Neuro-auditory+vestibular System

Question 1

what captures low frequency motion (movement )

Answer 1

vestibular organ

Question 2

what captures high frequency motion (movement )- and where is it found

Answer 2

hearing organ (organ of corti)- in basilar membrane of scala media

Question 3

what does the scala vestibuli and scala tympani contain and what is high in

Answer 3

perilymph - high in sodium

Question 4

what does the scala media contain and what is it high in

Answer 4

endolymph - high in potassium

Question 5

how is the basilar membrane organised

Answer 5

tonotopically-
base to capture high frequency- narrow and tight

apex= wide and loose for low frequency

Question 6

what are the hairs of the hair cells called and
what is the longest cilium called

Answer 6

stereocilia

kinocilium- longest cilium

Question 7

explain transduction in hearing- haircells

Answer 7

1. Deflection of the stereocilia towards (kinocilium) opens K+ channels
2. cell depolarises
   (opening VG Ca2+ channels. calcium enter)
   releasing NT (glutamate) to afferent nerve+ depolarises.
3. higher amplitude= greater stereocilia deflection + [K+] channel opening.

Question 8

Causes of conductive hearing loss outer vs middle ear

Answer 8

outer- wax/FB

inner- otitis/otosclerosis

Question 9

what is otitis

Answer 9

bubble can be seen through ear drum suggesting there is liquid inside middle ear

Question 10

Causes of sensorineural hearing loss- inner

Answer 10

inner- noise, presbycusis, ototoxicity

nerve- acoustic neuroma (vestibular schwannoma) - unliteral

Question 11

2 tests to do with tuning forks and what does it tests for

Answer 11

weber test and Rinne test

for gross hearing loss

Question 12

audiometry/audiogram what is this and the ranges for
normal hearing
mild hearing loss
moderate hearing loss
severe hearing loss
profound hearing loss

Answer 12

hearing threshold plotted to define if there is hearing loss or not- (dB)
normal hearing=0-20
mild hearing loss 20-40
moderate hearing loss 40-70
severe hearing loss 70-90
profound hearing loss 90-120

Question 13

what are OAE - otoacoustic emission

Answer 13

Low intensity sounds produced by normal cochlea​

from Expansion and contraction of OHCs​

Often tested in newborn hearing screening and as part of hearing loss monitoring

Question 14

treatment for hearing loss

Answer 14

underlying cause
hearing aid
cochlear implants
brainstem implants

Question 15

vestibular system- what are the input and outputs

Answer 15

input- movement and gravity

output - ocular reflex// postural control

Question 16

what are otoliths for

Answer 16

carbonated crystals that helps deflection of hairs

Question 17

what does the maculae contain

Answer 17

hair cells, gelatinous matrix and otoliths

Question 18

what happens when hairs move away from kinocilium

Answer 18

hyperpolarisation and reduction in nerve discharge

inhibition

Question 19

vestibular system functions- 3 examples

Answer 19

detects head movement
-keep image fixed in retina during head movement
-balance

Question 20

what are the 2 vestibular reflexes

Answer 20

VOR= vestibulo-ocular reflex

VSR= vestibulo spinal reflex

Question 21

what is the vestibulo-ocular reflex

Answer 21

-keeps image fixed in the retina
-connection between vestibular nuclei and oculomotor nuclei
-eye movement in opposite direction to head movement in same velocity and amplitude

Question 22

symptoms seen in acute (usually unilateral) vs slow ONSET

Answer 22

acute- imbalance/nausea + VERTIGO

slow -imbalance/nausea
NO vertigo

Question 23

balance disorders- location- peripheral (vestibular organ) vs central (CNS) causes

Answer 23

peripheral -BPPV (benign paroxysmal positional vertigo) /Meniere’s disease

central- stroke/MS/tumours

Question 24

what are the red flags in vestibular disorders

Answer 24

-headache
-gait problem
-acute onset
-hearing loss
-symptoms 4 days+

Question 25

balance disorders:
acute
intermittent
recurrent
progressive

Answer 25

acute- vestibular neuritis/stroke (HINTS exam)

intermittent- BPPV (Dix-Hallpike test)

recurrent-migraine/meniere’s disease

progressive - schwannoma vestibular (8th cranial nerve)/MS

Question 26

what is the HINTS exam

Answer 26

differentiating between vestibular neuritis or stroke

Head Impulse test- horizontal rotational VOR

Nystagmus

Test of Skew deviation- vertical misalignment

Question 27

what is the Dix-Hallpike test and what to do following it

Answer 27

for Benign paroxysmal positional vertigo

-epley manoeuvre