Editing Conductive hearing loss (section)

== Causes ==
Common causes of conductive hearing loss include:<ref>{{cite web|url=http://www.healthcentral.com/encyclopedia/408/598.html|title=Hearing Loss|publisher=HealthCentral|access-date=8 June 2013}}</ref>

=== 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).
** Ear canal stenosis & atresia can exist independently or may result from congenital malformations of the [[Auricle (anatomy)|auricle]] such as [[microtia]] or [[anotia]].
* 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.<ref name="merck">{{cite web|url=http://www.merckmanuals.com/home/ear_nose_and_throat_disorders/hearing_loss_and_deafness/hearing_loss_and_deafness.html?qt=&sc=&alt=|title=Hearing Loss and Deafness|last=Ruben|first=Robert J.|date=April 2007|publisher=The Merck Manual|access-date=8 June 2013}}</ref> Major causes are ear infections or conditions that block the [[eustachian tube]], such as allergies or tumors.<ref name=merck/> 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.<ref name=Haberman/>
* Acute or serous [[otitis media]]
* Chronic suppurative otitis media (CSOM)
* [[Perforated eardrum]]
* [[Tympanosclerosis]] or scarring of the eardrum
* [[Cholesteatoma]]
* [[Eustachian tube dysfunction]], inflammation or mass within the nasal cavity, middle ear, or eustachian tube itself
* [[Otosclerosis]], abnormal growth of bone in or near the middle ear
* Middle ear [[tumour]]
* Ossicular discontinuity as a consequence of infection or [[temporal bone]] trauma
* Congenital malformation of the [[ossicles]]. This can be an isolated phenomenon or can occur as part of a syndrome where development of the 1st and 2nd branchial arches is seen such as in [[Goldenhar syndrome]], [[Treacher Collins syndrome]], [[branchio-oto-renal syndrome]] etc.
* [[Barotrauma]], unequal air pressures in the external and middle ear.<ref name=Haberman>Page 152 in:{{cite book |author=Rex S. Haberman |title=Middle Ear and Mastoid Surgery |publisher=Thieme Medical Pub |location=New York |year=2004 |isbn=1-58890-173-4 }}</ref> 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 ===
Third window effect caused by:
* [[Superior canal dehiscence]] – which may require surgical correction
* [[Enlarged vestibular aqueduct]]
* [[Labyrinthine fistula]]