Hearing Loss
Mark Knudson
Approximately 28 million Americans have hearing loss. Among individuals aged more than 65 years, 7% to 8% report hearing loss, yet close to 20% will have evidence of hearing loss if screened (1).
Approach
In the evaluation of an individual with known or suspected hearing loss, separation into sensorineural hearing loss (SNHL), conductive hearing loss (CHL), and mixed hearing loss (MHL) helps in diagnosis (2).
A. Sensorineural hearing loss can be caused by a defect in the inner ear or cochlea, the eighth cranial nerve, or by loss of central nervous system (CNS) function. Common causes of SNHL include acoustic neuroma, multiple sclerosis (MS), hypothyroidism, vertebrobasilar insufficiency, or stroke, Ménière’s syndrome, drug toxicity, and idiopathic hearing loss.
B. Conductive hearing loss. Generally less worrisome than SNHL, CHL can result from cerumen impaction, perforation of the tympanic membrane (TM), middle ear effusion, atelectasis, and otosclerosis. In addition, a variety of tumors (e.g., squamous cell cancer, exostoses, or cholesteatoma) can cause CHL.
C. Mixed hearing loss. Presbycusis, medications, and noise-induced hearing loss are examples of mixed loss, where impairment of conduction can complicate a sensorineural component.
History
Proactive detection of minor hearing alterations is necessary because most patients with hearing loss do not present with a hearing complaint. Many elderly patients, in particular, accept hearing loss as an expected part of aging.
A. Presentation. A small number of patients will present with a complaint of decreased hearing, a few more will admit to abnormal hearing, but most will have no specific hearing concern. A patient’s depression, confusion, social isolation, or poor job performance can be caused or complicated by hearing impairment. Family members may describe abnormal, slow, or overly loud answers. A sudden tendency to monopolize or disrupt conversation, or to tilt the head in conversation, may suggest hearing loss.
B. Duration. CHL is often of sudden onset but of a mild degree. Complete occlusion or rapid collection of fluid in middle ear causes abrupt change in hearing. SNHL can be abrupt and severe (stroke, idiopathic, trauma) or gradual (Ménière’s syndrome, acoustic neuroma, hypothyroidism). Some forms may be intermittent (such as Ménière’s syndrome.)
C. Quality of hearing. CHL often affects quality of hearing first. Described as muffled “like a head in a drum,” the patient may lose high frequency and voice discrimination, yet still be able to detect subtle sounds. SNHL, when not associated with tinnitus, can have good quality but diminished hearing that is usually more profound than CHL.
D. Associated symptoms. Tinnitus is classically associated with Ménière’s syndrome or disease, but may be seen with other causes of SNHL. Vertigo is associated with inner ear disorders, and is often self-limited (Chapter 6.9). Associated fluctuating neurologic defects of many sites suggest MS, whereas focal deficits suggest CNS tumors or vascular insufficiency.
E. Family history. This may be positive in presbycusis, Ménière’s, otosclerosis, and acoustic neuroma.
F. Social and work history. Recreational history (loud music or target shooting) or work history (pilots, factory workers, firefighters) can implicate excessive noise exposure. Inquire about use of protective equipment and chronicity of exposure.
Physical examination
Gross tests of hearing are only helpful to confirm significant hearing asymmetry or to detect profound hearing loss. With one ear covered, the patient tries to hear soft sounds such as the tick of a watch, scratching of two fingers rubbed together, or a softly whispered voice.
A. Visual examination of ears. Inspect the canal and TM to rule out obvious causes of CHL. Cerumen impaction is a remarkably common and easily corrected cause of hearing loss. Pneumoscopy to check for normal movement of the TM helps rule out perforation, atelectasis, eustachian tube dysfunction, stiffened TM, ossicular disruption, and middle ear effusion.
B. Weber test. With a vibrating tuning fork placed on the top of the head, the patient is asked to describe the sound heard. The patient will perceive the sound to be louder in the affected ear in CHL, because the background noise will be absent on that side. The unaffected ear will be perceived as louder in SNHL.
