Sudden sensorineural hearing loss in adults: Evaluation and management

INTRODUCTION — Sudden sensorineural hearing loss (SSNHL) is characterized by an acute sensorineural hearing loss, nearly always unilateral, that occurs within a 72-hour period. Most cases are idiopathic, and the prognosis for hearing recovery depends largely upon the severity of the hearing loss.

The diagnosis and management of idiopathic SSNHL in adults are discussed here. The evaluation of non-acute hearing loss, the causes of hearing loss in adults, and the evaluation and management of hearing loss in children are discussed separately. (See "Evaluation of hearing loss in adults" and "Etiology of hearing loss in adults" and "Hearing loss in children: Etiology" and "Hearing loss in children: Screening and evaluation" and "Hearing loss in children: Treatment".)

EPIDEMIOLOGY AND PATHOGENESIS — The exact incidence of idiopathic sudden sensorineural hearing loss (SSNHL) is uncertain, since recovery may be spontaneous, and many affected people never seek medical attention. Estimates of incidence range from 11 to 77 per 100,000 people per year [1]. Idiopathic SSNHL can occur at any age but most commonly affects individuals 43 to 53 years old [2], with similar numbers of males and females affected [3].

Although SSNHL can result from a variety of identifiable causes (eg, neoplastic, infectious, autoimmune, neurologic, otologic, metabolic, or vascular diseases; ototoxic drugs; trauma), the majority of cases are idiopathic, with many proposed etiologies and risk factors (table 1) [4]. Postulated causes of idiopathic SSNHL include viral cochleitis [5], microvascular events due to a hypercoagulable state [6], and autoimmune disorders [7,8]. Herpes simplex type 1 virus (HSV-1) may be an etiologic factor in SSNHL, analogous to its possible role in Bell's palsy [9].

Compared with patients with unilateral SSNHL, those with bilateral disease are more likely to be older, to have cardiovascular disease, and to have a positive antinuclear antibody titer [3].

In observational studies, a poor diet (eg, a diet low in fresh vegetables), low serum folate levels, and metabolic syndrome have been associated with an increased risk of idiopathic SSNHL [10-12].

DIAGNOSTIC CRITERIA — The most widely accepted criteria for the diagnosis of sudden sensorineural hearing loss (SSNHL) include [13,14]:

●Hearing loss that is sensorineural in nature

●Hearing loss of at least 30 decibels (dB) over at least three consecutive test frequencies

●Hearing loss that occurs within a 72-hour period

In the absence of documented premorbid audiometry, the definition assumes premorbid hearing in the affected ear similar or identical to hearing in the unaffected ear.

SSNHL is considered idiopathic when no identifiable cause for the hearing loss can be identified.

Some studies use differing criteria for identifying SSNHL, including loss of 10 to 20 dB in two or three frequencies [15-17], or hearing loss that occurs within 12 hours, including hearing loss noted upon awakening [3].

CLINICAL MANIFESTATIONS — Patients with idiopathic sudden sensorineural hearing loss (SSNHL) typically experience an immediate or rapid hearing loss, or they report a loss of hearing upon awakening. As an example, in a series of 56 patients, 28 described acute hearing loss, 27 noted hearing loss upon awakening, and one experienced rapidly progressive hearing loss [15]. In idiopathic SSNHL, the majority of patients have unilateral hearing loss, but in up to 3 percent the hearing loss may be bilateral [3].

Many patients with idiopathic SSNHL, however, may only notice a sensation of a blocked ear or aural fullness at first, without recognizing that they have lost hearing. Because a blocked ear is a common occurrence and may be attributed to a number of less concerning conditions (eg, cerumen impaction, serous otitis media), patients may not seek immediate attention.

More than 90 percent of patients with unilateral SSNHL have ipsilateral tinnitus [3,15], and 20 to 60 percent experience vertigo [18]. Patients also occasionally report otalgia or paresthesias [3].

EVALUATION — All patients who experience sudden hearing loss or awaken with new hearing loss should be evaluated for sudden sensorineural hearing loss (SSNHL) within the first few days after symptom onset. In addition, all patients who report the sudden onset of a blocked ear or the sensation of aural fullness, particularly in the absence of upper respiratory infection symptoms, should be evaluated for the presence of sensorineural hearing loss. (See 'Clinical manifestations' above.)

