Automatic determination of optimal linear drilling trajectories for cochlear access accounting for drill-positioning error.

BACKGROUND: Cochlear implantation is a surgical procedure in which an electrode array is permanently implanted into the cochlea to stimulate the auditory nerve and allow deaf people to hear. Percutaneous cochlear access, a new minimally invasive implantation approach, requires drilling a single linear channel from the skull surface to the cochlea. The focus of this paper addresses a major challenge with this approach, which is the ability to determine, in a pre-operative CT, a safe and effective drilling trajectory.
METHODS: A measure of the safety and effectiveness of a given trajectory relative to sensitive structures is derived using a Monte Carlo approach. The drilling trajectory that maximizes this measure is found using an optimization algorithm.
RESULTS: In tests on 13 ears, the technique was shown to find approximately twice as many acceptable trajectories as those found manually by an experienced surgeon.
CONCLUSIONS: Using this method, safe trajectories can be automatically determined quickly and consistently. Copyright 2010 John Wiley & Sons, Ltd.