Efficacy of Hyperbaric Oxygen Therapy in Sudden Sensorineural Hearing Loss
Hyperbaric oxygen therapy (HBOT) combined with corticosteroids significantly improves hearing recovery in sudden sensorineural hearing loss (SSNHL), particularly when initiated within 2 weeks of symptom onset, with the most robust evidence supporting its use in patients with moderate to severe hearing loss. 1, 2
Primary Recommendation for Initial Therapy
Offer HBOT combined with steroid therapy within 2 weeks of SSNHL onset as initial treatment. 1 The American Academy of Otolaryngology-Head and Neck Surgery explicitly recommends this approach based on systematic reviews of randomized controlled trials, though they classify it as an "option" given the balance between benefit and harm. 1
Evidence Supporting Early Intervention
The most recent meta-analysis (2025) demonstrates that HBOT combined with medical therapy increases the odds of hearing recovery by 2.61-fold compared to medical therapy alone (95% CI 1.86-3.68, p < 0.001). 2
When specifically combined with systemic steroids, HBOT increases recovery odds by 2.54-fold (95% CI 1.63-3.97, p < 0.001). 2
A 2025 systematic review found that HBOT with systemic corticosteroids significantly improved low-frequency hearing thresholds (SMD: 0.83,95% CI: 0.66-1.00, p < 0.0001) and doubled the odds of complete recovery (OR: 2.05,95% CI: 1.41-2.98, p = 0.0002). 3
Treatment within the first 2 weeks yields superior outcomes compared to delayed intervention. 1
Salvage Therapy Recommendation
Offer HBOT combined with steroid therapy as salvage treatment within 1 month of onset for patients who failed initial corticosteroid therapy. 1 This recommendation is particularly relevant for patients with severe to profound hearing loss (30-90 dB) who demonstrate poor initial response. 4
Supporting Evidence for Salvage Use
The Underseas and Hyperbaric Medical Society approved HBOT for idiopathic SSNHL in 2011, recommending use within 14 days of symptom onset. 1
Between 2-4 weeks post-onset, HBOT remains a potential adjunct to corticosteroids, particularly in patients with severe and profound hearing loss. 1
Full hearing recovery occurred in 42.6% of patients treated with combined HBOT and steroids as salvage therapy, compared to 19.0% with oral steroids alone, 17.5% with HBOT alone, and 11.6% with intratympanic steroids alone. 1
Patient Selection Criteria
Prioritize HBOT for patients with moderate to severe hearing loss (>30 dB across three or more contiguous frequencies). 1, 4
Patients with moderate to severe hearing losses demonstrate greater improvement than those with mild losses. 1
The severity of hearing loss (30-90 dB) specifically indicates HBOT benefit. 4
Greatest recovery occurs at 1,000 Hz frequency, with median threshold improvement of 32 dB. 5
Treatment Protocol Specifications
Administer 100% oxygen at pressure >1 atmosphere absolute (ATA) in a specialized hyperbaric chamber, typically for 10-20 sessions of 30-90 minutes each. 4
Pressure Optimization
For low-frequency hearing loss, 2.5 ATA pressure demonstrates superior efficacy. 6
For higher frequency ranges, 2.0 ATA pressure yields better hearing gains. 6
Standard protocols include 90 minutes at 203 kPa (approximately 2.0 ATA) daily for 20 days. 5
Frequency-Specific Outcomes
Statistically significant improvement occurs at 500,1,000,2,000, and 4,000 Hz frequencies. 5
Low-frequency hearing thresholds show the most significant improvement with HBOT. 3, 6
High-frequency therapeutic benefits are comparatively lower. 6
Quantifiable Treatment Benefits
The number needed to treat (NNT) is 5 for achieving 25% improvement in hearing. 1
Supplementation with HBOT increases pharmacotherapy effectiveness by 11.5 dB, achieving final hearing gain of 20 dB. 7
The rate of hearing gain with HBOT is more than doubled (61.7%) compared to standard treatment alone (28.6%). 7
Complete recovery rates in all frequency groups: 19.15% at low frequencies, 21.13% at mid frequencies, and 6.38% at high frequencies with HBOT, compared to 14.29%, 4.76%, and 0% respectively without HBOT. 7
Critical Timing Considerations
Initiate HBOT within 7 days of hearing loss onset for optimal results. 7, 6
Treatment delay beyond 3 months results in minimal improvement (<5 dB). 1
The Cochrane review found no significant benefit using 50% improvement as the primary outcome, but did find significant benefit with 25% improvement as the outcome measure. 1
Adverse Events and Safety Profile
HBOT carries a relatively low risk profile with primarily minor complications. 1, 4
Common Complications
Difficulty equalizing pressure in the middle ear occurs in 17% of patients receiving HBOT for various indications. 1
Eustachian tube dysfunction affects 45% of patients undergoing HBOT. 1
In SSNHL patients specifically, ear or sinus barotrauma occurs in only 6.25% due to concurrent systemic steroid use reducing inflammation. 1
Rare but Serious Risks
Oxygen poisoning and rare seizures from oxygen toxicity. 1, 8
Damage to ears, sinuses, and lungs from pressure changes. 1
Important Clinical Caveats
HBOT should always be combined with corticosteroid therapy, never used as monotherapy. 1, 4 Most studies employed HBOT with concurrent or prior medical therapy, and few studies used HBOT without corticosteroids. 1
Practical Limitations
HBOT costs $600-700 per session and requires specialized facilities. 8
The Cochrane review included only 7 RCTs with 392 total subjects, limiting extensive subgroup analysis. 1
Significant heterogeneity (I² = 96.7%) exists across studies with variations in treatment protocols. 3
Contraindications and Special Populations
Patients with medical devices require careful evaluation, though history of medulloblastoma and brain shunt requires monitoring but is not an absolute contraindication. 4, 9
The potential benefit of hearing recovery outweighs manageable risks in appropriately selected patients. 4
Evidence Quality Assessment
The 2019 American Academy of Otolaryngology-Head and Neck Surgery guideline represents the highest quality evidence, classifying HBOT as an "option" based on systematic reviews of RCTs with balanced benefit-harm profile. 1
The most recent Cochrane review (2012) included RCTs published between 1985 and 2004, with no newer trials included in that specific review. 1
However, multiple high-quality studies published between 2018-2025 demonstrate consistent benefit, strengthening the evidence base. 3, 5, 2, 7, 6
The 2025 meta-analysis by Laryngoscope included 20 studies investigating 1,087 patients receiving HBOT and 600 receiving medical therapy alone, providing the most comprehensive contemporary evidence. 2