Cochlear Implantation Assisted by Noninvasive Image Guidance

Objective: We recently developed a new noninvasive registration method for image-guided otologic surgery (STAMP method). We investigated the benefit and potential drawback of our new method in clinical application and tested the feasibility of routine image-guided surgery. Study Design: Retrospective case review. Setting: Tertiary referral university hospital. Patients: Forty-six cases (45 patients) that underwent cochlear implantation in Kyushu University Hospital during the period of 2007 and 2010 were informed of the option to use navigated surgery. INTERVENTION: Twenty-five cochlear implantations were performed using STAMP-registered image-guided surgery. MAIN OUTCOME MEASURE: The error of image-guided surgery and time of surgery were collected and analyzed. Results: STAMP method offered serviceable accuracy in 18/25 cochlear implantations. The learning curve suggested that the accuracy is at least stabilizing, if not improving, and the success rate is expected to rise. Time of cochlear implant surgery was not significantly extended by the use of image guidance. Conclusion: STAMP method had comparable errors with minimal invasiveness. Our new method potentially enables routine use of image-guided surgery. © 2012, Otology & Neurotology, Inc.

Mice lacking ganglioside GM3 synthase exhibit complete hearing loss due to selective degeneration of the organ of Corti

The ganglioside GM3 synthase (SAT-I), encoded by a single-copy gene, is a primary glycosyltransferase for the synthesis of complex gangliosides. In SAT-I null mice, hearing ability, assessed by brainstem auditory-evoked potentials (BAEP), was impaired at the onset of hearing and had been completely lost by 17 days after birth (P17), showing a deformity in hair cells in the organ of Corti. By 2 months of age, the organ of Corti had selectively and completely disappeared without effect on balance or motor function or in the histology of vestibule. Interestingly, spatiotemporal changes in localization of individual gangliosides, including GM3 and GT1b, were observed during the postnatal development and maturation of the normal inner ear. GM3 expressed in almost all regions of cochlea at P3, but at the onset of hearing it distinctly localized in stria vascularis, spiral ganglion, and the organ of Corti. In addition, SAT-I null mice maintain the function of stria vascularis, because normal potassium concentration and endocochlear potential of endolymph were observed even when they lost the BAEP completely. Thus, the defect of hearing ability of SAT-I null mice could be attributed to the functional disorganization of the organ of Corti, and the expression of gangliosides, especially GM3, during the early part of the functional maturation of the cochlea could be essential for the acquisition and maintenance of hearing function