Conductive hearing loss

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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	D006314

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.

Contents 1 Causes of conductive hearing loss 1.1 External ear 1.1.1 Common 1.1.2 Uncommon 1.2 Middle ear 1.2.1 Common 1.2.2 Uncommon 1.3 Inner ear 1.3.1 Common 1.3.2 Uncommon 2 Differentiating conductive and sensorineuronal hearing loss

[edit] Causes of conductive hearing loss

[edit] External ear

[edit] Common

• Cerumen (earwax)
• Otitis externa

[edit] Uncommon

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

[edit] Middle ear

[edit] Common

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

[edit] Uncommon

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

[edit] Inner ear

[edit] 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.

[edit] Uncommon

• Superior canal dehiscence syndrome

[edit] 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

Criteria	Sensorineural hearing loss	Conductive hearing loss
Anatomical Site	Inner ear, cranial nerve VIII, or central processing centers	Middle ear (ossicular chain), tympanic membrane, or inner ear
Weber Test	Sound localizes to normal ear	Sound localizes to affected ear (ear with conductive loss)
Rinne Test	Positive Rinne; Air conduction > Bone conduction (both air and bone conduction are decreased equally, but the difference between them is unchanged).	Negative Rinne; Bone Conduction > Air Conduction (Bone/Air Gap)

v • d • e Diseases of the ear and mastoid process (H60-H99, 380-389) External ear Otitis externa Middle ear and mastoid Otitis media · Mastoiditis (Bezold's abscess, Gradenigo's syndrome) Cholesteatoma · Perforated eardrum Inner ear and central pathways Common pathway Labyrinthitis/Otitis interna Equilibrioception Vertigo/Balance disorder: peripheral (Ménière's disease, BPPV, Vestibular neuronitis, Perilymph fistula) · central (Central positional nystagmus) Hearing Hearing impairment Conductive hearing loss (Otosclerosis, Superior canal dehiscence) · Sensorineural hearing loss (Presbycusis, Central hearing loss) Excessive response Tinnitus · Hyperacusis/Phonophobia Deafblindness Wolfram syndrome · Usher syndrome Other Acquired auditory processing disorder ear navs: anat/pathways/physio/dev, noncongen/congen, eponymous signs, proc