Summary: HBOT in Sensorineural Hearing Loss
Key Findings
- HBOT with Medical Therapy: Improves complete and partial hearing recovery, especially in severe cases, with best results seen after 1200+ minutes of therapy. (Rhee et al., 2018)
- HBOT Alone: Achieves 71.4% complete recovery in patients contraindicated for steroids, with significant improvements regardless of demographics or severity. (Aldè et al., 2013)
- Timing Matters: Early HBOT significantly enhances outcomes, while delays reduce recovery. (Wang et al., 2023)
Idiopathic sudden sensorineural hearing loss is characterised by a rapid onset of auditory impairment, typically exceeding 30 decibels (dB) across three sequential frequencies within 72 hours. While not life-threatening, it has a significant impact on the quality of life of those affected. The annual occurrence of ISSNHL varies from 5 to 27 per 100,000 individuals, with around 66,000 new cases documented in the United States alone (Wang et al., 2023).
Several potential factors have been suggested as potential reasons for sudden sensorineural hearing loss, including viral infections, trauma, vascular compromise, autoimmune conditions, rupture of the inner ear membrane, and genetic components. Some patients may have experienced recent viral infections or upper respiratory illnesses, while others may not have a clear cause. Recently, it has been proposed that microcirculation disturbance may be the primary cause. The cochlea relies on the cochlear artery for its blood supply and does not have collateral vessels to compensate for vessel occlusion. Therefore, any condition that disrupts cochlear perfusion may lead to reduced oxygen supply and trigger sudden sensorineural hearing loss (Xie et al., 2020).
Cardiovascular and metabolic conditions such as high blood pressure, diabetes mellitus, and high levels of fats in the blood can lead to reduced flexibility of blood vessels and the development of atherosclerosis, which in turn causes microangiopathy. Numerous research studies have supported these conclusions, indicating that these concurrent health issues are closely linked to ISSNHL (Koo & Hwang, 2015).
To this date, systemic and intratympanic steroids are currently the most commonly employed treatments for sudden sensorineural hearing loss. The challenges it poses to both patients and healthcare providers have prompted the exploration of innovative treatments for especially idiopathic SNHL, one of which is Hyperbaric Oxygen Therapy (HBOT).
A study conducted by (Rhee et al., 2018) which assessed the effectiveness of HBOT in combination with medical therapy (MT) for SNHL, reported several key findings. In their meta-analysis involving 2401 SNHL patients, the authors found that hyperbaric oxygen therapy, when used in conjunction with systemic and/or intratympanic corticosteroids, offers a significant benefit as an adjunct treatment option. This study demonstrated that the combination of HBOT and MT leads to a significant improvement in complete hearing recovery, as well as any form of hearing improvement compared to MT alone. Notably, the benefit of HBOT was more pronounced in patients with severe to profound hearing loss at baseline, emphasising the potential advantages for this subgroup. Additionally, the authors noted that the efficacy of HBOT was enhanced when it was used as a salvage treatment and when the total HBOT duration was at least 1200 minutes.
Recent research by (Aldè et al., 2013) highlights that HBOT is particularly effective when initiated within 72 hours after the onset of symptoms. In this study, 49 adult SNHL patients who could not receive corticosteroids due to contraindications or concerns about side effects underwent HBOT therapy. The results were remarkably encouraging: 71.4% of patients achieved complete hearing recovery after just HBOT therapy. The mean hearing threshold saw a significant improvement, decreasing from 69.8 dB to 31.4 dB. Importantly, this improvement was consistent regardless of gender, affected ear, or the initial severity of hearing loss.
HBOT is a medical therapy involving the inhalation of pure oxygen at elevated atmospheric pressure within a specially designed chamber. This pressurised setting enables the body to absorb oxygen at significantly higher concentrations, yielding various therapeutic benefits. First and foremost, it facilitates the delivery of oxygen to tissues and cells, even in regions with limited blood flow, critical for tissue repair and healing. Secondly, HBOT reduces inflammation and exhibits antimicrobial properties, aiding in the resolution of infections. Finally, it stimulates the release of growth factors and stem cells, further promoting tissue repair (Hajhosseini et al., 2020).
The administration of HBOT for SNHL typically entails a series of sessions within a hyperbaric chamber. During each session, patients breathe in pure oxygen as the chamber’s pressure increases. The number of sessions and their duration may vary depending on the severity of SNHL and the specific treatment protocol should be recommended by a medical doctor with expertise in hyperbaric oxygen therapy individually. On average, a patient might need around 10 to 20 therapy sessions.
In summary, HBOT presents an exciting frontier in the treatment of sudden sensorineural hearing loss. Prompt and appropriate assessment and intervention could greatly enhance the quality of life for patients and decrease reliance on hearing aid devices. The effectiveness of HBOT is time-dependent and decreases with an increasing delay in administration. (Wang et al., 2023). Most of the individuals we treat are directed to our centre for HBOT as a final option after other treatments have proven unsuccessful. Yet, an increasing amount of research strongly advocates for starting HBOT early, as postponing the initiation of treatment diminishes its effectiveness—a conclusion that aligns with our clinical experiences.