the auditory and vestibular function Flashcards
what I hyperacusis
Hyperacusis is when everyday sounds seem much louder than they should
The middle ear conducts sound waves from the
the tympanic membrane to the oval window as vibrations along the malleus incus and stapes.
the endolymph is between the Scala vestibule and scale tympani
high in potassium - ecf
perilymph is found in the scala media
potassium
hair cells ( sterocilia on top) mallow potassium to move inside to out from endolymph to perilymph causing calcium channel to open which then causes AP in CN8
hair cell are between where
are between the basilar and tectorial membrane
where is your auditory cortex
temporal cortex
where does the primary auditory pathway cross over
superior olivary nucleus
high er pitch Is found at higher frequencies - where is this found on the cochlear
base of the cochlear
apex is lower frequencies
The width of the basilar membrane increases towards the apex
Therefore location on the membrane has a different resonant frequency
is the decibel threshold measured logarithmically
yes
what common antibiotic can cause ototoxicity
gentamicin
tinnitus - how long - start off and on constant leading to sudden blindness what could it be
posterior cerebellar stroke
when you’ve got vertigo need to figure out wether it is BBPV - things moving around you
lying down and turning head
or when you stand up like orthostatic hypertension
This involves holding a tuning fork in front of the ear (to elicit air conduction) and behind the ear on the mastoid process (to elicit bone conduction). As the table shows, if air conduction is better than bone conduction this could be NORMAL or it could be a SENSORINEURAL deficit.
rinnes test
You need to then conduct a Weber test to check. A Weber test is where you place the tuning fork in the middle of the forehead. If the patient hears the sound ‘in the middle’ then their hearing is normal. If they hear it louder in one ear than the other, they have a SENSORINEURAL deficit. The ear that hears the sound is the normal ear, the ear that doesn’t hear the sound has a sensorineural hearing loss. CONDUCTIVE hearing loss is a bit easier to work out. Basically, if bone conduction is better than air conduction (sound heard louder when tuning fork behind ear rather than in front of ear) then there is a conductive hearing loss. To work out which ear the hearing loss is in you then perform the Weber test. The patient will hear the sound LOUDER in the AFFECTED ear than the normal ear. Watch the video to see how one is performed.
Quantitative hearing testing is done with an
both bone conduction (triangles/brackets) and air conduction (O’s on right and X’s on left)
both lines overlapping sensioureuneral
audiogram
To do this, they basically play the patient lots of sounds at different decibels (volume) and frequency (pitch) and assess how loud the volume (how high the decibels) need to be for them to hear that sound. Normal is anything between 0 and 20dB! (so looking at the graph, any line that is above the line of 20dB on the graph - see blue arrow). Most audiograms will have a line for air and bone conduction plotted on the same chart. In a normal person, air conduction and bone conduction will have very similar plots (they will be along a similar line and overlap each other).
what crista ampullaris
The crista ampullaris is the sensory organ of rotation located in the semicircular canal of the inner ear.
difference between semicircular canals and otolith organs
There are two sets of end organs in the inner ear, or labyrinth: the semicircular canals, which respond to rotational movements (angular acceleration); and the utricle and saccule within the vestibule, which respond to changes in the position of the head with respect to gravity (linear acceleration).
Acceleration / gravity causes otoliths to move, creating a shearing effect in the gel matrix that activates the hair cells
Oculocephalic reflex
normally eyes turn opposite to head movement
abnormal if they have like a brain stem ( pontine ) ischaemia
both when the patient is unconscious s
60yr old female who feels the room spin when she turns over in bed or hangs the washing on the line for the last week - each episode lasts - 60seocnds
dix hall pike test postive
what is diagnosis
causes by calcium debris within semicircular canal ( loose otoconai from utricle)
have debris causes inappropriate mvoemtn of endolymph with linear accelerations such as gravity and causes the erroneous sensation of spinning when the head shifts with respect to gravity
BPPV
benign - not due to serious disease
paroxysmal - occurs in short burst of 1 minute
positional - provoked specifically by movement to from certain positions
vertigo - dizziness defined as an illusion of movement
pupillary reflex - reaction to bright light
2 - sensory
3 motor
corneal reflex - cotton wool on cornea
5
7
oculovestibular - saline to tympanic membrane
8
3,4,6
pain Epson e- supra orbitala
5,7,
agag reflex- instrument contact to pharynx
9,10
coug reflex - suction catheter to carina
10 both
35yr old female instead and dizzy like the room is spinning making her feel sick. it is often present when she wakes up and can start suddenly.
what is it
vestibular neuritis
due to inflammation of the vestibular nerve
may occur after a viral infection
no effect on hearing though
45yr female unsteady and dizzy like room spinning and feeling sick. it often present when she wakes up and it starts suddenly. she has noticed some hearing loss and tinnitus
what is it
labyrinthitis
inflammation of the membranous labyrinth
symptoms of vestibular neuritis and labyrinthitis are very similar but labyrinthitis does after hearing
sensorineural deafness
50yr old attacks of vertigo and vomtiign once a month. each episode lasts a couple hours. feeling of fullness in the ear and is beginning to lose hearing
menieres disease
progressive distension of the membranous labyrinth due to excessive endolymph
this may injure the vestibular system causing vertigo or the cochlea causing hearing loss
