[ Dr P Ringu ]
Hearing loss is the most common sensory deficit in humans today. Worldwide, it is the second cause for ‘years lived with disability’, the first being depression. Around 466 million people worldwide have disabling hearing loss and 34 million of these are children.
In India, according to WHO (2018) data, the prevalence of hearing impairment is around 6.3 percent (63 million people suffering from significant hearing loss). The estimated prevalence of adult-onset deafness is 7.6 percent and childhood-onset deafness is 2 percent.
For the sake of definition, let’s remember that hearing loss is hearing impairment (HI), ie, diminished hearing of various degrees. Examples are mild, moderate, severe and profound hearing loss.
Deafness is defined as the inability to use our hearing as a primary channel for hearing speech, even with amplification.
Causes of HI can be divided into two categories – the first one can be grouped as causes before and during birth. They are: (a) Genetic (hereditary) causes. Congenital causes mean those causes that are already present when the baby is born. The first group of congenital causes is genetic causes. Genes are the structures on the chromosomes in either the sperm (from father) or the ovum (from mother) that determine what we inherit from our parents. Hearing impairment could run in the family.
(b) Besides, consanguineous marriage, ie, marriage between people who are closely related, may give birth to a deaf baby.
(c) Also, diseases during pregnancy like Rubella (German measles) and other viral infections, syphilis and administration of drugs which can damage hearing can lead to deafness.
(d) Difficulties at birth, eg, premature or low birth weight baby, birth asphyxia, jaundice after birth can harm the baby’s hearing organs.
Risk factors and some preventive measures: (a) If parents were born deaf then there is a risk that their children will be born deaf. Counselling may be needed if such parents are thinking of having children.
(b) Rubella during pregnancy is a risk because it can damage the development of the hearing organ of the inner ear. Hence, parents should be encouraged to immunize all children against Rubella at 12 to 15 months of age. Adolescent girls, 13-15 years of age should be given a repeat dose of Rubella vaccination.
(c) Pregnant women should be screened for syphilis and treatment to be given if necessary.
(d) Drugs that can damage hearing should not be given or used during pregnancy unless prescribed by a doctor.
(e) Good antenatal care should be provided and births should be supervised.
(f) Jaundiced babies should be referred for diagnosis and possible treatment.
(g) Babies who suffer birth asphyxia should be screened for hearing loss.
(h) Babies with birth weight less than 1.5 kg are also at risk for hearing loss.
The second category of causes that lead to HI are – (a) Childhood disease like measles, mumps and meningitis.
(b) Ear infections. It is one of the commonest causes of hearing loss amongst the children of our country. Infections of the ear may be acute or chronic. Chronic infections are usually characterised by presence of recurrent or persistent discharge from the ears.
(c) Drugs which can damage hearing (ototoxic drugs), eg, Streptomycin, Gentamycin, Chloroquine, Quinine
(d) Noise, ie, working with noisy machinery, loud music, explosions (e) Accidents. Head injury or injury to the ear can cause hearing impairment. Slapping to face or ear is to be avoided at all cost.
(f) Old age. As people get older, they usually develop some hearing problems. This is age-related and such persons can be often helped with the use of hearing aids.
(g) Wax blocking the ear canal can cause HI at any age. It is one of the most widely prevalent ear conditions.
(h) Glue ear. It is a common cause of HI in children.
Less common causes, risk factors and some preventive measures: (a) Neonatal jaundice can damage the hearing nerve. They can prevent HI by referring these babies for treatment.
(b) Childhood infections can be prevented by applying the expanded programme of immunization (EPI) in their community.
(c) Early treatment of ear infections can prevent damage to the middle ear.
(d) Drugs that can damage hearing should only be given on prescription by a doctor.
(e) We need to educate the community about the harmful effects of loud noise.
(f) We should encourage cyclists and motorcyclists to always wear protective helmets.
The World Hearing day is an annual event held on 3 March to raise awareness on hearing loss prevention and hearing care.
The event is being observed in all the parts of the country and by the state NPPCD (National Programme for Prevention and Control of Deafness) cell, DHS office, and the districts where the programme is implemented. Various IEC activities, including free ear screening camps, are being organized on this day.
The long-term objective of the programme is to prevent and control major causes of HI and deafness, so as to reduce the total disease burden by 25 percent of the existing burden. (Dr P Ringu is State Nodal Officer, NPPCD)