Here's the way we use it......congential deafness is deafness at birth, or deafness occurring after birth for a viariety of congential (birth related) causes. Therefore, a chilkd can be exposed congenitally to a viral agent such as measles or CMV, but be born with normal or near to normal hearing that gets progrssively worse due to congenital exposure of the viral agent, or at times, ototoxic medications.
Deafness after birth is defined by 2 categories: congenital and acquired, depending upon the etiology. Then there is further division into pre-lingual and post-lingual categories that refer to deafness prior to language acquisition, and deafness subsequent to language acquisition. Post-lingual is further divided into early onset, middle onset, and late onset.
The reason for so many categories and sub-categories is that there are specific developmental and adjustment issues that affect each of the sub-categories, but not all of the sub-categories.
