The authors statistically studied 2656 cases who had consulted Visual and Auditory Research Institute of Fukuoka Medical Association from 1970 to 1976. The results were as follows.
1) 2515 of 2656 cases (94.7%) were children under 15 years of age and 141 cases were adults over 16 years of age. In 2515 cases, 1497 cases had hearing impairment and 826 cases had speech disorder without hearing impairment. In 141 adult cases, 140 cases were hearing impaired and one case was speech disordered.
2) In 1497 hearing impaired children, 1135 cases ha d perceptive deafness and showed a highest percentage. There were 241 cases with acquired conductive deafness, 33 cases with conginital conductive deafness and 51 cases with mixed deafness.
A age constitution of perceptively deafened children had a peak in 2 years of age, and children with acquired conductive deafness showed higher frequencies from 3 to 5 years of age. Speech disordered children without hearing impairment were most frequent from 2 to 3 years of age. The male-female ratio was 3 to 1.
3) In perceptively deafened cases, a large number of them had severe hearing loss and the cases over 70% had hearing loss over 60dB. In acquired conductive deafness, a great number of cases showed slight loss under 30dB, and only 11 ears had hearing loss over 45dB. The children with congenital conductive deafness had more severe hearing loss than the acquired and there were several cases with hearing loss over 60dB.
4) In respect to types of audiogram, sloping type commanded a greatest number of the perceptively deafened. Secondarily horizontal type and thirdly high-cut type were frequently observed. In acquired conductive deafness, horizontal type showed a highest frequency, secondarily low-tone-loss type and thirdly mountain type. In congenital conductive deafness, low-tone-loss type showed a highest frequency and secondarily horizontal type.
5) Causes of deafness of 1186 cases with perceptive deafness (involved mixed deafness) under 15 years of age were studied. The frequency of hereditary deafness was 18.4%, prenatal deafness 7.7%, paranatal deafness 26.9%, prenatal and paranatal deafness 3.4%, postnatal deafness 6.1% and unknown causes was 37.5%.
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