Any disease process which interferes with the conduction of sound to reach cochlea causes conductive hearing loss. The lesion may lie in the external ear and tympanic membrane, middle ear or ossicles up to stapediovestibular joint.<\/p>\n
<\/p>\n
The characteristics of conductive hearing loss are:<\/p>\n
\u25a1 Negative Rinne test, i.e. BOAC.
\n\u25a1 Weber lateralised to poorer ear.
\n\u25a1 Normal absolute bone conduction.
\n\u25a1 Low frequencies affected more.
\n\u25a1 Audiometry shows bone conduction better than air conduction with air-bone gap. Greater the air-bone gap, more is the conductive loss.
\n\u25a1 U Loss is not more than 60 db.
\n\u25a1 Speech discrimination is good.<\/p>\n
MANAGEMENT<\/p>\n
Most cases of conductive hearing loss can be managed by medical or surgical means. Treatment of these conditions is discussed in respective sections. Briefly, it consists of:<\/p>\n
\u25a1 Removal of canal obstructions, e.g. impacted wax, foreign body, osteoma or exostosis, keratotic mass, benign or malignant tumours, meatal atresia.
\n\u25a1 Removal of fluid. Myringotomy with or without grommet insertion.
\n\u25a1 Removal of mass from middle ear. Tympanotomy and removal of small middle ear tumours or cholesteatoma behind intact drum.
\n\u25a1 Stapedectomy, as in otosclerotic fixation of stapes footplate.
\n\u25a1 Tympanoplasty. Repair of perforation, ossicular chain or both.
\n\u25a1 Hearing aid. In cases, where surgery is not possible, refused or has failed.<\/p>\n
CONGENITAL CAUSES OF CONDUCTIVE HEARING LOSS<\/p>\n
\u25a1 Meatal atresia
\n\u25a1 Fixation of stapes footplate
\n\u25a1 Fixation of malleus head
\n\u25a1 Ossicular discontinuity
\n\u25a1 Congenital cholesteatoma
\n\u25a1 Tympanoplasty<\/p>\n
It is an operation to (i) eradicate disease in the middle ear and (ii) to reconstruct hearing mechanism. It may be combined with mastoidectomy if disease process so demands. Type of middle ear reconstruction depends on the damage present in the ear. The procedure may be limited only to repair of tympanic membrane (myringoplasty), or to reconstruction of ossicular chain (ossiculoplasty), or both (tympanoplasty). Reconstructive surgery of the ear has been greatly facilitated by development of operating microscope, microsurgical instruments and biocompatible implant materials.<\/p>\n
ACQUIRED CAUSES OF CONDUCTIVE HEARING LOSS<\/p>\n
External ear: Any obstruction in the ear canal, e.g. wax, foreign body, furuncle, acute inflammatory swelling, benign or malignant tumour or atresia of canal.<\/p>\n
Middle ear: Perforation of tympanic mem-brane, traumatic or infective. Fluid in the middle ear, e.g. acute otitis media, serious otitis media or haemotympanum. Mass in middle ear, e.g. benign or malignant tumour. Disruption of ossicles, e.g. trauma to ossicular chain, chronic suppurative otitis media, cholesteatoma. Fixation of ossicles, e.g. otosclerosis, tympanosclerosis, adhesive otitis media. Eustachian tube blockage, e.g. retracted tympanic membrane, serous otitis media.<\/p>\n
MYRINGOPLASTY<\/p>\n
It is repair of tympanic membrane. Graft materials of choice are temporalis fascia or the perichondrium taken from the patient.<\/p>\n
OSSICULAR RECONSTRUCTION<\/p>\n
It is required when there is destruction or fixation of ossicular chain. Most common defect is necrosis of the long process of incus, the malleus and the stapes being normal.<\/p>\n","protected":false},"excerpt":{"rendered":"
Any disease process which interferes with the conduction of sound to reach cochlea causes conductive hearing loss. The lesion may lie in the external ear and tympanic membrane, middle ear or ossicles up to stapediovestibular joint.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[34],"tags":[],"class_list":["post-5224","post","type-post","status-publish","format-standard","hentry","category-eye-care"],"yoast_head":"\n