Merck Manual

Please confirm that you are a health care professional

honeypot link

Sudden Hearing Loss

By

Lawrence R. Lustig

, MD, Columbia University Medical Center and New York Presbyterian Hospital

Last full review/revision Dec 2020| Content last modified Dec 2020
Click here for Patient Education
Topic Resources

General reference

Etiology of Sudden Hearing Loss

The following are common characteristics of sudden hearing loss:

Idiopathic: There are numerous theories for which some evidence (although conflicting and incomplete) exists. The most promising possibilities include viral infections (particularly involving herpes simplex Overview of Herpesvirus Infections Eight types of herpesviruses infect humans (see Table: Herpesviruses That Infect Humans). After initial infection, all herpesviruses remain latent within specific host cells and may subsequently... read more ), autoimmune attacks, and acute microvascular occlusion.

Obvious event: Some causes of sudden hearing loss are readily apparent.

Cogan syndrome Cogan Syndrome Cogan syndrome is a rare autoimmune disease involving the eye and the inner ear. Cogan syndrome affects young adults, with 80% of patients between 14 and 47 years. The disease appears to result... read more is a rare autoimmune reaction directed against an unknown common autoantigen in the cornea and inner ear; > 50% of patients present with vestibuloauditory symptoms. About 10 to 30% of patients also have a severe systemic vasculitis, which may include life-threatening aortitis.

Table
icon

Evaluation of Sudden Hearing Loss

Evaluation consists of detecting and quantifying hearing loss and determining etiology (particularly reversible causes).

History

History of present illness should verify that loss is sudden and not chronic. The history should also note whether loss is unilateral or bilateral and whether there is a current acute event (eg, head injury, barotrauma Otic Barotrauma Otic barotrauma is ear pain or damage to the tympanic membrane caused by rapid changes in pressure. To maintain equal pressure on both sides of the tympanic membrane (TM), gas must move freely... read more [particularly a diving injury], infectious illness). Important accompanying symptoms include other otologic symptoms (eg, tinnitus, ear discharge), vestibular symptoms (eg, disorientation in the dark, vertigo), and other neurologic symptoms (eg, headache, weakness or asymmetry of the face, abnormal sense of taste).

Past medical history should ask about known HIV or syphilis infection and risk factors for them (eg, multiple sex partners, unprotected intercourse). Family history should note close relatives with hearing loss (suggesting a congenital fistula). Drug history should specifically query current or previous use of ototoxic drugs Drug-Induced Ototoxicity A wide variety of drugs can be ototoxic. Factors affecting ototoxicity include Dose Duration of therapy Concurrent renal failure read more and whether the patient has known renal insufficiency or renal failure.

Physical examination

The examination focuses on the ears and hearing and on the neurologic examination.

The tympanic membrane is inspected for perforation, drainage, or other lesions. During the neurologic examination, attention should be paid to the cranial nerves (particularly the 5th, 7th, and 8th) and to vestibular and cerebellar function because abnormalities in these areas often occur with tumors of the brain stem and cerebellopontine angle.

Red flags

Findings of particular concern are

  • Abnormalities of cranial nerves (other than hearing loss)

  • Significant asymmetry in speech understanding between the 2 ears

  • Other neurologic symptoms and signs (eg, motor weakness, aphasia, Horner syndrome, sensory or temperature sensation abnormalities)

Interpretation of findings

Traumatic, ototoxic, and some infectious causes are usually apparent clinically. A patient with perilymphatic fistula may hear an explosive sound in the affected ear when the fistula occurs and may also have sudden vertigo, nystagmus, and tinnitus.

Focal neurologic abnormalities are of particular concern. The 5th cranial nerve, 7th cranial nerve, or both are often affected by tumors that involve the 8th cranial nerve, so loss of facial sensation and weak jaw clench (5th) and hemifacial weakness and taste abnormalities (7th) point to a lesion in that area.

Fluctuating unilateral hearing loss accompanied by aural fullness, tinnitus, and vertigo also suggests Meniere disease Meniere Disease Meniere disease is an inner ear disorder that causes vertigo, fluctuating sensorineural hearing loss, and tinnitus. There is no reliable diagnostic test. Vertigo and nausea are treated symptomatically... read more . Systemic symptoms suggesting inflammation (eg, fevers, rash, joint pains, mucosal lesions) should raise suspicion of an occult infection or autoimmune disorder.

Testing

Patients should have an audiogram, and unless the diagnosis is clearly an acute infection or drug toxicity, most clinicians do gadolinium-enhanced MRI to diagnose inapparent causes, particularly for unilateral losses. Patients with an acute traumatic cause also should have MRI. A perilymphatic fistula is typically suspected from an inciting event (eg, excessive strain, barotrauma), and testing may be done by using positive pneumatic pressure to evoke eye movements (nystagmus). CT of the temporal bones is usually done to show the bony characteristics of the inner ear and can help elucidate congenital abnormalities (eg, enlarged vestibular aqueduct), fractures of the temporal bone from trauma, or erosive processes (eg, cholesteatoma).

Patients who have risk factors for or symptoms that suggest causes should have appropriate tests based on clinical evaluation (eg, serologic tests for possible HIV infection or syphilis, complete blood count [CBC] and coagulation profile for hematologic disorders, erythrocyte sedimentation rate [ESR] and antinuclear antibodies for vasculitis).

Treatment of Sudden Hearing Loss

Treatment of sudden hearing loss focuses on the causative disorder when known. Fistulas are explored and repaired surgically when bed rest fails to control symptoms.

In viral and idiopathic cases, hearing returns to normal in about 50% of patients and is partially recovered in others.

In patients who recover their hearing, improvement usually occurs within 10 to 14 days.

Recovery from an ototoxic drug varies greatly depending on the drug and its dosage. With some drugs (eg, aspirin, diuretics), hearing loss resolves within 24 hours, whereas other drugs (eg, antibiotics, chemotherapy drugs) often cause permanent hearing loss if safe dosages have been exceeded.

For patients with idiopathic loss, many clinicians empirically give a course of glucocorticoids (typically prednisone 60 mg orally once a day for 7 to 14 days followed by a 5 day taper). Glucocorticoids can be given orally and/or by transtympanic injection. Direct transtympanic injection avoids the systemic side effects of oral glucocorticoids and appears equally effective except in profound (> 90 decibels) hearing loss. There are data showing that using both oral and intratympanic steroids leads to better outcomes than either alone. Although clinicians often give antiviral drugs effective against herpes simplex (eg, valacyclovir, famciclovir), data show that such drugs do not affect hearing outcomes. There are some limited data suggesting that hyperbaric oxygen therapy may be beneficial in idiopathic sudden hearing loss.

Key Points

  • Most cases are idiopathic.

  • A few cases have an obvious cause (eg, major trauma, acute infection, drugs).

  • A very few cases represent unusual manifestations of treatable disorders.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
OTHER TOPICS IN THIS CHAPTER
Professionals also read
Test your knowledge
External Ear Obstructions
When a patient presents with itching and pain of the ear, as well as conductive hearing loss, obstruction of the ear canal is a possible diagnosis. A typical cause of these symptoms is cerumen impaction due to the patient pushing cerumen further into the ear while attempting to clean the ear canal with cotton swabs. The best method for removing this cerumen from the ear includes which of the following?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
 

Also of Interest

 
TOP