Hearing loss

Hearing loss: Excerpt from Professional Guide to Signs & Symptoms (Fifth Edition)

Affecting nearly 16 million Americans, hearing loss may be temporary or permanent and partial or complete. This common symptom may involve reception of low-, middle-, or high-frequency tones. If the hearing loss doesn’t affect speech frequencies, the patient may be unaware of it.

Normally, sound waves enter the external auditory canal and travel to the middle ear’s tympanic membrane and ossicles (incus, malleus, and stapes) and then into the inner ear’s cochlea. The cochlear division of the eighth cranial (auditory) nerve carries the sound impulse to the brain. This type of sound transmission, called air conduction, is normally better than bone conduction—sound transmission through bone to the inner ear.

Hearing loss can be classified as conductive, sensorineural, mixed, or functional. Conductive hearing loss results from external or middle ear disorders that block sound transmission. This type of hearing loss usually responds to medical or surgical intervention (or in some cases, both). Sensorineural hearing loss results from disorders of the inner ear or of the eighth cranial nerve. Mixed hearing loss combines aspects of conductive and sensorineural hearing loss. Functional hearing loss results from psychological factors rather than identifiable organic damage.

Hearing loss may also result from trauma, infection, allergy, tumors, certain systemic and hereditary disorders, and the effects of ototoxic drugs and treatments. In most cases, though, it results from presbycusis, a type of sensorineural hearing loss that usually affects people older than age 50. Other physiologic causes of hearing loss include cerumen (earwax) impaction; barotitis media (unequal pressure on the eardrum) associated with descent in an airplane or elevator, diving, or close proximity to an explosion; and chronic exposure to noise over 90 decibels, which can occur on the job, with certain hobbies, or from listening to live or recorded music.

History and physical examination

If the patient reports hearing loss, ask him to describe it fully. Is it unilateral or bilateral? Continuous or intermittent? Ask about a family history of hearing loss. Then obtain the patient’s medical history, noting chronic ear infections, ear surgery, and ear or head trauma. Has the patient recently had an upper respiratory tract infection? After taking a drug history, have the patient describe his occupation and work environment.

Next, explore associated signs and symptoms. Does the patient have ear pain? If so, is it unilateral or bilateral? Continuous or intermittent? Ask the patient if he has noticed discharge from one or both ears. If so, have him describe its color and consistency, and note when it began. Does he hear ringing, buzzing, hissing, or other noises in one or both ears? If so, are the noises constant or intermittent? Does he experience any dizziness? If so, when did he first notice it?

Begin the physical examination by inspecting the external ear for inflammation, boils, foreign bodies, and discharge. Then apply pressure to the tragus and mastoid to elicit tenderness. If you detect tenderness or external ear abnormalities, ask the physician whether an otoscopic examination should be done. (See Using an otoscope correctly, page 289.) During the otoscopic examination, note any color change, perforation, bulging, or retraction of the tympanic membrane, which normally looks like a shiny, pearl gray cone.

Next, evaluate the patient’s hearing acuity, using the ticking watch and whispered voice tests. Then perform the Weber and Rinne tests to obtain a preliminary evaluation of the type and degree of hearing loss. (See Differentiating conductive from sensorineural hearing loss.)

Medical causes

Acoustic neuroma

This eighth cranial nerve tumor causes unilateral, progressive, sensorineural hearing loss. The patient may also develop tinnitus, vertigo, and—with cranial nerve compression—facial paralysis.

Adenoid hypertrophy

Eustachian tube dysfunction gradually causes conductive hearing loss accompanied by intermittent ear discharge. The patient also tends to breathe through his mouth and may complain of a sensation of ear fullness.

Allergies

Conductive hearing loss may result when an allergy produces eustachian tube and middle ear congestion. Other features include ear pain or a feeling of fullness, nasal congestion, and conjunctivitis.

Aural polyps

If a polyp occludes the external auditory canal, partial hearing loss may occur. The polyp typically bleeds easily and is covered by a purulent discharge.

Cholesteatoma

Gradual hearing loss is characteristic in this disorder and may be accompanied by vertigo and, at times, facial paralysis. Examination reveals eardrum perforation, pearly white balls in the ear canal and, possibly, a discharge.

Cyst

Ear canal obstruction by a sebaceous or dermoid cyst causes progressive conductive hearing loss. On inspection, the cyst looks like a soft mass.

External ear canal tumor (malignant)

Progressive conductive hearing loss is characteristic and is accompanied by deep, boring ear pain; a purulent discharge; and eventually facial paralysis. Examination may detect the granular, bleeding tumor.

Furuncle

Reversible conductive hearing loss may occur when one of these painful, hard nodules forms in the ear. The patient may report a sense of fullness in the ear and pain on palpation of the tragus or auricle. Rupture relieves the pain and produces a purulent, necrotic discharge.

Glomus jugulare tumor

Initially, this benign tumor causes mild, unilateral conductive hearing loss that becomes progressively more severe. The patient may report tinnitus that sounds like his heartbeat. Associated signs and symptoms include gradual congestion in the affected ear, throbbing or pulsating discomfort, bloody otorrhea, facial nerve paralysis, and vertigo. Although the tympanic membrane is normal, a reddened mass appears behind it.

