About 85% of US adults with hearing loss have unmet hearing needs, creating significant individual and population effects on chronic conditions, socioeconomics, and quality of life. This article reviews the diagnosis and management of hearing loss, overcoming systemic barriers, resources in limited primary care settings, and a multidisciplinary approach.
Key points
- •
Hearing loss occurs in all ages, but it is associated with a 20% mortality increase in the elderly.
- •
The etiology is often an accumulation of individual and environmental factors.
- •
Reducing noise exposure and timely intervention can significantly reduce disability.
- •
Digital tools on smartphones can help in resource-limited settings.
- •
Provider-dependent factors influence hearing disparities: failure to address hearing loss negatively impacts management of other health conditions.
Introduction and background
Approximately 40 million adults (15.5%) in the US report difficulties hearing. , Sixty-five percent of adults aged over 60 years experience hearing loss, which bears a 20% mortality increase due to social withdrawal and isolation, distress, dementia, lost productivity from early retirement, costs of care, mental and physical declines, and poorer quality of life. Hearing loss is also common in children and teens, affecting about 1 in 5 by the time they are 18 years of age. The prevalence of hearing loss doubles every decade from the age of 20 to 80 years. ,
Only about 15% of adults with hearing loss use hearing aids. Unaddressed hearing loss negatively impacts patients physically, mentally, socially, and financially. As the third largest source of “years lived with disability” globally, the health care costs, educational support, lost productivity, and societal costs of hearing loss amount to about US$980 billion annually worldwide.
Primary care providers (PCPs) are uniquely positioned to identify and address hearing loss. However, only about half of PCPs are comfortable formally identifying it. Many lack the knowledge to evaluate it, face time constraints, and believe that it is detected through conversation alone, that high hearing aid costs preclude interventions, and that short life expectancy excludes benefitting from hearing support. Although the United States Preventative Services Task Force (USPSTF) gives hearing screening a grade I for older adults, PCPs should still address hearing loss given its significant impact on quality of life. In this review, we aim to equip PCPs with the basic anatomy and pathophysiology of hearing loss, the tools available for the assessment in primary care, preventative guidance, effective treatments, and an awareness of social determinants in hearing loss.
Definitions
Hearing loss is categorized based on impairment, activity limitation, and social restriction, per the World Health Organization (WHO) and the International Classification of Functioning, Disability, and Health ( Table 1 ). WHO grades can help clinicians understand the extent of disability and whether interventions are beneficial.
| Grade | Hearing Threshold (dB) | Difficulty Hearing in Quiet Environments | Difficulty Hearing in Noisy Environments |
|---|---|---|---|
| Normal | <20 | None | None to minimal |
| Mild | 20 to <35 | None with conversational speech | May have difficulty with conversational speech |
| Moderate | 35 to <50 | May have difficulty with conversational speech | Difficulty hearing and participating in conversation |
| Moderately severe | 50 to <65 | Difficulty hearing and participating in conversation | Difficulty hearing most speech and participating in conversation |
| Severe | 65 to <80 | Does not hear most conversational speech; may have difficulty hearing and understanding raised voices | Extreme difficulty hearing speech and participating in conversation |
| Profound | 80 to <95 | Extreme difficulty hearing raised voices | Conversational speech cannot be heard |
| Deafness | 95 or greater | Cannot hear speech and most environmental sounds | Cannot hear speech and most environmental sounds |
| Unilateral | <20 in better ear, 35 or greater in affected ear | May not have problem unless sound is near affected ear. May have difficulty locating sounds | May have difficulty hearing speech and participating in conversations, or locating sounds |
Hearing loss is further classified by mechanism. Conductive hearing loss refers to problems within the outer or middle ear, which prevent sound wave transmission to the inner ear. The outer ear consists of the external structures of the ear and canal up to the tympanic membrane. The middle ear begins with the tympanic membrane, which attaches to the 3 bones that conduct sound to the inner ear: the malleus, incus, and stapes.
Sensorineural hearing loss results from loss of function or damage to the inner ear (cochlea, semicircular canals, and stria vascularis) or the vestibulocochlear nerve (cranial nerve [CN] VIII). In the aging US population, presbycusis is the most prevalent form, involving death of the inner ear hair cells and metabolic derangements in the stria vascularis.