Distinguish sensorineural from conductive hearing loss — When sudden hearing loss occurs, it is first necessary to determine if the hearing deficit is sensorineural or conductive in nature. Although all sudden hearing loss requires evaluation, there is more urgency when SSNHL is suspected since earlier diagnosis and treatment may improve the prognosis [19]. For all patients with sudden hearing loss:

●An initial examination should be performed to evaluate hearing. If no audiometry equipment (eg, tone-emitting otoscope) is immediately available, the whisper test can be performed to evaluate hearing in both ears. The whisper test is done by standing at arm's length behind the patient (to avoid the possibility of lip reading), occluding one ear canal at a time, whispering a short sequence of letters and numbers, and asking the patient to repeat them. (See "Evaluation of hearing loss in adults", section on 'Office hearing evaluation'.)

●The Weber and Rinne tests should be performed; these tests can help distinguish between sensorineural and conductive loss in the majority of patients (figure 1 and table 2). (See "Evaluation of hearing loss in adults", section on 'Weber and Rinne tests' and "Evaluation of hearing loss in adults", section on 'Interpretation'.)

For patients in whom conductive hearing loss is diagnosed based upon the initial exam, we proceed with further evaluation as reviewed elsewhere (table 3). (See "Evaluation of hearing loss in adults".)

Evaluation of all patients with suspected SSNHL

Clinical history and physical examination — For patients in whom SSNHL is suspected or diagnosed based upon the initial exam, we proceed with a focused clinical history and physical examination.

●Clinical history – We evaluate for:

•Recent head trauma, exposure to loud noise, or barotrauma. (See "Etiology of hearing loss in adults", section on 'Trauma' and "Etiology of hearing loss in adults", section on 'Noise exposure' and "Etiology of hearing loss in adults", section on 'Inner ear barotrauma'.)

•Recent eye pain or redness; hearing loss in association with acute keratitis may suggest Cogan syndrome (a chronic inflammatory disorder with primarily ophthalmic and vestibuloauditory manifestations) as the etiology of the sensorineural hearing loss. (See "Cogan syndrome", section on 'Inner ear disease'.)

•Prior history of hearing loss or fluctuating hearing loss, particularly in association with vertigo or tinnitus. These symptoms suggest Meniere disease as the etiology. (See "Meniere disease: Evaluation, diagnosis, and management", section on 'Clinical presentation'.)

•Focal neurologic symptoms (eg, diplopia, headache, vertigo, tinnitus), which may suggest cerebrovascular ischemia, hyperviscosity syndrome, or neoplasm such as meningioma, acoustic neuroma, or leptomeningeal carcinomatosis as the etiology. (See "Posterior circulation cerebrovascular syndromes", section on 'Basilar artery' and "Posterior circulation cerebrovascular syndromes", section on 'Intracranial vertebral arteries' and "Epidemiology, pathogenesis, clinical manifestations, and diagnosis of Waldenström macroglobulinemia", section on 'Hyperviscosity syndrome' and "Epidemiology, pathology, clinical features, and diagnosis of meningioma", section on 'Focal findings' and "Vestibular schwannoma (acoustic neuroma)", section on 'Clinical presentation' and "Clinical features and diagnosis of leptomeningeal disease from solid tumors", section on 'Cranial neuropathies'.)

•A known history of or other symptoms consistent with autoimmune disease or vasculitis. (See "Clinical manifestations of relapsing polychondritis", section on 'Nervous system involvement' and "Neurologic manifestations of Sjögren's disease", section on 'Multiple cranial neuropathies' and "Primary angiitis of the central nervous system in adults", section on 'Clinical manifestations'.)

•Risk factors for or recent exposure to Lyme disease (eg, travel to or residence in a Lyme-endemic region, recent tick bite). (See "Diagnosis of Lyme disease", section on 'Risk of exposure' and "Nervous system Lyme disease", section on 'Other cranial neuropathies'.)

•Ear pain, ear drainage, fever, or other symptoms suggestive of acute otitis media (AOM), chronic otitis media (COM), or mastoiditis. Acute or chronic infection or inflammation of the middle ear and associated structures may cause acute hearing loss. Although the hearing loss is more likely to be conductive in nature, it may rarely present as a sudden sensorineural hearing loss. (See "Acute otitis media in adults", section on 'Hearing loss' and "Chronic otitis media and cholesteatoma in adults".)

