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T h e n e w e n g l a n d j o u r n a l o f medicine

n engl j med 359;8 www.nejm.org august 21, 2008 833

Idiopathic Sudden Sensorineural

Hearing LossSteven D. Rauch, M.D.

From the Department of Otology and Lar-yngology, Harvard Medical School, Bos-ton. Address reprint requests to Dr. Rauchat Massachusetts Eye and Ear Infirmary,243 Charles St., Boston, MA 02114, or [email protected].

N Engl J Med 2008;359:833-40.

Copyright 2008 Massachusetts Medical Society.

A healthy 58-year-old woman answers the telephone and realizes that her hearing isdiminished on the left side. She notices aural fullness and loud tinnitus in the affectedear. Later that day she has several hours of mild vertigo that clears by the followingmorning. Over the next few days, repeated self-administered ear cleaning with theuse of an over-the-counter kit does not relieve the symptoms. How should she be eval-

uated and treated?

The Clinical Problem

Idiopathic sudden sensorineural hearing loss (i.e., unexplained unilateral sensorineu-ral hearing loss with onset over a period of less than 72 hours) has an estimated in-cidence between 5 and 20 per 100,000 persons per year.1 This is likely to be an under-estimate, since many who recover quickly never seek medical attention.2 Several largecase series, including a total of approximately 7500 cases in the United States, Eu-rope, and Japan,1,3-11 indicate that sudden sensorineural hearing loss typically oc-curs between 43 years and 53 years of age, with equal sex distribution. Vestibularsymptoms are present in 28 to 57% of patients.

The likelihood of recovery of hearing has been reported to vary with the severityof hearing loss at presentation: patients with mild losses usually achieve full recov-ery, those with moderate losses often show some spontaneous recovery but seldomhave a full recovery unless treated, and those with severe-to-profound hearing lossesrarely show spontaneous improvement or make a full recovery.1,4,12 The prognosisfor recovery of hearing also seems to be worse in older patients and those with as-sociated vestibular symptoms.1,3-5

Approximately 1% of cases of sudden sensorineural hearing loss are due to retro-cochlear disorders that may be related to vestibular schwannoma, demyelinatingdisease, or stroke.3 Another 10 to 15% are due to another identifiable cause, such asMenieres disease, trauma, autoimmune disease, syphilis, Lyme disease, or perilym-

phatic fistula.4,5,13,14

The remainder are idiopathic and almost exclusively unilateral.Rare cases of bilateral sudden deafness most often reflect a psychiatric (functional)cause or a neurologic process (e.g., neoplastic dural infiltration of the posteriorcranial fossa, paraneoplastic syndrome, or encephalitis); transient bilateral suddensensorineural hearing loss may also result from a sudden drop in intracranial pres-sure during a spinal tap or after intracranial surgery.

A common problem in sudden sensorineural hearing loss is delay in diagnosis. Earfullness, a common presenting symptom, is often attributed by patients and cliniciansto impaction of cerumen or congestion from upper respiratory illness or allergies.Insofar as evidence suggests that permanent hearing loss is more likely when treat-ment is delayed, it is important that a diagnosis of sudden sensorineural hearing loss

ThisJournal feature begins with a case vignette highlighting a common clinical problem.Evidence supporting various strategies is then presented, followed by a review of formal guidelines,

when they exist. The article ends with the authors clinical recommendations.

The New England Journal of Medicine

Downloaded from nejm.org on April 24, 2013. For personal use only. No other uses without permission.

Copyright 2008 Massachusetts Medical Society. All rights reserved.

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sitivity to sounds delivered as air-conducted stim-uli are equal in the affected ear, but both are re-duced (i.e., the threshold is elevated). In conductivehearing loss, the bone conduction is normal, butthe air-conducted thresholds are worse (elevated)

in the affected ear.Gadolinium-enhanced magnetic resonance im-aging (MRI) of the temporal bone and brain iswarranted in cases of acute sensorineural hearingloss to rule out a retrocochlear abnormality (e.g.,neoplasm, stroke, or demyelination). In patientswho cannot have brain MRI, alternatives includecomputed tomographic scanning, auditory brain-stemresponse audiometry, or both, althoughthese are less sensitive than MRI for the detec-tion of retrocochlear abnormalities.

