(2013; 50 pages)
The World Health Organization (WHO) estimated in 2008 that over 360 million persons have disabling hearing loss which represents 5.3% of the world population. Eighty per cent of these people reside in low- or middle-income countries (LMIC). In Europe, about 52 million people are affected and more than 50% of European adults beyond 65 years old present slight to severe hearing loss according 2010 estimates. Epidemiological surveys are scarce and particularly in low-income countries as a result of difficulty field testing of hearing levels, poor diagnosis and reporting as well as lack of awareness of the problem leading to shortage of funding to conduct surveys. With the aging of the world population these numbers are expected to rise substantially.
Hearing loss is an important public health concern with substantial economic and societal costs. In infants and children hearing impairment retards developmental language and educational progress. In adults, it causes difficulties in both professional and social life as well as stigmatization. Apart from consequences to the individual person, hearing loss also leads to high costs to society.
Hearing impairment can be caused by a number of factors including infections during childhood such as measles, mumps and meningitis, chronic otitis media, exposure to excessive or prolonged noise, head/neck injuries, use of ototoxic medications such as certain types of chemotherapies and antibiotics, industrial solvents, congenital abnormalities and infections and perinatal problems, certain nutritional deficiencies, genetic disorders and aging.
Use of hearing devices such as aids and cochlear implants as well as sign language, lip reading and special amplification systems in schools are strategies to help affected people manage their communication. Although the prevalence of hearing impairment is high, very little research towards pharmaceutical treatment has been made in the previous decades.
Within the past few years, exciting research on genetic manipulation, gene therapy, and stem cell transplantation as well pharmaceutical agents, suggest that a therapeutic treatment for hearing loss may eventually be possible in the future.