Transtympanic Injection of Sodium Thiosulfate Gel for Prevention of Cisplatin Ototoxicity: Preliminary Results

Introduction: Cisplatin ototoxicity is a common and permanent side effect of cancer treatment, with no established preventive strategies. This study aimed to evaluate the efficacy and safety of intratympanic (IT) sodium thiosulfate (STS) gel injection to prevent this adverse outcome.

Methods: A randomized controlled trial was conducted in 2023–2024, enrolling adults with head and neck cancer undergoing high-dose cisplatin chemotherapy. IT STS gel was injected into one ear within 3 hours before each cisplatin cycle, while the contralateral ear served as a control. Clinical and audiometric assessments were performed before each injection and three months after the completion of chemotherapy. Changes in hearing thresholds from baseline were measured. Ototoxicity was defined according to the American Speech- Language-Hearing Association criteria (ASHA) criteria. Adverse events associated with IT STS gel injections were also monitored.

Results: Sixteen patients were included in the study. Based on ASHA criteria, the incidence of ototoxicity in treatment and control ears was not significantly different (90% vs 95%). However, the treatment ears showed a trend toward lower threshold shifts from baseline compared to the control ears. Notably, in the 4–11 kHz range, the treatment ears exhibited better hearing outcomes of ≥5 dB relative to the control ears. A safety analysis of 44 injections revealed minor adverse effects, including otalgia (6.9%), transient vertigo (9.1%), dizziness (9.1%), and tympanic membrane perforation (4.5%).

Conclusions: Preliminary findings showed no significant difference in the incidence of cisplatin ototoxicity between treatment and control ears. Nonetheless, IT STS gel injections demonstrated potential benefits in preserving hearing at high and extended-high frequencies. The procedure was generally well-tolerated, with manageable adverse effects. Recruitment is ongoing to achieve the target sample size for further investigation