Delayed Complete Spontaneous Hearing Recovery in a Pediatric Chemotherapy Patient—A Case Report

Chemotherapy is a cornerstone of pediatric oncology, offering treatment for a diverse spectrum of cancers. Although side effects of chemotherapy, such as ototoxicity, are well known. Resulting high-frequency sensorineural hearing loss (HF SNHL) often progresses from high to low frequencies and is usually permanent, particularly in high-dose regimens. In this era of increased cancer survivability, children are especially vulnerable, and hearing loss can impair language development, education, and quality of life.1 Early detection through pure tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE) is critical for timely intervention, which may consist of hearing aids or dosage adjustments. Maximizing hearing preservation can improve both receptive and expressive communication.1 This case report documents a rare instance of complete delayed resolution of chemotherapy-induced HF SNHL in a pediatric patient with a supratentorial anaplastic ependymoma, challenging the common belief that chemotherapy-induced auditory damage is irreversible. A retrospective chart review was performed, with specific attention to the patient's chemotherapy course and audiograms. Parental written consent was provided for data collection, analysis, drafting, and publication. This study was considered exempt from review by the Virginia Commonwealth University Institutional Review Board. A previously healthy 18-month-old female presented in November 2018 with seizure-like activity, including right eye and mouth twitching and reduced responsiveness. Imaging revealed a large, left-sided supratentorial fronto-parietal mass without spinal metastasis. Gross total resection confirmed anaplastic ependymoma, grade III, with <2.5% RELA+ cells. The patient began Grundy's protocol, a radiation-avoiding chemotherapy protocol for intracranial ependymoma,2 consisting of seven cycles with combinations of Vincristine, Carboplatin, Methotrexate, Cyclophosphamide, and Cisplatin. Pre-chemotherapy audiology testing in December 2018 showed normal bilateral DPOAE and Visual Reinforcement Audiometry (VRA) responses, with a Speech Awareness Threshold (SAT) of 15 decibels, suggesting normal hearing bilaterally across 500 to 8000 Hz (Figure 1A). Audiologic tests in March, June, and September 2019 remained normal. By December 2019, after 23 of 28 chemotherapy courses, DPOAE indicated absent high-frequency responses (Left: response present 2 to 7 kHz, absent 8 to 10 kHz; Right: response present 2 to 4 kHz, absent 5-10 kHz), with VRA showing minimum age-appropriate responses. In April 2020, due to parental concerns about COVID-19 and the patient's immunocompromised state, Grundy's protocol was terminated after 25 courses, further detailed in Table 1. By July 2020, VRA revealed mild bilateral HF SNHL (Left: normal hearing 250-4000 Hz, sloping mild SNHL at 8000 Hz; Right: normal hearing 250-2000 Hz, sloping mild SNHL from 4000-8000 Hz), which worsened by June 2023 to moderate to moderately severe SNHL (Left: normal hearing 250-2000 Hz, sloping moderate to moderately severe SNHL from 4000-8000 Hz; Right: normal hearing 250-4000 Hz, sloping moderate to moderately severe SNHL from 6000-8000 Hz) (Figure 1B and C). Remarkably, an audiogram in December 2023, 45 months postchemotherapy, showed complete bilateral hearing normalization across 250 to 8000 Hz, confirmed by PTA and Speech Recognition Threshold (SRT) testing, although DPOAE responses were absent at 3 to 5 kHz (Figure 1D). Chemotherapy-induced HF SNHL is typically permanent, especially when it is progressive over years.1 Nevertheless, partial recovery has been documented.3, 4 This case is unique due to the complete spontaneous recovery 45 months postchemotherapy. While uncertain, possible explanations include endogenous cochlear repair mechanisms activated after chemotherapy cessation,3 and given the patient's young age, neural plasticity may have contributed. The absence of DPOAE despite normal PTA may suggest central mechanisms, such as auditory nerve adaptation, rather than hair cell recovery. Genetic variability in ototoxicity susceptibility and recovery may also play an idiosyncratic role.5 This case emphasizes the importance of long-term audiologic monitoring in pediatric chemotherapy patients, as hearing changes can occur years after treatment.1 The potential for late recovery, albeit rare, emphasizes the cautious use of prolonged rehabilitative interventions (to avoid overamplification and further cochlear damage) without frequent and extended surveillance. This is particularly applicable to definitive and irreversible procedures, including cochlear implantation. To be clear, appropriate early amplification in cases of hearing loss is still suggested, but caution and counseling should be exercised in patients for whom follow-up surveillance may be limited. Clinically, this case offers hope for recovery from chemotherapy-induced HF SNHL, challenges assumptions of its permanence, and may inform future counseling strategies by oncologists, audiologists, and otolaryngologists. Academically, this case begs further research into cochlear damage and repair mechanisms. This report describes the delayed complete spontaneous resolution of chemotherapy-induced HF SNHL in a pediatric patient. This remarkable recovery encourages the re-evaluation of long-held assumptions about the permanency of chemotherapy-induced pediatric cochlear toxicity, and advocates for extended audiologic monitoring and cautious intervention strategies. The authors have nothing to report. Mihai A. Bentan, MD, conception, design, data collection, data analysis, drafting, proofing/revision; Aaron Tucker, BA, conception, drafting, proofing/revision; Meghan Nemeth, AuD, CC-A, conception, data collection, drafting, proofing/revision; Daniel H. Coelho, MD, FACS, conception, design, data collection, data analysis, drafting, proofing/revision. None. None. Data available upon request from the authors.