•Exposure to ototoxic medications or drugs (eg, aminoglycosides, loop diuretics, platinum-based chemotherapy, salicylates). (See "Etiology of hearing loss in adults", section on 'Ototoxic substances'.)

●Physical examination - In addition to the initial hearing evaluation and Weber and Rinne testing, we perform:

•An examination of the external ear, evaluating for rash, infection, or trauma.

•An otoscopic examination of the ear, evaluating for obstructing cerumen or foreign body, AOM or COM, perforated tympanic membrane, serous otitis, or cholesteatoma. If obstructing cerumen (or other material) is present in the canal, we advise cautious removal with either gentle curettage or aspiration under direct visualization. If AOM is a concern, removal of cerumen via irrigation should be avoided because of risk of tympanic membrane rupture. If the obstruction cannot safely be removed via curettage or aspiration, referral to otorhinology is appropriate. After the obstruction is resolved, the patient's hearing, including the Weber and Rinne tests, should be re-evaluated.

•A focused cranial nerve examination on all patients with SSNHL. For those patients with any additional neurologic complaints, a more complete neurologic exam may be appropriate depending upon the symptoms. (See 'Differential diagnosis' below.)

Audiometry — Audiometry is necessary to establish the diagnosis of SSNHL. (See 'Diagnostic criteria' above.)

All patients with suspected idiopathic SSNHL should undergo formal audiometric evaluation within 14 days after symptom onset, but ideally as soon as possible. Accurate audiometric evaluation is essential to support the initial diagnosis of SSNHL and also to follow hearing changes over time. If, however, audiometry is unavailable or if access to testing is delayed, treatment should not be postponed.

Imaging: MRI preferred — For all patients with SSNHL, even in those for whom there is a seemingly obvious cause of the sudden hearing loss (eg, immediate antecedent loud noise exposure, barotrauma), we perform magnetic resonance imaging (MRI) with contrast to evaluate for retrocochlear pathology [14]; the MRI should be done within three months of symptom onset. If MRI is unavailable or not possible (due to the presence of an indwelling metallic device or other contraindication), we perform computed tomography (CT) of the temporal bone plus brainstem-evoked response audiometry (auditory brainstem response [ABR]). CT does not provide sufficient resolution for detecting small tumors of the cerebellopontine angle or small brainstem infarctions; the addition of ABR as a functional study to CT imaging can identify abnormalities of the auditory pathway and may suggest the presence of small acoustic neuromas not identified on CT. (See "Principles of magnetic resonance imaging", section on 'Precautions' and "Vestibular schwannoma (acoustic neuroma)", section on 'Imaging' and "Vestibular schwannoma (acoustic neuroma)", section on 'Audiometry'.)

Although the majority of patients with SSNHL likely have a viral, autoimmune, or microvascular etiology that cannot be diagnosed by any imaging study, other causes of unilateral sensorineural hearing loss may only be identified on MRI, including acoustic neuroma, meningeal carcinomatosis, ischemic cerebrovascular disease, and multiple sclerosis.

Retrocochlear pathology is the most frequently identifiable cause of SSNHL diagnosed by imaging. As examples, in a series of 16 patients with SSNHL, MRI revealed the etiology of the hearing loss in three patients, including acoustic neuroma, multiple sclerosis, and meningioma of the cerebellopontine angle [20]. In another series of over 550 patients with SSNHL, 3 percent had a retrocochlear tumor (including schwannoma, neurofibroma, or undifferentiated carcinoma) identified on imaging [21]. In other studies, vestibular schwannomas were identified in 3 to 10 percent of patients presenting with SSNHL [22].

Targeted laboratory evaluation — We do not perform routine blood testing in all patients with SSNHL [14]. We do, however, perform appropriate laboratory studies if there is a clinical suspicion for a particular etiology of the hearing loss (table 1). As examples, we check thyroid function tests when there is a concern for hypothyroidism; a complete blood count, serum protein electrophoresis, and serum viscosity if there is concern for hyperviscosity syndrome; and an erythrocyte sedimentation rate and/or C-reactive protein (as well as other specific serologies) if there is a concern over vasculitis. (See "Diagnosis of and screening for hypothyroidism in nonpregnant adults", section on 'Diagnosis' and "Epidemiology, pathogenesis, clinical manifestations, and diagnosis of Waldenström macroglobulinemia", section on 'Diagnosis' and "Overview of and approach to the vasculitides in adults", section on 'Laboratory tests'.)

