Conductive hearing loss

Conductive hearing loss is a hearing loss where the ears' ability to conduct sound into the inner ear is blocked or reduced. It can be caused by a range of developmental, congenital or acquired pathology to the external, middle or inner ear.

Pathology

Essentially any process that obstructs or disrupts the passage of sound waves through the outer or middle ear can cause conductive hearing loss and the list of causes is very long. The most common are included below.

External ear

• cerumen (earwax) or external auditory canal foreign body
• congenital, e.g. external acoustic canal (EAC) atresia
• trauma, e.g. tympanic membrane perforation (not seen radiologically)
• otitis externa
• external auditory canal benign lesions, e.g. osteoma, exostosis, keratosis obturans and medial canal fibrosis
• external acoustic canal tumors, e.g. cholesteatoma, squamous cell carcinoma
• barotrauma (unequal air pressure in the external and middle ear)

Middle ear

• congenital, e.g. congenital ossicular fixation
• trauma, e.g. ossicular chain disruption
• inflammatory, e.g. otomastoiditis
• middle ear tumors, e.g. glomus tympanicum, cholesteatoma, middle ear schwannoma
• Eustachian tube dysfunction

Inner ear

• congenital, e.g. oval window atresia (rare)
• fenestral otosclerosis
• superior semicircular canal dehiscence syndrome

Treatment and prognosis

A stapes prosthesis may help improve conductive hearing loss.