Medical Treatment

Oral Corticosteroids

The current standard treatment for sudden sen-sorineural hearing loss is a tapered course of oral

corticosteroids (prednisone or methylpredniso-lone). However, data to support this recommenda-tion are limited. An initial randomized, placebo-controlled trial involving 67 subjects with suddensensorineural hearing loss12 showed significantlyhigher rates of improvement among patients ran-domly assigned to either oral methylprednisoloneor dexamethasone (tapered over a period of 10 to12 days) than among patients assigned to placebo(61% vs. 32%, P

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n engl j med 359;8 www.nejm.org august 21, 2008836

similar to the rate of recovery without treatment(65%) that was reported elsewhere.4 More recent-ly, another randomized trial15 failed to show im-provement in hearing with the use of corticoster-

oids as compared with the use of carbogen (aninhalational vasodilator composed of 5% carbondioxide and 95% oxygen) or placebo. This studywas seriously underpowered: the 41 subjects wererandomly assigned to one of four groups (oral cor-ticosteroid, oral placebo, inhalational carbogen, orinhalational placebo), yielding only 9 to 11 sub-jects per group for the 5 days of treatment.

A recent Cochrane Review16 based on these twotrials, as well as another systematic review,17,18both concluded that the efficacy of corticosteroid

therapy for sudden sensorineural hearing loss re-mains unproven. However, because a short courseof oral corticosteroids is generally associated withacceptable adverse-event rates and may confer ben-

efit, routine practice at present is to administer acourse of oral corticosteroids tapered over a pe-riod of 10 to 14 days (e.g., 60 mg of prednisonedaily for 4 days, followed by a taper by 10 mg every2 days). Data comparing different doses or dura-tions of corticosteroid therapy are limited. A dou-ble-blind, randomized, controlled trial comparinga 7-day prednisone taper with a 3-day pulse of300 mg of dexamethasone per day (followed by4 days of placebo) showed no significant differ-ence in the rates of hearing recovery.19 Side effects

10

HearingLoss(dB)

Audiogram Frequency (Hz)

10

0

20

30

50

60

80

90

100

110

120

40

70

500250125 1000 2000 4000 8000 16,000

If bone-conduction thresholdsare normal but air-conduction

thresholds are not, therewill be an airbone gap,

indicating conductivehearing loss

If bone-conductionthresholds (with contra-

lateral masking) areelevated along with

air-conductionthresholds, the loss

is sensorineural

l

Figure 3. Standard Audiogram, Showing Sensorineural Hearing Loss in the Left Ear.

The frequency in hertz of the test tones is shown on the horizontal axis in octave steps: each doubling of the fre-

quency raises the pitch by one octave. Loudness in decibels is shown on the vertical axis. Red symbols indicate re-sponses for the right ear, and blue indicate responses for the left ear. The X and O symbols represent responses

to air-conducted stimuli presented by means of headphones. The bracket symbols represent responses to bone-con-ducted stimuli delivered by means of a bone oscillator applied to the skull just behind the ipsilateral pinna. During

testing of one ear with pure tones, the contralateral ear receives masking noise to be sure that responses are actu-ally from the ear being tested. In an ear with normal hearing, air- and bone-conduction thresholds are equal at

each test frequency and all thresholds are 25 dB or less. Most human speech sounds occur in the range of 500to 2000 Hz. This audiogram shows a sensorineural hearing loss of approximately 60 dB in the left ear, with slightly

better (lower) thresholds at lower frequencies and slightly worse (higher) thresholds at higher frequencies. Word-recognition scores were 98% for the right ear and 38% for the left ear. Normal word scores are greater than 90%.




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of corticosteroid treatment include elevated bloodsugar levels or blood pressure, mood changes,weight gain, gastrit is, and sleep disturbances;these typically resolve as treatment is tapered ordiscontinued.

A natural-history study has shown that spon-taneous recovery occurs almost exclusively with-

in the first 2 weeks after the onset of sudden sen-sorineural hearing loss.4 Studies assessing therelationship between the duration of sudden sen-sorineural hearing loss before treatment and out-comes have reported the greatest recovery of hear-ing when corticosteroids are initiated within thefirst 1 to 2 weeks after symptom onset, and littleif any benefit when initiated 4 weeks or longerafter the onset of symptoms.1,5,6,20 Some patientshave a very rapid and substantial recovery of hear-ing within the first 48 to 72 hours after the ini-tiation of corticosteroids, some improve steadily

after the onset of treatment and continue to im-prove after treatment is completed, and othershave no improvement; the proportion of patientsin each of these groups is uncertain. The sooner aresponse is seen, the better the overall prognosisappears to be. Patients who show no improvementat the completion of treatment with corticoster-oids have a poor prognosis. Symptoms of auralfullness and tinnitus tend to abate gradually, re-gardless of hearing outcome.