Glomus tympanum tumor

This cancerous middle ear tumor causes slowly progressive hearing loss and throbbing or pulsating tinnitus. It usually bleeds easily when manipulated. Late features include ear pain, dizziness, and total unilateral deafness.

Granuloma

A rare cause of conductive hearing loss, a granuloma may also produce fullness in the ear, deep-seated pain, and a bloody discharge.

Head trauma

Sudden conductive or sensorineural hearing loss may result from ossicle disruption, ear canal fracture, tympanic membrane perforation, or cochlear fracture associated with head trauma. Typically, the patient reports a headache and exhibits bleeding from his ear. Neurologic features vary and may include impaired vision and altered level of consciousness.

Herpes zoster oticus (Ramsay Hunt syndrome)

This syndrome causes sudden severe, unilateral mixed hearing loss, which may be accompanied by vesicles in the external ear, tinnitus, vertigo, ear pain, malaise, and transient ipsilateral facial paralysis.

Hypothyroidism

This disorder may produce reversible sensorineural hearing loss. Other effects include bradycardia, weight gain despite anorexia, mental dullness, cold intolerance, facial edema, brittle hair, and dry skin that’s pale, cool, and doughy.

Ménière’s disease

Initially, this inner ear disorder produces intermittent, unilateral sensorineural hearing loss that involves only low tones. Later, hearing loss becomes constant and affects other tones. Associated signs and symptoms include intermittent severe vertigo, nausea and vomiting, a feeling of fullness in the ear, a roaring or hollow-seashell tinnitus, diaphoresis, and nystagmus.

Multiple sclerosis

Rarely, this disorder causes sensorineural hearing loss associated with myelin destruction of the central auditory pathways. The hearing loss may be sudden and unilateral or intermittent and bilateral. Among other characteristics are impaired vision, paresthesia, muscle weakness, gait ataxia, intention tremor, urinary disturbances, and emotional lability.

Myringitis

Rarely, acute infectious myringitis produces conductive hearing loss when fluid accumulates in the middle ear or a large bleb totally obstructs the ear canal. Small, reddened inflamed blebs may develop in the canal, on the tympanic membrane, or in the middle ear and may produce a bloody discharge if they rupture. Associated findings may include severe ear pain, mastoid tenderness, and fever.

Chronic granular myringitis produces gradual hearing loss accompanied by pruritus and a purulent discharge.

Nasopharyngeal cancer

This type of cancer causes mild unilateral conductive hearing loss when it compresses the eustachian tube. Bone conduction is normal, and inspection reveals a retracted tympanic membrane backed by fluid. When this tumor obstructs the nasal airway, the patient may exhibit nasal speech and a bloody nasal and postnasal discharge. Cranial nerve involvement produces other findings, such as diplopia and rectus muscle paralysis.

Osteoma

Commonly affecting women and swimmers, osteoma may cause sudden or intermittent conductive hearing loss. Typically, bony projections are visible in the ear canal, but the tympanic membrane appears normal.

Otitis externa

Conductive hearing loss resulting from debris in the ear canal characterizes both acute and malignant otitis externa. In acute otitis externa, ear canal inflammation produces pain, itching, and a foul-smelling, sticky yellow discharge. Severe tenderness is typically elicited by chewing, opening the mouth, and pressing on the tragus or mastoid. The patient may also develop a low-grade fever, regional lymphadenopathy, a headache on the affected side, and mild to moderate pain around the ear that may later intensify. Examination may reveal greenish white debris or edema in the canal.

In malignant otitis externa, debris is also visible in the canal. This life-threatening disorder, which most commonly occurs in diabetics, causes sensorineural hearing loss, pruritus, tinnitus, and severe ear pain.

Otitis media

This middle ear inflammation typically produces unilateral conductive hearing loss. In acute suppurative otitis media, the hearing loss develops gradually over a few hours and is usually accompanied by an upper respiratory tract infection with sore throat, cough, nasal discharge, and headache. Related signs and symptoms include dizziness, a sensation of fullness in the ear, intermittent or constant ear pain, fever, nausea, and vomiting. Rupture of the bulging, swollen tympanic membrane relieves the pain and produces a brief bloody and purulent discharge. Hearing returns after the infection subsides.

Hearing loss also develops gradually in patients with chronic otitis media. Assessment may reveal a perforated tympanic membrane, purulent ear drainage, earache, nausea, and vertigo.

Commonly associated with an upper respiratory tract  infection or nasopharyngeal cancer, serous otitis media commonly produces a stuffy feeling in the ear and pain that worsens at night. Examination reveals a retracted—and perhaps discolored—tympanic membrane and possibly air bubbles behind the membrane.

Otosclerosis

In this hereditary disorder, unilateral conductive hearing loss usually begins when the patient is in his early twenties and may gradually progress to bilateral mixed hearing loss. The patient may report tinnitus and an ability to hear better in a noisy environment.

