Ear infections, chronic strep throats, and allergies are the usual complaints that doctors see from their youngest patients. At the otolaryngology (ear-nose-throat) clinic that I work at, we provide clinical intervention ranging from antibiotics to corrective surgery. Following the trend of previous articles regarding hearing loss, we will explore the less common complaint of congenital hearing loss.
Image Source: Jie Zhao
Congenital hearing loss is a type of hearing loss present at birth. Over 50% of all congenital hearing loss cases are based on hereditary (genetic) mutations, with the remainder due to external factors present in the uterus or at the time of birth. These factors may include prenatal infections, illnesses, or toxins consumed by the mother, factors that often result in damage to the hearing nerve akin to noise-induced hearing loss. Hereditary mutations, on the other hand, can be traced to autosomal dominant, autosomal recessive, or sex-linked mutations, which often lead to multisystem diseases that impact multiple organ systems.
The following is a quick explanation of the possible mutations:
- Autosomal dominant: One parent (who typically has hearing loss) carries the dominant gene for hearing loss and passes it on to the child. Looking at Mendelian genetics, there is a 50% probability that the child will also have some degree of hearing loss and that probability increases if both parents have the dominant genes. Autosomal dominant congenital hearing loss can be seen in disorders such as the Waardenburg Syndrome.
- Autosomal recessive: Both parents who typically have normal hearing, carry a recessive gene, which can combine to give a 25% change of the child having hearing loss, evidenced in the Usher Syndrome.
- X-linked/sex-linked: The mother carries the recessive trait for hearing loss on the sex chromosome, which, when passed to her offspring, leads to hearing loss only in her male children. Prime examples include Down Syndrome and Alport Syndrome.
Congenital hearing loss is often screened at birth as well as various grades in the American health and school system. Factors, such as the severity of hearing loss, age of child, developmental stage, personality, and desired end goals, all play a role in determining the treatment plan. Due to the complicated nature of congenital hearing loss, treatment teams typically consist of the child’s pediatrician, an ear-nose-throat doctor, a speech-language pathologist, and an audiologist.
Ending on that note, stay tuned next week for a breakdown of treatment options.
Feature Image Source: Justin Chin