DIFFERENTIAL DIAGNOSIS — Idiopathic sudden sensorineural hearing loss (SSNHL) can usually be distinguished from other causes of sensorineural hearing loss by the patient's presentation, including the characteristics of the hearing loss, the presence of other symptoms, and any precipitants. As examples, sensorineural hearing loss due to identifiable etiologies typically results in hearing loss that is bilateral (eg, meningitis, autoimmune disease), less acute in onset (eg, acoustic neuroma, meningioma), has an identifiable precipitant (eg, recent ototoxic drug, barotrauma, ear or head trauma, or loud noise), fluctuates over time (eg, Meniere disease), or is associated with other neurologic symptoms (eg, ischemic cerebrovascular disease) (table 1 and table 3).

Among the causes of unilateral SSNHL, one of the most concerning is an acute ischemic cerebrovascular event, typically due to occlusion of the anterior inferior cerebellar artery (AICA), which feeds the internal auditory (labyrinthine) artery [22]. However, isolated unilateral hearing loss without other neurologic signs or symptoms would be rare, as occlusion of the AICA typically manifests with other neurologic signs and symptoms (eg, ipsilateral Horner syndrome, diplopia, nystagmus, facial weakness, limb clumsiness, ataxia, and contralateral loss of pain or temperature sensation). Rarely, an isolated occlusion of the internal auditory artery may occur, which can present with unilateral hearing loss and acute vestibular syndrome (vertigo, tinnitus, and ataxia). Similarly, vertebral artery dissection may rarely present as occipital or posterior neck pain and isolated early hearing loss [23]. (See "Posterior circulation cerebrovascular syndromes", section on 'Distinguishing stroke-related vertigo from peripheral vertigo'.)

Less frequent neurologic causes of sensorineural hearing loss include meningitis, multiple sclerosis, and migrainous infarction. (See "Evaluation and diagnosis of multiple sclerosis in adults" and "Clinical features and diagnosis of acute bacterial meningitis in adults" and "Migraine-associated stroke: risk factors, diagnosis, and prevention".)

TREATMENT: GLUCOCORTICOID THERAPY FOR ALL PATIENTS — We treat all patients with sudden sensorineural hearing loss (SSNHL), including those with an identifiable cause and those with a presumed idiopathic etiology, with glucocorticoid therapy (algorithm 1). (See 'Initial therapy' below.)

SSNHL with identifiable cause — For patients with an identifiable cause of SSNHL, in addition to treatment with glucocorticoids, treatment is directed at the underlying cause as appropriate (table 1). In general, hearing outcome is largely dependent upon the particular etiology and degree of hearing loss. As examples, for patients with an identified infectious etiology, treatment of the particular infection (and complications) is initiated as appropriate. For patients with acoustic neuroma, complete surgical resection is typically attempted if feasible. (See "Etiology of hearing loss in adults" and "Neurologic complications of bacterial meningitis in adults", section on 'Sensorineural hearing loss' and "Vestibular schwannoma (acoustic neuroma)", section on 'Outcomes'.)

Idiopathic SSNHL — For those patients in whom there is no identifiable cause of SSNHL despite evaluation, the diagnosis of idiopathic SSNHL is made. We educate these patients about the natural history of the condition and the risks and efficacy of available treatments, and we engage in joint decision-making regarding management options.

Initial therapy — For all patients with SSNHL, we suggest treatment with glucocorticoids, ideally to be initiated within two weeks of symptom onset (algorithm 1). However, glucocorticoid therapy may reasonably be offered up to six to eight weeks after initial symptoms, since this is the only treatment option available to these patients. Glucocorticoids may be administered systemically, intratympanically, or as combination therapy.

The decision on which treatment modality to offer depends upon several factors, including any comorbidities which may preclude the administration of high-dose systemic glucocorticoids (eg, diabetes mellitus, previous adverse reaction to steroids) as well as patient preference (see "Major adverse effects of systemic glucocorticoids", section on 'General treatment considerations and monitoring'). In addition, we offer patients with severe to profound hearing loss initial combination treatment with both systemic and intratympanic therapy. Combination therapy may be given concurrently or sequentially.

