J Neurol Surg B Skull Base 2018; 79(S 01): S1-S188
DOI: 10.1055/s-0038-1633430
Oral Presentations
Georg Thieme Verlag KG Stuttgart · New York

Long-Term Hearing Outcomes following Stereotactic Radiosurgery in Patients with Vestibular Schwannomas

Peter L. Santa Maria
1   Department of Otolaryngology, Head and Neck Surgery, Stanford University, Palo Alto, California, United States
,
Yangyang Shi
1   Department of Otolaryngology, Head and Neck Surgery, Stanford University, Palo Alto, California, United States
,
Richard K. Gurgel
2   Department of Otolaryngology, Head and Neck Surgery, University of Utah, Salt Lake City, Utah, United States
,
Carleton E. Corrales
3   Division of Otolaryngology-Head and Neck Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States
,
Scott G. Soltys
4   Department of Radiation Oncology, Stanford University, Palo Alto, California, United States
,
Chloe Santa Maria
1   Department of Otolaryngology, Head and Neck Surgery, Stanford University, Palo Alto, California, United States
,
Steven D. Chang
5   Department of Neurosurgery, Stanford University, Stanford, California, United States
,
Nikolas H. Blevins
1   Department of Otolaryngology, Head and Neck Surgery, Stanford University, Palo Alto, California, United States
,
Iris C. Gibbs
4   Department of Radiation Oncology, Stanford University, Palo Alto, California, United States
,
Robert K. Jackler
1   Department of Otolaryngology, Head and Neck Surgery, Stanford University, Palo Alto, California, United States
› Author Affiliations
Further Information

Publication History

Publication Date:
02 February 2018 (online)

 

Objective To determine the long-term hearing results following stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) according to pretreatment hearing level and various tumor factors. To explain why the widely used Gardner-Robinson (G-R) method of reporting VS hearing outcomes in the radiation oncology literature is inadequate and advocate for adoption of an improved reporting system.

Methods We retrospectively reviewed 478 tumors (475 patients) treated with SRS for VS from 1992 to 2013 at a tertiary academic medical center with a minimum ≥ 1 year follow-up. Hearing outcomes were measured according to word recognition score (WRS) and pure tone average (PTA) according to the American Academy of Otolaryngology-Head and Neck Surgery 2012 Standardized Format for Reporting Hearing Outcomes in Clinical Trials.

Results There were 579 tumors (576 patients) treated with SRS over the study period. Of those, 83% (478) of tumors had ≥1 year and 59% (344) of tumors had ≥ 3 years of follow-up. The mean follow-up was 5.3 years (range: from 1.0 to 18.7). In the 244 tumor ears with measurable hearing before SRS who were followed up for ≥1 year, 6% (14) had improved hearing, 32% (79) unchanged hearing, and 62% (151) had worsened hearing. In 175 patients with ≥3 years of follow-up and who had measureable hearing pretreatment, 6% (11 ears) improved hearing, 31% (54 ears) unchanged hearing, and 63% (110 ears) had worsened hearing. Prior to SRS, 21% (66) tumor ears had normal hearing (≤ 20 dB PTA and ≥90% WRS). Following SRS, 42% (28 ears) followed up for ≥1 year retained normal hearing. Patients with tumors with a larger target volume (p < 0.001), larger maximum dimension (p = 0.004), and larger maximum dimension in the cerebellopontine angle (p = 0.004) were more likely to have a reduction in hearing levels. Hearing outcomes were not significantly worse in tumors with demonstrated growth before SRS compared with those four of undetermined growth, but the difference was not significant (p = 0.67). Neither gender (p = 0.09) nor age (p = 0.25) was predictive of hearing outcomes in this cohort. Traditionally reported hearing outcomes using Gardner Robertson maintenance of “serviceable hearing” was 48% at 3 years, which overestimates hearing outcomes compared with the above reporting standards.

Conclusion Hearing declines over time in VS treated with SRS in a high proportion of cases. The frequency and magnitude of long-term hearing decline following SRS argues against prophylactic radiation for small tumors in hearing ears with undetermined growth behavior. The 1988 Gardner Robinson hearing outcome scale should be supplanted by the 2012 American Academy of Otolaryngology, Head and Neck Surgery reporting standard. Misleading terms such as “serviceable hearing” should be avoided.