Hearing Loss in the Elderly

Etiology

Hearing loss in the elderly is complex and multifactorial. Aging is complex because age-related syndromes interact across organ systems, and basic homeostasis and physiology are altered with advancing age.[4] Hearing loss in older adults is predominantly attributed to age-related hearing loss (ARHL), or presbycusis, although the exact prevalence is difficult to quantify.[5] 

ARHL is defined strictly as bilateral sensorineural hearing loss solely attributed to age without any other causative explanation.[6] To fully manage hearing loss in the elderly, providers must approach it as they would any patient presenting with hearing loss, since ARHL is not the only diagnosis on the differential diagnosis of hearing loss in the elderly.

The traditional approach to hearing loss separates causes into conductive, sensorineural, or mixed.[7] Conductive hearing loss is due to the inability of stimulus (sound waves) to reach the inner ear structures. It is commonly caused by middle ear effusion, otosclerosis, cholesteatoma, and canal impaction, such as from cerumen. Sensorineural hearing loss is due to dysfunction of sound transmission from the inner ear to the brain. It can be attributed to ARHL, noise exposure, hereditary syndromes, Meniere disease, intracranial pathology, and infection.[8]

Epidemiology

Due to advances in individual healthcare and public health, the proportion of the population aged 65 and older is increasing rapidly.[9] Therefore, the conditions affecting an aging population continue to grow and remain a major focus of medicine. Hearing loss is prevalent among older adults, with over 80% of individuals aged 80 years and older experiencing some degree of hearing loss.[3] The prevalence alone indicates that hearing loss should be a key concern for healthcare providers caring for older adults.

By sex, males are more likely to experience hearing loss as they age.[3] A genetic component may be present, and those with a strong family history are often more affected with a more severe loss than those without a family history.[10] Interestingly, research suggests that less pigmented skin may be associated with higher rates of hearing loss in older adults.[11]

Pathophysiology

Hearing loss in the elderly is multifactorial, and a basic understanding of the pathophysiology of normal hearing is essential for diagnosing its various etiologies. Normally, the external ear’s primary function is to funnel and localize the sound wave into the ear. The middle ear then amplifies and transfers the sound wave from air to the fluid-filled inner ear. Lastly, the inner ear transduces mechanical energy from sound waves into electrochemical stimuli, which generate action potentials that travel to the cochlear nucleus in the brain.[12] Disruption of these pathways can result in hearing loss.

While there are countless causes of hearing loss in the elderly, the pathophysiology of the major causes is reviewed below:

Age-Related Hearing Loss (ARHL), or Presbycusis: An often-bilateral sensorineural hearing loss, with a broad, multifactorial etiology, including genetics, noise exposure, microvascular changes with age, and alterations in metabolism.[13] Age-related changes result in loss of hair cells of the cochlea, loss of cochlear nerve fibers, degeneration of the stria vascularis, and physical changes in the cochlear duct. ARHL primarily affects high tones and consonants (e.g., t, s, ch), leading to word-final cuts and poor speech comprehension and communication. Hearing loss can also result in difficulty localizing sound, particularly in the presence of background noise.[6]

Noise-induced: A generally bilateral sensorineural hearing loss, though it can be unilateral when the source of sound is greater from 1 side, such as in the case of shooting rifles.[14] This hearing loss results from excessive mechanical force (sound), which induces progressive shearing that damages the inner ear's structures, specifically the hair cells, and is often compounded by ototoxic exposures to environmental toxins.[15]

Cerumen impaction/external auditory canal debris: A unilateral or bilateral conductive non-pathologic hearing loss, causing the inability of sound to reach the middle and inner ear structures adequately. This condition may present suddenly (as cerumen accumulates to a perceptible level of change in hearing) and often demonstrates subjective normalization of a patient’s hearing and tuning fork exam after debris removal.[16]

Canal cholesteatoma: A typically unilateral conductive hearing loss, which may be acquired (following trauma or inflammation) or spontaneous. Often, the result is a localized area of abnormal squamous epithelium proliferation in the canal wall.[17]

Otosclerosis: This condition is becoming less common and typically presents as unilateral conductive hearing loss (often with gradual contralateral ear involvement), resulting from labyrinthine sclerosis that leads to stapes fixation and an inability to transmit sound waves from the tympanic membrane to the inner ear.[18] It is commonly associated with tinnitus, vertigo, and quiet speech (in which the patient’s own voice appears louder).[19]

History and Physical

Variability in patient presentation is related to the underlying pathophysiologic causes of hearing loss. A typical patient with hearing loss may present with a self-reported history of hearing loss. Family members or friends may notice that the patient has difficulty hearing, such as difficulty comprehending speech, requiring a loud television or radio, or changes in social interaction.[20] 

Careful attention is necessary when questioning the onset, duration, and timing of symptoms. One should also inquire about differences in the sides, fullness, otorrhea, and otalgia. Certain causes of hearing loss are also associated with higher rates of vertigo, tinnitus, and vestibular dysfunction; therefore, each should be assessed in the history.[21] Additionally, pertinent history of sound exposure, family history, and ototoxic substances are important considerations.

