The Use of Hyperbaric Oxygen Therapy and Corticosteroid Therapy in Acute Acoustic Trauma: 15 Years’ Experience at the Czech Military Health Service

Abstract

Background: Acute acoustic trauma (AAT) ranks, among others, as one common cause of inner ear function impairment, especially in terms of military personnel, who are at an increased exposure to impulse noises from firearms. Aim of this study: 1. We wanted to demonstrate whether early treatment of AAT means a higher chance for the patient to improve hearing after trauma. 2. We find the answer to the question of whether hyperbaric oxygen therapy (HBO2) has a positive effect in the treatment of AAT. Methods: We retrospectively analyzed data for the period 2004–2019 in patients with AAT. We evaluated the therapeutic success of corticosteroids and HBO2 in a cohort of patients with AAT n = 108 patients/n = 141 affected ears. Results: Hearing improvement after treatment was recorded in a total of 111 ears (79%). In terms of the data analysis we were able to ascertain, utilizing success of treatment versus timing: within 24 h following the onset of therapy in 56 (40%) ears—54 (96%) ears had improved; within seven days following the onset the therapy was used in 55 (39%) ears—41 (74%) ears had improved; after seven days the therapy started in 30 (21%) ears—16 (53%) ears had improved. Parameter latency of the beginning of the treatment of AAT was statistically significant (p = 0.001 and 0.017, respectively). The success of the medical protocols was apparent in both groups—group I (treated without HBO2): n = 61 ears, of which 50 (82%) improved, group II (treated with HBO2): n = 73 ears, of which 56 (77%) improved. Group II shows improvement at most frequencies (500–2000 Hz). The most serious sensorineural hearing loss after AAT was at a frequency of 6000 Hz. Conclusion: Analysis of our data shows that there is a statistically significant higher rate of improvement if AAT treatment was initiated within the first seven days after acoustic trauma. Early treatment of AAT leads to better treatment success. HBO2 is considered a rescue therapy for the treatment of AAT. According to our recommendation, it is desirable to start corticosteroid therapy immediately after acoustic trauma. If hearing does not improve during the first seven days of corticosteroid therapy, then HBO2 treatment should be initiated.

Efficacy of Oral Steroids for Acute Acoustic Trauma

“…The importance of early steroid treatment after AAT injury (within 24 h) is supported by Holy et al [2021], showing a direct correlation between the onset of treatment and audiometric outcomes; the best outcomes were observed in patients who were treated within 24 h after AAT injury. Patients who were treated within 7 days showed better outcomes compared to those who started treatment later than 7 days after AAT injury [Holy et al, 2021]. In addition, the authors offered a "rescue" protocol including HBOT in patients who showed no audiometrical improvement after 7 days of oral steroid treatment.…”

“…We acknowledge some limitations: (1) our study is limited by its retrospective nature; however, randomized control trials on the subject are not ethically feasible (2) because all our study subjects were recruits of young age (18-35 years), without any substantial morbidities and contraindications to steroid therapy, and thus our findings may not be generalizable to subjects with comorbidities presenting with AAT injury; (3) HBOT, with or without concurrent steroid treatment, is increasingly being investigated as playing a major role in AAT injury treatment [Yilikoski et al, 2008;Oya et al, 2019;Holy et al, 2021]. In our study cohort, it was not part of our study protocol, and therefore we cannot comment on the efficacy of this modality; (4) we observed a tendency to prescribe oral steroid treatment to subjects presenting with more severe hearing losses, when compared to those presenting with milder losses, as documented in the first audiometry.…”

“…However, the latter study did not compare between patients receiving only steroid treatment and patients treated with steroids and HBOT, and therefore the exact contribution of HBOT in AAT injury is not clear. A recent study by Holy et al [2021] showed that a combination of oral steroid therapy and HBOT given within 7 days after AAT injury is superior to oral steroid treatment alone, with significant better audiometric results in low frequencies (500 Hz and 2,000 Hz). Yet, most studies and meta-analyses included only relatively small cohorts of subjects (sample size ranges from 37 to 108 subjects), with a high degree of divergence in respect to the mechanism of injury (i.e., different kinds of weapons or other explosives), and lacked a uniform treatment protocol and sufficient long-term follow-up period.…”