●For patients who are able to tolerate high-dose systemic glucocorticoid therapy, we offer initial treatment with prednisone 60 mg orally once daily for 10 days.

●For patients who prefer to avoid systemic glucocorticoids, or who are not candidates for treatment with high-dose systemic glucocorticoids [24], we offer initial treatment with intratympanic dexamethasone, 10 mg/mL solution, approximately 0.5 mL injected into the affected ear. Intratympanic injections are administered once weekly for three weeks.

●For patients with more severe hearing loss (>50 decibel [dB]), we offer combination therapy (prednisone 60 mg once daily for 10 days plus intratympanic dexamethasone injections once weekly for three weeks, given concurrently or sequentially, in either order).

We assess the patient's response to initial therapy with repeat audiometry after treatment (two weeks after initiation of systemic glucocorticoids or four weeks after initiation of intratympanic glucocorticoids):

●For patients who experience ≥10 dB improvement in hearing, and who have <20 dB hearing loss compared with baseline hearing, no further treatment is necessary.

●For patients who have <10 dB improvement in hearing after initial therapy, or who continue to have ≥20 dB hearing loss, further treatment is offered. (See 'Patients refractory to initial therapy' below.)

Our approach is similar, but not identical to guidelines from the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS), which suggest that all patients with idiopathic SSNHL be offered initial treatment with oral glucocorticoids [14]. We agree that there is the greatest likelihood of response if treatment is started within two weeks of the onset of hearing loss.

Although systemic glucocorticoids are considered standard therapy for idiopathic SSNHL, there is a lack of high-quality evidence supporting the efficacy of treatment. However, the results of systematic reviews and meta-analyses comparing glucocorticoids with placebo are limited by the quality of available studies [25-27]. In addition, many of the trials employed steroid regimens that are no longer used. As examples:

●In a 2001 trial including 41 patients with SSNHL, five days of prednisone treatment was compared with carbogen inhalation, placebo tablets, or inhalation of room air [28]. There was no difference in hearing recovery between the four groups (two treatment and two placebo groups) at one and five weeks [28].

●In a 2012 trial including 93 patients with SSNHL, systemic prednisolone (begun within one week of the onset of symptom and administered with a tapering regimen over 8 to 30 days) was compared with placebo [29]. There was no difference in hearing improvement between the two groups at 90 days.

●In a 2024 trial among 325 patients with SSNHL, those receiving either five  days of high-dose intravenous prednisolone at 250 mg/d or five  days of high-dose oral dexamethasone at 40 mg/d did not have greater hearing improvement when compared with those assigned to low-dose oral prednisone (five  days at 60 mg/d followed by five  days of tapering doses), but did have greater frequency of adverse events [30].

The degree of initial hearing loss may impact the response to treatment, with a greater hearing loss more likely to respond to glucocorticoid therapy. As an example, in a retrospective review comparing patients with idiopathic SSNHL treated with systemic glucocorticoids with those who declined treatment, there was a significant improvement in hearing in the treated group among those with a severe to profound hearing loss; no difference was seen when milder cases were included in the analysis [31].

Evidence suggests similar efficacy with initial systemic or intratympanic glucocorticoids [27]. Intratympanic glucocorticoids are used for the treatment of SSNHL, both as initial treatment for those patients who cannot (or prefer not to) take systemic high-dose glucocorticoids and as salvage therapy for patients who are refractory to initial treatment with systemic glucocorticoids. In trials evaluating the efficacy of intratympanic glucocorticoids, regimens vary and include dexamethasone, methylprednisolone, or triamcinolone administered intermittently [32,33] or by continuous infusion [34]. Dexamethasone is typically used in clinical practice in the United States; transient side effects associated with intratympanic dexamethasone include otalgia, dizziness, and aural fullness.

In several systematic reviews and meta-analyses of randomized trials, intratympanic therapy was not as effective as systemic glucocorticoid treatment for primary therapy of idiopathic SSNHL, but showed benefit as salvage therapy for those with inadequate recovery with initial treatment [25,27,35,36]. In a subsequent meta-analysis, however, intratympanic glucocorticoids were as effective as systemic glucocorticoids for primary therapy of SSNHL [37].

