During 7 years since 1971, 97 preschool children of unilateral sensorineural hearing loss with normal hearing contralaterally were either screened out by the hearing screening tests for nursery-school children, or found by the consultations at the Children's Medical and Welfare Center.
Seventy-nine children attended for interviews and further examinations.
Among 6, 825, preschool children, 10 cases of unilateral sensorineural hearing loss were screened out. Neither sexual nor affected-ear difference was observed.
In 57 percent out of 79 patients, the disorder was discovered by their parents before their school age. Etiology was unknown in 89 percent, though about half of them had any suspicious factor in their history. Mumpus was the cause in 8 percent. In other 2 cases (3 percent), the rapid onset of hearing impairment appeared after high fever and earache. Eighty-one percent of them showed severe hearing loss. In 21 percent of the children, the hearing loss was progressed. Caloric test showed canal paresis of the affected ears in 24 percent of the patients. One third of them were in the progressive hearing loss group. No abnormality was discovered by X-ray tomography in the canal paresis group.
