Describe presbycusis.

Nature and Types

• Presbycusis is the bilateral, symmetrical, progressive sensorineural hearing loss of ageing.
• It is the commonest cause of hearing loss overall, and the commonest cause of disability in the elderly after arthritis and hypertension.
• It is a diagnosis OF exclusion, made only after noise exposure, ototoxicity, otosclerosis and a retrocochlear lesion have been considered — and an asymmetric loss is not presbycusis
• Contributing factors — genetic susceptibility; cumulative noise exposure over a lifetime; vascular disease, diabetes and hypertension; smoking; and ototoxic drugs
• Schuknecht described four pathological types.
• Sensory — loss of outer hair cells at the basal turn, giving an abrupt high-frequency loss with relatively good speech discrimination
• Neural — loss of spiral ganglion cells, giving a severe loss of discrimination out of proportion to the pure tone thresholds — the type that does worst with a hearing aid
• Strial (metabolic) — atrophy of the stria vascularis, giving a flat audiogram with good discrimination — the type that does best with an aid
• Cochlear conductive (mechanical) — stiffening of the basilar membrane, giving a gradually sloping loss

Management and Consequences

• There is no medical cure; management is rehabilitative and it is genuinely effective
• Hearing AIDS are the mainstay, fitted bilaterally where both ears are affected, with realistic counselling that an aid amplifies but does not restore normal hearing, and that background noise remains difficult
• Assistive devices — amplified telephones, television listeners, loop systems and alerting devices
• Communication strategies for the family.
• Cochlear implantation for those with severe to profound loss and poor benefit from aids, and age is not a contraindication — results in the elderly are good and this is frequently not offered
• The consequences OF untreated presbycusis are the reason IT matters, and are consistently under-appreciated: social withdrawal and isolation; depression; loss of independence; and an association with cognitive decline and dementia, hearing loss being one of the largest potentially modifiable risk factors for dementia
• Safety consequences — failure to hear alarms, traffic and doorbells, and increased falls
• Treat the treatable — wax is the commonest reversible cause of worsening hearing in an elderly person and should be excluded before anything else; and treat any coexisting middle ear disease
• An asymmetric loss is not presbycusis, and demands an MRI rather than a hearing aid
• Speech audiometry predicts aid benefit better than the pure tone average, and is the test that matters most