Symptoms of Hearing Loss (Deafblind) Deafblindness is a unique disability, distinct and much more debilitating than either blindness or deafness.
About 50% of all cases of acquired deafblindness are caused by Usher Syndrome, relatively rare, progressive and genetic. Other cases of acquired deafblindness are caused by accidents, aging, and a variety of medical reasons.
Helen Keller, born in 1880 with normal sight and hearing, contracted scarlet fever or meningitis 19 months later and became deafblind.
Toronto ophthalmologist Dr. John A. Parker has had many patients with Usher Syndrome and stresses that when the deficits of blindness and deafness are compounded, “deafblindness is a double whammy 10 times worse than either of its component parts — deafness or blindness.”
When both parents are carriers of a recessive gene that causes one of three types of Usher Syndrome, there is a 25% chance a child will be born with this condition and will grow up to a future of deafblindness.
Children born with profound hearing loss and retinitis pigmentosa have Usher Type I, where balance is often affected. In Types II and III, there are similar progressive hearing and vision losses but usually not as severe.
GRADUAL TUNNEL VISION
Retinitis pigmentosa causes gradual tunnel vision in Usher Syndrome.
At first there is night blindness and a noticeable loss of peripheral vision, which slowly begins to constrict fields of vision to a narrow, pinhole view.
As vision diminishes, the world slowly begins to close in.
People with acquired deafblindness caused by Usher Syndrome begin life with varying degrees of hearing loss and may appear to have normal vision.
Years later, often in their early to mid-teens or in their early 20s, they begin to notice vision problems. They’re diagnosed with Usher Syndrome and given the devastating prognosis of a life of silence and shadows, loss of communication, isolation, deafblindness — almost unimaginable.
The incidence of this disorder is almost impossible to quantify. Studies to determine its frequency and prevalence vary widely, says Dr. Ed Cohn, an ear, nose and throat specialist in clinical practice, treating people of all ages with Usher Syndrome at the National Centre for the Study and Treatment of Usher Syndrome at Boys Town National Research Hospital in Omaha, Neb.
“The only way to know the prevalence of Usher Syndrome is by doing genotyping early, in newborns, and that isn’t being done yet, except in research laboratories, which is very time-consuming and labour-intensive,” he says.
“Without early diagnosis, treatment options are limited. The earlier the diagnosis, the better.”
‘HOPE FOR THE CHILDREN’
Studies to reverse or retard the progress of retinitis pigmentosa are under way, with several other experimental retinal procedures.
“There is hope for the children,” he says.
Prevalence of Usher Syndrome can be disproportionately high in small, closed communities, where the gene pool is more confined.
Among Ashkenazi Jews, where marriage outside the faith is less common, there is a higher incidence of Usher Type I.
In Quebec, 1,500 cases have been identified, when some very conservative Canadian estimates suggest there are about 3,300 cases in all of Canada.
“Most estimates tend to be very low,” says Dominic Cosgrove, director of the division of therapeutic strategy development at Boys Town, which estimates that about 3% to 6% of all deaf children and an equal number of hard-of-hearing children have Usher Syndrome.
“That’s about five cases of the disorder in every 100,000 people, an underestimate.”
Because of the stigma surrounding deafness, an invisible disability, some people are often reluctant to admit to it or are in denial when they learn they have Usher Syndrome and will lose their sight.