Prospective longitudinal assessment of sensorineural hearing loss with hyperfractionated radiation therapy alone in patients with average-risk medulloblastoma

Abstract

Background: To report on sensorineural hearing loss (SNHL) in a cohort of patients treated with hyperfractionated radiation therapy (HFRT) without upfront platinum-based chemotherapy in average-risk medulloblastoma.

Methods: Hearing thresholds were assessed by ear-specific pure-tone audiograms at stimulus frequencies of 0.25, 0.5, 1, 2, 4, and 8 kilohertz. Audiometric assessments were done serially longitudinally at baseline, between 6-12 months after HFRT, and annually thereafter. Pure-tone audiograms were analyzed and graded according to Brock pediatric ototoxicity grading criteria.

Results: Five of 20 (25%) children had communicatively and developmentally significant SNHL (Brock grade 2 or worse) even before starting radiotherapy. On follow-up, new-onset Brock grade 2 or worse ototoxicity was documented in 6 previously normal ears. Eleven patients had preserved hearing in both ears on last audiometric follow-up. Compared with baseline testing, post-HFRT audiometry at 2-3 years showed modest decline in hearing threshold across all frequencies. Age at diagnosis and sex did not significantly impact hearing, while higher cochlear doses trended towards worse hearing outcomes. Tumors that extended more towards one side expectedly showed significant worsening in the ipsilateral ear. There was a differential impact of treatment on the right and left ears with the right ear (and not the left ear) showing significantly worse hearing thresholds in the low-to-intermediate speech frequency range over time.

Conclusion: The use of HFRT for craniospinal irradiation and conformal tumor bed boost without upfront platinum-based chemotherapy in children with average-risk medulloblastoma results in preserved hearing in a large proportion of patients in the audible speech range.

Keywords: audiometry; medulloblastoma; ototoxicity; radiotherapy; sensorineural hearing loss.

Fig. 1.

Bar graph showing proportion of patients and of individual ears with communicatively and developmentally significant ototoxicity (Brock grade 2 or worse) at different time points.

Fig. 2.

Box and whisker plots showing the median hearing threshold with interquartile range in decibels (dB) for the low (0.25–1 KHz), intermediate (2–4 KHz), and high (8 KHz) speech frequencies separately for both the right (A) and left (B) ears at baseline and then serially on follow-up at 6–12 months and 2–3 years for the study cohort.

Fig. 3.

Mean hearing threshold in decibels (dB) separately for the right (A) and left (B) ears for all the speech frequencies tested. Note the modest decline in hearing threshold over time for all the speech frequencies.