Unlike regular hearing aid wearers whose hearing loss is usually the result of exposure to loud noises, ototoxic (literally “ear poisoning”) drugs, or presbycusis (age-related hearing loss) most bone anchored hearing aid wearers are missing parts of their ears. Some are born without the internal components, such as their cochlea or ear canal, or have parts that are damaged. Others only have small portions of their pinna (outer ear) or don’t have an ear at all.
We feel it is important to provide information and insight into these rare conditions and how they affect hearing. Raising awareness will hopefully help those affected feel less alone, encourage understanding and compassion from others, and broaden knowledge of bone anchored hearing as a possible alternative to the hearing loss associated with these conditions.
Microtia (with or without Atresia)
Microtia (literally “little ear”) is a condition that occurs during the first trimester of pregnancy, which is when development of the ears should occur. The pinna (outer ear) is either underdeveloped, only partially present (e.g., just the earlobe), or nonexistent. This condition might only affect one ear or both and is often—but not always—accompanied by another condition, atresia. Typically, atresia refers to having an extremely narrow or missing ear canal.
While microtia, with or without atresia, may occur without any associated or underlying syndrome, it often appears as one of the multiple indications of the following conditions.
Treacher Collins Syndrome
This genetic disorder causes underdevelopment or malformation of various parts of the head, including eyes, cheekbones, jaws, mouth, and palate. People with Treacher Collins often experience hearing loss when the inner and/or outer parts of their ears are affected by microtia and/or atresia. They might also have conductive hearing loss due to issues with their middle ears that limit or prevent sound waves from traveling to the brain.
This is often used as an umbrella term to cover multiple conditions, including hemifacial microsomia, which is characterized by underdevelopment of one side of the head and face affecting the jaw, mouth, and ears and Goldenhar syndrome, which often affects the eyes, ears, and spine. These and similar conditions may be inherited but often simply occur spontaneously without any family history of the disorders. Again microtia, with or without atresia, is common with these conditions, as are issues with damaged or missing middle ear components.
Often caused by a random and spontaneous genetic mutation, this syndrome results when the “seams” between the bones of the skull close prematurely during fetal development. Those affected usually have a pointed or extended skull and malformations of the face, hands, and feet. The condition is often associated with conductive hearing loss in both ears due to fused ossicles (the tiny bones in the middle ear). Chronic ear infections are also often common. Other syndromes related to Apert syndrome involving hearing loss include Crouzon and Saethre-Chotzen.
This disorder results when a child is born missing part of Chromosome 22. It is also known by other names (e.g., DiGeorge syndrome, Catch-22 syndrome). Usually there is no family history of Velocardiofacial syndrome, although it can be inherited from either parent. Multiple symptoms may occur (although usually not all at once), including otitis media (chronic middle ear infections). Additionally, conductive hearing loss from a variety of abnormalities in the middle and/or inner ear have been reported as prevalent among people with this syndrome.
Treatment for conductive hearing losses due to syndromes
Hearing loss associated with a craniofacial condition is often conductive in nature, meaning there is a physical cause like a missing or nonfunctional portion of the ear. Some may be surgically reparable, as in a case where an ear canal is present, but the opening is sealed. Others would be best addressed by a bone anchored hearing system like Ponto™, which bypasses the damaged or missing ear entirely to conduct sound via the skull.