Mixed hearing loss refers to a combination of conductive and sensorineural hearing loss, while defects in neuronal transmission from CN VIII back to the auditory cortex of the superior temporal lobe result in the inability to interpret auditory input. This hearing loss is a defect in central auditory processing ( Fig. 1 ).
Etiology
Hearing loss is not the inevitable result of the aging process; it arises from a combination of genetic factors, medical comorbidities, lifestyle, and environmental effects. Many factors affect individuals of every age: smoking, secondhand smoke, cerumen impaction, trauma, and nutritional deficiencies (vitamin A, zinc), viral infections, and environmental hazards. Some etiologies only occur in certain ages. It is helpful, therefore, to narrow the differential by stratifying patients by age. Table 2 displays common causes of hearing loss by age and mechanism.
| Perinatal | Childhood/Adolescence | Adult/Elderly | All Ages | |
|---|---|---|---|---|
| Conductive | Genetic: CHARGE, Stickler, and Apert syndromes | Otitis media with effusion | Otosclerosis Cholesteatoma Nasopharyngeal tumors | Cerumen impaction Trauma/iatrogenic |
| Sensorineural | TORCH infections Hypoxia, Prematurity Genetic syndromic conditions (Waardenburg, Usher, Pendred, Jervell and Lange-Nielsen, and Alport) | — | Presbycusis Meniere’s Diabetes Vestibular schwannoma Autoimmune (rheumatoid, lupus, and Wegener’s) | Ototoxic medications Noise exposure Viral infections (HIV, HSV, and West Nile) Meningitis |
| Mixed | — | — | — | Noise exposure Trauma Infections |
| Central | Hyperbilirubinemia | Meningitis | Stroke | Zinc, Iron, Vitamin A deficiency |
In the perinatal period, genetic disorders account for about 50% of cases. Many syndromes can impair ear structures from properly forming or functioning. The toxoplasmosis, other (zika, syphillis, mumps, parvovirus), Rubella, Cytomegalovirus, Herpes Simplex or HIV (TORCH) infections (particularly cytomegalovirus [CMV], herpes simplex virus [HSV] 1 and 2, Rubella, and Zika) may result in damage to the inner ear from inflammation, edema, and the presence of viral antigens. Low birth weight and maternal conditions such as pre-eclampsia have been associated with hearing loss, as well as neonatal hyperbilirubinemia and low activity, pulse, grimace, appearance, respiration (APGAR) scores.
A common transient cause of conductive hearing loss in childhood is otitis media. Due to the lack of studies with consistent findings, no conclusions about the relationship between hearing loss and recurrent or chronic otitis media can be made. There have been rare cases documented of severe otitis media resulting in meningitis with permanent hearing loss.
For adults, common medical causes of hearing loss include chronic diseases (hypertension and diabetes), abnormal bone remodeling (otosclerosis), and presbycusis. However, the greatest modifiable risk factor for acquired hearing loss is loud noise, usually from occupational exposures above 80 dB daily for greater than 40 weeks. The occupations with the most noise exposure include construction and landscaping, transportation (such as airport ground staff), work involving loud music or entertainment, agriculture, and other occupations involving loud machinery. However, individuals are often exposed to loud noise even at home. The typical volume range for individuals listening to their personal devices is between 75 and 105 dB. About 50% of people aged 12 to 35 years listen to music too loudly by these standards.
Another major preventable risk factor is medications. Medications enter the endolymph of the inner ear, entering hair cells via passive diffusion, transporter channels, or endocytosis. Inner ear hair cells are among the few types of cell unable to actively clear ototoxins, leading to drug-mediated toxicities. Known ototoxic medications include aminoglycosides and cyclodextrins (incorporated in aripiprazole, ziprasidone, and voriconazole). Certain medications that may not cause ototoxicity alone can do so when administered with others (eg, pancuronium and loop diuretics). Any systemic process that reduces clearance (renal insufficiency, depletion of antioxidants, fever, infection, transient ischemia, or hypoxia) increases the odds of ototoxicity. Table 3 provides a list of common ototoxic medications.
