Hearing Loss

Question 1

Describe the process of sound transduction

Answer 1

• SOund waves enter the external auditory canal and bounce off the tympanic membrane.
• The tympanic membrane thn moves the malleus, incus and stapes
• When the STAPES FOOTPLATE moves, the pressure in the fluid filled inner ear changes and that triggers a travelling wave in the basilar membrane of the cochlea

Question 2

Inside the cochlea, hair cells are found where?

Answer 2

Organ of corti which rests on basilar membrane

Question 3

High frequency sounds displace the the basilar membrane where

Answer 3

Near the base of the cochlea

Question 4

As frequency decreases, the point of maximal membrane displacement moves in what direction?

Answer 4

Toward the apex

Question 5

What stimulates electrical activity along the auditory nerve?

Answer 5

The distortion of stereocilia on hair cells causes depolarization of the cell and that results in electrical activity along the auditory nerve

Question 6

Causes of conductive hearing loss?

Answer 6

Transmission of sound through the air is blocked.

You can mimic this by sticking your finger in your ear. Thus, anything blocking the external auditory canal causes it.

Question 7

Cuases of conductive hearing loss

Answer 7

• wax
• foreign object
• otitis externa
• tympanic membrane perforation
• otitis media with effusion
• otosclerosis

Question 8

Sensorineural heaing loss

Answer 8

Disorders of the cochlea, cochlear nerve, central pathways

• can be congenital
• Presbyacusis (age related hearing loss)
• viral infxn
• ototoxic drugs
• trauma
• meniere’s
• vestibular schwannoma

Question 9

What is otosclerosis

Answer 9

bony overgrowth of the stapes

Question 10

Meniere’s disease symptoms

Answer 10

-vertigo, fluctuating sensorineural hearing loss, tinnitus

Question 11

What causes Meniere’s

Answer 11

Decreased reabsorption of endolymphatic fluid causes hydrops (fluid build-up) which causes rupture of the membrane separating the endolymph from the perilymph. These two fluids have very different compositions and their mixture produces a sudden change in vestibular pressure and electric firing properties.

Question 12

In the early stages of meniere’s, symptoms remit between attacks and patients may be symptom free for a year or more.

Answer 12

Eventually hearing loss persists and worsens

Question 13

Tx of menieres

Answer 13

• low salt diet and diuretics

- vestibular sedatives when the pt has an attack

Question 14

Conductive hearing loss audiogram

Answer 14

fairly equal threshold elevation for each frequency.

Question 15

Otosclerosis audiogram

Answer 15

Can result in a much greater threshold elevation in the lower frequencies

Question 16

Middle ear effusion audiogram

Answer 16

Greater elevation of thresholds in the higher frequencies

Question 17

Sensorineural hearing loss audiogram

Answer 17

usually the higher the frequency the worse the hearing

Question 18

Noise induced hearing loss generally shows a selectively greater loss at what frequency

Answer 18

4,000 hz

Question 19

Meniere’s disease audiogram

Answer 19

Hearing thresholds elevated in the lower frequencies…hearing usually worse at lower than higher

Question 20

In perforation of the tympanic membrane, the degree of hearing loss depends on

Answer 20

The size of the hole

Question 21

Growth of abnormal bone around the otic capsule is called

Answer 21

otosclerosis…..leads to fixation of the stapes

Question 22

Otosclerosis is often accompanied by what type of hearing loss

Answer 22

sensorineural

Question 23

At what age range does otosclerosis generally start

Answer 23

20’s and 30’s and is BILATERAL (prob means I don’t have it)

Question 24

Family history for otosclerosis

Answer 24

usually

Question 25

Tumor of the cerebellar pontine angle?

Answer 25

Often a vestibular schwannoma (acoustic neuroma

Question 26

Meningiomas also occur in the angle between the cerebellum and the pons BUT>

Answer 26

They usually present with sensorineural hearing loss but no vertigo