Test 2: Auditory & Vestibular CC (these go together in my brain) Flashcards
Conductive deafness
- What is it
- **What causes it? **
- Deafness from obstruction–sound doesnt reach the tympanic membrane or cross the middle ear properly
- Causes: occlusion, middle/outer ear infection, OTOSCLEROSIS, temporal bone fracture (damage to ossicles)
Sensorineural deafness
- deafness from nerve damage
- Caused by: lesion to cocheal, cochlear portion of CN VIII, prolonged noise exposure, some antibiotics, infections or tumors, inner ear infection or labyrinithitis
What kind of deafness is caused by
- Otitis externa
- otitis media
- otitise interna
- Conductive deafness
- Conductive deafness
- sensoorineural deafness
Otosclerosis
- What is it (how does it happen?)
- **What kind of deafness does it cause? **
- tissue overgrowth that causes fixation of the stapes in the oval window
- **CONDUCTIVE **hearing loss 50% of the time.
What would happen if a bug got into your ear and ate up all you hair cells?
You’re screwed. hair cells DO NOT REGENERATE.
- What is the Rinne Test?
- What does it test?
- What is the normal response? what is a positive Rinne test?
- Negative Rinne test?
- Vibrating tuning fork is placed on mastoid process and then it is moved to the air in front of the ear
- Compares air vs bone conduction
- Normal: Air conduction should be greater than bone conduction. AC>BC= positive rinne test= normal
- Negative: Bone conduction>Air conduction **indicating conduction deafness on that side. **
- **What is the Weber’s test? **
- What does it test
- Normal response?
- Abnormal?
- Vibrating tuning fork is placed on the vertex of the head.
- Nerve or conduction deafness
- Normal: patient hears equally on both sides
- If the sound is louder on one side, that is indicative of ipsilateral conduction deafness OR contralateral nerve deafness.
You do a Rinne test and Weber test on a patient and find
- Weber: Right ear lateralization
- **Rinne: **BC>AC on Right, AC>BC on left
DDx?
Weber test tells us either: Conduction deafness in right ear OR nerve deafness in left ear
**Rinne test: **Conduction deafness on Right
_Diagnosis: conduction deafness in right ear _
You do a Rinne test and Weber test on a patient and find
- Weber: Left ear lateralization
- **Rinne: **BC>AC on Left; AC>BC on right
DDx?
Weber test tells us either: Conduction deafness in left ear OR nerve deafness in right ear
**Rinne test: **Conduction deafness on left.
Diagnosis: conduction deafness in left ear
You do a Rinne test and Weber test on a patient and find
- Weber: Right ear lateralization
- **Rinne: **Positive in both ears
DDx?
Weber test tells us either: Conduction deafness in right ear OR nerve deafness in left ear
Rinne test: (positive= AC>BC= normal) No conduction hearing loss
_Diagnosis: nerve deafness in left ear _
You do a Rinne test and Weber test on a patient and find
- Weber: Left ear lateralization
- **Rinne: **AC>BC both ears
DDx?
Weber test tells us either: Conduction deafness in left ear OR nerve deafness in right ear
**Rinne test: **No conduction hearing loss
_Diagnosis: nerve deafness in right ear _
Stria vascularis-
- what is it?
- Damage causes?
- Stria vascularis changes the endolymphatic potential via selective absorption and secretion of ions.
- Loss of endolymphatic potential = failure of mechanoelectrical transduction
How can you monitor cochlear function?
**Cochlear microphonic= **Recording stimulus-related changes in electrical potential between the perilymph and haircells
Treatment for **sensorineural hearing loss? **How does it work?
Cochlear implants- wire electrodes are tuned to specific frequencies and implanted so that each wire stimulates the appropriate nerve terminal in the cochlear spiral.
Cochlear damage causes ________ hearing loss and may cause ______.
Cochlear damage = sensorineural deafness and may cause tinnitus.
Monaural Deafness- What is it? Where’s the lesion?
- Deafness in ONE ear only
- Lesion of cochlear nerve or cochlear nucleus
**Why won’t you get monaural deafness if you damage the inferior colliculus? What are the sx of damaging CENTRAL pathway? **
- Inferior colliculus recieves input from BOTH ears (due to trapezoid body) so you won’t have complete hearing loss from one ear
- Inattention to stimuli on contralateral side OR inability to follow conversation in a noisy room.
What is the cocktail effect?
- Something I am lacking completely.
- The ability to focus your attention on ONE conversation in a noisy room.
I’m super jealous of all the people that have an intact cocktail effect. I’m going to destroy ______ so that everyone is like me!MWAHAHAHAHHAH
Damaging the central hearing pathway. Ie: superior olive –> inferior colliculus –> MGN –> cortex
I want to damage the ________ in order to sneak past the guard’s LEFT side and steal the gold.
RIGHT side central lesion
(central lesion causes inattention on CONTRAlateral side)
Blood supply to internal ear (and what that a. is a branch of)
labyrinthine a (internal auditory a.) <==AICA <==basilar a.
**SX: **
- Monaural hearing loss
- ipsilateral facial paralysis
- inability to look toward side of lesion
DIAGNOSE! (what would cause this?)
**Occlusion to AICA. **
Inner ear is ischemic (loss of labyrinthine a), facial nerve damage, pontine gaze center damaged.
What vessel would I occlude to kill:
- Cochlear n
- superior olive/lateral lemniscus
- Inferior colliculus
- MGN
- primary auditory cortex
- association cortex
- Cochlear n= labyrinthine a (from AICA)
- superior olive/lateral lemniscus= short circumferential of basilar
- Inferior colliculus=**superior cerebellar, quadrigeminal **
- MGN= **thalamogeniculate a. **
- primary auditory cortex=** M2 ** of MCA
- association cortex= M2 of MCA
**Central deafness (this is different than central LESIONS). **
Deafness cause by damage to cochlear nuclei or central pathways that move information to the auditory cortex.
Since it can be cochlear nerve or central lesion, then the symptoms for **central deafness are not always the same. **
Youre alone in your aparment and you start hearing an out of tune orchestra, buzzing of insects of strands of music.
- What’s going on?
- What are some other things that might be going wrong?
- Pontine auditory hallucinations.
- cranial nerve deficits and long tract signs.
Music still sounds the same (to patient), but everytime someone (not patient) “talks” it’s nonsense (to patient).
- Where’s the lesion
- What might cause this?
- Wernickes aphasia= Area 22 damaged
- MCA occlusion
Reading and writing are an important job for?
Area 39 (angular gyrus) and 40 (supramarginal gyrus)
the _______ connects broca’s area to primary and association auditory cortex.
**arcuate fasciculus **
Patient can understand everything, but everytime he/she tries to talk, it’s nonsense.
- Lesion?
- What can cause it?
- Broca’s (expressive) aphasia= area 44/45 (pars opercularis and pars triangularis)
- MCA branches
**Middle ear reflex= ___ muscles **
- What is it (pathway)
- What’s the purpose/function
- Is this more effective for LONG or SHORT stimuli?
2 Muscles= tensor tympani (CN V) and stapedius (CN VII)
**BILATERAL PATHWAY (afferent activates both efferents) **
- Loud sound ==> activate ear hair cellls==> sprial ganglion cells==> cochlear nucleus ==> superior olive (caudal) ==> facial nucleus==> stapedius to DAMPEN sounds (sound of your own voice)
- ==> superior olive (rostral)==> CN V ==> tensor tympani (chewing)
- More effective for LONG stimuli because it takes a while.