Presbycusis

Presbycusis is age related, progressive, bilateral sensorineural hearing loss. It is the commonest cause of hearing impairment in older adults and one of the most prevalent chronic conditions in this population.

It characteristically affects higher frequencies preferentially in its early stages, then progressively involves a broader range of frequencies as it advances.

It has a substantial, well established impact on communication and social engagement. Accumulating longitudinal evidence increasingly links it to cognitive function and dementia risk.

This underscores the importance of proactive identification and management of a common, though frequently underrecognised and undertreated, condition.

Pathophysiology

• Progressive, cumulative degeneration of the cochlear hair cells underlies the characteristic pattern of predominantly high frequency sensorineural hearing loss. It particularly affects the outer hair cells in the basal turn of the cochlea, which are responsible for high frequency sound transduction.
• The spiral ganglion neurons and stria vascularis also degenerate.
• The loss reflects the cumulative effect of age related cellular senescence. It is compounded by lifetime noise exposure, genetic susceptibility, and contributing factors including vascular risk factors and ototoxic medication exposure.
• Early involvement of higher frequencies is disproportionate and has particular functional relevance. These frequencies are especially important for speech discrimination, particularly consonant sounds.
• Affected individuals therefore characteristically report particular difficulty understanding speech, especially with background noise. This occurs even before overall hearing loss becomes subjectively apparent across the full frequency range.
• This pattern is relevant both to recognition and to counselling the patient about the nature of their hearing difficulty.

• The characteristic presenting pattern is gradual, bilateral, symmetrical hearing loss developing insidiously over years. There is disproportionate early difficulty understanding speech, especially in noisy or group settings, and difficulty hearing higher pitched sounds and voices.
• Family members or close contacts frequently recognise it first. Onset is gradual and insidious, and the individual unconsciously compensates and adapts over an extended period before the loss becomes consciously apparent.
• Tinnitus frequently accompanies presbycusis, reflecting the shared cochlear pathology. It is a persistent perception of sound (typically ringing, buzzing or hissing) without any external source. It can be a significant, independently troublesome and distressing symptom.
• Important, common secondary consequences of untreated or inadequately managed presbycusis are social withdrawal, communication difficulty and frustration. In more severe cases they include depression and social isolation.
• Accumulating, increasingly robust longitudinal evidence also supports a significant, independent association between untreated hearing loss and increased risk of subsequent cognitive decline and dementia. This is a relatively recently established consideration. It reinforces the importance of proactive identification and management.
• The gradual, insidious, bilateral, symmetrical nature of presbycusis distinguishes it from several other causes of hearing loss.
• Any asymmetric, rapidly progressive or unilateral hearing loss warrants specific further investigation to exclude an alternative cause, including vestibular schwannoma or another retrocochlear pathology. It should not be attributed to presbycusis alone.

• Pure tone audiometry is the essential, standard diagnostic investigation. It shows bilateral, symmetrical sensorineural hearing loss. The audiometric configuration is typically downward sloping, reflecting the disproportionate early involvement of higher frequencies.
• Carefully assess for any asymmetry between the two ears, or any other atypical feature. These include a rapidly progressive rather than gradual onset, and associated vertigo or significant tinnitus disproportionate to the degree of hearing loss.
• This identifies the small proportion of presentations warranting specific further investigation, including magnetic resonance imaging to exclude vestibular schwannoma or another retrocochlear pathology. These should not be attributed straightforwardly to typical, symmetrical presbycusis.
• Review medications fully, given the recognised range with potential ototoxic effects. These include certain diuretics and, with well established, significant ototoxic potential, aminoglycoside antibiotics and platinum based chemotherapy agents.
• Assess the cumulative noise exposure history. Together with the medication review, this identifies any specific, potentially modifiable contributing factor. It also supports counselling about the multifactorial nature of the hearing loss.

• Hearing aid fitting is the primary, effective management for the great majority of patients with symptomatically significant presbycusis. It follows full audiological assessment, with device selection and fitting by a qualified audiologist.
• Modern hearing aid technology offers substantial, meaningful improvement in speech discrimination and overall communication for the great majority of appropriately fitted, motivated patients.
• Educate and counsel patients on realistic expectations for hearing aid use. Allow an appropriate acclimatisation period, with ongoing audiological support and device adjustment as needed. This supports optimal, sustained benefit, given the common initial adjustment period before patients are fully accustomed to and satisfied with their hearing aids.
• Assistive listening devices and environmental modifications are valuable, complementary adjuncts to hearing aids. They are particularly relevant for challenging listening situations. Examples are amplified telephone handsets and television listening devices.
• Communication environments can be optimised by reducing background noise and ensuring good lighting to support lip reading and visual communication cues.
• Cochlear implantation is an effective option for patients with severe to profound hearing loss not achieving adequate benefit from conventional hearing aid amplification alone. Confirm candidacy for this more invasive, surgically implanted device through full audiological and, where relevant, specialist assessment.
• Untreated hearing loss is increasingly recognised as significantly associated with cognitive decline. It also has a substantial, well established impact on communication, social engagement and quality of life.
• Proactive screening for presbycusis in older adults is therefore an important component of holistic older adult health assessment. Refer promptly for audiological assessment and hearing aid fitting where significant hearing loss is identified.
• Regular, ongoing audiological follow up supports continued optimisation of hearing aid function and management of any progressive change in hearing over time.