For those who are born deaf, they are said to be congenitally deaf. People who are congenitally deaf tend to have "strong cultural affiliation to the ASL-Deaf community" (pg 299) rather than people who become deaf later in life. This makes perfect sense, because if a person was born Deaf, they would naturally become part of the Deaf community, rather than the hearing because that is all they have ever known. Congenitally deaf has multiple causes, including it being genetically transmitted, hereditary, or inherited deafness. However, it is important to realize "the congenital and hereditary deafness are NOT synonymous" (pg 299). Although this makes sense, it is easy (especially for me) to just assume that people who are born deaf have deafness that runs in the family, even though this is pretty rare. In addition, other causes of congenitally deafness include prenatal exposure to viruses, including rubella (German measles), cytomegalovirus (CMV), and Rh factor.
Even though hereditary deafness is quite rare, two accounts include Usher's syndrome and Waardenburg's syndrome. Before reading about these syndromes in HPO, I had never heard of these cases of hereditary deafness...
Usher's syndrome can be defined as "an autosomal recessive trait and a blanket term for several hereditary disorders in which profound sensorineural deafness is accompanied by progressively deteriorating vision" (pg 300). I could not imagine loosing both my sight and hearing, this syndrome sounds terrible and luckily it is extremely rare.
Waardenburg's syndrome can be defined as "an autosomal dominant trait, accompanied by partial albinism, such as white forelock, and extremely pale blue or different colored eyes, and facial anomalies such as wide separation of the inner corners of the eye, and a broad nasal bridge" (pg 300). However, unlike Usher's syndrome, this one does not always result in hearing loss.
For those who become deaf after birth, they are said to be adventitiously deaf. I thought this type of deafness was a little more complicated because it can be broken up into many categories. This deafness can either be prelingual (before the age of 3) or postlingual (after the age of 3). Then, postlingual deafness can be broken into being either childhood deafness, pre-vocational deafness (becoming deaf as a teenager), or post-vocational deafness (becoming deaf as an adult). There are many different ways that adventitious deafness can occur, including "accidents, bomb/shotgun blasts, injuries, extreme chill, high fever, bacterial, viral infections, cholesteatoma, and reactions to specific drugs" (pg 301). After reading this list, I found it crazy and slightly frightening to see how easily a person can loose their hearing.
In addition, I was introduced to two other specific types of deafness: sensorineural and conductive deafness. The chapter did a great job explaining how specifically deafness is caused in our ears. Sensorineural deafness is also know as 'nerve deafness', explaining that it affects the sensory cells of the cochlea. When the sensory cells in the ear are affected, it damages the center of hearing and balance, usually resulting in an irreversible deafness. "Conductive deafness affects the "hardware" of the middle ear: the ear drum, tiny bones, incus, and stapes" (pg 300). By affecting these specific areas of the ear, deafness can easily occur.
Another interesting thing about this chapter included how gradual hearing loss can occur through consistent loud noises. I think that this is a very common way for hearing loss, because it is extremely normal to hear older people talk about how they were losing due to the fact that they listened to music way too loud as a kid. This makes me cautious about how loud I listen to my music!
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