Hearing subclassification may predict long-term auditory outcomes after radiosurgery for vestibular schwannoma patients with good hearing

Abstract

OBJECTIVE In the era of MRI, vestibular schwannomas are often recognized when patients still have excellent hearing. Besides success in tumor control rate, hearing preservation is a main goal in any procedure for management of this population. The authors evaluated whether modified auditory subclassification prior to radiosurgery could predict long-term hearing outcome in this population. METHODS The authors reviewed a quality assessment registry that included the records of 1134 vestibular schwannoma patients who had undergone stereotactic radiosurgery during a 15-year period (1997–2011). The authors identified 166 patients who had Gardner-Robertson Class I hearing prior to stereotactic radiosurgery. Fifty-three patients were classified as having Class I-A (no subjective hearing loss) and 113 patients as Class I-B (subjective hearing loss). Class I-B patients were further stratified into Class I-B1 (pure tone average ≤ 10 dB in comparison with the contralateral ear; 56 patients), and I-B2 (> 10 dB compared with the normal ear; 57 patients). At a median follow-up of 65 months, the authors evaluated patients' hearing outcomes and tumor control. RESULTS The median pure tone average elevations after stereotactic radiosurgery were 5 dB, 13.5 dB, and 28 dB in Classes I-A, I-B1, and I-B2, respectively. The median declines in speech discrimination scores after stereotactic radiosurgery were 0% for Class I-A (p = 0.33), 8% for Class I-B1 (p < 0.0001), and 40% for Class I-B2 (p < 0.0001). Serviceable hearing preservation rates were 98%, 73%, and 33% for Classes I-A, I-B1, and I-B2, respectively. Gardner-Robertson Class I hearing was preserved in 87%, 43%, and 5% of patients in Classes I-A, I-B1, and I-B2, respectively. CONCLUSIONS Long-term hearing preservation was significantly better if radiosurgery was performed prior to subjective hearing loss. In patients with subjective hearing loss, the difference in pure tone average between the affected ear and the unaffected ear was an important factor in long-term hearing preservation.

Discrepancy between self-assessed hearing status and measured audiometric evaluation

“…There are conflicting opinions regarding the use of a reference for hearing thresholds [8,41,42]. We employed the reference value of 40 dB HL because it has been used in other studies [8,15].…”

Hearing Preservation in Stereotactic Radiosurgery for Vestibular Schwannoma

“…The latter group was further separated into whether the PTA in the affected ear was within 10 dB as compared with the contralateral ear (Class 1-B1 and Class 1-B2, respectively). 23 Following SRS, with a median follow-up of 65 months, serviceable hearing was preserved in Class 1-A, Class 1-B1, and Class 1-B2 patients in 98, 73, and 33%, respectively, and was significantly associated with the pretreatment GR class on multivariate analysis after controlling for age and gender. 23 Similarly, in a cohort of 77 VS patients, Kano and colleagues found that 71.4% of patients retained serviceable hearing with a median follow-up of 20 months after SRS and that GR Class 1 hearing before treatment was the only predictor for maintaining serviceable hearing.…”

“…23 Following SRS, with a median follow-up of 65 months, serviceable hearing was preserved in Class 1-A, Class 1-B1, and Class 1-B2 patients in 98, 73, and 33%, respectively, and was significantly associated with the pretreatment GR class on multivariate analysis after controlling for age and gender. 23 Similarly, in a cohort of 77 VS patients, Kano and colleagues found that 71.4% of patients retained serviceable hearing with a median follow-up of 20 months after SRS and that GR Class 1 hearing before treatment was the only predictor for maintaining serviceable hearing. 8 In a separate analysis, Hasegawa and colleagues reported on the outcomes of 117 VS patients with serviceable hearing treated with SRS utilizing a tumor margin dose of 12 Gy.…”

The Management and Imaging of Vestibular Schwannomas

“…Serviceable hearing was preserved in only 23–24% patients at 10 years 47–49 . Older age, larger tumors and poorer pre-treatment hearing were found to be risk factors for progressive post-treatment hearing loss 47,49–50 . Reducing cochlear dose to improve hearing preservation continues to be controversial and has not been confirmed to reduce long-term hearing deterioration 51 .…”