Initial treatment with combination therapy may not offer additional benefit beyond sequential treatment, although the evidence is mixed. In a meta-analysis including four trials and 300 patients, treatment with combination therapy was compared with systemic glucocorticoid therapy alone, and hearing outcomes were found to be similar between the groups [37]. However, in one of the included trials including 73 patients, hearing outcomes at one month were better for patients treated with combination therapy, particularly for those with more profound hearing loss [38]. In addition, in a case series including 229 patients with SSNHL, hearing recovery rates were higher in patients who received combination therapy compared with systemic therapy alone [39].

In addition, some evidence suggests that hyperbaric oxygen therapy (HBOT) may be beneficial as an adjuvant to initial glucocorticoid treatment. In a meta-analysis including three randomized controlled trials and 150 patients, the addition of HBOT to initial glucocorticoid therapy improved hearing outcomes in patients with hearing loss of >40 dB as well as patients with hearing loss of >70 dB (mean hearing difference 10.27 dB [95% CI 6.45-14.09] and 10.43 dB [96% CI 6.28-14.58], respectively) [40].

Patients refractory to initial therapy — For patients who have an inadequate response (<10 dB improvement in hearing after initial therapy, or who continue to have ≥20 dB hearing loss), we suggest salvage glucocorticoid therapy, ideally to be initiated within six to eight weeks of symptom onset; the treatment offered depends upon the initial therapy received (algorithm 1):

●For patients who received initial treatment with oral prednisone, we offer salvage treatment with intratympanic dexamethasone, 10 mg/mL solution, approximately 0.5 mL injected into the affected ear. Intratympanic injections are administered once weekly for three weeks. (See 'Initial therapy' above.)

●For patients who received initial treatment with intratympanic dexamethasone and are able to tolerate systemic high-dose glucocorticoids, we offer salvage treatment with prednisone, 60 mg orally once daily for 10 days. (See 'Initial therapy' above.)

●The addition of hyperbaric oxygen therapy (HBOT) as an adjuvant to salvage glucocorticoid treatment can be used if available, particularly for patients with more profound (>70 dB) hearing loss.

No additional glucocorticoid therapy is offered to patients who received initial combination (concurrent or sequential) systemic and intratympanic glucocorticoids.

Adjuvant HBOT may be of benefit when used with glucocorticoid salvage therapy for those with an inadequate response to initial treatment, particularly for those patients with a more profound hearing loss. As an example, in a meta-analysis of randomized trials and observational studies including 2400 patients with SSNHL receiving glucocorticoid (systemic and/or intratympanic) therapy, the addition of HBOT was associated with greater hearing improvement compared with glucocorticoid therapy alone (odds ratio [OR] 1.43; 95% CI 1.20-1.67) [41]. The benefit of HBOT was greatest among those with more severe hearing loss when used as salvage treatment after inadequate response to glucocorticoid treatment, and when the total treatment duration was ≥20 hours.

However, the lack of availability of HBOT facilities and the potential high out-of-pocket costs to patients may limit the utility of this option for the majority of patients. (See "Hyperbaric oxygen therapy".)

We check hearing with repeat audiometry one month following the initiation of salvage therapy, to assess response to treatment and to evaluate the need for hearing amplification.

TREATMENTS OF LIMITED BENEFIT — Although herpes simplex type 1 virus (HSV-1) may be an important etiology of sudden sensorineural hearing loss (SSNHL), there are no high-quality data supporting the benefit of the routine addition of antiviral therapy to glucocorticoid treatment. As an example, in a systematic review evaluating four small randomized trials of patients with idiopathic SSNHL, the addition of antiviral therapy (acyclovir or valacyclovir) to systemic glucocorticoids did not improve hearing compared with glucocorticoid treatment alone [42].

2019 clinical practice guidelines on SSNHL discourage the routine use of antiviral therapy, citing the lack of evidence for efficacy and the potential risk of medication side effects [14]. Nevertheless, if a patient is identified within the first 48 hours of symptom onset, we will offer treatment with an antiviral (eg, valacyclovir 1 gram orally three times daily for 7 to 10 days) as there may be a potential benefit and the risks of harm with this treatment are low.

