Access to the inner ear, specifically the cochlea, is currently required for cochlear implant (CI) surgery, in which an electrode array is used to stimulate the auditory nerve and allow deaf people to hear. More than 120,000 CIs have been placed worldwide. Projections indicate that up to 750,000 Americans with severe hearing loss may benefit from CI (Mohr, Feldman, Dunbar et al., 2000) many of whom are children. In our ongoing, NIH-funded adult project (R01 DC008408), we have demonstrated the feasibility of percutaneous cochlear implantation (PCI). PCI reduces CI surgery to a single pass of a drill from the lateral skull base to the cochlea. The drill path is planned and executed via image-guided technology so as to avoid vital adjacent anatomy and hit the target-the scala tympani of the cochlea. In clinical trials we have validated the technique on 15 adult patients with statistical projections indicating 99.9% avoidance of vital anatomy, specifically the facial nerve. In the attached submission, we propose to translate this technology to the pediatric population. To do this, modifications to our technique are necessary. Our current adult technique consists of the following six steps: (i) placing three bone-implanted fiducial markers/anchors surrounding the ear under local anesthesia in an out-patient setting, (ii) obtaining a clinically applicable CT scan, (iii) using the CT scan to plan a surgical trajectory from the surface of the skull to the basal turn of the cochlea avoiding vital anatomy, (iv) constructing a microstereotactic frame to constrain a drill to pass along the planned trajectory (for the adult study, frame construction requires 48 hours), (v) affixing the frame to the bone-implanted anchors, and (vi) employing the frame to confirm the drill trajectory. Because children and adults differ anatomically, we propose to modify our technique by using a large database of pediatric CT scans to produce age-stratified anatomical atlases that will allow us to perform step (iii) in an automated fashion, as we are currently doing for adults with a single atlas. Because federal guidelines prohibit clinical studies on children entailing greater than minimal risk without the prospect of benefit for children, we have substantially modified steps (ii) and (iv) such that both the acquisition of the CT scan and the design and construction of the microstereotactic frame occur simultaneously with traditional CI surgery, thus reducing the risk to an acceptable level under the guidelines. To do this, we have done extensive work incorporating intraoperative CT scanner into our protocols and designed, developed, and tested a novel microstereotactic frame which can be designed and constructed in 30 minutes-well below the shortest surgical time in our review of 2,256 surgeries. We have recruited two additional well-respected CI programs to participate in the study-Boys Town (Omaha, NE) and the busiest CI center in the world, Medical Hospital of Hannover (Hannover, Germany) with whom we have a standing collaboration. Our hope is that this technique, percutaneous cochlear implantation, will make CI surgery quicker, cheaper, and easier to perform, allowing more children to benefit from aural rehabilitation with CIs.
In the United States about 20,000 deaf children have benefitted from cochlear implantation, a 2+ hour surgery that involves removal of a portion of the bone behind the external ear to reach the inner ear, the cochlea, and place a wire which stimulates the cochlea allowing hearing. Using image guided surgical techniques-similar to GPS technology used to provide geographic directions-we have shown that a much less invasive surgical approach is possible by tracking and controlling the path of a drill such that the cochlea may be reached by a single drill-we call this technique Percutaneous Cochlear Implantation (PCI) and have demonstrated it in adult patients. We now propose to test and perform PCI in children with our efforts focused on the differences between adults and children (for example, (i) anatomy and (ii) federal regulations governing research) with the proposed benefits of PCI including decreased operative time, decreased surgical cost, standardized surgery, and possibly even improved hearing outcomes.
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