May 17 2007
Clinical research conducted in the Department of Communication Disorders at the University of Haifa revealed that some children who are born deaf "recover" from their deafness and do not require surgical intervention.
To date, most babies who are born deaf are referred for a cochlear implant. "Many parents will say to me: 'My child hears; if I call him, he responds'. Nobody listens to them because diagnostic medical equipment did not register any hearing. It seems that these parents are smarter than our equipment," said Prof. Joseph Attias, a neurophysiologist and audiologist in the Department of Communication Disorders at the University of Haifa, who made the discovery.
There are two causes of congenital deafness among children. One is the lack of hair cells, receptors in the inner ear that convert sounds into pulse signals that activate the auditory nerve. The second cause is a malfunction of the nerves. A child may be born with what appears to be a normal inner ear, but the hair cells do not "communicate" with the auditory nerves and the child cannot hear. To date, doctors have recommended the same treatment for all children born deaf. Once a child has been diagnosed as deaf, doctors recommend a cochlear implant, a surgically- implanted electronic device that bypasses the hair cells and directly stimulates the auditory nerve. Prof. Attias stresses that a cochlear implant is an excellent treatment for children with congenital deafness whose hearing does not improve over time. However, it appears that some children are born with "temporary deafness" a condition previously unidentified.
This discovery, like other revolutionary discoveries, was made by chance. A child who was born with malfunctioning hair cells and was scheduled for a cochlear implant was referred to Prof. Attias for a pre-surgical evaluation. The evaluation found that the child's brain and auditory nerves exhibited beginning responses to sound stimuli. The surgery was postponed. Follow-up visits showed increasing function of the hair cells and eventually the child reached a state of normal hearing. Prof. Attias, who is part of a cochlear implant team at Schneider Children's Medical Center, looked in the department archives and found other, similar cases. "Because these children go through a series of tests and evaluations by different doctors, a process that often takes months, there are cases of children who were initially referred for the procedure who didn't have it done. Sometimes parents decide not to do the surgery; sometimes they do it elsewhere. I called parents and found another seven cases of children who were diagnosed as deaf, did not have the procedure done, and began to hear," said Prof. Attias.
Prof. Attias then found another five children who had been referred to him for pre-operative testing who had begun to hear. At the end of his clinical research, he identified a "window of opportunity" of 17 months during which deaf children may begin to hear. "A child whose deafness is caused by a malfunctioning connection between hair cells and the auditory nerve should not have a cochlear implant in the first 17 months of life. Research results show the possibility that at least some of these children undergo the procedure for nothing," explained Prof. Attias.
He added that some of the children only develop partial hearing, which can be augmented with external hearing aids. Prof. Attias is now researching "temporary deafness" among young children, looking to find a way to identify those who will recover and those who will not.
Lurie Children's Hospital administers first gene therapy for Duchenne muscular dystrophy in Illinois