TREATMENT THAT WE DO NOT RECOMMEND — Other therapies (including pharmacologic, nonpharmacologic, and surgical interventions) for the treatment of idiopathic SSNHL have been evaluated, and although some have shown a benefit in small trials, there is a lack of high-quality data supporting a recommendation for their use [14]. Such therapies include treatment with a low sodium diet and a diuretic [43]; apheresis of fibrinogen and low-density lipoprotein (LDL) cholesterol [44,45]; mineral supplementation with zinc or magnesium [46-48]; administration of dextran, mannitol, pentoxifylline, nifedipine, heparin, or prostaglandin E1 [49-53]; use of herbal preparations such as gingko biloba or Chinese herbal medications [54,55]; surgical tympanotomy and sealing of the round window [56,57]; or inhalation of carbogen gas (a mixture of 95% oxygen, 5% carbon dioxide) [49,50,53].

EVALUATE THE NEED FOR HEARING AMPLIFICATION AND AUDITORY REHABILITATION — For all patients with idiopathic sudden sensorineural hearing loss (SSNHL), we obtain a follow-up audiogram approximately six months after the onset of symptoms to quantify the extent of permanent hearing loss (algorithm 1). No further improvement in hearing is expected after this time.

Those with any degree of permanent hearing loss should be referred to an audiologist for consideration of an assistive hearing device. A patient's hearing-related functional impairment depends upon several factors, including the degree of hearing loss and affected frequencies, hearing in the unaffected ear, the patient's occupation, and other factors. A complete audiologic evaluation is necessary to determine the need for hearing amplification and, if necessary, the appropriate modality (eg, traditional hearing aid, bone-anchored hearing aid [BAHA], cochlear implant). (See "Hearing amplification in adults".)

In addition, patients with permanent hearing loss should be referred for auditory (aural) rehabilitation if available. Auditory rehabilitation can reduce the impact of hearing-related functional impairment, thus improving the patient's quality of life.

The tinnitus which can accompany idiopathic SSNHL can be difficult to treat and may impact quality of life [22]. If hearing improves, tinnitus typically also improves but may not always completely resolve. In addition, vertigo can persist and may also require further management. Treatment of tinnitus and vertigo are reviewed elsewhere. (See "Treatment of tinnitus" and "Treatment of vertigo".)

PROGNOSIS — The overall prognosis for idiopathic sudden sensorineural hearing loss (SSNHL) is generally favorable; approximately two-thirds of patients recover some degree of hearing, although not necessarily complete [3,15,58-61].

In idiopathic SSNHL, recovery (spontaneous or with treatment) typically occurs early after the onset of symptoms. As an example, in a series of 156 patients treated for SSNHL, 78 percent recovered within three months; 54 percent recovered within 10 days, 78 percent within one month, and only one experienced any improvement beyond six months [62]. In general, patients who have not improved within three months are unlikely to experience significant hearing recovery.

The most important prognostic indicator for hearing recovery is the degree of hearing loss at presentation; the less severe the hearing loss at presentation, the greater the likelihood of recovery [59,63].

Other features associated with a favorable prognosis include:

●Isolated high- or low-frequency hearing loss (compared with a flat pattern hearing loss across all frequencies) [59]

●Among those with frequency-restricted hearing loss, isolated low-frequency compared with high-frequency hearing loss [64]

●Presence of tinnitus [59]

●Absence of vertigo [59,65]

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Hearing loss and hearing disorders in adults".)

SUMMARY AND RECOMMENDATIONS

●Etiology – Although sudden sensorineural hearing loss (SSNHL) can result from a variety of identifiable causes, the majority of cases are idiopathic (table 1). Postulated causes of idiopathic SSNHL include viral cochleitis, microvascular events due to a hypercoagulable state, and autoimmune disorders. (See 'Epidemiology and pathogenesis' above.)

●Diagnostic criteria – The most widely accepted criteria for the diagnosis of SSNHL include (see 'Diagnostic criteria' above):

•Hearing loss that is sensorineural in nature

•Hearing loss of at least 30 decibels (dB) over at least three consecutive test frequencies

•Hearing loss that occurs within a 72-hour period

●Clinical presentation – Patients with idiopathic SSNHL typically experience an immediate or rapid hearing loss, or they report a loss of hearing upon awakening. Many patients, however, may only notice a sensation of a blocked ear or aural fullness at first, without recognizing that they have lost hearing. Most patients with idiopathic SSNHL experience tinnitus, and many also have vertigo. (See 'Clinical manifestations' above.)

