Faculty Bibliography

This paper presents an optimal path planning method of steerable electrode arrays for robot assisted cochlear implant surgery In this paper, the authors present a novel design of steerable electrode arrays that can actively bend at the up An embedded strand in the electrode array provides an active steering degrees of freedom (DoF) This paper addresses the calibration of the steerable electrode arrays and the optimal path planning for inserting it into planar and three dimensional scala tympani models The goal of the path planning is to minimize the intracochlear forces that the electrode array applies on the walls of the scala tympam during insertion This problem is solved by designing insertion path planning algorithms that provide best fit between the shape of the electrode aunty and the curved scala tympani during insertion Optimality measures that account fittape discrepancies between the steerable electrode array and the scala tympam are used to solve for the optimal path planning of the robot Different arrangements of DoF and insertion speed force feedback (ISFF) are simulated and experimentally validated in this paper A quality of insertion metric describing the gap between the steerable electrode array and the scala tympam model is presented and as correspondence to the insertion force is shown The results of using 1DoF 2DoF and 4DoF electrode array insertion setups are compared The 1DoE insertion setup fiver nonsteerable electrode arrays The 2DoF insertion setup uses single axis insertion with steerable electrode arrays. The 4DoF insertion setup allows full control of the insertion depth and the approach angle of the electrode with respect to the cochlea while using steerable electrode arrays It is shown that living steerable electrode arrays significantly reducer the maximal insertion force (59.6% or more) and effectively prevents buckling of the electrode array The 4DoF Insertion setup further reduces the maximal electrode insertion forces The results of using ISFF for steerable electrodes show a slight decrease in the insertion forcer in contrast to a slight increase for nonsteerable electrodes These results show that further research is required in order to determine the optimal ISFF control law and its effectiveness in reducing electrode invention fortes [DOI 10.1115/1.3039513]

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

OBJECTIVE: To review our experience with partial standard and double-array cochlear implantation in the ossified cochlea. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Twenty cochleae in 19 adult and pediatric patients with ossified cochleae. INTERVENTION(S): Patients underwent either partial insertion of a standard electrode array or double-array electrode insertion for their cochlear implantation. MAIN OUTCOME MEASURE(S): Number of electrodes inserted, number of active electrodes at follow-up, and open-set speech performance. RESULTS: Twelve patients (four children and eight adults) had partial insertion of standard array electrode. The mean number of electrodes inserted and active at follow-up was 14.8 and 11.3, respectively. Eight patients (four children and four adults) had a double-array electrode implanted. The mean number of electrodes inserted and active at follow-up was 18.1 and 16.3, respectively. Open-set speech recognition was better in children regardless of duration of deafness. There were no complications. CONCLUSION: These findings suggest that the double array allows for more usable electrodes than in partially inserted cochlear implant. Compared with adults, children with ossified cochlea do well both in partial standard and double-array insertion. Both insertion techniques are safe, with no complications occurring in our patients. Straight and double arrays should be available in the operating suite for any patient in whom suspected cochlear ossification is confronted

OBJECTIVES: To date, numerous studies have compared functional outcomes between stereotactic radiosurgery (SRS) and microsurgery (MS) in the treatment of vestibular schwannomas (VS). However, most of them involve tumors of difference sizes, radiation dosages, and surgical approaches. Few have systematically compared issues of dysequilibrium. By studying only patients with small tumors and no hearing, we sought to minimize confounding variables. STUDY DESIGN: A retrospective chart review and telephone questionnaire. METHODS: From 1998-2006, 31 patients with small (<1.5 cm) VS and nonserviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery [AAO-HNS] Class C or D) were treated at our institution. Twenty-two were available for follow-up and telephone questionnaire, including the University of California Los Angeles Dizziness Questionnaire (UCLA-DQ). Twelve underwent SRS and 10 underwent MS. All MS patients underwent the translabyrinthine approach to their tumors. Outcomes measurements included tumor control, facial nerve function, tinnitus, trigeminal function, and imbalance. RESULTS: Patients undergoing SRS had comparable rates of tumor control, facial nerve function, tinnitus, and trigeminal function to MS patients. However, SRS did result in statistically significantly worse long-term imbalance when compared with MS patients. Detailed comparisons of the two modalities are made. CONCLUSIONS: In our study population, patients with small tumors and no serviceable hearing, these data suggest that MS results in comparable minimal morbidity with SRS, though posttreatment dysequilibrium is significantly decreased. While the authors recommend translabyrinthine resection of small VS with no hearing in patients able to tolerate surgery, the need for further prospective investigation is clear

