Conductive hearing loss


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 D006314

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 or alone.

The Weber test, in which a tuning fork is touched to the midline of the forehead, localizes to the affected ear in people with this condition. The Rinne test, which tests air conduction vs. bone conduction is negative (abnormal result).

Contents

Causes of conductive hearing loss

External ear

Common

Uncommon

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

Tympanic membrane

  • Tympanic membrane perforation
  • Membrane tension by different pressures in the external and middle ear.[1] 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 maneuvers to equalize the pressures.

Middle ear

Common

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 increased pressure in the middle ear relative to the external ear, and this causes decreased motion of both the ossicles and the tympanic membrane.[1]

Uncommon

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

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 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)

References

  1. ^ a b Page 152 in:Rex S. Haberman (2004). Middle Ear and Mastoid Surgery. New York: Thieme Medical Pub. ISBN 1-58890-173-4. 
  2. ^ a b Merck manuals > Hearing Loss and Deafness Last full review/revision April 2007 by Robert J. Ruben

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • conductive hearing loss — noun hearing loss due to problems with the bones of the middle ear • Syn: ↑conduction deafness, ↑middle ear deafness • Hypernyms: ↑hearing impairment, ↑hearing disorder …   Useful english dictionary

  • Hearing loss with craniofacial syndromes — is a common occurrence. Many of these multianomaly disorders involve structural malformations of the outer or middle ear, making a significant hearing loss highly likely. Treacher Collins syndrome Individuals with Treacher Collins syndrome often… …   Wikipedia

  • hearing impairment, hearing loss — A reduction in the ability to perceive sound; may range from slight inability to complete deafness. SEE ALSO: deafness, threshold shift. acoustic trauma hearing loss sensory hearing …   Medical dictionary

  • conduction hearing loss — conductive hearing loss hearing loss due to a defect of the sound conducting apparatus, i.e., of the external auditory canal or middle ear. Called also transmission h. l …   Medical dictionary

  • Sensorineural hearing loss — Classification and external resources Cross section of the cochlea. ICD 10 H …   Wikipedia

  • Congenital hearing loss — implies that the hearing loss is present at birth. It can include hereditary hearing loss or hearing loss due to other factors present either in utero (prenatal) or at the time of birth. Contents 1 Genetic factors 2 Hearing loss 2.1 Autosomal… …   Wikipedia

  • Central hearing loss — Classification and external resources MeSH D006313 Central hearing loss is a form of sensorineural hearing loss caused by damage to the auditory pathways. When the damage is to the primary auditory cortex, the impairment is called cortic …   Wikipedia

  • mixed hearing loss — hearing loss that is both conductive and sensorineural in nature …   Medical dictionary

  • transmission hearing loss — conductive h. l …   Medical dictionary

  • Noise-induced hearing loss — (NIHL) is an increasingly prevalent disorder that results from exposure to high intensity sound, especially over a long period of time. Contents 1 Description 2 Mechanism 3 Types 3.1 …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.