Deafness and hearing loss Flashcards
Deafness is defined as
impairment of hearing
- regardless of its severity.
It is a major community health problem
- requiring a high index of suspicion for diagnosis, esp. in children.
Types of deafness
Deafness may be:
- conductive
- sensorineural (SND) or
- a combination of both (mixed)
Causes
Deafness occurs at all ages
- but more common in the elderly—50%>80 yr
- that could be helped by a hearing aid.
People who have worked in high noise levels (>85 dB) are more than twice as likely to be deaf.
There is a related incidence of tinnitus with deafness.
Degrees of hearing impairment:
The threshold of normal hearing is:
- from 0 to 20 dB
- about the loudness of a soft whisper
Mild = loss of 20–40 dB (soft spoken voice is 20 dB)
Moderate = loss of 40–60 dB (normal spoken voice is 40 dB)
Severe = loss of 70–90 dB (loud spoken voice)
Profound = loss of over 90 dB (shout is 90–120 dB)
Probability diagnosis
Impacted cerumen
Serous otitis media (glue ear)
Otitis externa
Otitis media
Congenital (children)
Presbyacusis
Serious disorders not to be missed
Neoplasia:
- acoustic neuroma
- temporal lobe tumours (bilateral)
- otic tumours
Infection:
- generalised infections (e.g. mumps, measles)
- meningitis
- syphilis
Other:
- perforated tympanic membrane
- cholesteatoma
- perilymphatic fistula (post-stapedectomy)
- Meniere syndrome
Pitfalls (often missed)
Foreign body
Temporal bone fracture
Otosclerosis
Head injury
Barotrauma
Noise-induced deafness
Rarities:
- Paget disease of bone
- multiple sclerosis
- osteogenesis imperfecta
Masquerades checklist
Diabetes
Drugs (see list)
Thyroid disorder (hypothyroidism)
Is the patient trying to tell me something?
Unlikely.
Key history
- Onset and progression of any deafness
- noise exposure
- drug history
- swimming or diving
- air travel, head injury
- family history.
- recent or past episode of a generalised infection
- ssociated aural symptoms such as ear pain, discharge, tinnitus and vertigo.
- enquire about the effect of noise.
Key examination
Inspect the facial structures, skull and ears and the ear with an otoscope.
Ensure that the external auditory canal is clean
Perform simple office hearing tests including tuning fork tests
Key investigations
Audiometry and tympanometry
Swab of any ear discharge for M&C
Diagnostic tips
People with conductive deafness tend to speak softly, hear better in a noisy environment and hear well on the telephone.
The opposite applies for sensorineural deafness.
Ototoxic drugs:
- alcohol
- aminoglycosides e.g. streptomycin, neomycin, gentamicin, tobramycin
- chemotherapeutic agents
- quinine
- salicylates/aspirin excess
- diuretics e.g. ethacrynic acid, frusemide.
Red flags that warrant referral
asymmetric sensorineural hearing loss
cranial nerve defects
ear canal or middle ear mass
deep ear pain
discharging ear
