Drill selection

Choose a size that will be relatively large compared to the structure that you are trying to preserve.

To find a large structure, such as the sigmoid sinus, choose the largest burr you can. Even if a structure is small, it is important to choose the largest burr.

The most important structure in the temporal bone is the facial nerve and the burr needs to fit in with the constraints of the area which is being drilled. However if using a large drill, one that is even larger than the structure you are trying to find, you will usually find that the tubular structure will be found along a broad plane. If using a small burr there is a chance of drilling right through that structure without even identifying that you have found it.