The sudden onset of a hearing loss can be a devastating experience if it occurs in a better hearing ear. Fortunately this most often occurs in individuals with normal hearing and only involves one ear. Despite this the effects can be very disturbing at least. Such a loss can have many causes but how sudden is sudden and how much of a loss is needed before it can be called a loss? The usually accepted definition is of a loss of more than 30dB averaged over three consecutive frequencies and occurring within 3 days. The causes of such losses are:
- Conductive – from changes in the ear canal or middle ear so sound cannot be transmitted on to the inner ear.
- Sensorineural – from changes in the inner ear, acoustic nerve or the auditory parts of the brain
- Psychological – rarely as part of a depressive illness or other psychological disorder when the condition used to be called a conversion reaction but is now termed a functional neurological disorder. [Discussion of this will be covered in a separate entry which I have not yet written.]
CONDUCTIVE
The commonest form of a severe conductive loss is probably impacted wax that has got wet and swollen up, or has been pushed deep into the ear canal by a well-intentioned cotton bud and completely blocked the canal. The diagnosis is usually straightforward and treatment is by careful suction clearance using a microscope for magnification and illumination. Cure is usually instantaneous and the relief to the patient is immediate .
Below is a picture of an ear canal completely blocked with wax.
Less common severe sudden conductive losses usually come from trauma to the eardrum or middle ear. This can be due to, say, a diving injury, a blast exposure or by a cotton bud or other implement when the eardrum is extensively damaged This is often obvious from the history of events and a simple examination, which shows the ruptured eardrum. A maximum 40dB loss can occur with this type of damage. Below is an image of two small traumatic perforations caused by slapped over the ear. Fortunately these healed spontaneously.
Acute changes which are not enough to damage the eardrum and which can occur during scuba diving with a cold, can result in bleeding into the middle ear or just the out pouring of fluid from the lining of the middle ear to fill it and thereby minimize the pressure changes on the eardrum by reducing the volume (Boyle’s Law P1V1/T1=P2V2/T2).
Direct head trauma such as might occur in a car crash can disrupt the ossicular chain. The Commonest site of damage is the joint between the anvil and stapes [the incudo-stapedial joint]. When this occurs there is complete discontinuity and a 60dB conductive loss.
In all the above cases reliable pure tone audiometry with masked bone conduction must be performed to exclude an underlying sensorineural hearing loss caused by the trauma and which would alter the chances of full recovery. Tympanometry, when the eardrum is intact may show a tall, peaked wave typical of ossicular discontinuity or a flat trace if the middle ear is full of fluid. This can be removed by an incision in the eardrum [myringotomy] and careful suction through the incision to remove the fluid. Ossicular problems can frequently be cured by surgery. The eardrum is reconnected to the footplate or to the arch of the stirrup using either the patient’s own anvil which has been reshaped and re-inserted between the handle of the hammer and the stirrup or by using artificial bone. This is commonly made of hydroxy-apatite, one of the core elements of bone. The procedure is called an Ossiculoplasty. The eardrum can also be repaired again using microsurgical techniques and the procedure is called a Tympanoplasty or Myringoplasty.
SUDDEN SENSORINEURAL HEARING LOSS – SSNHL
A sudden sensorineural hearing loss in one ear that fails to recover is a relatively rare event. A list of causes from Trends in Amplification 2011is set out below.
Many of these causes are speculative, without any real evidence base to support their inclusion in this table for one sided hearing loss.
The list also fails to mention bacterial infection, middle ear and mastoid disease in the form of acute bacterial labyrinthitis and cholesteatoma, post anaesthetic, following cardiac bypass surgery, and following lumbar puncture which are all well recognized, if very uncommon, causes.
