Does drill-induced noise have an impact on sensorineural hearing during craniotomy procedure?

Objective: It is well known that exposure to noise can lead to hearing loss. Craniotomy drills have significant noise and vibration. Since a noise induced by the drill during craniotomy is thought to be one of the causes, we examined its effect on the sensorineural hearing in this study.

Methods: Thirty-nine patients who had undergone craniotomy operations served as the basis for this study between Jul. 2007 and Dec. 2008. Standard pure-tone audiometry (PTA) and speech recognition thresholds (SRT) were calculated for all subjects before, one week and 1 year after craniotomy.

Results: Statistically significant differences were not observed at the lower and middle frequencies (0.25-2 kHz), however, differences in the hearing thresholds at higher frequencies (4-6 kHz) were statistically significant before and after craniotomy. Mean pure-tone thresholds obtained was significantly more in older subjects when compared to young patients. Moreover, the correlation between increased number of burr holes and sensorineural hearing loss (SNHL) was statistically significant.

Conclusions: We conclude that drill-generated noise during craniotomy has been incriminated as a cause of SNHL. Possible noise disturbance to the inner ear can only be avoided by minimizing the number of burr holes and the duration of harmful noise exposure to the cochlear structures.