Usher syndrome is a rare inherited disorder that involves loss of both hearing and sight.
is usually present at birth or soon thereafter. It is due to an impaired ability of the auditory nerves to transmit sensory input to the brain. It is called sensorineural hearing loss.
The vision loss, called
(RP), begins later in childhood, usually after age ten. It slowly gets worse over time. During the teen years, loss of vision is characterized by night blindness and loss of peripheral vision. RP is a deterioration of the retina. The retina is a layer of light-sensitive tissue that lines the back of the eye. It converts visual images into nerve impulses in the brain that allow us to see.
Three types of Usher syndrome have been identified: types I, II, and III. The age of onset and severity of symptoms distinguish the different types.
Approximately 4 out of 100,000 infants born in the United States have Usher syndrome. Usher syndrome accounts for 3%-6% of all deaf children and 3%-6% of all hard-of-hearing children.
Usher syndrome is caused by a genetic mutation. It is passed from parent to child in an autosomal recessive manner. This means that a child must inherit one defective gene from each parent in order to develop Usher syndrome. If a child inherits one defective gene, he or she will be a carrier and will not have any symptoms. It is unclear what causes the mutation in the gene.
A risk factor is something that increases your chance of getting a disease or condition. The only known risk factor for Usher syndrome is having parents with the disorder and/or parents who carry the genes for the disorder. If both parents carry the abnormal gene, you have a 25% chance of inheriting both of these abnormal genes and therefore developing Usher syndrome.
The main symptoms of Usher syndrome are hearing and vision loss. Some people also have balance problems due to inner ear problems.
The progression of RP limits a person’s ability to see in dim light or the dark (night blindness). It also causes a person to lose peripheral (side) vision slowly over time. Eventually, any vision left is only in a small tunnel-shaped area. Almost everyone with RP becomes legally blind. There is no known way of predicting when or how quickly a person will lose vision.
Symptoms and characteristics of each type include the following:
Deaf at birth and receive little or no benefit from hearing aids
Severe balance problems
Slow to sit without support
Rarely learn to walk before age 18 months
RP begins by age 10 with difficulty seeing at night, and quickly progresses to blindness
Born with moderate to severe hearing loss, and can benefit from hearing aids
No balance problems
RP begins in the teenage years
Born with normal hearing that gets worse in the teenage years and leads to deafness by mid to late adulthood
Born with near-normal balance
RP begins in the early teenage years as night blindness, and leads to blindness by mid-adulthood
The doctor will ask about symptoms and medical history and perform a physical exam. Hearing loss is determined with standard hearing tests. Balance problems can be detected with a test called electronystagmography (ENG). In this test, the doctor flushes the ears with warm and then cool water. This causes nystagmus, which is rapid eye movements that can help the doctor detect a balance disorder.
An eye doctor will perform an eye exam, which will likely include the following:
Visual field test to check side vision
Test to check for ability to adapt to seeing in the dark
Test to check sensitivity to color and contrast
If any problems are found on these tests, an electroretinography (ERG) is done. This test confirms a diagnosis of RP. It measures the electricity given off by the nerves in the retina. The test is done while wearing special contact lenses and looking at a flashing light.
There is no cure for Usher syndrome. The best treatment is to identify the disorder as early as possible and begin educational programs and other services right away. This helps reduce the communication and learning problems that can result from hearing and vision loss.
The specific programs and services depend on the severity of the hearing, vision, and balance problems and the person's age and abilities. Options include:
Assistive listening devices
—a small device surgically put under the skin behind the ear to give deaf people some ability to hear
Adjustment and career counseling
Training to help with balance and movement
Low vision services
Skills in living independently
Currently, there is no known way to prevent Usher syndrome.
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a