Severe acute sensorineural hearing losses (SSNHL) are not particularly common and most general practitioners will not see more than a handful in their lifetimes. This has made evaluation of the best forms of treatment very difficult. A few people have a specific causative condition such as blast injury, a major head injury or surgical damage which has traumatized the cochlea. Others will have had meningitis or mumps. Severe middle ear infections or cholesteatoma can invade the inner ear. An acoustic neuroma can also make itself known by producing a sudden deafness. A few people will have had a Herpes infection and in addition to some blisters in the ear or on the roof of the mouth might have vertigo and a facial palsy in addition to the deafness. This triad is called a Ramsay Hunt syndrome.
There are other rarer conditions, but in general there is no proven cause for most cases of sudden onset SNHL When this happens, doctors tend to label the condition as being due to a virus or to a blood clot affecting the blood supply to the inner ear. There is no good evidence to support either of these causes as being “real” although the second has more intuitive “appeal”. The inner ear has only a single small artery [the labyrinthine artery] supplying it, whilst most other parts of the body have two so that if one is blocked the other continues the blood supply. The labyrinthine artery divides to supply separately the cochlea and the vestibular labyrinth. Blockage of the artery at various points could theoretically cause deafness, dizziness or both. Whilst this is an attractive proposition and has formed the basis for many treatments, there is no proof that this is the cause and indeed such changes would now be seen on high resolution MRI scans and this has not been the case. Treatments to clear blocked arteries have also had no effect whatsoever. For this reason most cases of acute SNHL are called “idiopathic”, which means without cause.
What is the incidence of idiopathic sudden sensorineural hearing loss?
This analysis comes from the 2008 edition of the standard British ENT text book i.e. Scott-Brown’s Otolaryngology
Evidence Based medicine (EBM) guide: Eight per 100,000 per year
The natural history of sudden idiopathic sensorineural hearing loss.
There are few papers describing the natural history of idiopathic, sensorineural hearing loss, that is what happens without treatment. There is, it seems, a natural tendency to spontaneous resolution and so many people who develop a loss will have got better quite quickly and will not seek medical advice. This has a major impact on the validity of studies attempting to assess the success of treatment without using a time equivalent untreated control group.
Probably the best (and nowadays likely the only) study of what happens to people with a sudden onset of a hearing loss was performed by Doug Mattox and Blair Simmons in the USA in the 1970s. In a large hospital setting and the surrounding townships they let it be known that they would see any one with a sudden hearing loss immediately and all the individual had to do was turn up in the department. The patient had a hearing test and was then observed with serial audiograms until the hearing recovered or did not. No treatment was given to this group. The authors found that 65% of their patients recovered completely within two weeks and another 15% recovered more or less completely during this time. The maximal rate of recovery was within the first few days.
Mattox and Simmons wrote:
Thus, it is difficult to interpret the publications on the incidence of the condition if patients are not seen within the first few days of onset. This data is rarely given in the published articles.
Furthermore, for an uncommon condition without a cause, and a strong tendency to natural resolution or improvement, treatment cannot be planned on any logical basis. Indeed, in proper trials, no form of treatment has been shown to be any more effective than doing nothing, provided other underlying conditions have been excluded. The UK Cochrane reviews of various forms of treatment (see www.cochrane.org) show that there is no form of treatment that is effective in improving the hearing. Untreated 60-70% of individuals recover completely or nearly completely and usually within the first week. Therefore, any treatment has to be more effective than spontaneous resolution to be useful and so far none has been found. The factors that suggest poor recovery are:
- losses involving the 8 kHz region
- a loss averaging more than 70dB at 1, 2 and 4kHz
- associated vertigo.
For a trial of treatment to be considered as an acceptable piece of work, there should be a placebo arm, that is management with nothing or a non active susbstance. In addition, treatment and control groups have to be very similar in the time of onset of the hearing loss because of the rapid and major spontaneous recovery. To find enough patients to show that a “treatment” is, say, 10% better than no treatment requires so many patients to give the study statistical “Power” that there are no studies that fulfill this criterion.
