Role of hyperbaric oxygen (HBOT) in sudden hearing loss

Question: I recently developed sudden hearing loss in my left ear. Is there a role for hyperbaric oxygen?

Answer: An article in the 2012 May-June issue of the Undersea and Hyperbaric Medicine Journal published that idiopathic sudden sensorineural hearing loss (ISSHL) is the newest indication approved by the Undersea and Hyperbaric Medical Society’s Hyperbaric Oxygen Therapy Committee.

There are obviously many different types of hearing loss and it is important to see the ENT surgeon as soon as possible to evaluate the type of hearing loss and to look for possible treatable causes. Broadly, hearing loss can be divided into conductive and sensorineural. The former is due to a problem with sound being blocked from reaching the inner ear. It could be as simple as wax in the external ear canal or it could be a middle ear disease like a hole in the ear drum, fluid in the middle ear and infection in the middle ear. In a pure conductive hearing loss, the inner ear and nerves are normal. If there is no blockage, then it is either the inner ear or nerves which are abnormal, this is termed sensorineural. A sudden sensorineural hearing loss is an ENT emergency as treatment must be instituted as soon as possible to have the best chance of recovery.

There are many possible causes of sensorineural hearing loss, ranging from infections, circulatory problems, autoimmune problems, tumours etc. Normally a panel of tests are carried out and when none is found, it is termed idiopathic. If a cause is found, that cause should be treated. If not, a combination of steroid treatment, vasodilators and antiviral therapy has been empirically started with variable results. It is generally agreed that treatment must be started within 2 weeks to have any chance of working. A figure close to 60% has classically been quoted if treatment is started within 2 weeks but no benefit has been shown if treatment is started beyond 2 weeks. It must be noted that there is also a certain degree of spontaneous recovery even without treatment. Hyperbaric oxygen therapy is a relatively new modality of treatment.

A review of the literature reveals more than 100 publications evaluating the use of hyperbaric oxygen (HBO2) for the treatment of ISSHL, including eight randomized controlled trials. The best and most consistent results are obtained when HBO2 is initiated within two weeks of symptom onset and combined with corticosteroid treatment. The average hearing gain is 19.3 dB for moderate hearing loss and 37.7 dB for severe cases. This improvement brings hearing deficits from the moderate/severe range into the slight/no impairment range. This is a significant gain that can markedly improve a patient’s quality of life, both clinically and functionally.

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