Talking About Genetic Hearing Loss
An extremely common birth defect is hearing loss, or congenital deafness, which affects up to three out of every 1,000 babies born. There can also be a delayed onset of hearing loss that is still caused by genetic issues. Genetic hearing loss can be in one or both ears, and can either be progressive, becoming worse over time, or non-progressive, staying the same. There are an estimated over 400 forms of genetic hearing loss that vary in severity and progression. Hearing loss is usually not associated with other hereditary conditions (60 to 70 percent of the time), and is referred to as non-syndromic. Hearing loss that is syndromic is associated with gene mutations that affect more than just hearing. Three common forms of genetic hearing loss are otosclerosis, Usher’s syndrome, and Pendred syndrome.
Otosclerosis affects the bones in the middle and inner ear and causes them to become fused together into a mass that doesn’t transmit sound as well as when they are flexible. Otosclerosis is inherited, and you have a 50 percent chance of getting it if one parent has it. Not everyone with the gene develops osteosclerosis, but symptoms usually begin between the ages of 10 and 30. There can be two types of hearing loss with otosclerosis; when it affects the bones in the middle ear it is conductive and can be helped by hearing aids. When it involves the bones of the inner ear it results in a sensory type of hearing loss, and this type can be more difficult, though not impossible, to correct.
Symptoms of otosclerosis begin as sensory hearing loss, and usually both ears are affected. Hearing loss usually progresses to conductive loss and usually reaches its maximum in a patient’s 30s—it doesn’t usually progress past this. Many people with otosclerosis have tinnitus (ringing in the ears), and dizziness can also be present. Caucasian and Asian people are more likely to get otosclerosis, and women are twice as likely as men. Otosclerosis is often diagnosed after pregnancy, and it is thought that pregnancy hormones play a role.
Usually it is a family history combined with a progressive pattern of conductive loss that leads to a diagnosis of otosclerosis. Tympanometry will often show the stiffening of the bone area, and CT scans of the temporal bone could reveal early signs.
Otosclerosis is not life-threatening and does not require treatment. However, hearing impairment can really affect your quality of life, and if you are experiencing worsening hearing you may want to look into hearing aids as a great way to regain lost sounds. There has been research regarding using sodium fluoride to help otosclerosis, but it has not been proven to be effective. Stapedectomy is a surgical treatment where the stapes of the inner ear are removed and replaced with prosthetics. While this treatment can help some types of hearing loss, and might help tinnitus, it often cannot affect the vertigo that some patients experience. Stapedectomy is an involved surgical procedure that takes a lot of skill to perform. Beethoven was suspected to possibly have otosclerosis.
Usher’s syndrome affects both hearing and vision, and approximately three to six percent of all children that are deaf have Usher’s syndrome. About four out of every 100,000 babies born have this syndrome, which is an autosomal recessive trait. You can be a carrier of the Usher syndrome gene and not know it, and if two carrier parents have a child there is a one in four chance that the child will have Usher’s syndrome.
There are three types of Usher’s syndrome: type 1, type 2, and type 3, with types 1 and 2 accounting for more than 90 percent of all cases. Children who have type 1 are profoundly deaf at birth and have severe balance problems. Intervention as soon as possible can help children learn to communicate, before they lose the ability to see. Children with type 1 usually are slow to learn to sit and walk due to balance issues and start to develop vision problems before they are 10. Vision impairment starts with not seeing well at night and progresses rapidly to complete blindness. Type 2 presents with children born with moderate to severe hearing loss but normal balance. These children usually benefit from hearing aids, and don’t have as severe vision problems. Their vision problems usually are not apparent until they are in their teens. Type 3 children have normal hearing at birth and don’t have balance issues. Hearing and vision decline over time, but the severity varies. Hearing aids can assist hearing issues and blind spots will usually progress in the late teens to total blindness as an adult.
Usher’s syndrome is diagnosed with an evaluation of hearing, balance, and vision. Their vision may be tested with a field test and with an electroretinogram to measure the eye’s response to light. Hearing evaluation is also part of the diagnosis, and the earlier you can diagnose it the earlier you can start treatment to manage hearing and vision loss.
There is no cure, currently, for Usher’s syndrome, but early detection is essential for the best outcome. Treatment options can include hearing aids, learning alternative communication such as American Sign Language, Braille instruction, low-vision services, and educational alternatives for hearing and vision impairment. High doses of vitamin A have been used to slow, but not stop, retinitis pigmentosa, RP, but more studies need to be done.
Pendred syndrome is a rare disorder that involves the thyroid and hearing loss. People with the syndrome develop a goiter, or enlargement of the thyroid gland, usually after hearing loss is evident, and the goiter usually does not interfere with thyroid function. Pendred syndrome usually presents with an ear abnormality called an enlarged vestibular aqueduct (EVA) that is the bony canal that connects the inner ear with the skull. There also may be abnormalities in the cochlea, the part of the ear that helps with sound processing. If you have both of these abnormalities it is known as Mondini malformation.
People with Pendred syndrome usually have severe to profound hearing loss at birth, but sometimes it can develop in later infancy or early childhood. Children affected can have issues with balance due to a disruption in the inner ear. Loss of hearing usually happens in sudden stages, and sometimes after a decrease will return to the previous level. Hearing loss is often greater in one ear.
A clinical geneticist will often diagnose Pendred syndrome taking into account hearing ability, the structure of the inner ear, and the thyroid. How hearing loss has progressed can be a key factor in diagnosis. MRI and CT scans can also be used to look for the key signs of Pendred syndrome: a cochlea with too few turns, or EVA.
Treatment options for Pendred syndrome usually include the counsel of several specialists working together. To protect hearing loss in patients it is recommended that they do not play contact sports that could lead to head injury, wear head protection when bike riding or skiing, and avoid rapid changes in pressure such as with scuba diving. There is no cure for Pendred syndrome, but early intervention will help children learn skills to communicate, use sign language, or help with hearing aids. Hearing loss and the thyroid gland should be monitored.
These genetic forms of hearing loss just begin to touch on the many variations that exist. Thankfully, there are many advances being made in genetic research regarding hearing loss, and just recently 52 new genes were discovered as critical for hearing. These genes help to provide further insight into the causes of genetic hearing loss and to develop treatment and identification. While more research is done to hopefully find cures to genetic hearing loss, Factory Direct Hearing is proud to offer hearing solutions that you can buy online. We sell the leading hearing aid brands including Widex, ReSound, Siemens/Signia, and Oticon at a fraction of the price you would pay elsewhere. If you are wanting a convenient way to buy your hearing aids online and have them delivered right to your door, Factory Direct Hearing is here for you!