Current guidelines for management of idiopathic SSNHL
A publication by the American Academy of Otolaryngology, Head and Neck Surgery (2019. Vol 161 (IS) S1-45) was entitled “Clinical Practice Guideline: Sudden Hearing Loss (Update)”. This is the most authoritative publication on the subject so far. In the section relating to the management of sudden sensorineural hearing loss a rigorous analysis of the various forms of treatments that have been suggested was performed and allowed the following categories to be defined:
Strong Recommendation – Clinicians should follow this
Recommendation – Clinicians should generally follow this recommendation but should remain alert to new information and sensitive to patient preferences
Optional – this means the quality of the evidence is suspect or that well-done studies show little clear advantage. Clinicians should be flexible in their decision…patient preference should have a substantial influencing role.
Strong recommendation against- this management protocol is strongly disadvised because of the inherent risks and lack of benefit in any trial.
The conventional remedies of oral steroids or hyperbaric oxygen are optional at the onset and intra tympanic steroids are recommended only when patients have incomplete recovery some two to six weeks after the onset of the sensori neural loss.
Other pharmacological remedies – antivirals, vasodilators , thrombolytics (clot busters) and vaso-active substances – had a strong recommendation against their use.
I reproduce a section from table 4 showing that initial steroid therapy is only an option and is not mandatory.
The 2013 UK Cochrane review on the use of “Steroids for idiopathic sudden sensorineural hearing loss” (Cochrane Database of Systematic Reviews 2013, Issue 7. Art. No.: CD003998.) only found three papers in the world literature which satisfied their inclusion criteria and “all three studies were at high risk of bias”. Only 267 patients were included.
They concluded “the value of steroids in the treatment of idiopathic SSNHL remains unclear since the evidence obtained from randomised controlled trials is contradictory in outcome, in part because the studies are based upon too small a number of patients”
The 2018 NICE guidelines state under “research recommendations” : “First-line treatment options for idiopathic SSNHL can include oral steroids, intra‑tympanic steroid injections or a combination of both. There is a paucity of evidence assessing the effectiveness of these different treatment options. There is heterogeneity in doses and types of steroids and this makes the findings unreliable. Therefore, it is difficult to establish the most clinically and cost-effective route of administration of steroids as first-line treatment for idiopathic SSNHL. This has a direct impact on the care provided to people with SSNHL and on our ability to develop robust guidelines and policy.”
When it comes to treatment the NICE guidelines simply state: “1.4.1 Consider a steroid to treat idiopathic sudden sensorineural hearing loss in adults.”
A recent -2023- well researched paper from the Tel Aviv Medical School looked at the “Spontaneous recovery rate of ISSNHL”. Their rationale was that: “Steroids comprise the mainstay of treatment for idiopathic sudden sensorineural hearing loss (ISSNHL). Since steroidal treatment was integrated to clinical practice guidelines, newly published no-treatment or placebo arms in clinical trials are scarce. To evaluate the effectiveness of steroidal treatment ± hyperbaric oxygen therapy, the data should be compared to spontaneous recovery. The aim of this paper is to find the most accurate spontaneous recovery rate, in the light of which, other treatment modalities should be judged.”
The group found that 60% of ears recovered spontaneously within three months.
Their conclusion included the following statement:
“A recovery rate ranging from 6% to 60% had been reported in a recent systematic review and meta-analysis of intratympanic steroid injection and hyperbaric oxygen therapy. Another recent systematic review and meta-analysis described a complete recovery rate of 33% in the group of patients who received a combination of intratympanic and systemic [steroid] treatment, and a 30% complete recovery rate in the systemic treatment only group. Comparing these recent results to the results of the current meta-analysis and previous studies, it appears that the natural history of ISSNHL may not be worse than the outcome of treatment. This may have implications on the discussion held with the patients when describing their treatment options.”
An even more recent, 2024, paper from the Japanese Research Group on Intractable Hearing Disorders reviewed the results collected over several years from the Japanese population. They outline treatment options based on the quality of the evidence from Level I (best) to Level VI (worst) and on their assessments of treatments from A, which has strong scientific evidence to support its use, through to D with evidence of ineffectiveness. Recommendation C1 is “lacks scientific evidence but is still recommended” which is possibly the equivalent of the “Optional Treatment Category” in the larger American study.
