Nonsyndromic hearing loss (NSHL) is a partial or total loss of hearing that is not associated with other signs and symptoms. The most important risk factor is genetic predisposition. There are various types of inheritance and depending on the genes involved there is a different presentation of NSHL. It can be sensorineural (sound can't be perceived or the signal transmitted to the brain), conductive (sound waves don't reach the inner ear), or mixed, stable or progressive, prelingual or postlingual, mild or severe. The screening examinations in children (during routine checkups with pediatricians) are important to prevent language, communication, and cognitive complications. The treatment usually involves hearing aids to improve the hearing loss.
Hearing loss is one of the most common birth defects with a prevalence of 1-3 in every 1000 newborns and 70% of those cases are nonsyndromic. It is estimated to be 0,14% at birth and getting higher with age.[1] Genetic predisposition is the most important risk factor. Some environmental causes can contribute to the development of hearing loss, these include certain medications, specific infections before or after birth, and exposure to loud noise over an extended period. Age is also a major risk factor. Presbycusis (age-related hearing loss) has both genetic and environmental factors influencing its development.
There are various genes responsible for the development of NSHL. Around 75-80% of cases are inherited in an autosomal recessive pattern, 20-15% in autosomal dominant, and the rest of the cases are either X-linked or mitochondrial.[1]
Most of the cases are described as sensorineural, which means they are associated with damage to structures in the inner ear. Less commonly, it is conductive, meaning it results from changes in the middle ear. Rarely nonsyndromic hearing loss can be mixed. Hearing loss can be stable, or it may be progressive, becoming more severe as a person gets older. It can be prelingual (before the child starts to speak) or postlingual. Particular types of nonsyndromic hearing loss show distinctive patterns of hearing loss, it may be more pronounced at high, middle, or low tones.
For example, autosomal recessive NSHL is generally prelingual, non-progressive (stable), and severe-to-profound and autosomal dominant NSHL is primarily characterized as post-lingual and progressive. Hearing loss that is undetected and untreated can result in speech, language, and cognitive delays.
Screening for hearing loss should be a part of routine health assessment in children. Pure tone audiometry, tympanometry, or otoacoustic emission (OAE) testing may be performed to diagnose any hearing loss Often a simple look into the ear canal can lead to a diagnosis and subsequent treatment..
Management of NSHL should be multidisciplinary involving a pediatrician, general practitioner, ORL/ENT specialist, speech therapist, and hearing aid specialist. The best option for improving hearing loss is hearing aids. Some forms of conductive hearing loss can be fixed surgically.
Early identification and effective treatment of hearing loss can prevent language, communication, and cognitive complications.
Generally the prognosis is really good. Hearing aids can improve your hearing and let you have a normal life.
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