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SUDDEN HEARING LOSS

Timothy C. Hain, MD. Hearing Page Page last modified: September 18, 2014

What is Sudden Hearing Loss?

Sudden hearing loss (SHL) is defined as greater than 30 dB hearing reduction, over at least three contiguous frequencies, occurring over 72 hours or less. It occurs most frequently in the 30 to 60 year age group and affects males and females equally. Although called sudden, it seems unlikely that hearing loss is abrupt but rather it probably evolves over a few hours.

SHL can affect different people very differently. SHL is usually unilateral (that is, it affects only one ear); and is often accompanied by tinnitus. vertigo, or both. The amount of hearing loss may vary from mild to severe, and may involve different parts of the hearing frequency range. SHL may be temporary or permanent. About one third of people with SHL awaken in the morning with a hearing loss.

Sudden hearing loss is associated with vertigo in between 20 to 60% of patients (Rambold et al, 2005).

There is presently no convincing evidence that any oral or intravenous treatment for idiopathic SHL is better than placebo. The question remains open regarding injections of steroids through the ear drum, but the authors opinion is that these are also no better than placebo.

What Causes Sudden Hearing Loss?

If one knows what causes SHL, it isn't idiopathic (by definition).

Autoimmune Vascular Neurological Neoplastic Trauma or Toxin Infections and viral
Autoimmune inner ear disease (AIED) Cardiopulmonary bypass Acoustic Neuroma Large vestibular aqueduct syndrome Cryptococcal Meningitis
Cogan's syndrome Red blood cell deformability Contralateral deafness after acoustic neuroma surgery Inner ear concussion Cytomegalovirus
Lupus Sickle cell Focal pontine ischemia Inner ear decompression sickness Herpes-simplex I
Meniere's Small vessel disease Leukemia Otologic surgery HIV
Polyarteritis nodosa Vascular disease associated with mitochondriopathy Meningeal carcinomatosis Ototoxicity Lassa Fever
Relapsing polychondritis Vertebrobasilar insufficiency Migraine Perilymph Fistula Meningococcal meningitis
Ulcerative Colitis Blood dyscrasias Multiple sclerosis Temporal bone fracture Mumps
Wegeners's granulomatosis   Myeloma CSF leak, such as caused by lumbar puncture Rubeola
        Rubella
        syphilis
        Toxoplasmosis

Table adapted from Wynne, 2003

Although some hold that this disease is generally idiopathic (of unknown cause), the differential diagnosis includes viral disease, Lyme disease and its relatives (Lorenzi et al, 2003), vascular disease (1%), autoimmune phenomena, perilymph fistulae and Meniere's disease, and acoustic neuroma (about 4 to 6% of SHL -- see table above and Daniels et al, 2000 for a longer list of diagnoses).

Viral disease has been claimed to be the basis for about 60% of all cases of SHL. Viruses detected at a study at the Massachusetts Eye/Ear infirmary included influenza type B, CMV (Seguira et al, 2003), mumps, rubeola, and varicella-zoster (Harris, 1998). Others include measles, herpes-1, and infectious mononucleosis. Many of these are in the herpes family. Numerous other causes are possible (see next section).

A temporal bone study of 17 bones from the Mass Eye/Ear infirmary suggests that pathology does not support the concept of membrane breaks (e.g. Meniere's), perilymphatic fistulae or vascular occlusion (Merchant et al, 2005). An additional study of 11 more temporal bones in 2013 (Linthicum et al), was suggestive of a viral etiology. In our view, these studies included too few temporal bone samples to be relied upon. More temporal bone donations are needed. Interestingly, the laboratory that reported the recent 11 bones, had been in operation for 50 years. This tiny number of samples over 50 years points out that the infrastructure to gather temporal bones in the USA is suboptimal. We ourselves have had situations where a patient indicated a willingness to have their temporal bone "harvested" but a "harvester" -- an otologic surgeon -- was not available. Once this happens, one loses one's enthusiasm in encouraging patients to be generous.