OBJECTIVE AND IMPORTANCE: In rare cases, posterior fossa meningiomas can involve the endolymphatic sac. Such involvement can result in endolymphatic hydrops and a constellation of symptoms suggestive of Meniere's disease. The diagnosis and management of patients with these tumors is discussed. CLINICAL PRESENTATION: Three patients, each of whom presented with symptoms consistent with Meniere's disease, were found to have posterior fossa meningiomas limited to the dura overlying the endolymphatic sac. INTERVENTION: All 3 patients were diagnosed by magnetic resonance imaging and underwent complete surgical resection. In all cases, the symptoms resolved after tumor removal. CONCLUSION: Clinicians should have a degree of suspicion of posterior fossa meningioma when patients present with symptoms suggestive of Meniere's disease. Failure to do so may result in delayed diagnosis or worse outcomes for an otherwise treatable tumor

OBJECTIVE: To describe a safe and effective technique for the implantation of common cavity cochleae. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Fifteen cochleae in 9 adults and children with common cavity deformities implanted with and without the use of intraoperative fluoroscopy. INTERVENTION(S):: Fluoroscopically assisted cochlear implantation. MAIN OUTCOME MEASURE(S): Rates of extracochlear placement, bending, kinking, intrameatal placement, and complications were analyzed. Numbers of electrodes inserted, number of active electrodes, and speech performance were compared between the 2 groups. RESULTS: Half of the nonfluoroscopy group had suboptimal placement of their electrode arrays. This group also had a higher rate of complications, lower numbers of electrodes implanted, and lower number of active electrodes at follow-up. Results of speech perception testing suggest that fluoroscopically assisted implantation of the common cavity results in improved performance. CONCLUSION: Intraoperative fluoroscopy is an easy, safe, and effective technique that results in improved outcomes for cochlear implant patients with common cavity deformities

This article describes results on using steered molecular dynamics (SMD) simulations and experimental single molecule force spectroscopy (SMFS) to investigate the relationship between hydrogen bonding and mechanical stability of a series of homodimeric beta-sheet mimics. The dimers consisting of 4, 6, and 8 H-bonding sites were modeled in explicit chloroform solvent and the rupture force was studied using constant velocity SMD. The role of solvent structuring on the conformation of the dimers was analyzed and showed no significant contribution of chloroform molecules in the rupture event. The simulated stability of the dimers was validated by force data obtained with atomic force microscopy (AFM)-based SMFS in toluene. The computational model for the 8H dimer also offered insight into a possible mismatched dimer intermediate that may contribute to the lower than expected mechanical stability observed by single molecule AFM force studies. In addition, atomic level analysis of the rupture mechanism verified the dependence of mechanical strength on pulling trajectory due to the directional nature of chemical bonding under an applied force. The knowledge gained from this basic study will be used to guide further design of modular polymers having folded nanostructures through strategic programming of weak, non-covalent interactions into polymer backbones

HYPOTHESIS: The current hybrid electrode can be inserted without trauma to the temporal bone and, after insertion, assumes a position within the scala tympani near the outer cochlear wall just beneath the basilar membrane. BACKGROUND: Conservation of residual hearing after cochlear implant electrode insertion requires a special insertion technique and an atraumatic short electrode. This allows electroacoustic stimulation in ears with significant residual hearing. METHODS: Human cadaveric temporal bones were implanted with soft surgical technique under fluoroscopic observation. Dehydrated and resin-impregnated bones are dissected. Real-time electrode insertion behavior and electrode position were evaluated. The bones are examined for evidence of insertion-related trauma. RESULTS: No gross trauma was observed in the implanted bones, and the electrode dynamics evaluation revealed smooth scala tympani insertions. CONCLUSION: Atraumatic insertion of the 10-mm hybrid electrode can be accomplished using an appropriate cochleostomy and insertion technique