2010 Copyright @ Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited. Inroads Toward Robot-Assisted Cochlear Implant Surgery Using Steerable Electrode Arrays *Jian Zhang, *Wei Wei, *Jienan Ding, †J. Thomas Roland, Jr., ‡Spiros Manolidis, and *Nabil Simaan *Department of Mechanical Engineering, Columbia University; ÞDepartment of Otolaryngology and Neurosurgery, New York University School of Medicine; and þBeth Israel Medical Center, New York, New York, U.S.A. Hypothesis: Robotic insertions of actively steerable perimo- diolar electrode arrays can substantially reduce insertion forces and prevent electrode buckling. Background: Perimodiolar electrodes have been proven to be effective in reducing insertion forces. However, the dedicated techniques of atraumatic electrode insertion require intensive surgeon training. Although some specialized medical robots have been developed to help surgeons in certain minimally invasive surgeries, none are applicable to electrode insertions. Methods: A robot prototype capable of automatically inserting novel steerable electrode array and adjusting its approach angle toward the scala tympani has been constructed and tested. Comparisons of insertion forces using robotically assisted steerable and straight electrodes on scala tympani models are presented. Simulations and experiments are conducted to com- pare the robotic insertion outcomes and insertion forces. Results: The use of robotically assisted steerable electrodes for insertions significantly reduces the insertion forces compared with straight electrodes. Based on the results from the experi- ments, a second-generation robot with insertion force-sensing capability and haptic control to be used in the operating room has been designed for cochlear implant surgery. Conclusion: Preliminary experimental results using robot- assisted steerable electrode prototype show that it is effective in reducing insertion forces and preventing electrode buckling. A second-generation robot has been designed and constructed for cochlear implant surgery under operating room conditions. Key Words: Cochlear implantVRobotic assistanceVSteerable electrodeVTrauma. Otol Neurotol 31:1199Y1206, 2010. Cochlear implantation is an accepted medical treatment of choice for the rehabilitation of congenital and acquired sensorineural hearing loss. The surgical procedure re- quires that an electrode be inserted into the cochlea to directly stimulate the spiral ganglion cells and provide auditory information to the central auditory pathways. More recently, and coincident with the development of more atraumatic electrodes and insertion techniques, there is great interest in implanting patients with more residual hearing (1,2). Additionally, recent studies (3) confirm that patients are able to use even small amounts of residual hearing effectively to hear better in noisy environments, appreciate music, and have better overall auditory performance. Existing electrode products include external-wall or straight electrodes, that is, C40+ electrode (MedEl, Inns- bruck, Austria) and K electrode (Cochlear Corp., Engle- wood, CO, USA). During insertions, straight electrodes first make contact with the outer wall of the cochlea at approximately 180 degrees of insertion, which corresponds to the mid pars ascendens. After the first contact, the elec- trodes slide against the external wall and bend as more insertion pressure is exerted on the electrode to overcome frictional forces and stiffness properties of the electrode array to follow the curvature of the scala tympani (4,5). Direct contact with the external wall results in high cu- mulative friction forces in a manner similar to the appli- cation of a band break (6). Some buckling of the electrode typically occurs because of large insertion forces, and this, combined with upward forces that are generated, result in intracochlear trauma (7Y10). Alternatively, perimodiolar electrodes have been devel- oped, that is, Contour Advance electrode (Cochlear Corp.) and HiFocus Helix Electrode (Advanced Bionics Corp., Address correspondence and reprint requests to Nabil Simaan, Ph.D., Rm 234 S.W. Mudd Building, 500 W 120th Street, New York, NY 10027; E-mail: ns2236@columbia.edu Sources of support that require acknowledgment: This work is funded by National Science Foundation Grant No. 0651649. Otology & Neurotology 31:1199Y1206 Ó 2010, Otology & Neurotology, Inc. 1199