Some authors maintain that vascular disease is the most likely cause (Rambold et al, 2005). This is largely a conclusion based on exclusion of other causes. In general, when viruses or vascular etiologies are held out as the "cause" of a particular illness, it often means that the details are unclear. Recently there has been some weak recent evidence that blood flow plays a role as some measures of hearing improve in animals after a "stellate ganglion block" that improves blood flow (Firat et al, 2008). High levels of cholesteral and low levels of Coenzyme Q are associated with SHL (Cadoni et al, 2007). Use of some agents that affect blood flow, such as sildenafil (Viagra) but not vardenafil (Levitra) or Tidalafil (Cialis), have been associated with hearing loss (McGwin, 2010; Khan et al, 2011). 

Migraine is also associated with SHL, presumably through vascular mechanisms. Migraine is very common (15% of the population), far more so than SHL, and even occasional SHL due to migraine could be very significant. The author's opinion is that migraine is a much more common cause of SHL than is generally appreciated in the otolaryngologic community.

Cerebrospinal fluid (CSF) leak is a particularly interesting causal variant of SHL. CSF leaks may be caused by diagnostic or therapeutic procedures in medicine such as. lumbar puncture, spinal anesthesia or epidural anesthesia (Johkura et al. 2000). Symptoms may occur weeks after the procedure (Lybecker and Anderson, 1995). CSF leak may occur spontaneously and may follow trauma. While CSF leak is generally accompanied by an orthostatic (upright only) headache, this association is not universal and in fact, hearing loss may be more common than headache (Oncel et al, 1992). Orthostatic tinnitus is also possible.(Arai, Takada et al. 2003). The hearing loss of CSF leak likely results from lowering of CSF pressure, which lowers perilymphatic (inner ear) pressure, and results in a picture similar to Meniere's disease. (Walsted et al., 1991). Fortunately, the hearing loss is generally temporary. The treatment is with blood patch.

How is Sudden Hearing Loss Diagnosed?

Bottom line: we favor audiometry, MRI of the posterior fossa with gadolinium, CBC and sed-rate in all persons with SHL, and additional testing decided based on historical features.

In essence, SHL is diagnosed by documenting a recent decline in hearing. This generally requires an audiogram.

Other studies are performed mainly to look for specific causes. Evaluation usually begins with a careful history looking for potential infectious causes such as otitis media and exposure to known ototoxic medications. Autoimmune hearing loss is suggested by good recovery, response to steroids, and relapse.

Tests worth considering

Tests worthwhile in special cases

Tests unlikely to be helpful

 

Natural History of Sudden Hearing Loss

Mattox and Simmons (1977) reported a rate of 65% spontaneous recovery to "functional hearing levels." Byl also reported a recovery rate of about 69% (Byl, 1984). Those that recover 50% of hearing in the first 2 weeks following SHL have a better prognosis than those who do not recover at this rate (Ito et al, 2002). Serum antiendothelial cell antibodies are associated with a poorer prognosis (Cadeni et al, 2003). Recurrence of SHL is rare but possible (Furohashi et al, 2002).

Cvorocic et al recently reviewed the prognosis of SHL (2008). Using step-wise discriminant analysis, they reported that a "recovery value" was predicted by the following formula.

R=0.968-.216*Severity-.231*Vertigo+.211*speed of treatment+.113*other ear-.064*audiogram shape

It is better to have a minor hearing loss, no vertigo, and rapid treatment (within 1 week). Less important features are hearing in the other ear and the pattern of the hearing test.

How is Sudden Hearing Loss Treated?

Bottom line: At this writing (9/2014) almost everything looks like a placebo. Because hearing tends to recover spontaneously at such a high rate, treatment is not always felt necessary, especially when impairment is minor. Nevertheless the prospect of being permanently deaf in one ear is daunting and has prompted many trials of therapy.

Steroids:

As of 2011, there was an immense variability in otology/neurotology practice in regards to use of management and steroids for SHL (Coelho et al, 2011).  26% preferred oral steroids alone and 22% a combination of oral and intratympanic steroids.

