tumor, and the surgeon's preference, as each procedure has its strengths in exposing regions of the internal auditory canal or cerebellopontine angle. The preservation rate of MCFA and RSA varies...

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Section: Discussionmentioning

confidence: 89%

Machine learning approach for prediction of hearing preservation in vestibular schwannoma surgery

Cha

Shin

Kim

et al. 2020

Sci Rep

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“…Overall, the progression free survival (PFS) after GammaKnife SRS is approximately 84–94% [ 197 , 198 , 199 ]. However, some studies have shown that larger VS tumors and those from NF2 patients have an overall lower rate of tumor control than those published for sporadic tumors that are small and medium sized [ 34 , 35 , 200 ].…”

Section: Radiobiology and Radiation Resistance In Vestibular Schwannomamentioning

confidence: 99%

Understanding the Radiobiology of Vestibular Schwannomas to Overcome Radiation Resistance

Thielhelm

Goncalves

Welford

et al. 2021

Cancers

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Vestibular schwannomas (VS) are benign tumors arising from cranial nerve VIII that account for 8–10% of all intracranial tumors and are the most common tumors of the cerebellopontine angle. These tumors are typically managed with observation, radiation therapy, or microsurgical resection. Of the VS that are irradiated, there is a subset of tumors that are radioresistant and continue to grow; the mechanisms behind this phenomenon are not fully understood. In this review, the authors summarize how radiation causes cellular and DNA injury that can activate (1) checkpoints in the cell cycle to initiate cell cycle arrest and DNA repair and (2) key events that lead to cell death. In addition, we discuss the current knowledge of VS radiobiology and how it may contribute to clinical outcomes. A better understanding of VS radiobiology can help optimize existing treatment protocols and lead to new therapies to overcome radioresistance.

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“…The 20-Gy doses were delivered at rates of 1.5-2.5 Gy/min, whereas the 10-Gy dose was delivered at a much faster rate of 6.4 Gy/min, which, in turn, is related to the respective use of lower (90-320 kV) and higher (6 MeV) energies of radiation. More recently, in a study 25 involving irradiation of the vestibular nerve with a dose of approximately 17 Gy, the dose rate was found to be an important variable in irradiating nervous tissue since deleterious effects-i.e., facial nerve dysfunction and hearing loss-were found to be greater when irradiating at dose rates higher, but not lower, than 2.7 Gy/min. This radiation-induced toxicity to nervous tissue found at higher dose rates would be consistent with a dose of 20 Gy being effective for treating SCI when delivered at a lower, but not a higher, dose rate, as has been observed.…”

Section: Fig 2 Cmentioning

confidence: 99%

Therapeutic target for external beam x-irradiation in experimental spinal cord injury

Zeman¹,

Wen²,

Etlinger³

2020

Journal of Neurosurgery: Spine

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OBJECTIVEX-irradiation has been shown to be beneficial to recovery from spinal cord injury (SCI); however, the optimal therapeutic target has not been defined. Experiments were designed to determine the optimal target volume within the injured spinal cord for improving functional recovery and sparing tissue with stereotactic x-irradiation.METHODSSCI was produced in rats at the T10 level. A 20-Gy dose of radiation was delivered with a single, 4-mm-diameter, circular radiation beam centered either on the injury epicenter or 4 or 8 mm caudal or rostral to the injury epicenter. Locomotor function was determined for 6 weeks with the Basso, Beattie, and Bresnahan locomotor scale and tissue sparing by histological analysis of transverse sections along the spinal cords.RESULTSX-irradiation of spinal cord segments at 4 mm, but not 8 mm, caudal or rostral to the contusion epicenter resulted in increases in locomotor recovery. Consistently, significant tissue sparing also occurred with x-irradiation centered at those sites, although irradiation centered 4 mm rostral to the epicenter led to tissue sparing along the greatest length of the spinal cord. Interestingly, regression analysis of these variables demonstrated that the quantitative relationship between the amount of tissue spared and the improvement in locomotion recovery was greatest in a region several millimeters rostral to the injury epicenter.CONCLUSIONSThese results indicate that x-irradiation in a region rostral to the injury epicenter is optimal for recovery from SCI. This minimal target should be attractive for therapeutic application since it allows a greatly reduced target volume so that uninjured tissue is not needlessly irradiated.

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Treatment Outcomes and Dose Rate Effects Following Gamma Knife Stereotactic Radiosurgery for Vestibular Schwannomas

Cited by 41 publications

References 64 publications

Machine learning approach for prediction of hearing preservation in vestibular schwannoma surgery

Machine learning approach for prediction of hearing preservation in vestibular schwannoma surgery

Understanding the Radiobiology of Vestibular Schwannomas to Overcome Radiation Resistance

Therapeutic target for external beam x-irradiation in experimental spinal cord injury

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