Assessing Inner Ear Function Flashcards
What do you do in the caloric test?
you inject warm or cold water into the ear and look for nystagmus
What is the direction of the nystagmus with warm vs cold water?
warm water = same direction as the ear you put it in
cold water - opposite direction of the ear you put it in
COWS
So…if you put warm water in a patient’s right ear, which diretion is the VOR pursuit?
the VOR pursuit be twoards the right and the saccade will be to the left
If the patient is comatose, but with normal brain stem function, what would you see on calorics?
you’d see the VOR pursuit, but no saccade correction
If the patient is braindead, what would you see on calorics?
no pursuit and no nystagmus
Why do you tilt the patient’s head when you’re doing calorics?
you want to isolate the lateral semicirculat canals
WHere is the issue in the pathway for the cocktail party effect - a central auditory processing disorder?
the inferior colliculus
they’ll look totally normal on an audiogram - it’s only an issue when they’re in a loud environmenta nd their brain can’t figure out what sound to pay attention to
In a normal audiograph, what has lower thresholds, air or bone conduction? why?
air - air conduction utilizes the amplification that comes from the middle ear while bone conduction skips it
Normal audiograms will show the patient responding to sounds at what hearing level? WHat does a negative number mean? What does a positive number mean?
0 DB
it’s a reference point for normal
negative values mean the patient can hear at lower thresholds than normal - better than average
positive values mean the patient needs louder volumes to hear any given frequency - worse than average
What hearing level is considered deafness?
80 DB
In conductive hearing loss, what will the results be for bone and air conduction?
bone conduction will be normal (or close to normal)
air conduction will be decreases
About how many decibels does the middle ear contribute? So what would an audiogram of middle ear dysfunction look like?
about 45-50 DB
so conductive hearing loss form the middle ear would result in normal bone conduction, but air conduciton at about 50 DB
What would a sensorineural hearing loss audiograpm look like for bone and air conduction?
bone and air conduction will both be impaired equally for the most part
A positive Rinne test would suggest what type of hearing loss/
a positive would mean their air conduction threshold did not differ from their bone conduction threshold (should have been better)
this means they have conductive hearing loss
What hair cells are being tested in otoacoustic emission measurements?
outer hair cells (type 2)