They state.
“Treatment:iSSNHL [this relates to high frequency or “flat” losses and not to low frequency losses] is treated with corticosteroids and other medications during the acute phase of the disease. In an epidemiological survey conducted by the “Research Group on Intractable Hearing Disorders,” corticosteroids were administered in more than 80 % of cases. Although scientific evidence remains limited, this is practically used as the standard treatment… Evidence Level I, Recommendation Grade C1”.
An intriguing graph from the report shows the “before and after” hearing levels in several of the treatment groups. The “Hearing threshold” is the average from the audiogram at 250, 500, 1k, 2k and 4k Hertz. The groups are oral steroids, oral steroids plus prostaglandins, intra tympanic steroids and no treatment. There are no clinically significant difference in the outcomes. The delay following the onset of the hearing loss and the start of treatment is not clear from the paper.
In other words there is no evidence that “treatment” with whatever modality makes any difference to the outcome at least as far as a significant change in the audiogram is concerned.
A paper by Mitesh Patel et al was, surprisingly, published in the Lancet and compared the outcomes in patients with Meniere’s diseases who were managed by either intra tympanic steroids or intra tympanic gentamicin. No control group was included which is the “surprise”. The results showed a benefit in terms of the symptom of vertigo but no effect whatsoever, on the hearing levels. I know Meniere’s is not the same as an idiopathic SSNHL but it is idiopathic and there is a SNHL which comes on suddenly during flare-ups of the condition.
Another, even more recent paper published in September 2024 by the UK SEASHEL group, has become “fashionable” in that has been taken up by many interested groups as the confirming the need to use steroids as a first line treatment which works. The trial was a UK multicentre collaboration from 76 hospitals and it was stated that all the patients who entered the trial had some form of steroid on first presentation. They were tested, treated and followed. These conclusions were that: “that earlier time-to treatment, lower severity of hearing loss at presentation, absence of vertigo, and younger patient age are predictors of hearing recovery.” The results also showed that low frequency losses recovered better than high frequency losses. This has striking similarity to the 1977 paper from Mattox and Simmons noted above.
In fact, not all the patients had steroids. Of the 458 patients in the trial all had audiograms but 33 did not have steroids. There are no details about the duration of the hearing loss in the 33 who did not have steroids although this group had 20% complete recovery which was the same as the group who had steroids more than 14 days after onset – 19% recovery.
So, in effect this was an uncontrolled trial as patient were not randomised to “treatment” or “no treatment” groups and in the group that did not receive steroids the duration of the hearing loss when they became part of the trial is not recorded. This pushes the study into the “poor quality” classification outlined below.
In clinical medical research there exists the concept of “levels of evidence”. He list below is from The Oxford Centre for Evidence Based Medicine.
Evidence Level. Category: Therapy/Prevention/Cause/Harm.
1a Systematic Review with homogeneity of Randomised Control Trials.
1b. Individual Randomised Controlled Trials with narrow confidence levels.
2a. Systematic reviews (with homogeneity) of Cohort studies.
2b. Individual Cohort study (including low quality RCT with less than 80% follow up.
2c. Outcomes research; ecological studies.
3a. Systematic Review with homogeneity of case control studies.
3b. Individual Case control studies.
4. Case-series and poor-quality cohort and case control studies
5. Expert Opinion without explicit critical appraisal or based on physiology, bench research or “first principles”.
The title of the paper was “A Prognostic Model to Predict Hearing Recovery in Patients With Idiopathic Sudden Onset Sensorineural Hearing Loss” and the authors do confirm what has been known since 1977 but the paper does not address the value of steroids in the management of this unfortunate condition. Whilst well intended, this recent multicentre UK trial is Evidence Level 4 as far as the use of steroids is concerned and the authors unfortunately ignored advice, prior to starting the study, of including a randomised controlled “no steroid group” to the trial.
