Conductive hearing loss

Conductive hearing loss
Ear-anatomy-text-small-en.svg
Anatomy of the human ear.
Classification and external resources
Specialtyotolaryngology
ICD-10H90.0-H90.2
ICD-9-CM389.0
DiseasesDB3043
MeSHD006314

Conductive hearing loss occurs when there is a problem conducting sound waves anywhere along the route through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). This type of hearing loss may occur in conjunction with sensorineural hearing loss (mixed hearing loss) or alone.

Causes

Common causes of conductive hearing loss include:[1]

External ear

  • Cerumen (earwax) or foreign body in the external auditory canal
  • Otitis externa, infection or irritation of the outer ear
  • Exostoses, abnormal growth of bone within the ear canal
  • Tumor of the ear canal
  • Congenital stenosis or atresia of the external auditory canal (narrow or blocked ear canal).
  • Acquired stenosis (narrowing) of the external auditory canal following surgery or radiotherapy

Middle ear

Fluid accumulation is the most common cause of conductive hearing loss in the middle ear, especially in children.[2] Major causes are ear infections or conditions that block the eustachian tube, such as allergies or tumors.[2] Blocking of the eustachian tube leads to decreased pressure in the middle ear relative to the external ear, and this causes decreased motion of both the ossicles and the tympanic membrane.[3]

  • Barotrauma unequal air pressures in the external and middle ear.[3] This can temporarily occur, for example, by the environmental pressure changes as when shifting altitude, or inside a train going into a tunnel. It is managed by any of various methods of ear clearing manoeuvres to equalize the pressures, like swallowing, yawning, or the Valsalva manoeuvre. More severe barotrauma can lead to middle ear fluid or even permanent sensorineural hearing loss.

Inner ear

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