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Timothy C. Hain, MD. 
Hearing Page
Page last modified:
July 6, 2008
Sudden hearing loss (SHL) is defined as greater than 30 dB hearing reduction, over at least three contiguous frequencies, occuring 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 tinnitis. 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).
Treatment of SHL has recently changed (see section on intratympanic steroids below).
| 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 appears 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). In our view, this study includes too few temporal bone samples to be relied upon. More temporal bone donations are needed !
Nevertheless, 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.
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.
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. Tumors, such as an acoustic neuroma, can even cause SHL that resolves completely (Nageris and Popovtzer, 2003), and MRI or ABR testing may be warranted even in this situation. Brain MRI testing is also useful in detecting other causes of SHL such as CSF leak, and stroke.
Autoimmune hearing loss is suggested by good recovery, response to steroids, and relapse.
Anti-cochlear antibodies are not useful in SHL (Samuelson et al, 2003). Antiendothelial antibodies may be useful (Cadoni et al, 2003) but at this writing there is no commercially available test.
Mor general tests tha tmay be useful include CBC, Sed-rate, Hemoglobin electropheresis (for sickle cell), Urinalysis, electrolytes, comprehensive metabolic screen. FTA (for syphilis), HIV test, Lyme test. and CT of the temporal bone.
Audiometric testing might include pure tone and speech audiometry, otoacoustic emissions (OAE), tympanometry and acoustic reflexes. Other tests that may be helpful might include middle and late evoked potentials, ENG and rotatory chair testing. If OAE's are present, prognosis is better (Schweinfurth et al, 1997).
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.
Bottom line: At this writing (6/2008) intratympanic steroids are promising.
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.
The present consensus in the literature is that while there are many interesting treatments, none have been proven to work. As a few examples, Finger and A. O. Gostian (2006), in "Idiopathic sudden hearing loss: contradictory clinical evidence, placebo effects and high spontaneous recovery rate--where do we stand in assessing treatment outcomes? concluded that the lack of a standard protocol among trials made comparison difficult and a conclusion unreachable. Similarly, Kanzaki, J., Y. Inoue, et al. (2003) found no statistically significant effect of any oral or intravenous drug among many agents.
Steroids: When a treatment of SHL is used, it often consists of burst of steroids such as prednisone. Eisenman and Arts recently reviewed the topic of steroid treatment (2000). Evidence to date for a good effect is generally mixed. A recent meta-analysis of steroid treatment (Conlin and Parnes, 2007) 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).
Our impression is that systemic steroids, while conventional, are presently simply an unproven treatment for SHL with a small amount of evidence of a positive effect.
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, abeit nearly all uncontrolled, over time.
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 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 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.
Here are a few obvious problems with the treatment approach:
Nevertheless, at this writing, in the author's opinion, the transtympanic/intratympanic treatment approach to steroid delivery is recommended for a significant SHL. While a clear indication for transtympanic steroids has not yet been established in SHL, if they can be administered quickly (i.e. within 4-10 days) and a decision to use steroids has been arrived at, they do make more sense than oral steroids alone. The recent study by Battaglia suggests that the optimum protocol is to use both IT and oral steroids.
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.
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.
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.
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. We are very unenthused about this treatment suggestion deriving from this uncontrolled treatment 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.
Vitamins and minerals:
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.
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.
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.
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