Cochlear function after type-1 tympanoplasty: endoscopic versus microscopic approach, a comparative study

Purpose: To investigate and compare the effect of endoscopic and microscopic type 1 tympanoplasty on the cochlear function, to determine if they have a different impact on the inner ear function. Methods: 72 ears treated by transcanal endoscopic type 1 tympanoplasty and 84 ears treated by microscopic type 1 tympanoplasty in 3 tertiary referral centers were enrolled in the study. Microscopic type 1 tympanoplasty were performed by transcanal or retroauricular approach. Only patients with mobile and intact ossicular chain were involved in the study. A retrospective chart review was performed. Main outcome measures were: (1) change in bone conduction thresholds at 250, 500, 1000, 2000, 4000 Hz; (2) change in bone conduction Pure Tone Audiometry; (3) correlation of audiometric outcomes with surgical technique, graft type and graft position. Results: A mild postoperative bone conduction threshold shift was observed at 2000 Hz and 4000 Hz in both groups, without significant differences between the two groups. No statistically significant modifications in bone conduction were observed at any frequencies in patients operated by transcanal endoscopic approach compared with those who underwent transcanal or retroauricular microscopic type 1 tympanoplasty. Moreover, neither the placement nor the type of the graft seemed to influence the cochlear function preservation. Conclusions: The endoscopic and the microscopic approaches have a similar impact on the bone conduction threshold during type 1 tympanoplasty. In particular, the one-handed manipulation of the ossicular chain during the endoscopic technique did not show an increased risk of inner ear damage.