●Evaluate hearing loss – All patients who experience sudden hearing loss or awaken with new hearing loss should be evaluated for SSNHL. It is first necessary to determine if the hearing deficit is conductive or sensorineural in nature. The Weber and Rinne tests should be performed; these tests can help distinguish between sensorineural and conductive loss in the majority of patients (figure 1 and table 2). (See 'Distinguish sensorineural from conductive hearing loss' above.)

Audiometry is necessary to establish the diagnosis of SSNHL. All patients with suspected SSNHL should undergo audiometric evaluation within 14 days after symptom onset, but ideally as soon as possible. (See 'Audiometry' above.)

●Imaging for all patients – For all patients with SSNHL, we perform imaging with magnetic resonance imaging (MRI) with contrast to evaluate for retrocochlear pathology. The MRI should be done within three months of symptom onset. If MRI is unavailable or not possible, computed tomography (CT) of the temporal bone plus auditory brainstem response (ABR) should be obtained. Although the majority of patients with SSNHL likely have an etiology that cannot be diagnosed by any imaging study, other causes of unilateral sensorineural hearing loss may only be identified by MRI. Retrocochlear pathology is the most frequently identifiable cause of SSNHL diagnosed by imaging. (See 'Imaging: MRI preferred' above.)

●Laboratory tests in select patients – We do not perform routine blood testing in all patients with SSNHL. We do, however, perform appropriate laboratory studies if there is a clinical suspicion for a particular etiology of the hearing loss (table 1). (See 'Targeted laboratory evaluation' above.)

●Glucocorticoid treatment for all patients – For all patients with SSNHL, we suggest treatment with glucocorticoids to be initiated within two weeks of symptom onset (Grade 2C). Options include systemic glucocorticoids, intratympanic glucocorticoids, or combination treatment; which treatment modality to offer depends upon several factors, including any comorbidities which may preclude the administration of high-dose systemic glucocorticoids (eg, diabetes mellitus, previous adverse reaction to steroids), the degree of hearing loss, and patient preference (algorithm 1) (see 'Initial therapy' above):

•For patients who are able to tolerate high-dose systemic glucocorticoid therapy, we offer initial treatment with prednisone 60 mg orally once daily for 10 days.

•For patients who prefer to avoid systemic glucocorticoids, or who are not candidates for treatment with high-dose systemic glucocorticoids, we offer initial treatment with intratympanic dexamethasone injections once weekly for three weeks.

•For patients with more severe hearing loss (>50 decibel [dB]), we offer combination therapy (prednisone 60 mg once daily for 10 days plus intratympanic dexamethasone injections once weekly for three weeks, given concurrently or sequentially, in either order).

●Salvage therapy for patients with inadequate response to initial treatment – For patients who have an inadequate response after initial therapy (<10 dB improvement in hearing, or who continue to have ≥20 dB hearing loss), we suggest salvage glucocorticoid therapy rather than no additional treatment (Grade 2C). Treatment should ideally to be initiated within six to eight weeks of symptom onset, and the treatment offered depends upon the initial therapy received (see 'Patients refractory to initial therapy' above):

•Patients who received initial systemic glucocorticoids are offered salvage therapy with intratympanic glucocorticoid injections.

•Patients who received initial intratympanic glucocorticoid injections are offered salvage therapy with systemic glucocorticoids if there is no contraindication.

No additional glucocorticoid therapy is offered to patients who received initial combination systemic and intratympanic glucocorticoids. Adjuvant HBOT may be of benefit when used with glucocorticoid salvage therapy for those with an inadequate response to initial treatment, particularly for those patients with a more profound (>70 dB) hearing loss.

●Antiviral therapy offered within 48 hours of symptom onset – If a patient is identified within the first 48 hours of symptom onset, we will offer treatment with an antiviral (eg, valacyclovir 1 gram orally three times daily for 7 to 10 days) as there may be a potential benefit and the risks of harms are low. (See 'Treatments of limited benefit' above.)

●Evaluate need for hearing amplification and auditory rehabilitation – Patients with any degree of permanent hearing loss should be referred to an audiologist for consideration of an assistive hearing device and auditory (aural) rehabilitation if available. (See 'Evaluate the need for hearing amplification and auditory rehabilitation' above.)