C. Rinne test. With the vibrating tuning fork placed on the mastoid, the patient detects bone conduction (BC). The tuning fork is removed when the patient can no longer hear the sound. Then the tuning fork is held next to the ear to test for air conduction (AC). In an individual with normal hearing, AC is significantly better than BC. CHL will reduce AC, with little effect on BC.
Testing
A simple audiogram performed at several frequency responses may detect individuals at risk for hearing loss. Although the sensitivity is good (93% to 95%), the poor specificity (60% to 74%) can result in many false-positive findings (3).
A. Audiography. Two forms of testing provide reproducible information about the patient. Pure tone testing documents the exact number of decibels heard at a given frequency. Unfortunately, it describes nothing about the ability to discriminate language. On the other hand, speech detection better estimates impairment of actual language function, but requires a much more cooperative and attentive patient.
B. Auditory-evoked response. Able to detect the electroencephalographic stimulation caused by repetitive sounds, this examination is useful in the obtunded, uncooperative, or very young patient.
C. Computed tomography (CT). In the setting of traumatic loss of hearing, CT is fast, less expensive than magnetic resonance imaging (MRI), and able to detect abnormalities within the petrous ridge where fractures can affect hearing (4). Likewise, bleeding in the CNS is readily seen. CT is also useful to examine for causes of CHL such as tumors, middle ear anomalies, myringosclerosis, and cholesteatoma.
D. MRI. In patients with SNHL, MRI with gadolineum is superior to CT because certain CNS diseases (MS or vascular infarcts) are more easily identified. In addition, acoustic neuromas and labyrinth disorders, often too small to be seen with CT, may be visualized with MRI (4).
Diagnostic assessment
Separation into CHL and SNHL, and assessment of severity help determine the best diagnostic approach (2).
A. Conductive hearing loss. Although bothersome, these disorders are rarely severe or life threatening. Systematic history and physical examination normally will easily localize the site of hearing loss.
B. Sensorineural hearing loss. Acoustic neuroma (AN), one of the most feared causes of hearing loss, is actually a nerve sheath tumor accounting for 1% of SNHL; 95% of patients with AN present with gradual progression of unilateral hearing loss (4). Tinnitus and vestibular symptoms are less common. In contrast, Ménière’s disease causes a fluctuating but progressive loss of hearing associated with tinnitus and episodic vertigo. Other causes of SNHL can be severe, rapidly progressive, and associated with severe side effects or potential mortality. Rapid systematic evaluation, including MRI in patients aged less than 65 years, should be conducted. For patients over the age of 65 years, exclusion of presbycusis and otosclerosis should prompt the same thorough evaluation.
References
1. Maggi S, Minicuci N, Martini A, et al. Prevalence rates of hearing impairment and comorbid conditions in older people: the Veneto Study. J Am Geriatr Soc 1998;46:
1069–1074.
2. Weber P, Klein A. Hearing loss. Med Clin North Am 1999;83:125–137.
3. Weissman J. Hearing loss. Radiology 1996;199:593–611.
4. Moore A, Siu A. Screening for common problems in ambulatory elderly: clinical confirmation of a screening instrument. Am J Med 1996;100:438–443.
Book Source Details
- Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
- Author(s): Robert B. Taylor (editor)
- Year of Publication: 2000
- Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.
Other Book Chapters Related to Sensitive hearing
Read excerpts from these other book chapters related to Sensitive hearing:
Medical Books Excerpts
- DEAFNESS
- "Algorithmic Diagnosis of Symptoms and Signs" (2003)
- [ read ]
- TINNITUS
- "Algorithmic Diagnosis of Symptoms and Signs" (2003)
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- Tinnitus
- "In A Page: Pediatric Signs and Symptoms" (2007)
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- Tinnitus
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
- [ read ]
- Deafness
- "A Pocket Manual of Differential Diagnosis" (1999)
- [ read ]
- Hearing loss
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
- [ read ]
- Tinnitus
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
- [ read ]
- Hearing Loss
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
- Tinnitus
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
- Tinnitus
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
- [ read ]
- Tinnitus
- "Nursing: Interpreting Signs and Symptoms" (2007)
- [ read ]
Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2008 Williams & Wilkins.
More About Causes of Sensitive hearing
» Next page: Tinnitus (The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter)
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