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Flashcards in Hearing Loss Deck (26):
1

Describe the process of sound transduction

- 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

2

Inside the cochlea, hair cells are found where?

Organ of corti which rests on basilar membrane

3

High frequency sounds displace the the basilar membrane where

Near the base of the cochlea

4

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

Toward the apex

5

What stimulates electrical activity along the auditory nerve?

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

6

Causes of conductive hearing loss?

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.

7

Cuases of conductive hearing loss

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

8

Sensorineural heaing loss

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

9

What is otosclerosis

bony overgrowth of the stapes

10

Meniere's disease symptoms

-vertigo, fluctuating sensorineural hearing loss, tinnitus

11

What causes Meniere's

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.

12

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

Eventually hearing loss persists and worsens

13

Tx of menieres

-low salt diet and diuretics
- vestibular sedatives when the pt has an attack

14

Conductive hearing loss audiogram

fairly equal threshold elevation for each frequency.

15

Otosclerosis audiogram

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

16

Middle ear effusion audiogram

Greater elevation of thresholds in the higher frequencies

17

Sensorineural hearing loss audiogram

usually the higher the frequency the worse the hearing

18

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

4,000 hz

19

Meniere's disease audiogram

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

20

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

The size of the hole

21

Growth of abnormal bone around the otic capsule is called

otosclerosis.....leads to fixation of the stapes

22

Otosclerosis is often accompanied by what type of hearing loss

sensorineural

23

At what age range does otosclerosis generally start

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

24

Family history for otosclerosis

usually

25

Tumor of the cerebellar pontine angle?

Often a vestibular schwannoma (acoustic neuroma

26

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

They usually present with sensorineural hearing loss but no vertigo