A long-term follow up study of juvenile bilateral sensorineural deafness of unknown etiology

One hundred and fifty one cases of juvenile bilateral sensorineural deafness of unknown etiology were followed up for a period from 5 to 22 years (average 12 years and 2 months) in our department. Hearing (average of 1-4KHz or 1-2KHz) was unchanged ( 15dB) in 22 cases (14.6%) and deteriorated permanently in 29 cases (monaurally in 13 cases and bilaterally in 16 cases). The degree of hearing deterioration ranged from 15 to 43dB (average 27dB).The incidence of hearing deterioration showed no significant difference (α=5%) between aided and unaided ears. The incidence to fluctuation of hearing were significantly higher in deteriorated ears.The deterioration of hearing occurred in every age groups observed: 6 ears (under10 years), 16 ears (11-15 years), 11 ears (16-19 years) and 12 ears (20-30 years). The discrimination score was high (over 80%) in 37% of the patients but low (0-35%) in 30%.