Gender Cue: Otosclerosis affects twice as many women as men and may worsen during pregnancy.

Skull fracture

Auditory nerve injury causes sudden unilateral sensorineural hearing loss. Accompanying signs and symptoms include ringing tinnitus, blood behind the tympanic membrane, scalp wounds, and other findings.

Syphilis

In tertiary syphilis, sensorineural hearing loss may develop suddenly or gradually and usually affects one ear more than the other. It’s usually accompanied by a gumma lesion—a chronic, superficial nodule or a deep, granulomatous lesion on the skin or mucous membranes. The lesion is solitary, asymmetrical, painless, and indurated. The patient may also exhibit signs of liver, respiratory, cardiovascular, or neurologic dysfunction.

Temporal arteritis

This disorder may produce unilateral sensorineural hearing loss accompanied by throbbing unilateral facial pain, pain behind the eye, temporal or frontotemporal headache, and occasionally vision loss. The hearing loss is usually preceded by a prodrome of malaise, anorexia, weight loss, weakness, and myalgia that lasts for several days. Examination may reveal a nodular, swollen temporal artery. Low-grade fever, confusion, and disorientation may also occur.

Temporal bone fracture

This fracture can cause sudden unilateral sensorineural hearing loss accompanied by hissing tinnitus. The tympanic membrane may be perforated, depending on the fracture’s location. Loss of consciousness, Battle’s sign, and facial paralysis may also occur.

Tuberculosis

This pulmonary infection may spread to the ear, resulting in eardrum perforation, mild conductive hearing loss, and cervical lymphadenopathy.

Tympanic membrane perforation

Commonly caused by trauma from sharp objects or rapid pressure changes, perforation of the tympanic membrane causes abrupt hearing loss along with ear pain, tinnitus, vertigo, and a sensation of fullness in the ear.

Wegener’s granulomatosis

Conductive hearing loss develops slowly in this rare necrotizing, granulomatous vasculitis. This multisystem disorder may also cause cough, pleuritic chest pain, epistaxis, hemorrhagic skin lesions, oliguria, and nasal discharge.

Other causes

Drugs

Ototoxic drugs typically produce ringing or buzzing tinnitus and a feeling of fullness in the ear. Chloroquine, cisplatin, vancomycin, and aminoglycosides (especially neomycin, kanamycin, and amikacin) may cause irreversible hearing loss. Loop diuretics, such as furosemide, ethacrynic acid, and bumetanide, usually produce a brief, reversible hearing loss. Quinine, quinidine, and high doses of erythromycin or salicylates (such as aspirin) may also cause reversible hearing loss.

Radiation therapy

Irradiation of the middle ear, thyroid, face, skull, or nasopharynx may cause eustachian tube dysfunction, resulting in hearing loss.

Surgery

Myringotomy, myringoplasty, simple or radical mastoidectomy, or fenestrations may cause scarring that interferes with hearing.

Special considerations

When talking with the patient, remember to face him and speak slowly. Don’t shout at the patient or smoke, eat, or chew gum when talking.

Prepare the patient for audiometry and auditory evoked-response testing. After testing, the patient may require a hearing aid or cochlear implant to improve his hearing.

Pediatric pointers

About 3,000 profoundly deaf infants are born in the United States each year. In about half of these infants, hereditary disorders (such as Paget’s disease and Alport’s, Hurler’s, and Klippel-Feil syndromes) cause the typically sensorineural hearing loss. Nonhereditary disorders associated with congenital sensorineural hearing loss include albinism, onychodystrophy, cochlear dysplasia, and Pendred’s, Usher’s, Waardenburg’s, and Jervell and Lange-Nielsen syndromes. Sensorineural hearing loss may also result from maternal use of ototoxic drugs, birth trauma, and anoxia during or after birth.

Mumps is the most common cause of unilateral sensorineural hearing loss in children. Other causes are meningitis, measles, influenza, and acute febrile illness.

Congenital conductive hearing loss may be caused by atresia, ossicle malformation, and other abnormalities. Serous otitis media commonly causes bilateral conductive hearing loss in children. Putting foreign objects in the ears can also cause conductive hearing loss.

Hearing disorders in children may lead to speech, language, and learning problems. Early identification and treatment of hearing loss is thus crucial to avoid incorrectly labeling the child as mentally retarded, brain damaged, or a slow learner.

When assessing an infant or a young child for hearing loss, remember that you can’t use a tuning fork. Instead, test the startle reflex in infants younger than age 6 months, or have an audiologist test brain stem evoked response in neonates, infants, and young children. Also, obtain a gestational, perinatal, and family history from the parents.

Geriatric pointers

In older patients, presbycusis may be aggravated by exposure to noise as well as other factors.

Patient counseling

Instruct the patient to avoid exposure to loud noise and to use ear protection to arrest hearing loss. If the patient has an upper respiratory tract infection, tell him to avoid flying and driving.

Pictures

Book Source Details

• Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
• Author(s): Springhouse
• Year of Publication: 2006
• Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.

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More About This Book: Title: Professional Guide to Signs & Symptoms (Fifth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2006 ISBN: 1-58255-510-9

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