When a treatment of SHL is used, it often consists of burst of steroids such as prednisone. Eisenman and Arts reviewed the topic of steroid treatment (2000). Evidence to date for a good effect is generally mixed. Two recent meta-analysis of steroid treatment (Conlin and Parnes, 2007; Labus et al, 2010) suggested there was no benefit.

Nevertheless, most (generally uncontrolled) studies suggest a better hearing prognosis for treated vs. untreated patients (Haberkamp and Tanyeri, 1999; Alexiou et al, 2001; Chen et al, 2003; Slattery et al, 2005; Jeyakumar and Francis, 2006), but a few, a worse prognosis (Minoda et al, 2000). In the study of Alexiou et al, a better prognosis was associated with very high doses of intravenous prednisolone. Hearing outcome is not altered differentially by IV steroids administered in the first day vs. within the first week ( Huy and Sauvaget, 2005). A recent metaanalysis concluded that there was no significant effect (Labus et al, 2010).

Our impression from the literature is that systemic (i.e. oral) steroids, while conventional treatment, are ineffective for SHL.

Transtympanic (aka intratympanic) Steroids.

Gianoli reported a good response to transtympanic steroids, in persons who were unable to tolerate oral steroids (Gianoli, 2001). Many others, in uncontrolled studies, have made made a similar reports (Banerjee and Parnes, 2005; Gouveris, and Selivanova, 2005; Slattery and Fisher, 2005; Plaza and. Herraiz 2007; Haynes et al, 2007; Van Wijck and Staecker 2007). There is an obvious trend for an increasing number of positive reports, albeit nearly all uncontrolled, over time. One wonders why there are no controlled studies ? Perhaps this is because good controlled studies show no effect, and studies that show no effect are hard to publish.

Ng et al (2014) performed a metaanalysis of transtympanic steroids and reviewed 187 randomized trials, but found only 5 that met their inclusion criteria. They concluded that in the 5 surviving studies, there was a benefit. Lets look more closely.

Studies that are suggestive of good results but have obvious flaws:

There has been a "controlled" study, and also a recent placebo controlled study. Xenellis, J., N. Papadimitriou, et al. (2006) reported a "rescue" approach where intratympanic steroids were used after 10 days of intravenous steroids. They used patients as their own controls. They reported a statistically better effect in the IT patients, with no change in the controls. We are hopeful but a little dubious. The problem with this study is that it is not a protocol likely to be helpful clinically, as it is not presently common to give 10 days of intravenous steroids in the treatment of SHL. Another concern with this study is that it is implausible in that conventional thought is that treatments provided after 10 days of illness are intrinsically unlikely to work.

A slightly better recent double-blinded study of only 60 patients split into 3 groups (Battaglia et al, 2008) indicated that patients treated with a combination of intratympanic dexamethasone and high dose steroids are more likely to recover hearing than those treated with high dose steroids alone. Placebo IT injections were used in one arm. The steroid regimen involved prescribing 66 tablets of prednsone (10 mg) given in a dose of 6 tablets for 7 days, then 5 capsules for 2 days, then 1 less capsule per day until finished. IT steroids or placebo were administered once/week for a total of 3 weeks. This study suggested a powerful treatment effect where the combination group did far better than groups with either IT dexamethasone alone or high dose steroids + placebo injections. This protocol also would be expected to have numerous steroid side effects due to the prolonged use of high-dose prednisone.

This trial was stopped prematurely due to slow subject accumulation. Because of this it may be underpowered and the conclusions may reflect random statistical events combined with the known tendency of journals to publish "positive" results.A concern that we have with this trial is that the placebo arm involved 4 injections of saline through the ear drum. It seems to us that the injections themselves might have an adverse effect on hearing (compared to oral steroids given without a placebo injection). In other words, this study needs to be repeated, preferably with different subject groups - -combination vs. IT dex vs. oral alone, as realistically these groups are the one that a clinician might choose.

