Hearing loss
Hearing loss: Excerpt from Handbook of Signs & Symptoms (Third 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 then travel to the middle ear’s tympanic membrane and ossicles (incus, malleus, and stapes) and into the inner ear’s cochlea. The cochlear division of cranial nerve (CN) VIII (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 CN VIII. 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, however, 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. 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, or 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 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, notify the physician to discuss whether an otoscopic examination should be done. (See Using an otoscope correctly, page 237.) During the otoscopic examination, note 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 Weber’s and the Rinne tests to obtain a preliminary evaluation of the type and degree of hearing loss. (See Differentiating conductive from sensorineural hearing loss, page 316.)
Medical causes
Acoustic neuroma
Acoustic neuroma, which is a CN VIII 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 causes gradual 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.
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 It can be accompanied by vertigo and, at times, facial paralysis
Examination reveals eardrum perforation, pearly white balls in the ear canal, and possible 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, purulent discharge and, eventually, facial paralysis Examination may detect the granular, bleeding tumor.
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.
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 an altered level of consciousness.
Ménière’s disease
Initially, Ménière’s disease, an 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.
Nasopharyngeal cancer
Nasopharyngeal 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.
Otitis externa
Conductive hearing loss resulting from debris in the ear canal characterizes acute and malignant otitis externa With 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.
With malignant otitis externa, debris is also visible in the canal. This life-threatening disorder, which most commonly occurs in the patient with diabetes, causes sensorineural hearing loss, pruritus, tinnitus, and severe ear pain.
Otitis media
Otitis media is a middle ear inflammation that typically produces unilateral conductive hearing loss In patients with acute suppurative otitis media, the hearing loss develops gradually over a few hours and is usually accompanied by an upper respiratory tract infection with a 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, a fever, nausea, and vomiting. Rupture of the bulging, swollen tympanic membrane relieves the pain and produces a brief, bloody, 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, an 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
Otosclerosis is a hereditary disorder in which unilateral conductive hearing loss usually begins when the patient is in his early twenties and may gradually progress to bilateral mixed loss The patient may report tinnitus and an ability to hear better in a noisy environment
The deafness is usually noticed between ages 11 and 30.
Gender cue
Otosclerosis affects twice as many women as men, and the condition 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.
Temporal bone fracture
Temporal bone 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.
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.
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, 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 typically sensorineural hearing loss. Nonhereditary disorders associated with congenital sensorineural hearing loss include albinism, onychodystrophy syndrome, cochlear dysplasia, and Pendred’s, Usher’s, Waardenburg’s, and Jervell and Lange-Nielsen syndromes
This type of hearing loss may also result from maternal use of ototoxic drugs, birth trauma, and anoxia during or after birth.
Mumps is the most common pediatric cause of unilateral sensorineural hearing loss. Other causes are meningitis, measles, influenza, and acute febrile illness.
Disorders that may produce congenital conductive hearing loss include atresia, ossicle malformation, and other abnormalities. Serous otitis media commonly causes bilateral conductive hearing loss in children. Conductive hearing loss may also occur in children who put foreign objects in their ears.
Hearing disorders in a child 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 an infant younger than age 6 months, or have an audiologist test brain stem evoked response in a neonate, an infant, and a young child. 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.
Pictures
Book Source Details
- Book Title: Handbook of Signs & Symptoms (Third Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Handbook of Signs & Symptoms (Third Edition), Copyright © 2006 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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