Since there may be only a 2-to-4-week windowfor effective treatment of sudden sensorineuralhearing loss, it is prudent to start therapy as soonas possible. Ideally, an audiogram should be per-formed before or within 24 to 48 hours after theinitiation of treatment to document the sen-sorineural hearing loss and its magnitude. If imag-ing studies cannot be obtained promptly, treat-ment should be initiated pending this evaluation.Improvement in hearing after treatment withcorticosteroids does not eliminate the need forimaging. Demyelinating lesions can have a fluc-tuating course or a transient response to corticos-

teroids, and occasionally, acute enlargement of anacoustic neuroma (e.g., from hemorrhage) can re-sult in sudden sensorineural hearing loss that im-proves over days or weeks.

Intratympanic Steroid Injections

In lieu of oral corticosteroids, some otolaryngol-ogists recommend local corticosteroid therapy forsudden sensorineural hearing loss, administeredeither by intratympanic injections (methylpredni-solone or dexamethasone) or as eardrops by means

of a ventilating tube or a wick running from aventilating tube to the round window membranein the medial wall of the middle ear. The rationalefor intratympanic corticosteroid treatment is thatit delivers a high concentration to the target tis-sue with minimal systemic exposure. Data to sup-port the use of intratympanic corticosteroids for

primary therapy are currently limited to case seriesreporting success rates similar to those reportedwith oral therapy.20-25 Among these are anecdotalcases in which hearing improved despite a 6-weekor greater delay in treatment. Several reports ofintratympanic corticosteroid therapy as salvagetherapy in patients who did not improve with theuse of oral treatment26-29 have suggested that in-tratympanic therapy may yield better hearing out-come than placebo or no treatment, but thesestudies have been small or retrospective. Intratym-panic therapy is much more costly than oral ther-

apy, with charges in excess of $2,000 for a courseof treatment at some centers.

Other Therapies

Randomized trials comparing corticosteroids aloneto corticosteroids plus antiviral agents for suddensensorineural hearing loss have failed to show anadded benefit for antiviral therapy30-32; none ofthese studies included a placebo group. Other treat-ments, including volume expanders, anticoagu-lants, inhalational vasodilators, herbal remedies,and hyperbaric oxygen, have been suggested, butadequately powered randomized trials are lackingto support clinical benefit with their use. A retro-spective observational study of 112 patients withsudden sensorineural hearing loss who were treat-ed with tapered corticosteroids after a high-doseintravenous bolus of either 600 mg or 1200 mgof hydrocortisone showed a significantly great-er incidence of complete recoveries in the higher-dose group,33 but randomized trials of treatmentwith high doses of intravenous corticosteroids arelacking.

Certain recommendations should be made toall patients with new monaural hearing loss tominimize the risk of hearing loss in the good ear.First, scuba diving should be prohibited becauseof the associated risk of ear injuries; these includerupture of the tympanic membrane (reported in5.9% of 709 experienced scuba divers34) as well aspermanent disabilities such as hearing loss, tin-nitus, and balance problems (in 2.3% of 709 ex-perienced scuba divers). Even patients who haveregained full hearing after an episode of sudden




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sensorineural hearing loss should be wary of scubadiving, since it is uncertain whether a history ofsuch hearing loss increases vulnerability in the af-fected ear. Second, noise protection should be usedwhen indicated. Acoustic trauma can result fromexposure to loud music and the noise of powertools and yard equipment, for example. Earplugs

or earmuffs designed for noise protection are in-expensive, widely available, and very effective whenused properly. Finally, an immediate otolaryngo-logic evaluation (i.e., within 24 hours after theonset of symptoms) is recommended to assess anysymptoms in the good ear.

Prognosis

Although long-term data are lacking, there is con-cern that persons who have had an episode of sud-den sensorineural hearing loss may be at higherrisk of accelerated age-related hearing loss in the

future. There is no evidence that sudden sensori-neural hearing loss is more likely to occur in thecontralateral ear of an affected person than it isto occur in the general population. A recent pro-spective cohort study suggested a slightly greaterrisk of stroke (adjusted hazard ratio over a 5-yearperiod of follow-up, 1.64; 95% confidence inter-val, 1.31 to 2.07) among patients with sudden sen-sorineural hearing loss than among a comparisongroup of patients who had undergone appendec-tomy,35 although this warrants confirmation.

