Bone removal
There are indications which exist for microscopic surgery which preclude total EES; for example, if cholesteatoma is present within the mastoid cavity proper, then microscopic ear surgery is recommended for removal of disease.2 All mastoid procedures were carried out within our microscopic group (Table 1). This raises the question of whether differing degrees of bone removal account for the difference in pain scores between endoscopic and microscopic groups. Similarly, Kakehata et al. , also reported mastoid surgery only within the microscopic group.4 To overcome this, they conducted subgroup analysis between procedures with no bony removal and those with varying degrees of removal. Between these subgroups, no significant difference was detected in pain scores, and it was concluded that bony removal has no influence over pain scores. We also carried out a subgroup analysis based on bone removal and no statistically significant result was found between pain scores between groups. As this subgroup analysis was underpowered (n=1) in the microscopic non-bone removal group), this was not included within our main results (Supplementary Table 2, Supplementary Figure 1). It is therefore difficult to make any statement about the influence of bone removal on our results.