Conductive hearing loss

Conductive hearing loss
Classification and external resources
Anatomy of the human ear.
ICD-10	H90.0-H90.2
ICD-9	389.0
DiseasesDB	3043
MeSH	[1]

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

Causes of conductive hearing loss

External ear

Common

• Cerumen (earwax)
• Otitis externa

Uncommon

• Foreign body in the external auditory canal (not always)
• Exostoses
• Tumour of the of canal
• Congenital atresia

Middle ear

Common

• Acute otitis media
• Serous otitis media
• Tympanic membrane perforation

Uncommon

• Cholesteatoma
• Otosclerosis
• Middle ear tumour
• Temporal bone trauma

Inner ear

Common

Severe Otosclerosis, form of mechanical conductive hearing loss most commonly found in people who have been subjected to intense noise. Occurs when there is an obstruction in either the oval window and/or the round window. This type of hearing loss can usually be repaired by surgical opening of the blockage.

Uncommon

• Superior canal dehiscence syndrome

Differentiating conductive and sensorineuronal hearing loss

When a Weber test is carried out, sound localizes to the ear affected by the conductive loss. A Rinne test, in which air conduction is normally greater than bone conduction, is usually negative (abnormal - note unusual terminology here compared with other medical tests!), and shows higher greater bone conduction than air conduction.

Table 1. A table comparing sensorineural hearing loss to conductive