Dose Volume Histogram Analysis Of Hearing Preservation As A Function Of Mean And Partial Cochlear Dose In Treatment Of Vestibular Schwannoma With Gamma Knife RadiosurgeryInteractive Manuscript
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What is the background behind your study?
What is the purpose of your study?
To assess auditory acuity outcome with Gamma Knife Radiosurgery (GKRS) in treating Vestibular Schwannoma (VS), results of a Dose-Volume Histogram (DVH) analysis of cochlear dose are presented.
Describe your patient group.
From 2006-09, 28 patients were treated at our institution with GKRS for VS and had serial auditory testing (Gardner Robertson GR & AAO).
Describe what you did.
For all patients, marginal dose was 12.5 Gray (Gy) prescribed to the 50% isodose volume. Plugging was used to minimize cochlear dose. Pre- and post-treatment auditory acuity tests GR/AAO were done at 6, 12, 18and 24 mo after GKRS. The acuity testing results were correlated with the cochlear mean, maximal dose and % cochlear volume receiving 3, 5, 8 and 10 Gy (V3, V5, V8, V10).
Describe your main findings.
Median age was 62.9 (26.0 - 88.4). Median follow-up (FU) was 16.5 mo with auditory tests to minimum 18 mo. The cochlear mean dose was 2.7 Gy. The V3, V5 and V8 ranged from 0-84%, 0-44%, and 0-15%, respectively. Linear regression analysis revealed a GR decrement > V8 and V10 (p=0.012, 0.029 respectively). Analysis showed an AAO decrement > V10 (p=0.039). These cochlear volumes receiving 3, 5, 8 and 10 Gy showed that the higher the % cochlear volume receiving > 8 Gy resulted in hearing decrement of GR/AAO. With V3 at > 72% and V5 at > 13% there is a trend in decrement of AAO (p=0.102, 0.206). Advancing age showed less incremental AAO change (p=0.02). Maximal cochlear dose had a trend toward significance for GR (p=0.056). Mean cochlear dose, maximal tumor volume and dimension had no significance for GR and AAO.
Describe the main limitation of this study.
This is a retrospective study.
Describe your main conclusion.
Hearing preservation with GKRS is a function of patient & treatment-related factors. In DVH analysis of maximal dose and % cochlear volume receiving > 8 Gy to resultant hearing outcome GR/AAO, a significant decrement in GR and AAO is found with % cochlear volumes receiving > 8 Gy and > 10 Gy, respectively. Increasing age shows less change in AAO.
Describe the importance of your findings and how they can be used by others.
Continued FU and additional patients will be needed to determine long-term hearing preservation as a function of age and partial cochlear organ dose with GKRS for VS.
To assess auditory acuity outcome with Gamma Knife Radiosurgery (GKRS) in treating Vestibular Schwannoma (VS), results of a Dose-Volume Histogram (DVH) analysis of cochlear dose are presented.
From 2006-09, 28 patients were treated at our institution with GKRS for VS and had serial auditory testing (Gardner Robertson GR & AAO).
For all patients, marginal dose was 12.5 Gray (Gy) prescribed to the 50% isodose volume. Plugging was used to minimize cochlear dose. Pre- and post-treatment auditory acuity tests GR/AAO were done at 6, 12, 18and 24 mo after GKRS. The acuity testing results were correlated with the cochlear mean, maximal dose and % cochlear volume receiving 3, 5, 8 and 10 Gy (V3, V5, V8, V10).
Median age was 62.9 (26.0 - 88.4). Median follow-up (FU) was 16.5 mo with auditory tests to minimum 18 mo. The cochlear mean dose was 2.7 Gy. The V3, V5 and V8 ranged from 0-84%, 0-44%, and 0-15%, respectively. Linear regression analysis revealed a GR decrement > V8 and V10 (p=0.012, 0.029 respectively). Analysis showed an AAO decrement > V10 (p=0.039). These cochlear volumes receiving 3, 5, 8 and 10 Gy showed that the higher the % cochlear volume receiving > 8 Gy resulted in hearing decrement of GR/AAO. With V3 at > 72% and V5 at > 13% there is a trend in decrement of AAO (p=0.102, 0.206). Advancing age showed less incremental AAO change (p=0.02). Maximal cochlear dose had a trend toward significance for GR (p=0.056). Mean cochlear dose, maximal tumor volume and dimension had no significance for GR and AAO.
This is a retrospective study.
Hearing preservation with GKRS is a function of patient & treatment-related factors. In DVH analysis of maximal dose and % cochlear volume receiving > 8 Gy to resultant hearing outcome GR/AAO, a significant decrement in GR and AAO is found with % cochlear volumes receiving > 8 Gy and > 10 Gy, respectively. Increasing age shows less change in AAO.
Continued FU and additional patients will be needed to determine long-term hearing preservation as a function of age and partial cochlear organ dose with GKRS for VS.
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