Stapedotomy with microdrill or carbon dioxide laser: influence on inner ear function.

Objectives: A prospective randomized audiological analysis of 336 otosclerosis operations was conducted to compare the evolution of bone conduction thresholds after primary stapedotomy with two different techniques to open the footplate: microdrill and carbon dioxide laser stapedotomy.

Methods: To monitor the inner ear function, we compared the preoperative bone conduction thresholds with the postoperative levels at day 2, week 2, week 6, and month 6. Evolution of the bone conduction was compared for the two studied groups (laser versus microdrill).

Results: An average bone conduction loss of 1.8 dB was measured at day 2 for the middle frequencies (0.5, 1, and 2 kHz). At 4 kHz, a bone conduction loss of 7 dB was found. The bone conduction thresholds measured in the first and second months after surgery showed a gradual recovery with overclosure as the end result.

Conclusions: Our results confirm the transient depression of inner ear function in the immediate postoperative period, with recovery within the first weeks after surgery. In the studied population, no statistically significant difference was found between the two techniques that were used to make the calibrated hole (laser versus microdrill). These results demonstrate that both techniques possess the same early effect regarding inner ear function. The authors hypothesize that an early inflammatory reaction could be the cause of the transient bone conduction shift.