Conductive Hearing Loss

Question 1

Definition

Answer 1

Diseases interfere with sound conduction.
Lesion in external ear / tympanic membrane / middle ear / ossicles (upto stapediovestibular joint.

Question 2

Characteristics

Answer 2

Negative Rinne (BC>AC)
Weber lateralization (poorer ear)
Normal absolute BC
Low frequency more affected
Audiometry
Better BC
Air-Bone gap (more loss)
Loss (not > 60dB)
Good speech discrimination

Question 3

Causes /Aetiology

Answer 3

Congenital
Meatal atresia
Fixation of stapes footplate
Malleous head foxation
Ossicular discontinuity
Cholesteatoma
Acquired
External ear
Obstruction / tumour / atresia
Middle ear
Perforation (tymapic membrane)
Fluid (OM /haemotympanum)
Mass (tumour)
Ossicle disruption (CSOM / cholesteatoma)
Ossicle fixation (otosclerosis / adhesive OM)
Eustachian tube blockage (serous OM)

Question 4

Classification

Answer 4

Non-Organic
Organic
Conductive
Sensoneural
Sensory (cochlear)
Neural
Peripheral (8th CN)
Central (central auditory pathway)

Question 5

Lesions in conductive apparatus

Answer 5

Complete obstruction of ear canal (30)
Tympanic perforation (10-40)
Ossicular interuption
+ Intact drum (54)
+ Perforation (38)
Malleous fixation (10-25)
Closure of oval window (60)

Question 6

Management

Answer 6

Canal obstruction removal
Fluid removal (Myringotomy)
Middle ear mass removal (tympanotomy)(removal of tomours / cholesteatoma)

Stapedectomy
Tympanoplasty
Hearing aid

Question 7

Tympanoplasty

Answer 7

Eradicate disease in middle ear
Reconstruct hearing mechanism

Tympanic membrane (myringoplasty)
Ossicular chain (ossiculoplasty)
Both (tympanoplasty)

Question 8

Principles of tympanoplasty

Answer 8

Intact tympanic membrane
Ossicular chain
2 functioning windows
Acoustic separation of 2 windows
Functioning eustachian tube
Functioning sensoneural apparatus

Question 9

Types of tympanoplasty

Answer 9

Type 1 (perforated tympanic membrane)(myringoplasty)

Type 2 (perforated tympanic membrane + erosion of malleus)(graft on incus / remnant of malleus)

Type 3 (absent malleus + incus)(graft on stapes head)(myringostapediopexy / columella tympanoplasty)

Type 4 (foot plate of stapes only)(graft between oval and round window)

Type 5 (stapes footplate is fixed)(round window functioning)(another window created - fenestration operation)

Question 10

Degree of hearing loss (WHO classification)

Answer 10

Mild (26-40dB)
Moderate (41-55)
Moderately severe (56-70)
Severe (71-91)
Profound (> 91)
Total loss

Question 11

Handicap definition

Answer 11

Disability firther restricts the duties and roles expected from an individual by society.

Question 12

Disability definition

Answer 12

When impairment affects the ability to perform certain functions in the range considered normal for that individual.