Hearing Loss in the Elderly

Etiology

Hearing loss in the elderly is complex and multifactorial. Aging is complicated since syndromes of age interplay among various organ systems, and basic homeostasis and physiology become altered with advancing age.[4] Hearing loss in the elderly is predominantly attributed to age-related hearing loss (ARHL), or presbycusis, although the specific prevalence is difficult to define.[5] 

ARHL is defined strictly as bilateral sensorineural hearing loss solely attributed to age without any other causative explanation.[6] Although to fully manage hearing loss in the elderly, providers must approach hearing loss as they would any patient presenting with hearing loss since ARHL is not the only diagnosis on the differential 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 over age 65 is expanding rapidly.[9] Therefore, the conditions that affect an aging population will continue to grow and settle at the forefront of medicine. Hearing loss is prevalent in the elderly, with over 80% prevalence in those over 80 years old suffering some degree of loss.[3] The prevalence alone indicates that hearing loss should be a key concern for providers caring for elderly patients.

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 more severe loss than those without a family history.[10] Interestingly, research suggests that less pigmented skin is potentially associated with higher rates of hearing loss in the elderly.[11]

Pathophysiology

Hearing loss in the elderly is multifactorial, and a basic understanding of the pathophysiology of normal hearing is key to diagnosing the various etiologies of hearing loss. 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 to electrochemical stimuli as an action potential to the cochlear nucleus of the brain.[12] Any disruption in these pathways can result in hearing loss.

While there are countless causes of hearing loss in the elderly, pathophysiology for 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 impacts higher tones and consonants (sounds like t, s, ch), which results in words being cut off, resulting in poor speech comprehension and communication. The hearing loss can also result in difficulty localizing sound, especially 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 one side, such as in the case of shooting rifles.[14] This hearing loss is due to excess mechanical force (sound), causing progressive shearing force that damages the structures of the inner ear, specifically the hair cells, which are 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 of a localized area of abnormal squamous epithelium proliferation in the canal wall.[17]

Otosclerosis: This condition is becoming less common and often presents as unilateral (although often with gradual contralateral ear involvement) conductive hearing loss, resulting from labyrinthine sclerosis, which leads to stapes fixation and thus 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 (the condition causes the patient’s own voice to seem 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 self-reported hearing loss. Family members or friends may notice that the patient has difficulty hearing, such as difficulty comprehending speech, requiring 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 also have higher rates of vertigo, tinnitus, and vestibular dysfunction, so each should be assessed in a 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 exam techniques may first lead a provider in the correct diagnostic direction and typically have reliable specificity.[22] Of perhaps most diagnostic importance is obtaining audiometry, which will be expanded upon below.

Evaluation

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

Workup also commonly includes sound perception, speech recognition, tympanometry, and acoustic reflex.[21] In addition to audiology, if specific underlying causes of hearing loss are of concern, such as schwannoma or cholesteatoma, the role of imaging, with computerized 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 upon proper diagnostic workup and ensuring all additional causes have been addressed. Specific treatment depends on diagnosing the most likely cause. Among those discussed above, treatments are often separated broadly based on sensorineural or conductive causes.[7] Generally, conductive causes of hearing loss are diagnosis-specific; for example, otosclerosis management is stapedectomy, while cerumen impaction management is cerumen removal.[18] (B3)

Conversely, sensorineural causes are 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 system), 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 for hearing loss in the elderly is broad, and although ARHL is common, other causes of hearing loss must be considered. Key components in distinguishing ARHL from other causes of hearing loss are a thorough history and physical exam and a comprehensive audiogram. By first distinguishing conductive, sensorineural, or mixed hearing loss, providers can subsequently perform more advanced diagnostics 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, perforation of the tympanic membrane, 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 in the elderly is extremely common. Overall, hearing loss in the elderly has a large impact on the quality of life in the elderly. The WHO ranks hearing loss as the second-largest handicap among the elderly with a considerable impact on quality of life. The burden of hearing loss in the elderly creates a significant financial burden. It is estimated to account for more than three billion dollars in excess medical expenditures per year in the United States alone.[26] 

Hearing loss in the elderly has independently shown an increased correlation with multiple co-morbidities. 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 fraction or risk attributed 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, management of hearing loss is correlated with improved quality of life and social functioning, thereby demonstrating the importance of proper early diagnosis and management. Since many causes of hearing loss in the elderly, including ARHL, are often irreversible, early diagnosis, treatment, and education are critical to best help 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, incorrect diagnosis may lead to improper treatment, or unnecessary workup, which may also prolong the effects of hearing loss on patients or result in harm from additional workup.