By Dr Firdous Quader Minu
M.B.B.S, D.L.O ENT, Head-Neck
& Cosmetic Surgeon,
Last week we delved into the social disruptions caused by loss of hearing in the elderly population. This week we zero in on the clinical aspects:
Anatomic and physiologic correlates of hearing loss
Aging affects the external ear and canal primarily by altering the nature of skin and cerumen glands present therein. Cerumen glands are modified sweat glands and are found in addition to apocrine glands in the ear canal. The secretions from these glands, in addition to desquamated skin, combine to form cerumen.
The aging process causes a reduction in the activity of the apocrine sweat glands and a decrease in the number of modified apocrine or cerumen glands. The reduced activity and number of cerumen glands do correlate with the tendency for the cerumen or the wax of individuals to become dryer.
Thus, cerumen or wax impactions tend to be more common in the ear canals of older patients, causing conductive type of deafness. Dryness of the skin contributes to itching in the external auditory canal.
The skin is often atrophic and is injured by insertion of cotton tip applicators provoked by itching. This may cause trauma to the tympanic membrane and infection leading to otitis externa and otitis media and thus conductive type of hearing loss.
The effectiveness of the middle ear sound conduction mechanism depends on the function of the small bones and its joints present. The aging process causes degenerating changes in the articular surfaces throughout the body and those of the ears are not spared.
Histological studies have shown degenerating changes in the joints with age. Calcification and even obliteration of the spaces may occur. This causes stiffness of joint movement and ultimately deafness occurs. Also, repeated infections of the middle ear cause loss in bony function leading to deafness.
The main function of the inner ear is sensory transmission of sound through the cochlea and the auditory nerves to the higher centre, and also to maintain balance through the vestibular apparatus.
As with so many other organ systems in the body, the auditory system also starts to function with decreasing efficiency after the fourth and fifth decades of life. This is mainly due to degenerative changes in our body. Due to this, the patient may develop sensory neural deafness which is also known as presbyacusis.
Cells of the auditory pathways are unique, they cannot reproduce, they have very limited regenerative ability; therefore, the length of their cell life is determined by environmental influences and their ability to adjust and adapt. Numerous variables contribute to the degeneration of sensory and neural elements. These may include diet and nutrition, cholesterol metabolism, arteriosclerosis and the organs' response to physical stress. It is precisely not known how these affect the auditory pathway and contribute to the onset of age-dependent hearing loss.
Clinical evaluation of hearing loss
The identification and evaluation of hearing disorders should be an integral component of geriatric medicine, although the subject is often neglected by primary caregivers. It has been suggested that primary caregivers look onto hearing loss at old age as something inevitable -- a by product of aging and that there is little value in diagnosis and rehabilitation of the patient.
Identification of hearing loss
Even though the elderly do not generally appear with medically manageable hearing loss, physical examination of the ear is necessary and important, so as to rule out treatable causes. Then careful history should be taken regarding specific hearing difficulties, like hearing in the distance, hearing on the phone and so forth.
Usually, the individual will be able to hear quite well in the confines of the office but not in crowded places. The best tool to diagnosing hearing loss is to conduct a proper audiological evaluation. This includes an audiogram and speech discrimination test.