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Hearing Loss
A growing problem that affects quality of Life

S. Rakholiya, S. Savaliya, A. Marar, M. Donasiya – EON Meditech Pvt. Ltd.

Introduction 

In this article, the term hearing loss, used by itself, denotes any or all levels of severity of hearing difficulty. These levels of hearing impairment comprise mild HL (26-40 decibel hearing level, dB), moderate HL (41-60 dB), severe HL (61-80 dB), and profound HL (81 dB or greater)1. Hearing loss is the most frequent sensory deficit in human populations, affecting more than 255 million people2,3 in the world (2002). Consequences of hearing impairment include inability to interpret speech sounds, often producing a reduced ability to communicate, delay in language acquisition, economic and educational disadvantage, social isolation and stigmatization2.
Most congenital and childhood onset hearing loss is included as sequel to various disease and injury causes already included in the Global Burden of Disease Study. Examples include otitis media, meningitis, rubella, congenital anomalies and non-syndromal inherited hearing loss2.

Those 192 million people with adult-onset loss (age 20 years and above) and 63 million people with childhood-onset loss make up almost 4.1 percent of the world's population and just over 40 percent of all people globally with hearing loss of any severity. Numbers with childhood-onset hearing loss by cause have so far not been estimated separately but are included among sequel of other diseases (for example, infectious diseases such as meningitis, otitis media, congenital conditions).


Causes and Characteristics

Hearing loss is grouped according to International Classification of Diseases and Related Health Problems, 10th revision, version for 2003 (ICD-10) into conductive and Sensorineural loss and other hearing loss, ICD-10 codes 90-91(WHO 2003).

Chronic otitis media (COM) includes chronic suppurative otitis media and otitis media with effusion. These forms of otitis media, together with some other middle ear diseases, such as perforation of the tympanic membrane, cholesteatoma, and otosclerosis, are the major causes of conductive hearing loss1.


Conductive hearing loss
is caused by anything that interferes with the transmission of sound from the outer to the inner ear. Below are some possible causes of conductive hearing loss.

  1. Middle ear infections (otitis media).
  2. Collection of fluid in the middle ear ("glue ear" in children).
  3. Blockage of the outer ear, most commonly by wax.
  4. Otosclerosis.
  5. Damage to the ossicles.  

Sensorineural hearing loss is due to damage to the pathway that sound impulses take from the hair cells of the inner ear to the auditory nerve and the brain. Below are some possible causes.

  1. Age-related hearing loss (presbyacusis).
  2. Acoustic trauma (injury caused by loud noise) can damage hair cells.
  3. Meningitis can lead to loss of hair cells or other damage to the auditory nerve.
  4. Meniere’s disease.
  5. Acoustic neuroma. This is a benign tumor affecting the auditory nerve.

Deafness in children
If a pregnant woman gets rubella, the baby is at risk of being born with profound deafness (among other possible birth abnormalities). This is one reason why vaccination against rubella, available in the UK as the MMR (measles, mumps and rubella) vaccine, is so important. Cytomegalovirus is a common and relatively harmless virus in healthy adults, but if a woman gets exposed to it for the first time while pregnant, it can cause significant hearing loss in the unborn child.


Statistics Data Hearing Loss

Total world population at the end of 2008 is 6.75 billion. There is 6-8% deaf population suffering from Moderate to Severe Hearing loss. According to WHO, There are 255 million (4.25%) deaf people out of total 6 billion (Census, IDB) world population. There are approx. 500 million (AHAA) deaf people round the world.  By the year 2015 the figure is estimated to be 700 million (Hear-it) (Figure1). (Source: WHO & Hear-it)

(Figure-1: Percentage of Deaf People Worldwide)

More than 50% deaf people are in Asia region. The elderly were more likely than any other age group to have hearing problems. Persons 50 years and older are eight times more likely to have hearing impairment than persons ages 16-35 (Figure-2, Figure-3).

(Figure-2, Worldwide Deafness, Source:
www.wrongdiagnosis.com  census (IDB))

(Figure-3, Source: RNID, Annual Survey Repot, 2005)


The prevalence of hearing loss differs according to gender. The overall prevalence is 10.5 percent for males and 6.8 percent for females. While males at all ages are more likely than females to be deaf or hard-of-hearing, the gap widens after age 18 (Figure-4, (Source: National Academy of Aging Society).

Of the estimated 500 million deaf and hard-of-hearing people, 23.4% report that their loss is due to some sort of noise.

  1. Otosclerosis.
  2. Damage to the ossicles.  

Sensorineural hearing loss is due to damage to the pathway that sound impulses take from the hair cells of the inner ear to the auditory nerve and the brain. Below are some possible causes.

  1. Age-related hearing loss (presbyacusis).
  2. Acoustic trauma (injury caused by loud noise) can damage hair cells.
  3. Meningitis can lead to loss of hair cells or other damage to the auditory nerve.
  4. Meniere’s disease.
  5. Acoustic neuroma. This is a benign tumor affecting the auditory nerve.

Deafness in children
If a pregnant woman gets rubella, the baby is at risk of being born with profound deafness (among other possible birth abnormalities). This is one reason why vaccination against rubella, available in the UK as the MMR (measles, mumps and rubella) vaccine, is so important. Cytomegalovirus is a common and relatively harmless virus in healthy adults, but if a woman gets exposed to it for the first time while pregnant, it can cause significant hearing loss in the unborn child.


Statistics Data Hearing Loss

Total world population at the end of 2008 is 6.75 billion. There is 6-8% deaf population suffering from Moderate to Severe Hearing loss. According to WHO, There are 255 million (4.25%) deaf people out of total 6 billion (Census, IDB) world population. There are approx. 500 million (AHAA) deaf people round the world.  By the year 2015 the figure is estimated to be 700 million
(Hear-it) (Figure1).

(Source: WHO & Hear-it) % report that their loss is due to some sort of noise.
Another 28% report that their loss is due to age, while 12.2% report that it is due to infection or injury. Only 4.4% report the presence of hearing loss at birth (Figure-5). (Figure-4: Percentage of Deaf in Gender, Age wise)
(Figure-5, Causes of Hearing Loss, Source: National Centre for Health Statistics)


Conclusion
Hearing loss and deafness are serious disabilities that can impose a heavy social and economic burden on individuals, families, communities and countries. Children with hearing impairment often experience delayed development of speech, language and cognitive skills, which may result in slow learning and difficulty progressing in school. In adults, hearing impairment and deafness often make it difficult to obtain, perform, and keep employment. Its big challenge to our society is to help and support the deaf people who are unable to afford and are uncapable to take of own health.


Reference

Chapter 50, Loss of vision and hearing, Nature, Causes, and Epidemiology of Hearing Loss, Disease control priority project.

  1. Colin Mathers, Andrew Smith, Marisol Concha, Global burden of Hearing loss in the year 2002, World Health Organization, Geneva.
  2. Bridget Shield, Evaluation of the social and economic costs of hearing impairment, a report for hear-it, October 2006.
  3. World Health Organization Report, 2001.
  4. www.hear-it.org
  5. RNID Annul Survey Report.
  6. National Academy of Aging Society.
  7. National Centre for Health Statistics.
     
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