Hearing loss Flashcards
Conductive hearing loss
Sound isn’t transferred effectively to the internal ear
from the external/middle ear
Conductive hearing loss - cause
Obstruction in the passage of the external/middle ear - blood build up behind ear drum - effusion - CSF - foreign body Tympanic membrane perforation Ossicle damage (mainly incus) Stapes fixation
Conductive hearing loss - audiometry (graph) findings
Significant gap between air and bone conduction thresholds
- bone conduction thresholds are within normal limits
Sensorineural hearing loss
Damage to the hair cells within the cochlea or CNVIII nerve (or both)
Sensorineural hearing loss is permanent/non-permanent?
Permanent
- hearing will not be regained
Sensorineural hearing loss - cause
Exposure to loud noise (as cochlear hair cells will be damaged)
- factory work
Age related hearing loss (presbycusis)
Ototoxic drugs (gentamicin)
Sensorineural hearing loss - audiometry (graph) findings
No significant gap between air and bone conduction thresholds
Sensorineural hearing loss - management
Hearing aids
- this stimulated the hair cells in the cochlea
Mixed hearing loss
Combination of conductive and sensorineural hearing loss
- there is damage in the outer/middle ear AND in the inner ear
Mixed hearing loss - audiometry (graph) findings
At parts there is a significant gap between air and bone conduction thresholds but bone conduction thresholds are not all within normal limits
Audiometry - what is it?
First line test to assess the nature and degree of hearing loss in adults and young children
Audiometry - what does it measure?
Measures an individuals hearing sensitivity for calibrated pure tones and testing is carried out over a range of frequencies
The patient responds to sounds they hear by pressing a button
Audiometry - measuring air conduction
Use headphones and assess the entire auditory pathway
Audiometry - measuring bone conduction
Use a bone conductor and bypass the external and middle ear, stimulating the cochlea directly
Audiometry - what is the symbol for air conduction on the right side?
Right = Round + Red
Audiometry - what is the symbol for air conduction on the left side?
Left = Blue + Cross
What is masking?
Put sound into ear you are NOT testing which distracts that ear whilst the opposite ear is being tested
When is masking required?
When there is a difference in hearing thresholds between ears
Consequences of not masking
It can give an inaccurate measure of threshold leading to
- incorrect diagnosis
wrong management
Tympanometry - what is it?
Measure of middle ear function
Tells you how well the ear drums vibrate
Distinction between sensorineural and conductive hearing loss
Tympanometry - what is it a test of?
It is a test of function of the middle ear.
It is not a test of hearing
