Pathology of hair cells and neurones
Overview / Aminoglycosides / Noise Trauma / Excitotoxicity / Presbycusis / Tinnitus

Presbycusis: deafness of ageing
Among sensory systems, hearing is certainly the most commonly impaired in the elderly. This is explained in humans by the inability to regenerate cochlear sensory cells. With ageing, hair cells and neurones disappear, leading to a progressive hearing loss starting in the high frequencies.

Main factors of presbycusis: Hawkins' formula (ref.e1)
This formula of Joe Hawkins is still a very good one indeed. It shows that presbycusis is actually the result of the sum of ototoxic drugs + the sum of noise trauma + the age itself. To update this formula, only genetic factors may be added, which account for a differential susceptibility to any one of these factors.

Ageing and hearing loss
These two curves represent average audiograms at 65 years (blue) and 90 years (red).

These are control subjects: i.e. with no history of significant exposure to ototoxic drugs or noise.

The younger generation, increasingly exposed to loud leisure noise, may well reach the blue level at 30, and the red one at 50 !

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