“Adult onset hearing loss is the most common cause of disability globally, and the third leading cause of years lost due to disability. Moreover, adult onset hearing loss is the 15th leading cause of burden of disease and is projected to move up to 7th by the year 2030”
The loss of hearing can be one of the most debilitating and life limiting conditions encountered. In today’s consideration, we address primarily the condition known as “Idiopathic Sudden Sensorineural Hearing Loss”
This is defined as: A sudden loss of hearing of at least 30 db occurring within 3 days over at least 3 neighboring frequencies.
Structures within the cochlear require high levels of oxygen owing to their high metabolism and limited vasculature. Diffusion of oxygen via the cochlear capillary networks of the perilymph and cortilymph facilitates oxygen transport and delivery in this area. Perilymph being the main source of oxygen for intracochlear structures.
In cases of Idiopathic Sudden Sensorineural Hearing Loss, a significant decrease in oxygen tension in the perilymph is observed and this can be stabilised and restored with hyperbaric oxygenation. Hearing loss of this kind is associated with low oxygen levels and the resulting hypoxia experienced by these tissues.
The above description is paraphrased from the indications guidelines for use of HBOT from the Undersea and Hyperbaric Medical Society (UHMS). Their list of approved indications for use of HBOT includes Idiopathic Sudden Sensorineural Hearing Loss (ISSHL). Their article goes into greater detail of treatment windows inside which optimal results are achieved and the clinical management of patients.
Cases such as these would likely fall into a category that involves pre and post examination by specialised medical professionals. Certain hyperbaric facilities would simply provide the service they call for. Since the management of a chamber is not strictly medical, the diagnosis of such conditions is better left to the doctors while the equipment can be managed by the technicians. The facility wouldn’t strictly need to be a hospital based unit. It’s worth noting that many of the 120 or more charitable chambers in the UK are not directly supervised by medical professionals but rather guided by established protocols developed and adopted by experts in the field including professors of hyperbaric medicine. Technicians and hyperbaric medics are sourced from industries such as commercial diving and related industries, or can be specifically trained for the purpose. Hospital based units which are few, are generally directed by a supervising medical officer and deal with additional conditions the charitable type 3 chambers do not. They too incidentally source chamber technicians and personnel from the diving industry. While this condition would be considered reasonably emergent, it is unlikely to require advanced life support and can accordingly be treated at a type 3 facility.
Detailed also in the article linked in below is a suggested treatment protocol of 100% or close to 100% oxygen at 2 to 2,5 atmospheres absolute (ata) for 90 minutes a day for between 10 and 20 treatments. (2,4 ata is most commonly used at multiplace facilities). Provision is made for concurrent treatment with corticosteroids for those who tolerate them.
The addition of ISSHL was approved and ratified by the HBO board of the UHMS in 2011 and is one of the newer additions to the list of indications approved for commissioning of HBOT.
Deliberately kept separate from the above discussion is the topic of tinnitus. This is deliberately separated to avoid any potential confusion. Tinnitus is currently not considered an indication for treatment with HBOT by the UHMS. Not everyone agrees with that determination though.
Being somewhat related to hearing loss, and a common problem experienced by many, it will be briefly covered here with some supporting published and reviewed findings.
The mechanism of tinnitus isn’t clear and is most often described as “Phantom perception of sound in the absence of overt acoustic stimulation”. Whether it is neurological or actually present in the ear is unknown.
Many people experience varying degrees of tinnitus from tolerable to completely intolerable, with some reports of it being so loud even a live music concert can be drowned out. As a diver it’s to be expected that at times my ears have been subject to undue stress and have indeed been damaged on a few occasions. Accordingly some tinnitus is present after years of such exposures. It is relatively minor though in comparison to some of the stories we have come across. Very seldom would this be above 30 or 40 decibels.
For those whose sound perception does drown out other sound above 40 db this can be most disconcerting.
The abstract entitled:
Provides evidence based research and observed results indicating that HBOT is an effective treatment even if the complete mechanism isn’t fully understood. Perhaps the oxygen sensitivity of the cochlear and it’s requirement for high levels of oxygen saturation have something to do with it. Perhaps an injury somewhere along the line has compromised oxygen transport to that part of the ear resulting in the perception of a whining sound in the ears. Only further research will tell. For now, there is at least some indication that HBOT can help.
The abstract cited here concludes:
“We have shown that both methods [of] treatment of tinnitus are statistically significant. HBO₂ therapy was recommended for the general public.”
It certainly won’t make anything worse and certainly won’t hurt to try being a benign, non invasive and safe modality.
In the charity based business model these treatments would be affordable and adequately demonstrates that no false hope is being sold. Our aim is to provide treatment as close to free as possible to those who may benefit from it, and in doing so add to the amount of evidence available in support of the use of HBOT for tinnitus. There is no guarantee that it would help but indications are positive that it may.