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.

Prevalence


Geriatric Considerations

• 24.7% of 60 to 69 year olds in United States have bilateral speech-frequency hearing loss.
• ~80% of people aged >85 years have hearing loss.
• Loss of communication is a source of emotional stress and a physical risk for the elderly.
• Consider auditory rehabilitation (facing people when talking, improving lighting, minimizing background noise).

Pediatric Considerations

• Early diagnosis and treatment improve outcome.
• 60% of childhood hearing loss is secondary to preventable causes.
• Mandatory screening in >97% of newborns with otoacoustic emission (OAE) and auditory brainstem response (ABR) testing

Etiology and Pathophysiology

• CHL: Hearing loss can result from middle ear effusion, obstruction of canal (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).
• SNHL: damage along the pathway from oval window, cochlea, auditory nerve, and brainstem. Examples include 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

• Connexin 26 (13q11–13q12): most common cause of nonsyndromic genetic hearing loss
• Otosclerosis: familial
• There are several 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
  • Mechanical ventilation lasting ≥5 days
  • 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 or large vestibular aqueduct)
  • Infectious diseases (chickenpox, measles, encephalitis, influenza, mumps, bacterial meningitis)
  • Vasculitis (Kawasaki disease)

General Prevention

• Limit noise exposure; use hearing protection.
• Avoid ear canal instrumentation (e.g., cotton swabs).
• Avoid or limit ototoxic medications.

Commonly Associated Conditions

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