Dallan et al (2011) reported that intratympanic steroids had identical results to a mixture of oral steroids, pentoxifylinne, low molecular weight heparin and vitamin E. While Dallan suggested that this result meant that intratympanic steroids were recommended as "first line therapy", in our view, their result suggested that intratympanic steroids was equvalent to a mixture of oral steroids plus placebo (e.g. vitamin E). Again, the evidence doesn't seem to support IT steroids.

Here are a few obvious problems with the intratympanic dexamethasone treatment approach:

 The data is clearly not strong enough right now to make steroid injections the "standard of care".   We would put this instead as an equivical cost/benefit ratio with low cost (in terms of complications but high $ cost), but unfortunately also low benefit (in terms of efficacy).

Bottom line: We ourselves recommend IT steroids in persons who cannot be given oral steroids, and in whom the time frame is short (i.e. 4 days from onset), and in whom the hearing loss is very significant. We are not sure ourselves whether oral or IT steroids are superior in terms of hearing results to doing nothing, but we are certain that large amounts of oral steroids cause significant side effects, and also that IT steroids are very costly.

Other immunosuppresants

In a person whose hearing improves to a useful level during administration of steroids, and then relapses after steroids are stopped, ongoing immunosuppressant therapy should be considered (such as etanercept). Detection of this pattern requires monitoring of hearing past initial treatment. This doesn't happen very often, and there is an obvious fallacy in that if hearing tends to improve anyway, improvements cannot necessarily be attributed to steroids.

Antivirals seem reasonable, given the frequency that herpes family viruses have been associated with SHL. Nevertheless, studies do not show that they work (Conlin and Parnes, 2007).

In a recent animal study, combination treatment with an antiviral (acylovir) and steroids reduced damage in animals whose ears were inoculated with herpes simplex virus type 1 (HSV-1) (Stokroos, 1999), compared to treatment with either acyclovir or prednisolone alone. Similar results were found in a human study by Zadeh et al (2003). On the other hand, several groups using good methodology and substantial numbers of patients have reported no benefit of Valacyclovir or Acyclovir plus steroids over steroids alone (Tucci et al, 2002; Uri et al, 2003; Westerlaken et al. 2003) and as mentioned above, a meta-analysis showed no effect (Conlin and Parnes, 2007).

Medications like acyclovir or valacyclovir may be unhelpful when the cause is a virus that is not in the herpes family, and one rarely knows at the time of the hearing loss which if any virus is responsible. It is also possible that this sort of treatment is just too late in the course of the disorder, as the average time to treat in the Tucci et al study was 4 days.

Unusual treatments for SHL that are probably ineffective.

SHL is a very disturbing experience and there have been many unusual protocols and drugs advocated.

There are several protocols involving increasing blood flow or oxygenation:

Fattori et al (2001) suggested that hyperbaric oxygen therapy was the treatment of choice. This involved 10, 90-minute sessions of breathing pure oxygen at 2.2 atmospheric pressure in a chamber. Horn et al (2005) also reported some good responses to hyperbaric treatment in an uncontrolled study of 9 patients. Similar results were reported in a larger but still uncontrolled study by Racic, G., S. Maslovara, et al. (2003). Again, Narozny, W., Z. Sicko, et al. (2004) advocate combining steroids with hyperbaric oxygen. This is based on an unblinded and retrospective data.

While these studies are encouraging, is is difficult to see why this treatment should work and we would like to see this result confirmed with larger rigorous studies. In particular, a careful controlled study is needed. We would doubt that it would be positive, as we don't see how oxygen can cause hearing neurons to come back to life. Inner ear hair cells in humans don't regenerate. A return to life from the dead would be a miracle.

Somewhat similarly, Mora, R., M. Barbieri, et al. (2003) reported a positive effect of "Intravenous infusion of recombinant tissue plasminogen activator for the treatment of patients with sudden and/or chronic hearing loss." TPA is a powerful anticoagulant and somewhat dangerous, due to bleeding. We are very unenthused about this treatment suggestion deriving from this uncontrolled trial.

Carbogen and MgS04 treatment have also been advocated for SHL (Gordin et al, 2002).

