Faculty Bibliography

HYPOTHESIS: Robotic insertions of actively steerable perimodiolar 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 compare 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 experiments, 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

Electrode insertion is the most important step in cochlear implant (CI) surgery. Optimal electrode placement is a prerequisite for maximizing CI success. This article describes CI electrode insertion in the normal and abnormal cochlea, including technical considerations unique to cochlear malformations, dysplasia, ossification, and revision implantation. Currently available electrodes and device specific operative techniques are reviewed. 2010 Elsevier Inc

OBJECTIVES: To present a rare case of facial nerve paraganglioma and novel use of a processed allograft for facial nerve reconstruction. STUDY DESIGN: Case report and review of the literature. METHODS: A 34 year old female presented with progressive onset right sided facial palsy for 5 months. CT and MRI demonstrated an irregular mass in the right facial nerve canal from the intratympanic segment to the stylomastoid foramen. RESULTS: Following transmastoid resection, the defect was repaired using processed allograft. Pathologic analysis was consistent with a paraganglioma. Facial nerve paraganglioma is a rare entity that has been reported only 10 times in the literature. CONCLUSIONS: Traditional methods of facial nerve reconstruction, including autologous and cadaveric grafting, can lead to significant patient morbidity. Autologous nerve grafts are the 'gold standard' for superior regenerative capability, but are limited by the length and potential neuroma formation at the donor site. Allogenic grafts from donors or cadavers have shown some efficacy, but can require immunosuppression. The Avance nerve graft is a cadaveric graft, processed and decellularized to maintain an extracellular matrix with laminin and intact endoneural tubes, thus providing support for the growing axon without generating an immune response. Initial studies of the Avance graft in animals and humans have examined repair of peripheral nerves, but this is the first reported case of human facial nerve reconstruction

HYPOTHESIS: An objective cochlear framework, for evaluation of the cochlear anatomy and description of the position of an implanted cochlear implant electrode, would allow the direct comparison of measures performed within the various subdisciplines involved in cochlear implant research. BACKGROUND: Research on the human cochlear anatomy in relation to tonotopy and cochlear implantation is conducted by specialists from numerous disciplines such as histologists, surgeons, physicists, engineers, audiologists, and radiologists. To allow accurate comparisons between and combinations of previous and forthcoming scientific and clinical studies, cochlear structures and electrode positions must be specified in a consistent manner. METHODS: Researchers with backgrounds in the various fields of inner ear research as well as representatives of the different manufacturers of cochlear implants (Advanced Bionics Corp., Med-El, Cochlear Corp.) were involved in consensus meetings held in Dallas, March 2005, and Asilomar, August 2005. Existing coordinate systems were evaluated, and requisites for an objective cochlear framework were discussed. RESULTS: The consensus panel agreed upon a 3-dimensional, cylindrical coordinate system of the cochlea using the 'Cochlear View' as a basis and choosing a z axis through the modiolus. The zero reference angle was chosen at the center of the round window, which has a close relationship to the basal end of the Organ of Corti. CONCLUSION: Consensus was reached on an objective cochlear framework, allowing the outcomes of studies from different fields of research to be compared directly

OBJECTIVE: To examine speech perception outcomes as related to a reduction in the number of functional electrodes postimplantation and to determine the effect of electrode reduction on subsequent device failure. STUDY DESIGN: Retrospective review. SETTING: Tertiary academic referral center. PATIENTS: Of 1,520 children and adults with full insertions of the Advanced Bionics, Med El, and Nucleus devices, 15 (1%) were patients. Patients were included in the study if all electrodes were functional at initial stimulation, but the number of electrodes in use was subsequently reduced at follow-up programming sessions. Exclusion criteria included partial and split-array electrode insertions. INTERVENTION(S): Patients with bilateral severe to profound sensorineural hearing loss underwent either unilateral or bilateral cochlear implantation. MAIN OUTCOME MEASURE(S): Postimplantation speech perception tests obtained with a full complement of functional electrodes were performed and the results compared to those obtained with 1 or more electrodes removed from the user program. Electrode deactivation was also correlated with device failure. RESULTS AND CONCLUSION: The results of this study indicate that deactivation of cochlear implant electrodes is relatively uncommon, and although the deactivation does not have a direct influence on speech performance outcomes, the loss of 5 or more electrodes can suggest impending device failure. Additionally, those patients with electrode deactivation coupled with a decline in speech perception scores should also be considered at risk for device failure