A thorough head and neck physical exam should always be performed in patients with hearing loss, including visualization of the tympanic membrane and in-office hearing tests, including tuning-fork exams (Weber and Rinne) and gross hearing exam (finger rub test). These simple examination techniques may initially guide a provider toward the correct diagnostic direction and typically exhibit reliable specificity.[22] Perhaps most diagnostic is obtaining audiometry, which is expanded upon below.

Evaluation

The audiogram is the cornerstone of the diagnostic evaluation in hearing loss. Therefore, referral for audiologic assessment is a crucial component of care for any patient with suspected hearing loss. The audiometric workup typically involves pure-tone audiometry to assess both bone and air conduction across frequencies from low to high and to determine hearing thresholds. The test determines the range and nature (conductive, sensorineural, or mixed) of hearing loss.[23] 

The workup also commonly includes sound perception, speech recognition, tympanometry, and the acoustic reflex.[21] In addition to audiology, if specific underlying causes of hearing loss are of concern, such as schwannoma or cholesteatoma, imaging with computed tomography or magnetic resonance imaging is often required for diagnosis.[24]

Treatment / Management

The treatment and management of hearing loss in the elderly are based on a thorough diagnostic evaluation and the assurance that all additional causes have been addressed. Specific treatment depends on diagnosing the most likely cause. Among the above, treatments are often broadly classified as sensorineural or conductive.[7] Generally, the conductive causes of hearing loss are diagnosis-specific; for example, otosclerosis is managed with stapedectomy, whereas cerumen impaction is managed with cerumen removal.[18] (B3)

Conversely, sensorineural hearing loss is typically managed with amplification, which requires specific fitting, planning, and follow-up with an audiologist.[25] There are numerous hearing aids and amplification devices, including external amplification devices (such as FM systems), behind-the-ear, in-the-canal, and implantable. Hearing aid choice and type is based on multiple patient factors, including the cause and degree of hearing loss and functional and physical factors.[21] Unfortunately, the cost of treatment can also be a determining factor.(A1)

Differential Diagnosis

The differential diagnosis of hearing loss in the elderly is broad; although ARHL is common, other causes must be considered. Key components for distinguishing ARHL from other causes of hearing loss include a thorough history and physical examination and a comprehensive audiogram. By first distinguishing among conductive, sensorineural, or mixed hearing loss, providers can subsequently perform more advanced diagnostic tests if indicated.

Conductive hearing loss is caused by a problem with the external ear, ear canal, tympanic membrane, or middle ear ossicles – all of which transmit sound waves to the inner ear. Common causes include cerumen impaction, foreign bodies, otitis externa, otitis media, tumors, tympanic membrane perforation, cholesteatoma, and otosclerosis. 

Sensorineural hearing loss results when there is a problem with the cochlea, auditory nerve, or sound processing. Differential diagnoses include ARHL, noise exposure, toxin exposure, Meniere disease, labyrinthitis, viral infection, acoustic neuromas, and other inner-ear and skull-base lesions.

Prognosis

Hearing loss among older adults is extremely common. Overall, hearing loss among older adults has a significant impact on quality of life. The WHO ranks hearing loss as the second-largest handicap among the elderly, with a considerable impact on quality of life. The prevalence of hearing loss among older adults imposes a significant financial burden. It is estimated to account for more than $3 billion in excess medical expenditures annually in the United States alone.[26] 

Hearing loss in older adults has been independently associated with multiple comorbidities. In particular, the relationship that appears between ARHL and dementia is of significant prognostic impact. A recent meta-analysis demonstrated that ARHL and dementia had the highest population attributable fractions (PAFs) or risk attributable to hearing loss.[27] Additionally, hearing loss in the elderly directly relates to interpersonal health, with higher rates of loneliness, depression, and cognitive decline demonstrated in those affected.[20]

To date, no treatment reverses ARHL. However, the management of hearing loss is associated with improved quality of life and social functioning, underscoring the importance of early diagnosis and appropriate management. Because many causes of hearing loss in the elderly, including ARHL, are often irreversible, early diagnosis, treatment, and education are critical to effectively support patients with hearing loss.

Complications

Key complications of hearing loss in the elderly relate to the proper identification and workup of the underlying etiology. Perhaps most important is the possibility of a missed or delayed diagnosis. Hearing loss in the elderly has a significant prognostic impact on patients, and without proper identification and management, the risk of adverse outcomes such as social withdrawal increases.

Due to the gradual and sometimes difficult-to-diagnose nature of hearing loss, many elderly patients go untreated or undiagnosed.[28] Additionally, misdiagnosis may lead to inappropriate treatment or unnecessary workup, which can prolong the effects of hearing loss or cause harm from additional testing.