Patients who do not recover symmetric hearingpermanently lose their ability to localize wheresounds are coming from. These patients are at adisadvantage in adverse listening situations (e.g.,situations with high ambient noise, poor acoustics,multiple talkers, or speakers who have foreignaccents). Though both wearable and implantabledevices are available to receive sound on the badside and route it to the better ear, conventionalhearing aids are of limited use if the contralateralear is normal; however, their use on one or bothears may be beneficial if the contralateral ear is not

normal.It is commonly advised that patients with sud-den sensorineural hearing loss have audiometricmonitoring repeated over the course of a year (e.g.,at 2 months, 6 months, and 12 months after theonset of the hearing loss) to document recovery,guide aural rehabilitation (especially the fitting ofhearing aids), and monitor for signs of relapse inthe affected ear or development of hearing loss inthe contralateral ear, which would warrant consid-

eration of other diseases (e.g., Menieres disease orautoimmune disease) that may have been misdiag-nosed as sudden sensorineural hearing loss. Par-ticularly in patients with low-frequency hearingloss, the sudden loss may be an early manifesta-tion of Menieres disease. If so, further fluctua-tions in hearing and attacks of vertigo are likely

to occur within a 3-year period. Menieres diseasehas also been reported to occur as a late outcomein 4 to 8% of cases of sudden sensorineural hear-ing loss (i.e., years after onset).1,36

Area s of Uncertainty

The causes of sudden sensorineural hearing lossremain uncertain, as does the specific site of in-ner ear damage. Oral corticosteroids are routinelyused for primary treatment of sudden sensorineu-ral hearing loss, although data are limited to sup-

port their use; there are also limited data to sup-port the use of intratympanic corticosteroids forprimary therapy or for treatment of those whosehearing did not improve with initial therapy. A clin-ical trial sponsored by the National Institutes ofHealth that compares oral with intratympanic cor-ticosteroid treatment for primary therapy is underway (ClinicalTrials.gov number, NCT00097448).Randomized trials are also needed to assess vari-ous other corticosteroid regimens and to evaluatetreatments other than corticosteroids. Longitudinalstudies of long-term outcome are lacking for anytreatments of sudden sensorineural hearing loss.

Guidelines

There are no published guidelines for the evalua-tion or management of sudden sensorineural hear-ing loss.

Conclusions and

Recommendations

Patients such as the woman described in the vi-gnette, who present with unilateral ear blockageor fullness, should promptly be evaluated for pos-sible sudden sensorineural hearing loss. Suddensensorineural hearing loss is considered by otol-ogists to be a true otologic emergency, given theobservation that there is less recovery of hearingwhen treatment is delayed. Hearing loss can be as-sessed over the telephone (e.g., by asking the pa-tient to move the phone from ear to ear for com-




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parison). If hearing is reduced, the patient shouldbe asked to hum and to report on which side thesound is louder; although the test is imperfect,sound usually localizes toward a conductive lossand away from a sensorineural loss. An office eval-uation and complete audiogram is indicated if thereis any suspicion of sensorineural hearing loss. If

an audiogram reveals unilateral sensorineural hear-ing loss, then an MRI with gadolinium is neededto rule out a retrocochlear abnormality, such as de-myelinating disease, neoplasm, or stroke. In theabsence of these findings, sudden sensorineuralhearing loss is the presumed diagnosis. Treatmentshould not be delayed, even if imaging cannot beobtained promptly.

Although supporting data are limited, corticoste-roid therapy (usually a 2-week burst and taper oforal prednisone, starting at 60 mg per day, orequivalent doses of methylprednisolone) is the

current standard of care, according to a random-

ized trial suggesting that it may improve or re-store hearing and because of the absence of otherknown effective therapies. Intratympanic injec-tions of corticosteroids may be an alternative,particularly for patients who have or are at highrisk of complications from oral therapy, althoughevidence to support this strategy is even more

limited.After sudden sensorineural hearing loss has led

to damage in one ear, it is imperative to protectthe better-hearing ear from excessive pressure(e.g., scuba diving should be avoided) or exposureto noise. Development of hearing loss, tinnitus,pain, or discharge in the good ear warrants animmediate otolaryngologic evaluation.

Dr. Rauch reports receiving consulting fees from Best Doc-tors, IMEDECS, and Partners Online Specialty Consultations.No other potential conflict of interest relevant to this article wasreported.

An audio version of this article is available at www.nejm.org.

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Copyright 2008 Massachusetts Medical Society.



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