HEARING LOSS


I. Pathophysiology

  1. Conductive hearing loss
    1. Impairment of transmission of sound to cochlea
    2. Causes:
      1. Cerumen impaction
      2. Serous otitis media
      3. Cholesteatoma (accumuulation of desquamated cells and keratin debris on tympanic membrane; can be associated with otalgia, dizziness, and otorrhea; treated surgically)
      4. Otosclerosis (abnormal remodeling of middle ear bones; peak incidence between 15-50yo; can be accompanied by vertigo and tinnitus; may be unilateral or bilateral; can be treated with hearing aid or stapedectomy)
  2. Sensorineural hearing loss
    1. Impairment of transduction of sound in the cochlea and/or transmission to the brain through the auditory nerve
    2. Causes:
      1. Ototoxic drugs (aminoglycosides, macrolides, loop diuretics, salicylates, NSAIDs, beta-blockers)
      2. Presbycusis (progressive, age-related loss of cochlear hair cells; initially affects high frequencies most)
      3. Meniere's Disease
      4. Rarely, acoustic neuroma or CNS event (e.g. stroke or demyelinating process)
  3. Note-It is possible to have both conductive and sensorineural hearing loss

II. Evaluation of a patient presenting with hearing loss

  1. History
    1. Sudden vs. gradual
    2. Symmetric vs. asymmetric
    3. Presencce of other symptoms including vertigo, tinnitus, or ear pain or discomfort
  2. Physical
    1. Weber test-Use in pts who perceive their hearing loss to be asymmetrical
      1. Place a vibrating tuning fork on pt's forehead and ask whether the sound is louder on either side.
      2. If sound seems louder in better-hearing ear, suggests sensorineural hearing loss in the poorer-hearing ear.
      3. If sound seems louder in the poorer-hearing ear, suggests conductive hearing loss in the poorer-hearing ear
    2. Rinne test
      1. Place a vibrating tuning fork near external ear then on the mastoid process
      2. If the sound is perceived as louder with the latter, suggests conductive hearing loss.
  3. Audiologic evaluation
    1. Pure-tone hearing thresholds ("audiogram")
    2. Speech descrimination

III. Management of hearing loss

  1. For sudden-onset sensorineural hearing loss (usually idiopathic;etiology may involve viral infection, autoimmunity, or vascular events), prednisone (starting at 60mg/d and tapering over 2wks) may increase likelihood of recovery.
  2. Education of patient and family
  3. Environmental manipulation (e.g. minimize background noise; flashing light for doorbell)
  4. Training in speech reading
  5. Hearing aids (generally advised with hearing loss of 40dB or more)
  6. Active middle ear implants
  7. Cochlear implants

IV. Congenital hearing problems

  1. Risk factors for congenital hearing deficits (Pediatrics 111:436, 2003)
(Sources include Core Content Review of Family Medicine, 2012)