Hyperbaric Oxygen Therapy a Potential Option for Sudden Sensorineural Hearing Loss

By Marilynn Larkin

November 08, 2021

NEW YORK (Reuters Health) - A systematic review and meta-analysis including three studies suggests that hyperbaric oxygen therapy (HBOT) should be considered as part of a combination treatment for patients with sudden sensorineural hearing loss (SSNHL).

"The most surprising finding to me was the clinically important difference in hearing improvement that patients who received HBOT in addition to standard steroid treatment demonstrated," Dr. Desmond Nunez of the University of British Columbia in Vancouver told Reuters Health by email. "This amounted to an average of just over 10 dB in absolute hearing gain."

"The advantage of combining HBOT with steroid therapy was already apparent to me based on the findings of an as yet unpublished retrospective study of SSNHL patients attending my and colleagues' clinics," he noted.

That said, he added, "The randomized controlled trials analyzed all began HBOT within 7-10 days of the onset of the hearing loss. Therefore, the benefit we identified relates to early treatment. Further studies are required to determine if patients presenting later than 10 days after the onset of SSNHL will benefit from HBOT."

As reported in JAMA Otolaryngology-Head and Neck Surgery, Dr. Nunez and colleagues analyzed data from prospective randomized controlled trials (RCTs) involving only adults with SSNHL and comparing HBOT, as a single or combination therapy, with control therapies, such as steroids and/or placebo.

The primary outcome was the mean difference in absolute hearing gain recorded by pure-tone audiometric (PTA) thresholds averaged across 4 low frequencies (0.5, 1, 2, and 3 or 4 kHz) or 3 high frequencies (3 or 4, 6, and 8 kHz).

The secondary outcomes were the odds ratio of hearing recovery defined as a hearing gain of 10 or more dB in PTA average and treatment-related adverse effects.

Of the 826 records initially identified, 358 duplicates and 451 articles were excluded based on article type, title, and abstract. The full texts of 17 articles were reviewed, of which 14 were excluded because they were either not prospective RCTs (11), the participants were less than 18 years old (2), or the PTA was not reported at frequencies of interest (1).

Therefore, three prospective RCTs with a total of 88 participants who received HBOT in the intervention groups and 62 who received only medical therapy in the control groups were included.

As Dr. Nunez noted, the intergroup difference in mean absolute hearing gain (mean difference, 10.3 dB) and the odds ratio of hearing recovery (4.3) favored HBOT over the control therapy.

Only one trial reported treatment-related adverse effects - i.e., transient otalgia in two patients during the first week of treatment.

Limitations included the small number of studies, the risk of bias and inability to assess the secondary outcome.

Dr. Nunez said, "Accessibility (of SSNHL) is a downside. Lack of awareness of SSNHL and its treatment in the general public and amongst some clinicians contributes to reduced access to this treatment option. Furthermore, referral bottlenecks and limited treatment capacity due to the paucity of HBOT facilities in most jurisdictions and the cost of treatment when not publicly funded add further barriers to timely access."

Dr. Stephanie Moody-Antonio of Eastern Virginia Medical School in Norfolk commented in an email to Reuters Health, "HBOT has a long history of controversy when applied to the treatment of SSNHL, but has reached the threshold for approval for treatment of complete hearing loss by the FDA and lesser severity of hearing loss by the Undersea and Hyperbaric Medical Society, if treated within 14 days of onset."

The American Academy of Otolaryngology-Head and Neck Surgery's clinical practice guidelines (state) that HBOT is an option, with a balance between benefit and harm," she said.

"HBOT is expensive with respect to both time and cost," she noted. "Complications such as barotrauma and oxygen toxicity can occur. It is not available in many communities. However, shared decision making should allow for a discussion of HBOT as an adjunct to steroid treatment and the evidence is strong enough that patients should be afforded access to HBOT by insurers."

"The downstream negative effects of hearing loss, including difficulty with social interaction, job performance, and safety, should be weighed against the cost and risks of treatment, including HBOT," Dr. Moody-Antonio concluded.

SOURCE: https://bit.ly/2ZY7tYV and https://bit.ly/3bJcXtl JAMA Otolaryngology-Head and Neck Surgery, online October 28, 2021.