In order to be able to hear and understand speech, three basic processes of the auditory system are required to work together to accomplish this: the peripheral auditory system can receive stimuli from external sounds, the auditory nerve can transmit these sounds to the central auditory system, and the central auditory system can analyze and perceive the sounds.
However, as people age, the auditory system degenerates and leads to dysfunction of the auditory system (both peripheral and central components). This hearing loss that occurs as a result of age-related degeneration of the auditory system, excluding the involvement of noise, ototoxic drugs and middle ear infections, is known as age-related deafness.
Age-related deafness is a disease of the elderly that occurs gradually with age and can lead to profound deafness in severe cases, and is a manifestation of the aging process of the human body in the auditory organs. 2005, the proportion of elderly people over 65 years of age in China was 7.69%, and by 2050, this proportion will reach 25%. Hearing loss is a very common phenomenon among the elderly population. Relevant epidemiological surveys show that the incidence of pure tone hearing threshold greater than 25dB is 10.1% in people aged 55-64 years, and with further increase in age, the proportion of their hearing loss increases to 26.2% in people aged 65-74 years. Age-related deafness has become one of the most common chronic diseases in modern society.
Age-related deafness can be caused not only by damage to the peripheral auditory organs, but also by dysfunction of the entire auditory conduction pathway. There are two types of deafness: central and peripheral, but most of them are mixed. Pathological changes in the auditory center in patients with senile deafness are related to age-related degeneration of the auditory center, or to reduced or absent peripheral input to the center. In addition, with increasing age, cerumen tends to accumulate in the external auditory canal, leading to embolization of cerumen. The external auditory canal collapses, especially as the skin atrophies, becomes less elastic, and dehydrates and dries. These changes result in reduced resistance of the external auditory canal to injury as well as less tolerance to hard materials. Damage to the skin of the external ear canal should be considered when patients are fitted with canal hearing aids or require ear molds.
As age increases, changes in the middle ear are manifested by reduced vascularity, thinning and elasticity of the tympanic membrane, aging of the anvil and anvil joint, as well as atrophy and degeneration of the middle ear muscles and ligaments, and calcification and ossification of cartilage. In conclusion, the above mentioned changes in the middle and outer ear that occur due to age are common, however they have less impact on sound transmission but can affect the effectiveness of hearing aid use.
Clinical manifestations of senile deafness
1. Bilateral symmetrical sensorineural deafness is predominant. In a few cases, the degree of bilateral deafness may not be the same, and in a few cases, the hearing loss may be mixed with degenerative lesions of the outer ear or middle ear.
2. Hearing loss is slowly progressive. In the early stage, it is not noticed. When the hearing loss reaches a certain level, the patient will suddenly feel the hearing loss and have difficulty in communication, which will be misdiagnosed as sudden deafness. Most of the elderly hearing loss starts with high-frequency hearing loss, and patients are only insensitive to high-frequency sounds such as doorbell, telephone ringing, bird chirping, etc.
3. Low speech recognition is the first symptom. This symptom only appears in special environment at the beginning, such as when many people talk at the same time in public, and then the difficulty of conversation occurs gradually. Most elderly people have some degree of tinnitus, mostly high tonality, which starts only at the late night and gradually worsens and lasts all day.
4. Central age-related deafness is caused by aging of the brain. The study of central deafness in the elderly is often affected by the aging of peripheral auditory organs again, which can be clinically manifested as decreased perception of external sound, distortion of perception of external sound, disorder of central processing of external information, obvious hearing impairment in noisy environment, impaired localization of sound, etc., and make the detection and judgment of central auditory function in the elderly complicated.
Hearing aids, the “life partner” of elderly deaf patients
Currently, there is no effective medication for the treatment of senile deafness, and the main effective strategy for intervention is to wear hearing aids. Generally speaking, it takes 1-2 months to get used to wearing hearing aids. In addition, hearing aids work better indoors to distinguish various languages, but not in public places and noisy environments because the noise is also amplified.
Mild deafness generally does not require hearing aids, and hearing aids can be worn by people with a hearing loss of 35-85 decibels. Hearing loss of about 60 decibels is the best. Severe deafness can also be fitted, but the distortion of the hearing aid increases and often does not achieve the desired effect. For very severe deafness, although hearing aids can increase the sound, their speech recognition rate is very low, so there is no practical value, and cochlear implants can be considered at this time.
Currently, cochlear implantation is carried out in foreign countries for elderly deaf patients with severe and profound deafness and has achieved better results, and the patients’ speech rehabilitation has been significantly improved and their quality of life has also been significantly improved.
When communicating with the elderly deaf patients in daily life, they should speak clearly and naturally without shouting. In addition, when talking with the elderly, the presence of competing sound sources should be avoided, so the TV and radio should be turned off and other sound sources.
How to prevent age-related deafness
Aging is a gift from nature that we cannot refuse, but we can take steps to delay the arrival of this “gift”. This requires an understanding of the causes of age-related deafness.
The etiology of age-related deafness is complex and its pathogenesis is not yet fully understood. The possible causes include not only the aging process of the auditory system, but also the influence of environmental and social factors in life. The age of onset and the rate of progression of senile deafness are associated with genetic factors. The author is currently engaged in related research with the aim of providing new strategies for the prevention and treatment of age-related deafness. In addition, senile deafness is also related to environmental factors, such as environmental noise, atherosclerosis, hypertension, high-fat diet, smoking and alcohol abuse, ototoxic drugs or chemical reagents, infections, and increased stress in thought life. Avoiding noise in daily life should be done from a young age to avoid chronic damage to the auditory organs.
The prevention of senile deafness should also pay attention to the combination of work and rest, keep a relaxed mood; pay attention to dietary hygiene, reduce fatty foods; quit smoking and alcohol, prevent and control cardiovascular diseases and other systemic diseases; avoid exposure to noise; use ototoxic drugs with caution; and perform appropriate physical exercise.
In addition, we should pay attention to the fact that due to long-term hearing impairment, elderly deaf patients may feel socially isolated and their quality of life may decrease due to reduced communication with people around them. This emotional disorder deserves the attention of family and society.