Inner Ear Disorders Flashcards
What are the causes of presbyacusis? (4)
C of coat
Sensory
Metabolic
Neural
Mechanical
Sensory
- hair cell degeneration
- mainly at basal end - doormat effect
- resulting in HF loss
Neural
- degeneration of ganglion cell, reduction in number of synapses (junction of nerves)
- loss of nerve cells that transmit impulses to brain
- nerve cells worn out
- not specific to HF
- will not effect hearing until 90% of nerve junction’s have been degenerated
Metabolic
- astrophy of stria vascularis (pumps potassium into endolympth)
- capillaries reduced blood supply
Mechanical
- ticketing of BM reduced elasticity
- more severe at basal turn (BM is narrow)
- greatest effect at HF
What are the risk factors for presbyacusis?
C of Coat
Thrombosis
Noise damage
O toxicity drugs
Diabetes
Poor diet
stress constriction of blood vessels
Cochlea requires a constant supply of oxygen
What are the symptoms of presbyacusis?
O of coat
Speech unclear
High pitched sounds difficult to hear
Tinnitus may occur
Difficult conversation especially in background noise
What are the treatments for prebyacusis?
T of coat
Hearing aids
- work / change
- amplify
- quiet sounds more
- loud sounds less
- high frequencies more
- low frequencies less
What are the causes of Ménière’s disease?
C of coat
Idopathic
- unknown cause
Episodic
- episodes / attacks
Endolymphatic
- endolympth related
Hydrops
- excessive pressure
Explain why Menieres creates the symptoms it does?
- over production of endolympth
- endolympthatic sac becomes swollen with excess fluid
- membrane may bulge (Scala media fills the Scala vestibuli/tympani)
- greatest effect at apical end of cochlea (hence low frequency loss) (basilar membrane effected at low end due to being wide and loose)
What are the stages of classic meunières disease?
Stage 1
Mainly disabling vertigo
Associated nausea
Episodes 20mins to several hours
Between attacks hearing returns to normal
Stage 2
Hearing loss becomes established but still fluctuates, often unilateral (sensori neural and low frequency loss, reverse slope)
Episodes of vertigo reach a maximum, then begin to subside
Tinnitus more noticeable
Stage 3
HL becomes more severe and permanent the becomes the prime disability
50% of long term suffers will develop a bilateral loss
Vertigo diminishes
Stage 4
Treatments (different card)
What are the treatments for Ménière’s disease?
Medication
- anti vertiginous
- Diuretics
- Gentamicin (damages hearing)
- steroid injections (anti inflammatory) via tm through grommet
- diet changes, low salt
- tinnitus management
- hearing aids
- counselling
- if vertigo remains a problem
- endolympahtic shunt, drains sac
- preserves hearing
How does ototoxicity effect hearing?
- damage within the cochlea via blood supply (stria vascularis)
- main effect chemical imbalance of endolympth
- permanent but mostly temporary
- usually rapid
- 1st symptom usually high pitched tinnitus
- mainly bilateral
What are the causes of inner ear infection? Viral or bacterial
Some reach via bloodstream
Some arrive via middle ear
Acquired
Temp or perm damage
High frequency mild to total loss
Toxins can infiltrate semi circular canals, lead to vertigo
What are the routes bacterial infections can enter the inner ear? (4)
Via mastoid air cells
Direct spread of the inflammations
Penetration of oval or round windows
Through nerves
*bacterial inner ear infections are an extension of middle ear infections
What bacterial infections can effect inner ear? (3)
Labrinthitis
An inflammation of the membranous labyrinth, again because of otitis media or meningitis
Bacterial Meningitis
Finds it’s way into inner ear either by the internal auditory meatus or the cochlea aqueduct. Bilateral SNHL usually profound
Syphilis
This has not been fully eradicated by penicillin treatment. SNHL is common in all forms of acquired syphilis
What viral infections effect inner ear? (4)
CMV
Loss - child profound s/n, mother ‘flu’
Common cause of congenital HL
Rubella
Loss - bilateral SNHL, reissners membrane
Measles
Loss - bilateral mixed, mixed loss due to ME erosion
Herpes Zoster (shingles)
Sudden cochlea and retro cochlea loss, associated pain and external ear rash
What types of trauma effect the inner ear? (3)
Fractures may result in leakage of fluid
Barotrauma - oval / round window
Noise - the biggest trauma
Explain what happens in ‘Diplacusis’
One sound presented to both ears is perceived to have a different tonal characteristics
Causes difficulty when fitting 2 hearing aids as the pitch perception is still imbalanced
Usually with asymmetric loss