Even the Royal National Institute for Deaf People (RNID) – who should know better – have fallen for the implied suggestion in the article that steroids help.
A critical review of the studies mentioned above and more adds weight to the suggestion that treatment with steroids whether oral, intamuscular, intra venous or intra tympanic makes no difference to the outcome of the hearing levels in idiopathic SSNHL.
Why does the medical ENT community – rather than the evidence based community – recommend intratympanic steroid injections? I fear the answer is purely finance driven especially in the US, Europe and private practice in the UK. Intra tympanic steroid injection is a “medical procedure” and attracts a significant payment whilst being relatively risk free and is easy to perform. As far as I can tell, from a review of the literature there are no robust studies which show any benefit as far as the audiogram is concerned.
All of this enthusiasm and conviction for using steroids in one form or another is starting to resemble Betrand Russell’s “orbiting teapot argument”. Betrand Russell was a famous English philosopher and from aged 18 was an atheist. In 1952 in an article titled “Is there a God?” he wrote:
“If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes.
But if I were to go on to say that, since my assertion cannot be disproved, it is intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense.
If, however, the existence of such a teapot were affirmed in ancient books, taught as the sacred truth every Sunday, and instilled into the minds of children at school, hesitation to believe in its existence would become a mark of eccentricity and entitle the doubter to the attentions of the psychiatrist in an enlightened age or of the Inquisitor in an earlier time”.
One interpretation of this is that if an assertion, however false, is repeated often enough and with belief in its truth, then it becomes generally accepted. To my mind this is what has occurred with using steroids to treat a condition that usually gets better by itself.
Patient management.
However, this is not to say that patients do not need to be managed, and guidelines express strong support for holistic management because of the devastating nature and impact of the condition. A full history should be taken, an examination performed, and appropriate investigations ordered, including an MRI scan, to exclude underlying disease. Some ENT surgeons like to admit their patients for bed rest and sedation and even an “optional” medication as the onset of a severe SNHL can be very disturbing especially if accompanied by vertigo. Should spontaneous recovery not occur then support and hearing rehabilitation can be provided.
The only reason for giving steroids as a form of treatment is for the treating doctor to be able to say to the patient whose hearing loss persists: “We gave you the best treatments available and unfortunately you were one of the unlucky few that did not respond”. If the patient happens to get better, then the Physician can be happy that his treatment “did the trick”
This is not a cynical view of management but a realistic appraisal of what happens in medical practice.
Overall, there is no evidence that “treatment” with steroids alters the outcome of SSNHL at least as far as the hearing is concerned. It may make the patient feel better in that “treatment” was given but it does not alter the objective outcome as far as the audiogram is concerned, compared to not giving steroids.
References.
Natural History of Sudden Sensorineural Hearing Loss
Mattox DE Simmons FB
Annals Otology Rhinology Laryngoolgy. 1977, 86, 463-480.
Spontaneous recovery rate of idiopathic sudden sensorineural hearing loss: A systematic review and meta-analysis
Hen Chaushu, OmerJ.Ungar, Rani AbuEta, Ophir Handzel, Nidal Muhanna, Yahav Oron
Clinical Otolaryngology. 2023;48:395–402.
Intratympanic methylprednisolone versus gentamicin in patients with unilateral Ménière’s disease: a randomised, double-blind, comparative effectiveness trial
Mitesh Patel, Kiran Agarwal, Qadeer Arshad, Mohamed Hariri, Peter Rea, Barry M Seemungal, John F Golding, Jonny P Harcourt, Adolfo M Bronstein.
Lancet 2016; 388: 2753–62.
Clinical practice guidelines for the diagnosis and management of acute sensorineural hearing loss.
Ryosuke Kitoh et al.
Auris Nasus Larynx 51 (2024) 811–821
Rishi Mandavia, Nikhil Joshi, Gerjon Hannink, et al
JAMA Otolaryngol Head Neck Surg. 2024;150(10):896-906. doi:10.1001/jamaoto.2024.2598