Disorders of the Ear Flashcards
1
Q
Example of conductive hearing loss
A
otosclerosis
2
Q
Otosclerosis: disease process
A
- osteodystrophy of endochondral bone leading to bone remodeling
- effects otic capsule bone (temporal bone), where stapes footplate articulates w/ the vestibule
- slowly progressive so hearing loss occurs gradually
3
Q
Otosclerosis: inheritance
A
- autosomal dominant, 40% penetrance
- can also affect inner ear function
4
Q
Otosclerosis: treatment
A
- hearing aids
- surgical replacement (stapedectomy, most common): >90% improve, 1% with severe hearing loss
- observation
5
Q
Sensorineural hearing loss: disease process
A
- occurs when there is damage to inner ear
6
Q
Sensorineural hearing loss: 3 categories
A
- sensory: damage to hair cells
- neural: damage or loss of auditory neurons
- strial: damage or degeneration of stria vascularis
- *most patients have components of each**
7
Q
Sensorineural hearing loss: examples
A
- DFNB1
- noise induced hearing loss
- auditory neuropathy
8
Q
DFNB1: disease process
A
- autosomal recessive SNHL due to mutation in GJB2 that encodes connexin 26
- accounts for 50% of congenital, autosomal recessive nonsyndromic hearing loss
9
Q
DFNB1 treatment
A
- cochlear implantation effective in most patients
10
Q
Noise induced hearing loss: prevelance
A
- most common cause of preventable SNHL
- common diagnosis for workman’s compensation
11
Q
Noise induced hearing loss: cause
A
- most frequently occurs from exposure through years >90dB
- can result from single exposure to very loud noise
12
Q
Noise induced hearing loss: disease process
A
- initial damage occurs at post-synaptic structures and afferent fibers innervating inner hair cells
- later there is loss of hair cells and auditory neurons and fibers
13
Q
Auditory neuropathy: clinical presentation
A
- absent ABR with intact otoacoustic emissions
14
Q
Auditory neuropathy: cause and treatment
A
- DFNB9: mutation in otoferlin
- treatment: excellent results with cochlear implantation
15
Q
Auditory neuropathy: otoferlin (DFNB9)
A
- otoferlin is a calcium sensitive protein involved in synaptic vesicle release from hair cells
- otoferlin mutation hair cells are present and function except fail to release glutamate to activate auditory nerve
16
Q
Hearing assessment: subjective vs. objective
A
- subjective: audiogram
- objective: auditory brainstem response(ABR), otoacoustic emissions(OAE)
17
Q
Auditory brainstem response
A
- test integrity of auditory system through the brainstem
- NOT used as a screening test
- used when newborn fails OAE
18
Q
Otoacoustic emissions
A
- low intensity sounds recorded from ear canal response to stimuli
- reflect OUTER HAIR CELL function
- most common test for newborn hearing
19
Q
How can you still pass OAE and be deaf
A
- auditory nerve dysfunction
20
Q
Chochlear implants
A
- electrodes placed in chochlea that directly stimulate the auditory nerve, bypassing the non functioning hair cells
- patients usually get about 8 channels
21
Q
Hybrid hearing process
A
- shorter and thinner chochlear electrodes preserve residual low frequency hearing
- patients use both acoustic and electrical stimulation
22
Q
Vestibular ocular reflex
A
- allows for gaze stabilization during head motion
- hair cells of utricle, saccule and semicircular canals are activated or inhibited and lead to movement of eyes in opposite plane/direction so images remain stable on the retina
23
Q
Nystagmus
A
- acute abnormal activation or inhibition of vestibular nerve that drive eye movements in absence of head motion
24
Q
Vertigo
A
- illusion that the external environment is in motion
- due to nystagmus
25
Videonystagmogram (VNG) & Electronystagmogram (ENG)
- use caloric stimulation to create currents in endolymph that drive VOR
26
Caloric stimulation
- irrigation of external auditory canal with cold or warm water/air
27
ENG/VNG caloric testing
- Cold water: inhibitory current like a head turn to opposite side; slow phase towards irrigated ear and fast (nystagmus) towards opposite ear
- Warm water: excitatory current like a head turn to same side; slow phase away from irrigated ear and fast (nystagmus) towards irrigated ear
28
Meniere's disease signs
1. fluctuating, low frequency SNHL
2. recurrent vertigo
3. tinnitus in affected ear
4. aural fullness or pressure
29
Does meniere's disease effect one ear or both
- only ONE ear
30
Cause of meniere's disease
- unknown
- affected ear always has endolymphatic hydrops (swelling of endolymphatic fluid compartment)
* **not everyone with endolymphatic hydrops has meniere's disease***
31
Treatment of meniere's disease
- low salt diet and diuretic: common and effective treatment
- steroids
- surgery for intractable cases (
32
Surgical management of intractable meniere's disease
- endolymphatic shunt (most common)
- labyrinthectomy
- vestibular nerve section
33
Endolymphatic shunt
- silastic shunt into endolymphatic sac
- controversial: 70% success rate
- non destructive outpatient with short recovery
34
Labyrinthectomy
- destruction of vestibular organs, requires compensation period (3-6weeks)
- surgical: 95% success rate, total hearing loss-best for those with poor hearing
- chemical (gentamicin): 70% success rate, 20% hearing loss, long term compensation sometimes not complete
35
Gentamicin
- affects vestibular cells first and then chochlear cells
- must assess vestibular function not hearing because by the time it effects hearing there will already be perminent hearing loss
36
Vestibular nerve section
- most complex procedure, required craniotomy
- 90-95% success rate, 5% hearing loss
- best for young patients with good hearing
- 3-6 weeks recovery period
37
Conductive hearing loss
- problem with ear canal, tympanic membrane and or ossicles
| - does not effect ability to discriminate sounds or understand words