Haberkamp and Tanyeri (1999) noted that while numerous treatments have been studied aiming to improve blood flow, such as carbogen inhalation or stellate ganglion block, all remain controversial or simply lack convincing evidence of efficacy. Very few placebo controlled studies have performed of treatment of SHL and for this reason, there is presently a limited ability to determine what is the optimal treatment of SHL. At this writing we do not feel that there is enough evidence for either treatment to advocate for its use.

Recently, Kim et al (2011) compared steroids +carbogen+lipoprostaglandin E1 to several other variants including steroids alone, but not including placebo, They found a small advantage for the combination group. We are uncertain how to interpret this paper. We are dubious about an unblinded study that does not include a placebo arm.

Migraine treatment:

We have had a few patients improve remarkably with migraine treatment (mainly verapamil). No conclusion can be drawn from these occasional good responses. Presumably they had a reversable central hearing disturbance. This cannot be a common situation.

Surgical exploration

Surgery is NOT the standard of care for sudden hearing loss. Rather, there are a few unusual institutions that perform surgery in spite of the general opinion that surgery is not indicated.

At the University of Freiburg, exploration of the middle ear and patching is recommended for patients with SHL. We find this very bizzare. According to their recent article on their experience in 97 patients, surgery can be beneficial if performed within 7 days (Maier et al, 2008). These authors reported that 34% of persons with SHL had a fistula. Their method of judging whether or not a fistula was present was direct observation of the round window while displacing the stapes footplate.

There are several problems with this report. First, it is difficult to follow the logic described by the authors that led them to designated fistula or no-fistula. If the logic is faulty, then their conclusions are also faulty. Second, the natural history of SHL is such that improvement cannot be necessarily attributed to surgical exploration and patching. Without a control group, nothing can be concluded with certainty.

Similar results are reported in another German Otolaryngology Dept, in Cologne (Kampfner et al, 2013). In this report, it seems that patients with SHL were explored for fistula. They reported a substantial improvement for operated patients. It is puzzling that these patients were operated, and even more puzzling that they got better. Of course, it would be impossible to blind a study like this.

Vitamins, and minerals, and other odd treatments.

Ahn, J. H., T. Y. Kim, et al. (2006) wrote that Lipo-prostaglandin E1 in combination with steroid therapy is effective for treatment of sudden sensorineural hearing loss in Korean patients with Type 2 diabetes. Even if there is an additional effect of adding prostaglandin, this is a very narrow population and it seems doubtful that this experience generalizes to others. The lack of a control group also is worrisome.

Hatano, M., N. Uramoto, et al, in a paper entitled Vitamin E and vitamin C in the treatment of idiopathic sudden sensorineural hearing loss. (2007) reported a positive effect. Similarly, Joachims, H. Z., J. Segal, et al. (2003) reported a positive effect of vitamin E, when combined with steroids. We think that these positive result are likely to be erroneous and related to the greater ease of publishing positive results over the lack of results. While it is doubtful that vitamin E does any harm, we think it is best to remain cautions given the general lack of efficacy of vitimin E in other contexts. We think it is fine to take vitamin E, but would not criticize care in which it was omitted. A much larger controlled study of these agents would be helpful.

Nageris, B. I., D. Ulanovski, et al. (2004). recommended magnesium treatment for sudden hearing loss based on a small but controlled study in which steroids were combined with either magnesium or a placebo. In our opinion, a much larger trial would be needed to establish efficacy. We also do not see a clear mechanism for this effect.

Xiong et al (2012). This study from china suggests that intravenous administration of a mushroom extract improves hearing in SHL. We are very dubious. Hearing tests are subjective measures, and vulnerable to placebo effect.

Research Studies in Sudden Hearing Loss

Wang et al recently reported that etanercept given acutely in experimental labyrinthitis resulted in much better hearing results. While this animal study may not apply to humans, it suggests that acute treatment with etanercept or a related anti-TNF drug (Remicade, Humira), may improve hearing results for sterile inflammation. See the autoimmune-hearing loss page for more information about these drugs.

References

Copyright September 18, 2014 , Timothy C. Hain, M.D. All rights reserved. Last saved on September 18, 2014