Study the Effect of Tubotympanic Disease on Bone Conduction Threshold.

Tubo-tympanic disease of middle ear cleft can temporarily detoriate the bone conduction threshold specially in higher frequency in long standing cases. It mainly affects the inertial ossicular component of the bone conduction mechanism. (1) Study the effect of tubotympanic disease on bone conduction threshold (SN loss). (2) Study the duration of the disease on bone conduction threshold. 84 cases of tubotympanic disease were taken for the study. There pre-operative PTA was done and effect of the disease on the bone conduction threshold was noted. Results were analyzed by using analysis of variance. The significance level α was taken 0.05 as at marginally significant, 0.01 significant and 0.001 as highly significant. The bone conduction at all frequencies increased significantly < 0.05 with duration of ear discharge. The differences in the bone conduction at all frequencies amongst normal ears were significantly lower as compared to the diseased ear. Duration of ear discharge and type of hearing loss reveals that in patients with ear discharge less than 11 years there were 24 (77.41%) subjects with conductive hearing loss, 1 (3.22%) subject with mixed hearing loss. As the duration increased 11-20 years, the cases of conductive hearing loss decreased 13 (56.52%) and cases of mixed hearing loss increased to 3 (13.04%). In patients with ear discharge of > 21 years conductive subjects were 19 (63.33%) and subjects with mixed hearing loss increased to 5 (33.33%) cases. The average hearing loss and the average bone conduction threshold increases as the duration of disease increases. In patients of safe CSOM who have poor BCT, it is the higher frequencies which are more affected.