They Listen but Cannot Hear
International Symbol for Deafness
Auditory Nerve Neuropathy
These children suddenly speak ambiguously. When their parents speak, they wouldn't listen and appear indifferent. Their behavior will be described as ruthless, autistic, or assumed to be a sign of a temper tantrum. However, these children may be suffering from neuropathy involving their auditory nerve. Although they can hear the speech, they cannot understand the spoken content. Premature birth, birth infections, low birth weight, jaundice and hereditary conditions are some of the causes leading to this auditory nerve neuropathy, which gives the child a reduced ability to identify the sound he is listening to and a reduced responsiveness.
Doctors estimate that 2.4% of hearing problems in school-age children are caused by auditory nerve neuropathy. Dr Lam Kin Yip, an ENT surgeon in Hong Kong, explained that the sound could still access the inner ear normally. "However, the transmission of sound from the inner ear to the brain is at fault. This accounts for the bizarre phenomenon that patients with normal hearing fail to comprehend the spoken sentence and to respond appropriately."
This auditory nerve condition is sometimes caused by dysfunction of the inner ear hair cells which relay the message of the sound preceived to the brain. The disease can occur at any age, but many patients have their onset of this condition in childhood. Dr Lam pointed out that children with health problems at birth, including premature birth, low birth weight, birth asphyxia and jaundice, etc., were more proned to develop auditory nerve neuropathy. Some drugs can also damage the inner ear hair cells in young children.
Adults are hardly immune to the condition and can develop acute auditory nerve neuropathy when they suddenly fail to understand phrases and statements they are not familiar with and their language skills progressively decline.
Current infant hearing screening practice is not useful in detecting auditory nerve neuropathy as these affected children have normal hearing. Tests on comprehension of spoken speech are more appropriate to make a diagnosis. Treatment of the condition consists of speech therapy, hearing aids and cochlear implants. However, the outcome of these treatment modalities is unpredictable. A significant proportion of patients end up dependant on lip reading and signing. Their hearing tends to deteriorate unless early diagnosis and life-long rehabilitation is instituted.