Approach to deafness and hearing loss

Key points:

- Deafness may be conductive, sensorineural or a combination of both (mixed).

- deafness occurs at all ages but is more common in the elderly. Fifty per cent of people over 80 years have deafness severe enough to be helped by a hearing aid.

- The threshold o normal hearing is from 0 to 20 decibels, about the loudness of a soft whisper.

- One in seven of the adult population suffers from some degree of significant hearing impairment

- One child in every 1000 is born with a significant hearing loss

- Degrees of hearing impairment:
--- mild = loss of 20-40 dB (20 dB is soft-spoken voice)
--- moderate = loss of 40 - 70 dB (40 dB is normal spoken voice)
--- severe = loss of 70-90 dB (shout)
--- profound = loss of over 90 dB

- More women than men have a hearing loss

- People who have worked in a high-noise levels (>85dB) are more than twice as likely to be deaf

- There is a related incidence of tinnitus with deafness

- It is useful to consider the causes of deafness in terms of pathophysiology (conductive or sensorineural hearing loss) and anatomical sites

- Diagnostic strategy model

• Probability diagnosis 
• Impacted cerumen
• Serous otitis media 
• Otitis externa
• Congenital 
• Presbyacusis 
• Serious disorders not to be missed
• Neoplasia
• acoustic neuroma
• temporal lobe tumours (bilateral)
• otic tumours
• Severe infections
• generalised infections (e.g. mumps, measles)
• meningitis
• syphilis
• perforated tympanic membrane
• cholesteatoma
• Perilymphatic fistula 
• Meniere syndrome
• Pitfalls (often missed)
• Foreign body
• Temporal bone fracture
• Otosclerosis
• Barotrauma
• Noise-induced deafness
• Rarities
• paget disease of bone 
• multiple sclerosis 
• osteogenesis imperfecta 

- When to refer 

• sudden deafness
• any child with suspected deafness, including poor speech and learning problems, should be referred to an audiology centre
• Any child with middle-ear pathology and hearing loss should be referred to a specialist
• Unexplained deafness

Reference:

John Murtagh General practice 5th edition