Description

• Decrease in the ability to perceive and comprehend sound; it can be partial, complete, unilateral, and/or bilateral.
• Typically, defined as a deficit of >25 dB
• Types of hearing loss include conductive hearing loss (CHL or air–bone gap), sensorineural hearing loss (SNHL), or mixed hearing loss.
• System(s) affected: auditory; outer and middle ear (CHL) or inner ear, auditory nerve, and/or brainstem (SNHL).
• Sudden hearing loss is defined as rapid-onset, subjective sensation of hearing impairment in one or both ears (1).

Epidemiology

• All ages affected; common in children (CHL) and elderly (SNHL)
• Usually more severe at an earlier age in men

Incidence

• Increases with age
• Sudden sensorineural hearing loss (SSHL) occurs in 5 to 27 per 100,000 persons per year.

Geriatric Considerations

• 24.7% of 60- to 69-year-olds in the United States have bilateral speech-frequency hearing loss.
• ~80% of people aged >85 years have hearing loss.
• Hearing impairment is an independent and modifiable risk factor for cognitive decline in the elderly, and may lead to emotional distress and physical risk secondary to the loss of communication. (2)
• Consider auditory rehabilitation (facing people when talking, improving lighting, minimizing background noise).

Pediatric Considerations

• Early diagnosis and treatment improves outcome.
• 60% of childhood hearing loss is secondary to preventable causes.
• Screen newborns with otoacoustic emission (OAE) and auditory brainstem response (ABR) testing.

Etiology and Pathophysiology

• CHL: Hearing loss can result from middle ear effusion, or obstruction of the auditory canal (chronic otitis media, eustachian tube dysfunction, cerumen/foreign body, osteomas/exostoses, cholesteatoma, tumor), loss of continuity (ossicular discontinuity), stiffening of the components (myringosclerosis, tympanosclerosis, and otosclerosis), and loss of the pressure differential across the tympanic membrane (TM) (perforation). (3)
• SNHL: acoustic damage from vascular/metabolic insult, mass effect, infection and inflammation, and acoustic trauma.
  • Noise-induced hearing loss is caused by acoustic insult that affects outer hair cells in the organ of Corti, causing them to be less stiff. Over time, severe damage occurs with fusion and loss of stereocilia. Eventually this may progress to inner hair cells and auditory nerve as well.
• Large vestibular aqueduct or superior canal dehiscence: Third mobile window shunts acoustic energy away from cochlea.

Genetics

• Nonsyndromal genetic hearing loss is most common; connexin 26 (chromosomes 13q11–13q12).
• Otosclerosis: frequently familial
• Congenital syndromes (e.g., Alport syndrome, Stickler syndrome)

Risk Factors

• Loud noise/acoustic trauma
• Medications (aminoglycosides, loop diuretics, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), quinine, chemotherapeutic agents, especially cisplatin, vancomycin)
• Tobacco, alcohol use
• Vestibular schwannoma/skull base neoplasm
• Previous ear surgery
• Sensorineural, pediatric specific
  • Perinatal asphyxia
  • Congenital infections (toxoplasmosis, other agents, rubella, cytomegalovirus, herpes simplex [TORCH] syndrome)
  • Toxemia of pregnancy; maternal diabetes; Rh incompatibility
  • Prematurity or birth weight <1,500 g
  • Severe hyperbilirubinemia; exchange transfusions
  • Anomalous temporal bone (Mondini dysplasia or large vestibular aqueduct)
  • Infectious diseases (chickenpox, measles, encephalitis, influenza, mumps, zika, bacterial meningitis, etc.)

General Prevention

• Limit noise exposure; use hearing protection.
• Avoid or limit ototoxic medications.

Commonly Associated Conditions

Tinnitus: common for patients to experience both tinnitus and hearing loss