Lecture - Hearing Loss In The Community Flashcards
Audiometry
- measurement of hearing
- dBHL based on normal hearing
- 20 dBHL is a tenfold change in sound pressure levels
Normal audiogram
- less than 30 dBHL loss
Mild hearing loss
- 30-45 dBHL loss
- unable to hear a whisper
- difficulty hearing a background noise
Moderate hearing loss
- 50-65 dHBL loss
- hear conversational voice like a whisper
- corrected by a hearing aid
Severe hearing loss
- 70-85 dBHL loss
- unable to hear conversational voice at all without a hearing aid
Profound hearing loss
- 90 dHBL loss or greater
- unable to hear clearly even using a hearing aid
Rinne’s test
- test for conductive hearing loss
- 512 Hz tuning fork pressed against mastoid and then 1 cm away from ear
- if can hear the sound better when pressed against bone - conductive hearing loss
Weber’s test
- tuning fork in midline of forehead
- if can hear better on one side - sensory hearing loss on the other side
Common causes of a conductive hearing loss
- Wax
- perforted TM (trauma or infection)
- otisis media with effusion
- dislocation of ossicles
- otosclerosis
TM perforations
- trauma: can repair on its own
- infection: cannot clear unless infection is clear
- small holes cause no hearing loss
- total loss of pars tensa leads to a 60dBHL loss
Otitis media with effusion
- effusion in the middle ear
- poor eustachain tube function
- usually resolves when permanent teeth appear and ET function improves
- present at some time 20% of children
- mild conductive hearing loss
- difficulty hearing in class
- poor concentration and school performance
- can lose one year in academic performance
Grommets indication
- No: intermittent episode, intermittent ear infections, intermittent periods of hearing loss, dizziness
- yes: constant for at least 3 months with associated loss of hearing
Cholesteatoma and complications
- growth of skin inside the ear
- causes erosion of bone
- hearing loss due to erosion of ossicles
- vertigo due to thinning of wall of inner ear
- labyrinthitis
- facial palsy
- meningitis
- brain abcess
- treatment is surgical
Otosclerosis
- stapes bone becomes fixed by abnormal bone growth
- stapedectomy surgery
Hearing devices for conductive hearing loss
- conventional hering aids
- bone conductor hearing aids
- bone anchored hearing aids: skull bone, skin and subcutaneous tissue, implanted titanium fdixture, titanium abutment
- bonebridge
- for patients suffering from conductive or mixed hearing loss due to chronic otitis media, congenital atresia or external otitis
Seonsory hearing loss
- loss of hair cells within the inner ear
causes:
1) congenital: genetic, intrauterine viral illness, ototoxic medication, birth problems (jaundice, anoxia, prematurity)
2) Acquired: infection, trauma, noice, ototoxic medication (gentamicin/codeine), meniere’s disease, autoimmune disorder, late onset genetic, presbyacusis
Problems with children with profound hearing loss
- no useable speech development
- poor language
- lack of educational opportunities
- loss of employment opportunities
Incidence of hearing loss in children
- approximately 0.9/1000 live births
- further 0.5/1000 deafened during childhood
Ancient methods for hearing loss in children
- auditory oral: teaching the child by lip reading to say the speech sounds not heard
- total communication: a forlorn attempt to increase language by combining signed english with other methods of communication such as speech
- Auslan: a system of signs which does not follow the rules of spoken language
Cochlear implant
- directly stimulates surviving spiral ganglion cells
- straight incision immediately behind the ear about 4-7 cm in length
- incision: the younger the child the easier to make a shorter incision as the skin is so elastic
- adults, especially men, may require a longer incision as the periosteum is difficult to lift
- about 60 children a year in NSW need cochlear implant
Adults with hearing loss issues
- loss of ease of communication
- loss of self esteem
- withdrawal from social situations
- loss of employment
If a deaf children receives a cochlear implant before the age of 18 months and has no other disability, what percentage learn to communicate using speech and receive regular schooling?
- 100 %
- because of neural plasticity
- early detection of hearing loss via SWISH - Automated Auditory Brainstem REsponse (AABR)
- if a child fails SWISH - referred for diangostic testing
