Hearing disorders can occur during pregnancy, and the most common ones are caused by congenital malformations of the auditory system. These abnormalities can affect the development or structure of the external auditory pavilion, depending on how severe they are.
The most prevalent congenital ear malformations involve abnormalities in the growth of the pinna, resulting in either an overdeveloped, underdeveloped, or completely absent ear canal. These malformations occur in approximately 1 in 5,000 births. The most common type is microtia, characterized by the underdevelopment of the auricle, which gives it the name "small ear." The second most common type is macrotia, involving the excessive growth of the ear. While quite rare, some cases of microtia are also accompanied by the absence of the external auditory canal, known as atresia, which can manifest in different degrees. The rarest form among these malformations is the complete absence of the outer ear, referred to as anotia.
Microtia is a congenital deformity of the outer ear where the ear does not develop fully, primarily affecting the size of the auditory pavilion. It is classified into four grades based on the extent of the deformity, ranging from a minor ear abnormality with minimal impact on hearing to the complete absence of the outer ear. Typically, microtia affects only one ear, often the right ear, and is more common in males. This condition is frequently associated with related conditions like atresia and anotia.
Microtia is classified into four grades.
Microtia, along with other congenital ear malformations, is typically not hereditary. In fact, around 95 percent of reported cases have no prior family history of microtia.While the exact cause of these malformations is still uncertain, they are believed to occur during the first trimester of pregnancy.
Factors such as inadequate blood flow due to fetal positioning or disrupted ear development caused by oxygen deficiency are commonly associated with microtia. In some instances, there may be a potential association with the misuse of certain toxins, although this connection has not been definitively proven.
The treatment for microtia varies depending on its severity: surgery and hearing aids are a some of the most common treatment alternatives. The malformation of the ear can be addressed using cartilage grafts from the patient's own body, or by utilizing hearing implants or prostheses.
However, these surgical procedures are typically postponed until the patient is between three and eight years old, depending on the individual case. It's important to note that some patients may choose not to undergo reconstructive surgery. As for managing hearing loss, a common approach involves the placement of bone-conduction implants. Among these, the Bone Anchored Hearing Aids (BAHA) system is a popular choice known for its effectiveness.