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Hearing impairment (Clinical
presentation (Lack of response to
noises or…
Hearing impairment
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Diagnosis
Examination
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Otoscopy
Signs of external/middle ear
disease e.g. wax, otitis media
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Investigations
Bloods
FBC (infection), CRP/ESR, U+E, LFT (bilirubinaemia),
clotting, glucose (DM), lipids
Genetic screens (neurodegenerative disorders)
Autoimmune profile (MS)
Special tests
Impedence audiometry: detects type
Conductive: bone normal, air abnormal
Sensorineural: bone and air reduced
MIxed: both reduced, air>bone
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Imaging
CT head (meningitis, encephalitis)
History
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POH
Scans, bloods, growth, gestation,
delivery, weight, complications
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PC/HPC
Speech and language delay,
behavioural problems
FH
Hearing impairment,
genetic conditions
SH
Living arrangements, school/nursery,
social support, social services
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Pathophysiology
Physiology of hearing
Frequency (hertz) and pressure (decibels)
Frequency (number of vibrations) is pitch (normal 20-20,000Hz); vowels are low freq and consonants higher
Pressure (amplitude) is loudness (normal -10 to 25db)
Types
Sensorineural
Usually a genetic cause, thus irreversible
Pathology in the cochlear, CN VIII or CNS (auditory cortex)
Sensory issue if between oval window and middle ear, neural if involves CN VIII or CNS pathways
Air and bone conduction reduced, as even if sound can get to the tympanic membrane it is not conducted to the brain
Mixed
Conductive and sensorineural loss
Conductive
Usually acquired disorder e.g. glue ear or other blockage, occasionally due to Eustachian tube deformity
Often mild and transient
Blockage between EAM and middle ear, thus bone conduction>air
Aetiology
Conductive
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Congenital/developmental
Down syndrome, cleft palate, midfacial hypoplasia
Congenital abnormalities of pinna, EAM, drum, ossicles
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Sensorineural
Infection
Congenital, meningitis, encephalitis,
measles, mumps, syphilis
Trauma
Head injury, noise induced
Metabolic
Hypoxic injury, hyperbilirubinemia, B12 deficiency
Congenital/genetic
Genetic syndromes e.g, Alport's
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Drugs
Aminoglycosides (gentamycin, vancomycin),
furosemide, chloroquine
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Management
Conductive
Conservative
Information, advice, support
Referral (audiometry and assessment)
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Surgical
Tympanostomy tubes
Indication: glue ear
MOA: drainage tubes (grommets)
to allow effusion to drain, restores hearing
Adenoidectomy
Indication: grommets not worked
MOA: removal of adenoids, reduces
incidence of adenoiditis and middle ear infections
Bone anchored hearing aids
Indication: intolerant of standard aids, congenital malformation
MOA: sound transmitted to cochlea via bone
Sensorineural
Medical
Hearing aids
Indication: severe, bilateral loss
MOA: amplification of sound; bone conduction
aids if underdeveloped ears
Surgical
Cochlear implant
Indication: hearing aids insufficient
MOA: electrode inserted into cochlea which
stimulates the auditory nerve when electrical
signal applied, need therapy to understand the new sounds
Conservative
Information, advice, support
Referral (audiometry and assessment)
Schooling (hearing units in mainstream schools,
special schools, seat front of the class, visual content)
SALT (sighning e.g. Makaton, lip reading)
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Screening
Universal newborn hearing screening
Within weeks of birth, OAE or ABR
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