Assessment Of Auditory Vestibular Pathways

Question 0

What are characteristics of the lateral vestibular spinal tract (LVST)?

Answer 0

• Afferent source is entire labyrinth
• Nucleus lateral vestibular nucleus
• Functions to postural changes to compensate for tilts and movements of the body
• efferent connection is ipsilateral
• adjustment of posterior limbs

Question 1

What does the vestibulospinal reflex do?

Answer 1

Maintaining the head In an upright position during movement

Question 2

What are characteristics of the MVST?

Answer 2

• afferent source is semicircular canals
• nucleus is the medial and descending vestibular nuclei to the MLF
• stabilize head when walking
• bilateral
• Excitatory and inhibitory
• relaxation of upper back and neck muscles

Question 3

What are some characteristics of the VOR?

Answer 3

Dolls eyes, the eye stays in position when the head is moving
If you move your head in one direction your eyes will move in the opposite direction, adjust eye position

Question 4

How can you see the VOR?

Answer 4

Cortical control has to be suppressed or eliminated

VOR is slow compared to cortex

Question 5

What are the steps to the VOR?

Answer 5

1. Turn your head to the left
2. Get depolarization on the left and hyperpolarization on the left
   (If you lesion the right you get depolarization of the left)
3. Get excitatory on the left VN, inhibitory on the right
4. Excitation on the left excited the left occularmotor nucleus and the right abducens nucleus to get contraction of the left medial rectus and right lateral rectus
5. Inhibition of the opposite muscles
6. Eyes go right

Question 6

What happens where your cortex and VOR are competing where your eye should be?

Answer 6

Nystagmus
VOR moves your eye slow (pursuit)
Cortex moves your eye fast (saccade)
Can provoke

Question 7

What is the caloric test?

Answer 7

If you inject cold water into one ear you get the opposite side nystagmus. If warm you get same side nystagmus

If you get pursuit only, you have a cortex lesion
If you get neither you have a brainstem lesion
Tilt the head to isolate the horizontal canal

Question 8

How do you distinguish conductive(external/middle ear) and sensory neuro(hair cells, auditory nerve, cochlear nucleus) hearing loss?

Answer 8

Rime and weber test

Question 9

What is the most common CNS auditory hearing loss?

Answer 9

“Cocktail party” effect
Inferior colliculus
Have a hard time distinguishing noise and important sounds
Processing disorder

Question 10

What are the two ways to access an audio gram?

Answer 10

Absolute - same for all frequencies, 0-140 dB (worse is top)

Relative - mapped relative to normal (worse is bottom)

Question 11

What is profound hearing loss and normal?

Answer 11

Above 80 dB is profound hearing loss

Above 25 is normal (not dB?)

Question 12

What is the normal audio gram?

Answer 12

Air conduction gives lower thresholds than bone conduction

Question 13

What is conductive hearing loss?

Answer 13

Injury to the middle of external ear

Question 14

What symbols represent bone and air conduction?

Answer 14

Air conduction - circles for rt ear, X for right

Question 15

What do you see in an audio gram for conductive and sensory neuro hearing loss?

Answer 15

In conductive, bone is better than air conduction

In sensory neuro, both are low

Question 16

What does the rinne test, test for?

Answer 16

Conductive hearing loss and sensory neuro
Difference in hearing on both sides

Bone versus air conduction

Question 17

What is the weber test?

Answer 17

Tests for Lateralizarion

Localizes side of defect

Question 18

What do acoustic reflex tests test for?

Answer 18

Middle ear problems

And brainstem function

Question 19

What information does the rinne test give?

Answer 19

On the middle ear

Question 20

What do you need to be function in weber test?

Answer 20

Middle ear
Cochlea
Superior olivary nucleus