Presbycusis is a hearing disorder manifested by a gradual and constant decrease in hearing acuity with age. It is caused by the natural physiological aging of the auditory system. Often imperceptible before the age of 60, presbycusis can quickly become disabling. Its diagnosis is carried out by a doctor specializing in Otorhinolaryngology who then passes the baton to an audioprosthetist in order to set up suitable hearing aids.

Definition of presbycusis

Presbycusis is a hearing disorder that manifests itself as a gradual and constant decrease in hearing acuity with age. It is caused by the natural aging of the hearing system.

Presbycusis begins at the age of 25, affecting the auditory field in very high frequencies. It often remains imperceptible before the age of 60. Average hearing loss, which varies greatly from person to person, then declines by 0,5 decibel (dB) per year from age 65, 1 dB from age 75 and 2 dB from age 85.

Types of presbycusis

Four main types of presbycusis can be isolated:

• Sensory presbycusis results in a drop in hearing that only affects high frequencies;
• Nervous presbycusis leads to altered high frequency thresholds and vocal frequency distinctions;
• Presbycusis linked to blood circulation affects all frequencies;
• Mechanical presbycusis reaches high frequencies.

In reality, most presbycusis are mixed in form and combine these different types to varying degrees.

There are also indeterminate forms of presbycusis, especially in situations where hearing impairments affect the low frequencies.

Causes of presbycusis

Presbycusis results from various changes, directly related to aging, within the auditory system:

• Sensory cells in the organ of Corti undergo degeneration. The external, non-renewable hair cells are the most affected: these contractile cells in particular allow frequency selectivity (sensory presbycusis);
• The ossicles which amplify and transmit vibrations from the eardrum to the cochlea lose their flexibility;
• The regular decrease, at a rate of about 2 neurons per decade, of some 100 neurons present in the cochlea (nervous presbycusis);
• Damage to the central nervous system: the nerve fibers transmitting auditory information from the cochlea to the brain and the centers in the brain analyzing this information are less efficient;
• The vascular stria – richly vascularized tissue that lines the lateral wall of the cochlear canal – is less well irrigated and causes less oxygenation of the hearing organs (presbycusis linked to blood circulation);
• The basilar membrane and the spiral ligament are damaged (mechanical presbycusis).

Diagnosis of presbycusis

The diagnosis of presbycusis is carried out by a specialist in Otorhinolaryngology (ENT) using a series of specific examinations:

• Otoscopy is used to check the normal condition of the ear canal and the tympanic membrane;
• Tonal audiometry tests the hearing threshold at different frequencies on the right side and on the left side. It detects hearing loss of pure tones, bilateral and symmetrical, affecting the treble more than the bass;
• Speech audiometry detects disorders related to the understanding of words, syllables, phonetics and discrimination of background noise.

People affected by presbycusis

Presbycusis affects the entire population. It increases from the age of 60 and remains the most common cause of deafness in the elderly.

Factors favoring presbycusis

Different factors, which vary greatly from person to person, can contribute to the early onset and worsening of presbycusis:

• Genetic factors: some families demonstrate a heredity of precocious presbycusis;
• Arteriosclerosis: people who suffer from excess cholesterol, high blood pressure or smokers;
• Diabetes: this disease causes serious disorders of the small blood vessels in the cochlea;
• Medicines toxic to the cochlea when taken frequently: certain antibiotics and non-steroidal anti-inflammatory drugs (aspirin, paracetamol, ibuprofen, etc.).

Diminished conversational intelligibility

The patient is embarrassed during conversations with several people, during meetings, in the presence of background noise or background music.

Raised hearing thresholds

The hearing discomfort is clear and the intensity of the perceived sound must be increased so that the subject can perceive it.

Decrease in frequency discrimination

Speech comprehension is disturbed even when its volume is amplified.

Other symptoms

• Acouphenes ;
• Social impact: the patient has difficulty communicating;
• Isolation: the patient gives up communicating;
• Installation of a depressive syndrome;
• Total deafness.

No drug has yet been proven to treat presbycusis. But it can, on the other hand, be corrected using a hearing aid. Its prescription must be as early as possible and a fortiori as soon as the hearing loss exceeds an intensity of 30 decibels (dB) from a frequency of 2 Hertz (Hz) – knowing that the human ear perceives sounds between 000 Hz and 20 Hz.

After the examination of the ENT doctor, an experienced hearing care professional will allow the choice and the optimal adjustment of a hearing aid adapted to the specific needs of the patient.

The prescription of rehabilitation sessions carried out by a speech therapist allowing the learning – or improvement – of lip reading can advantageously complement these devices.

Here are a few tips to avoid worsening presbycusis and to remedy it as soon as possible:

• Avoid chronic exposure to loud noises, such as listening at too high a volume through headphones or earphones;
• Regularly monitor the quality of his hearing.