Bone Electric Conductivity

Minimally invasive cochlear implantation surgery has been proposed to replace conventional mastoidectomy for the placements of chochlear implant. To achieve this aim, a microsurgical robotic system is being developed by the group for image guided therapy of the ARTORG Centre. This system is designed to precisely drill a small tunnel through the temporal bone. However, due to the small distance between the tunnel and the facial nerve (0.3 – 0.5mm), an important challenge of this technique is the preservation of the facial nerve during the drilling procedure.
Neuromonitoring is a technique widely used in surgery to locate and assess nerve function. An electrical stimulus is injected into the tissue surrounding the nerve, and electromyography is used to detect action potential elicited muscle responses. In the case of minimally invasive surgery, this technique can be used intra-operatively to monitor the distance between drill bit and the facial nerve. To detect critical distance to the FN, an electrical stimulation is sent through the drill. However, past experiments showed that it is difficult to give accurate distance predictions only based on the electric signal. For this reason, patient-specific parameters and modeling should be included to quantify the distance to the nerve. An experimental test bench has been produced to quantify the bone electric properties. The initial numerical simulations indicated that the porous network filled of marrow is mainly responsible for the flow of electric current in the tissue.