Deafness in Adults

Question 1

conductive deafness

Answer 1

There is impaired sound transmission via the external canal and middle ear ossicles to the front of the stapes through a variety of causes.

Question 2

causes of conductive deafness

Answer 2

• fluid eg blood, effusion, CSF
• external canal obstruction
• TM perforation
• inadequate Eustachian tube ventilation of middle ear
• problems with ossicular chain eg trumatic, erosion, otosclerosis

Question 3

imaging of conductive deafness

Answer 3

CT

Question 4

otosclerosis

Answer 4

can cause conductive deafness - abnormal growth on bone which can cause the stapes to fixate to the oval window

Question 5

which ossicular chain bone is the most common site of injury

Answer 5

incus

Question 6

sensorineural deafness

Answer 6

Results from defects central to oval window in cochlea, cochlear nerve or, rarely, more central pathways

Question 7

which type of deafness is permanent

Answer 7

sensorineural

Question 8

causes of sensorineural deafness

Answer 8

• drugs
• post infective
• cochlear vascular disease
• ménière’s
• trauma
• presbycusis

Question 9

imaging of sensorineural deafness

Answer 9

MRI

Question 10

Weber’s test: sensorineural deafness

Answer 10

sound is heard louder on side of intact ear

Question 11

Weber’s test: conductive deafness

Answer 11

Sound is heard louder on affected side as BC > AC

• This is because the ear with the conductive hearing loss is only receiving input from bone conduction, and no air conduction.
• Conduction problem of middle ear masks ambient noise of the room, while the well-functioning inner ear picks the sound up via the bones of the skull

Question 12

what tuning fork is used for Weber test

Answer 12

512Hz

Question 13

Rinne’s test: normal

Answer 13

air conduction> bone conduction

Rinne’s positive

Question 14

Rinne’s test: sensorineural deafness

Answer 14

AC > BC as both are equally diminished

Question 15

Rinne’s test: air conductive deafness

Answer 15

BC>AC

Question 16

normal range of hearing

Answer 16

20dB or quieter

Question 17

moderate hearing loss

Answer 17

can hear between 40 and 60 dB

Question 18

what is considered symmetrical hearing loss

Answer 18

if the points for each ear occur within 10dB of each other

Question 19

Presbycusis

Answer 19

sensorineural hearing loss due to natural ageing of auditory system

occurs gradually and affects ability to hear high pitched sounds

Question 20

Answer 20

presbycusis

Question 21

Answer 21

noise induced hearing loss

Question 22

Answer 22

conductive hearing loss (bone conduction is represented by blue triangles)

Question 23

Answer 23

sensorineural hearing loss

Question 24

tympanometry: when does peak compliance occur

Answer 24

when the middle ear pressure is equal to that of the ear canal pressure

Question 25

tympanogram type AD

Answer 25

high compliance - due to disruption of the ossicles, or if part of the drum is flaccid

Question 26

tympanogram type B and B high

Answer 26

Type B - middle ear involvement from fluid, making drum stiff. ear canal volume is normal Type B high - suggests middle ear involvement from a perforation/patent grommet, equivalent ear canal volume exceeds normal limits

Question 27

tympanogram type C

Answer 27

shift in peak curve to left results when there is negative ear pressure (Eustachian tube dysfunction)