| Class | Examples |
|---|---|
| Chemotherapeutics | Cisplatin, vincristine |
| Antibiotics | Aminoglycosides (gentamicin and neomycin) Macrolides Quinolones Vancomycin Imipenem + cilastin |
| Antivirals | Ganciclovir, ribavirin + interferon |
| Antifungals | Amphotericin |
| Antimalarials | Chloroquine and mefloquine |
| Analgesics | Aspirin and NSAIDs |
| Cardiac | Loop diuretics, acetazolamide, beta blockers, ramipril |
| Neurologic | Depakote and entacapone |
| Immunosuppressants | Tacrolimus and hydroxychloroquine |
Outer and inner hair cells cannot be regenerated. The spiral ganglia—which transmit the sensory input from the hair cells to CN VIII—cannot be bypassed if damaged, even with the insertion of cochlear implants. Vigilance about ototoxicity is, therefore, critical in any specialty.
Clinical history
A detailed history is essential in determining the type, severity, and potential interventions for hearing loss. In most infants, universal hearing screening catches hearing impairments. Monitoring language and functional developmental milestones can further elucidate abnormal hearing. , In many cases, family members who have experienced difficulty communicating with patients are the ones to raise the alarm. Other findings include having to increase the volume on devices, frequently asking for repetition, social avoidance, and difficulty in noisy spaces or with background noise. Decreased hearing may also present with sensitivity to loud noises, tinnitus, or vertigo. Presbycusis classically presents with bilateral hearing loss, with difficulty recognizing speech regardless of the environment.
Causes of sudden onset unilateral hearing loss include Meniere’s disease, vestibular schwannoma, autoimmune diseases, trauma, viral infections (coronavirus disease 2019), and vascular impairments. Providers should ask about common risk factors: noise exposure (both recreational and environmental), ototoxic medications, ear infections, cotton tip use for ear cleaning, diabetes mellitus, stroke, vasculitis, head or ear trauma, and family history.
Lastly, the American Academy of Otolaryngology–Head and Neck Surgery’s 10 “Red Flags” for hearing loss can help determine when urgent referral is warranted.
- 1.
Hearing loss with a positive history of ear infections, noise exposure, familial hearing loss, tuberculosis, syphilis, HIV/AIDS, Meniere’s disease, autoimmune disorder, ototoxic medication use, otosclerosis, von Recklinghausen’s neurofibromatosis, and Paget’s disease of bone, ear, or head trauma related to onset.
- 2.
History of pain, active drainage, or bleeding from an ear.
- 3.
Sudden onset or rapidly progressive hearing loss.
- 4.
Acute, chronic, or recurrent episodes of dizziness.
- 5.
Evidence of congenital or traumatic deformity of the ear.
- 6.
Visualization of blood, pus, cerumen plug, foreign body, or other material in the ear canal.
- 7.
An unexplained conductive hearing loss or abnormal tympanogram.
- 8.
Unilateral or asymmetric hearing loss (a difference of >15 dB pure tone average between ears) or bilateral hearing loss greater than 30 dB.
- 9.
Unilateral or pulsatile tinnitus.
- 10.
Unilateral or asymmetrically poor speech discrimination scores (a difference of >15% between ears) or bilateral speech discrimination scores of less than 80%.
Evaluation
The physical examination is the next step in evaluation. For infants and children, findings associated with genetic syndromes include heterochromia of the irises, malformations of the auricle or ear canal, dimpling or skin tags around the auricle, cleft lip or palate, asymmetry, hypoplasia of the facial structures, and microcephaly.
Otoscopic inspection of the external auditory canal will reveal cerumen impaction, foreign objects, canal edema, erythema, and otorrhea. Cerumen impaction is particularly important to check for in patients with intellectual disabilities as they may not be able to express concerns about their hearing impairment or participate in subjective hearing tests. In fact, the prevalence of cerumen impaction in this population has been found to be 20%, compared to the 2% in the general population.
The tympanic membrane should be inspected for its color, presence of bulging, perforation, and absence of normal landmarks such as the cone of light, handle of the malleus, umbo, pars tensa, and pars flaccida. Typically, the tympanic membrane is gray-colored and variably translucent, which allows for visualization of the incus and stapes. With pneumatic otoscopy, the normal tympanic membrane concaves to applied air pressure; this finding can confirm resolution of otitis media, while a flat tympanogram may signify effusion or perforation ( Figs 2 and 3 ).
