BACKGROUND: Deterioration in hearing after Gamma Knife radiosurgery of vestibular schwannomas is a well-documented risk. Recent studies suggest a correlation between cochlear radiation dose and hearing preservation. OBJECTIVE: This study identifies additional variables that predict hearing loss after radiosurgery. METHODS: Retrospective analysis of 53 patients with audiogram follow-up. Median marginal tumor dose was 12.5 Gy. Mean tumor volume was 1.11 cm. Statistical analysis included multivariate stepwise backward linear regression and multivariate logistic regression. Variables included age, prescription dose, tumor volume, intracanalicular length, and maximum and mean cochlear dose. Dose volume histograms were generated. The percentage of the cochlear volume that received 3.6 Gy or greater, 4.7 Gy or greater, and 5.3 Gy or greater was calculated. Plan conformality indicators were calculated. RESULTS: Forty-two patients had a less than 20-dB change in their pure tone average, with a hearing preservation rate of 79%. Two statistically significant predictors of hearing loss were identified using multivariate analysis: tumor coverage (odds ratio: 1.38 × 10) and age (odds ratio: 1.1 per year). Multivariate linear regression was used to predict change in pure tone average. Age and percentage of the cochlear volume receiving 5.3 Gy or greater were found to be statistically significant predictor variables. CONCLUSION: Older patients are more vulnerable to detrimental effects of Gamma Knife radiosurgery on hearing. We propose that cochlear dose volume histograms be created and used to reduce the percentage of the cochlear volume exposed to radiation doses greater than 5.3 Gy. This is the first report to suggest that the conformity index tumor coverage may be an important predictor of hearing outcomes.
BACKGROUND: Deterioration in hearing after Gamma Knife radiosurgery of vestibular schwannomas is a well-documented risk. Recent studies suggest a correlation between cochlear radiation dose and hearing preservation. OBJECTIVE: This study identifies additional variables that predict hearing loss after radiosurgery. METHODS: Retrospective analysis of 53 patients with audiogram follow-up. Median marginal tumor dose was 12.5 Gy. Mean tumor volume was 1.11 cm. Statistical analysis included multivariate stepwise backward linear regression and multivariate logistic regression. Variables included age, prescription dose, tumor volume, intracanalicular length, and maximum and mean cochlear dose. Dose volume histograms were generated. The percentage of the cochlear volume that received 3.6 Gy or greater, 4.7 Gy or greater, and 5.3 Gy or greater was calculated. Plan conformality indicators were calculated. RESULTS: Forty-two patients had a less than 20-dB change in their pure tone average, with a hearing preservation rate of 79%. Two statistically significant predictors of hearing loss were identified using multivariate analysis: tumor coverage (odds ratio: 1.38 × 10) and age (odds ratio: 1.1 per year). Multivariate linear regression was used to predict change in pure tone average. Age and percentage of the cochlear volume receiving 5.3 Gy or greater were found to be statistically significant predictor variables. CONCLUSION: Older patients are more vulnerable to detrimental effects of Gamma Knife radiosurgery on hearing. We propose that cochlear dose volume histograms be created and used to reduce the percentage of the cochlear volume exposed to radiation doses greater than 5.3 Gy. This is the first report to suggest that the conformity index tumor coverage may be an important predictor of hearing outcomes.
Authors: Kunal S Patel; Edwin Ng; Taranjit Kaur; Tyler Miao; Tania Kaprealian; Percy Lee; Nader Pouratian; Michael T Selch; Antonio A F De Salles; Quinton Gopen; Stephen Tenn; Isaac Yang Journal: J Neurooncol Date: 2019-09-24 Impact factor: 4.130
Authors: Mitchell R Dobberpuhl; Stevie Maxwell; Jonathan Feddock; William St Clair; Matthew L Bush Journal: Otol Neurotol Date: 2016-10 Impact factor: 2.311
Authors: Lawrance K Chung; Nolan Ung; John P Sheppard; Thien Nguyen; Carlito Lagman; Winward Choy; Stephen Tenn; Nader Pouratian; Percy Lee; Tania Kaprealian; Michael Selch; Antonio De Salles; Quinton Gopen; Isaac Yang Journal: J Neurol Surg B Skull Base Date: 2017-11-10
Authors: Teo Soleymani; David Pieton; Patrick Pezeshkian; Patrick Miller; Alessandra A Gorgulho; Nader Pouratian; Antonio A F De Salles Journal: Surg Neurol Int Date: 2011-10-29