OBJECTIVES: The purpose of this study is to determine if the performance of the first implanted member of a family predicts the performance of subsequently implanted family members. STUDY DESIGN: Retrospective chart review. METHODS: Seventy-one cochlear implant recipients, each belonging to a family with two or more implanted members, were the subjects of this study. Routine audiometric measurements and age-appropriate speech perception tests were performed pre- and postoperatively. In addition, length of deafness, age at implantation, etiology, and length of device usage were correlated to outcome. RESULTS: All implant recipients within a family showed improvement postimplantation, and the predictive component between family members was strong. Presence of GJB2 mutations and greater age at implantation were predictive of poorer rehabilitative outcome, while length of device usage was associated with improved speech perception scores. CONCLUSIONS: On average, if the first implanted family member performs well with a cochlear implant, those following will do well; however, GJB2-related deafness and increased age at implantation are associated with poorer outcome. These findings have important implications for members of families considering cochlear implantation

OBJECTIVES/HYPOTHESIS: Widespread universal newborn hearing screening has led to increased identification of infant hearing loss. Supported by improved diagnostic tools allowing more definitive diagnosis of profound sensorineural hearing loss in young children, cochlear implantation in children <12 months of age is now common. Literature supports short-term safety and improved auditory outcomes in these young children, however long-term data is lacking. The study examines issues of long-term safety and efficacy in cochlear implant patients implanted <1 year of age. STUDY DESIGN: Retrospective chart review. METHODS: Fifty children who received cochlear implants before 1 year of age were followed for up to 7 years. Age at implantation ranged from 5 to 11 months with a mean of 9.1 months. Three patients had simultaneous bilateral implantation at 8 to 9 months of age. Medical records were reviewed for complications incurred during length of device usage, including time of complication, management, and resolution. Auditory assessment included both the Infant-Toddler Meaningful Auditory Integration Scale and tests of speech perception. RESULTS: All 50 patients had full insertions of the electrode array. There were a total of eight complications (16%) in seven patients, three major (6%) and five minor (10%), which occurred at or before 10 months postoperatively. There were no perioperative anesthetic complications. CONCLUSIONS: Cochlear implantation in children <12 months of age is safe and efficacious over an extended period of time. Rates and nature of both major and minor complications are comparable to studies in adults and older children and support continued monitoring of these patients over the long-term

OBJECTIVE: Bilateral sequential cochlear implantation outcomes are dependent on many different factors. Newer technology in the second implanted ear may also contribute to outcome. This study examines the effect of cochlear implant technology on speech recognition outcomes in a population of adult patients who have undergone bilateral sequential implantation using different technologies in each ear. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary referral center. PATIENTS: Twenty adults who underwent bilateral sequential cochlear implantation with different technologies and processing strategies in each ear were patients for this study. Control Group A included patients (n = 8) who were simultaneously implanted, and Control Group B (n = 3) were patients who were sequentially implanted with the same technology. INTERVENTION: Bilateral sequential cochlear implantation. OUTCOME MEASURES: The outcome measure was the Consonant-Nucleus-Consonant monosyllabic word test administered in each implanted ear and in the binaural condition before and 1 year after operation. A multivariate analysis was performed to account for factors including duration of deafness, length of device usage, and severity of deafness. RESULTS: There was significant improvement from before to 1 year after the operation in word scores for the individual ears and in the binaural condition for all groups. All patients were consistent users of both devices, and the use of different technology in the second implanted ear did not affect the patients' ability to benefit from bilateral implantation despite the use of different devices and processing strategies. CONCLUSION: Bilateral sequential implantation with newer and/or differing technology in the second implanted ear did not reduce the benefits of bilateral stimulation and should not be considered a deterrent to second-sided implantation

PURPOSE OF REVIEW: Cochlear implantation is a well tolerated and effective procedure in the rehabilitation of profoundly and severely hearing-impaired individuals. Cochlear reimplantation may be necessary for a variety of reasons. The recent literature regarding the indications, surgical considerations, and outcomes in revision cochlear implant (RCI) surgery is reviewed here. RECENT FINDINGS: A small but significant percentage (3-8%) of all cochlear implant procedures requires RCI surgery. The most common indication for RCI is hard failure (40-80%), but other common indications include soft failures, wound complications, infection, improper initial placement, and electrode extrusions. There is a high rate of surgical success in RCI with preservation or improvement of preoperative performance in the majority of patients, in addition to the alleviation of prereimplantation symptoms. Both children and adults benefit from RCI when indicated and experience similar auditory successes following RCI. SUMMARY: The need for RCI is uncommon, but the potential for restoration or improvement in speech perception and alleviation of symptoms exists. Regardless of indication, RCI surgery is well tolerated, and, with thoughtful preparation, individualized patient counseling, and proper surgical technique, most patients can expect successful outcomes