According to the recent infant screening in India 5-6 infants out of 1000 born with hearing loss. It is not identified till they attain 2 or more years of age but by then the irreversible damage would have been done. So, it is advised to have the screening for the hearing of newly born.
Hearing loss at the time of birth is called congenital hearing deafness. Approximately 50% of the hearing loss caused is genetic,25% is acquired and 25% caused due to an unknown cause. Inner ear abnormality such as Mondini dysplasia with variable inheritance patterns results in 20% of the Congenital sensorineural deafness and the remaining does not have distinguishing features. It depends on 2 factors:
Genetic factors(Inherited congenital deafness)
Hearing loss from the genetic defect can be present at the time of birth or develop later in life. It causes more than 50 % of the hearing loss.
- Non-syndromic deafness- About 80% of genetic disorder is non- syndromic. It has two types, Autosomal dominant (DFNA) and Autosomal recessive (DFNB).
- Syndromic deafness-About 20% of genetic disorder is syndromic.
- X-linked Charcot Marie Tooth (CMT)
Non-genetic factors(Non inherited congenital deafness)
It causes 20 % congenital deafness. These disorders can be linked to genetic disorders but mostly occur independently.
- Viral syndrome- It is often connected with prenatal infections with viruses such as measles. Infants exposed to a bodily fluid such as breast milk, saliva and urine can transfer these viruses.
- Mancini and Michel dysplasia- It is caused due to membranous abnormality, a bony abnormality or a combination of both two.
- Malformation of inner auditory meatus- It is caused because of the unusually sized opening between the inner ear and the brain(inner auditory meatus) and their association with the other bone abnormality
There are others factors also such as lack of oxygen(anoxia), Maternal diabetes, complications associated with the RH factor in the blood/Jaundice, Toxemia during pregnancy etc.
For a healthy and fully active life, early detection of hearing loss is a must. So, consult the doctor because congenital hearing loss requires identification as soon as possible.