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deafness

deafness / hearing loss

introduction

  • deafness is classified as either conductive or sensorineural hearing loss / deafness or mixed and these are generally differentiated at the bedside by using Rinne and Weber tuning fork tests:
    • Rinne test:
      • place tuning fork on the mastoid bone behind the ear (tests bone conduction (BC)).
      • when the patient indicates sound is no longer heard, move fork (held at base) beside ear and ask if now audible.
      • in a normal test, AC > BC; patient can hear fork at ear.
      • in conductive loss, BC > AC; patient will not hear fork at ear
    • Weber test:
      • tuning fork is placed in middle of forehead
      • normal person should hear it equally in both ears
      • hearing it best in one ear implies either:
        • conductive loss in THAT ear, or,
        • sensorineural loss in the OPPOSITE ear
  • in addition, hearing loss may be due to a central cause such as from a stroke (CVA) or present as auditory dyssynchrony (auditory neuropathy or auditory neuropathy spectrum disorder)

conductive deafness

aetiology

blocked outer ear canal

  • wax
  • foreign body
  • otitis externa
  • blood from trauma
  • exostosis (eg. surfers in cold waters)
  • osteoma
  • squamous cell carcinoma
  • congenital microtia or atresia

middle ear disease

  • otitis media
  • perforated tympanic membrane
  • cholesteatoma
  • otosclerosis
  • temporal bone trauma
  • glomus tumors
  • surgery
  • congenital atresia or ossicular chain malformation
deafness.txt · Last modified: 2018/10/09 14:35 (external edit)