Increased cochlear radiation dose predicts delayed hearing loss following both stereotactic radiosurgery and fractionated stereotactic radiotherapy for vestibular schwannoma
Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are noninvasive therapies for vestibular schwannomas providing excellent tumor control. However, delayed hearing loss after radiation therapy remains an issue. One potential target to for improving hearing rates is limiting radiation exposure to the cochlea.
We retrospectively reviewed 100 patients undergoing either SRS with 12 Gy (n = 43) or fSRT with 50 Gy over 28 fractions (n = 57) for vestibular schwannoma. Univariate and multivariate analysis were carried out to identify predictors of hearing loss as measured by the Gardner Robertson scale after radiation therapy.
Deterioration of hearing occurred in 30% of patients with SRS and 26% with fSRT. The overall long term (> 2 year) progression rates were 20% for SRS and 16% for fSRT. Patients with a decrease in their Gardner Robertson hearing score and those that loss serviceable hearing had significantly higher average minimal doses to the cochlea in both SRS and fSRT cohorts. ROC analysis showed that a cut off of 5 Gy and 35 Gy, for SRS and fSRT respectively, predicted hearing loss with high sensitivity/specificity.
Our data suggests the minimal dose of radiation that the cochlear volume is exposed to is a predictor of delayed hearing loss after either SRS or fSRT. A threshold of 5 Gy/35 Gy may lead to improved hearing preservation after radiotherapy. Further prospective multi center studies can further elucidate this mechanism.
KeywordsVestibular schwannoma Stereotactic radiosurgery Fractionated radiotherapy Serviceable hearing Cochlea
Isaac Yang was partially supported by a Visionary Fund Grant, an Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research UCLA Scholars in Translational Medicine Program Award, the Jason Dessel Memorial Seed Grant, the UCLA Honberger Endowment Brain Tumor Research Seed Grant, and the STOP CANCER Research Career Development Award. The remaining authors have no disclosures or conflicts-of-interest.
Compliance with ethical standards
Conflict of interest
All authors that they have no conflict of interest.
- 6.Delbrouck C, Hassid S, Massager N et al (2003) Preservation of hearing in vestibular schwannomas treated by radiosurgery using leksell gamma knife: preliminary report of a prospective Belgian clinical study. Acta Otorhinolaryngol Belg 57:197–204Google Scholar
- 10.Massager N, Nissim O, Delbrouck C et al (2013) Irradiation of cochlear structures during vestibular schwannoma radiosurgery and associated hearing outcome. J Neurosurg 119(Suppl):733–739Google Scholar
- 15.Kano H, Kondziolka D, Khan A et al (2013) Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma: clinical article. J Neurosurg 119:863–873Google Scholar
- 19.Chung LK, Ung N, Sheppard JP et al (2018) Impact of cochlear dose on hearing preservation following stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of vestibular schwannoma. J Neurol Surg B 79:335–342. https://doi.org/10.1055/s-0037-1607968 CrossRefGoogle Scholar
- 23.Aoyama H, Onodera S, Takeichi N et al (2013) Symptomatic outcomes in relation to tumor expansion after fractionated stereotactic radiation therapy for vestibular schwannomas: single-institutional long-term experience. Int J Radiat Oncol Biol Phys 85:329–334. https://doi.org/10.1016/j.ijrobp.2012.05.003 CrossRefGoogle Scholar
- 24.Okunaga T, Matsuo T, Hayashi N et al (2005) Linear accelerator radiosurgery for vestibular schwannoma: measuring tumor volume changes on serial three-dimensional spoiled gradient-echo magnetic resonance images. J Neurosurg 103:53–58. https://doi.org/10.3171/jns.2005.103.1.0053 CrossRefGoogle Scholar
- 27.Lee T-F, Yeh S-A, Chao P-J et al (2015) Normal tissue complication probability modeling for cochlea constraints to avoid causing tinnitus after head-and-neck intensity-modulated radiation therapy. Radiat Oncol 10:194. https://doi.org/10.1186/s13014-015-0501-x CrossRefPubMedCentralPubMedGoogle Scholar