From the Guidelines
Presbycusis is a complex age-related hearing loss that occurs due to progressive degeneration of the auditory system, involving multiple mechanisms including loss of sensory hair cells, atrophy of the stria vascularis, neural degeneration, and microvascular changes, as supported by recent studies 1. The pathophysiology of presbycusis involves several key factors, including:
- Loss of sensory hair cells in the cochlea, especially in the basal turn which processes high-frequency sounds, leading to high-frequency hearing loss as the first manifestation
- Atrophy of the stria vascularis, which maintains the endocochlear potential necessary for proper hair cell function, resulting in metabolic dysfunction
- Neural degeneration, including deterioration of spiral ganglion neurons and central auditory pathways, reducing signal transmission efficiency
- Diminishing cochlear blood supply with age, causing microvascular changes and oxidative stress that further damage hearing structures
- Genetic factors influencing susceptibility, while environmental factors like noise exposure, ototoxic medications, and vascular diseases can accelerate the process
- Mitochondrial dysfunction and accumulated oxidative damage contributing to cellular death in the cochlea These changes typically manifest gradually over decades, resulting in bilateral, symmetric, sensorineural hearing loss that progresses from high to low frequencies, often accompanied by reduced speech discrimination that exceeds what would be expected from the pure-tone audiogram alone, as described in a recent clinical practice guideline 1. Key factors that contribute to the development and progression of presbycusis include:
- Age, with hearing loss increasing significantly after the age of 50
- Genetic predisposition, with approximately half of the variance in age-related hearing loss estimated to be heritable
- Environmental factors, such as noise exposure and ototoxic medications
- Chronic medical conditions, such as hypertension, diabetes, and hypercholesterolemia, which may influence the development of hearing loss
- Sociodemographic factors, including higher prevalence of age-related hearing loss in males compared to females, and increased risk of hearing loss in individuals with lower household income and unemployment.
From the Research
Definition and Characteristics of Presbycusis
- Presbycusis, or age-related hearing loss, is a progressive, bilateral, and symmetrical sensorineural hearing loss due to age-related degeneration of inner ear structures 2.
- It is a multifactorial complex disorder with environmental and genetic factors contributing to its development 2, 3.
- Presbycusis typically affects the high frequencies of hearing, leading to poor speech recognition and negative impacts on cognitive, emotional, and social function in older adults 2.
Pathophysiology and Contributing Factors
- The pathophysiology of presbycusis involves molecular, electrophysiological, and histological damage at different levels of the inner ear 2.
- Contributing factors include mitochondria DNA mutation, genetic disorders, hypertension, diabetes, metabolic disease, and other systemic diseases, as well as extrinsic factors such as noise, ototoxic medication, and diet 3.
- Age-related changes also develop in the central hearing system, leading to functional decline and reduced speech-understanding in noisy backgrounds 3.
Classification and Types of Presbycusis
- Presbycusis is classified into six categories based on audiometric tests and temporal bone pathology: sensory, neural, metabolic or strial, cochlear conductive, mixed, and indeterminate types 3.
- Metabolic presbycusis is considered the mainstay of presbycusis types 3.
Impact and Treatment of Presbycusis
- Presbycusis can have a significant impact on patients' quality of life, leading to symptoms such as depression, social isolation, and lower self-esteem 2, 3.
- Hearing aids are the most commonly used devices for treating presbycusis, and technical progress in implantable hearing devices allows for effective hearing rehabilitation even in elderly patients with severe hearing loss 2.