Arneborg Ernst

Intracochlear Pressure Changes due to Round Window Opening: A Model Experiment

To preserve residual hearing in cochlea implantation, the electrode design has been refined and an atraumatic insertion of the cochlea electrode has become one aspect of cochlea implant research. The opening of the round window can be assumed to be a contributing factor in an atraumatic concept. The aim of our study was to observe intracochlear pressure changes due to different opening conditions of an artificial round window membrane. The experiments were performed in an artificial cochlea model. A round window was simulated with a polythene foil and a pressure sensor was placed in the helicotrema area to monitor intraluminal pressure changes. Openings of the artificial round window membrane were performed using different ways. Opening the artificial round window mechanically showed a biphasic behaviour of pressure change. Laser openings showed a unidirectional pressure change. The lowest pressure changes were observed when opening the artificial round window membrane using a diode laser. The highest pressure changes were seen when using a needle. The openings with the CO2 laser showed a negative intracochlear pressure and a loss of fluid. In our model experiments, we could prove that the opening of the artificial round window membrane causes various intracochlear pressure changes.

Intracochlear Fluid Pressure Changes Related to the Insertional Speed of a CI Electrode

Introduction. To preserve residual hearing the atraumaticity of the cochlea electrode insertion has become a focus of cochlear implant research. In addition to other factors, the speed of insertion is thought to be a contributing factor in the concept of atraumatic implantation. The aim of our study was to observe intracochlear fluid pressure changes due to different insertional speeds of an implant electrode in a cochlear model. Materials and Methods. The experiments were performed using an artificial cochlear model. A linear actuator was mounted on an Advanced Bionics IJ insertional tool. The intracochlear fluid pressure was recorded through a pressure sensor which was placed in the helicotrema area. Defined insertions were randomly performed with speeds of 0.1u2009mm/sec, 0.25u2009mm/sec, 0.5u2009mm/sec, 1u2009mm/sec, and 2u2009mm/sec. Results. A direct correlation between speed and pressure was observed. Mean maximum values of intracochlear fluid pressure varied between 0.41u2009mmu2009Hg and 1.27u2009mmu2009Hg. Conclusion. We provide the first results of fluid pressure changes due to insertional speeds of CI electrodes in a cochlear model. A relationship between the insertional speed and intracochlear fluid pressure was observed. Further experiments are needed to apply these results to the in vivo situation.

MRT der Ligg. alaria symptomatischer Patienten nach HWS-Distorsionstrauma

ZusammenfassungZiele dieser Arbeit waren die Darstellung der Ligg. alaria in der MRT und der Nachweis signifikanter Veränderungen nach HWS-Distorsionstrauma bei symptomatischen Patienten. Bei 73 Patienten mit persistierenden Beschwerden nach Schleudertrauma sowie 20 Probanden der Kontrollgruppe wurden die Ligg. alaria mit Hilfe der MRT-Dünnschichttechnik untersucht (TR 800 ms, TE 40 ms, Schichtdicke 2 mm axial, koronal und sagittal). Die verwendeten MRT-Sequenzen gewährleisteten eine gute Darstellung der Anatomie der Kopfgelenkbänder. Bei >30% der Patienten nach Schleudertrauma ergaben sich in der MRT-Untersuchung als pathologisch bewertete Veränderungen der Ligg. alaria. Signalerhöhungen, asymmetrisch nur innerhalb eines Lig. alare, sowie seitendifferente Kaliber zeigten sich nur in der Gruppe der Patienten mit HWS-Distorsionstrauma. Diese Veränderungen der Ligg. alaria wurden signifikant (p < 0,01) häufiger bei einem kaudokranialen Bandverlauf beobachtet. Mit der MRT können nach Schleudertrauma Veränderungen der Ligg. alaria nachgewiesen werden. Hyperintense Regionen in nur einem Band sowie Asymmetrie des Kalibers sind Hinweis auf partielle Rupturen.AbstractThe aims of the present study were to evaluate the magnetic resonance (MR) tomographic appearance of the alar ligaments and to demonstrate any significant changes after whiplash injury. A series of 73 symptomatic patients (age range 9–64 mean, 38 years) with a history of whiplash injury of the cervical spine underwent MR imaging of the cervical spine and the alar ligaments. In addition, 20 healthy volunteers were examined. Standardized examination included coronal and axial proton-weighted turbospin echo sequences (repetition time 800 ms, echo time 40 ms, slice thickness 2 mm, FOV 165 mm, matrix 256×205). This sequence was also repeated in the coronal plane with orientation toward the right or left alar ligament. In more than 30% of the symptomatic whiplash injury patients there were pathologic findings in the alar ligaments on MR imaging. Hyperintensive regions were found in only one alar ligament in 24 patients, reflecting partial tears. There were no asymmetrically changed signals from the alar ligaments in healthy volunteers (significant difference between volunteers and patients: P < 0.01). There is a significant (P < 0.01) correlation between pathologic findings and orientation of the fibers of the alar ligaments in the caudocranial direction. It was possible to demonstrate changes in the alar ligaments after whiplash injury with MR imaging. Hyperintensive regions in one alar ligament were interpreted as a sign of partial tears.

Effects of Different Insertion Techniques of a Cochlear Implant Electrode on the Intracochlear Pressure

To achieve a functional atraumatic insertion, low intracochlear pressure changes during the procedure are assumed to be important. The aim of this study was to observe intracochlear pressure changes due to different insertion techniques in a cochlear model. Cochlear implant electrode insertions were performed in an artificial cochlear model to record intracochlear pressure changes with a micropressure sensor to evaluate the maximum amplitude and frequency of pressure changes under different insertional conditions. We found statistically significant differences in the occurrence of intracochlear pressure peak changes comparing different techniques. Based on our model results, an insertion should be maximally supported to minimize micromovement-related pressure changes.

Intraoperative Electrophysiologic Variations Caused by the Scalar Position of Cochlear Implant Electrodes.

Objective The position of cochlear implant (CI) electrodes in the cochlea is fundamental for the interaction between the implant and the neurons of the spiral ganglion. The scalar position of the electrode in the cochlea is assumed to be an important parameter for the clinical outcome. In our study, the intraoperative electrophysiologic characteristics in dependence of the position of CI electrodes in the scala tympani or in the scala vestibuli after scalar change should be determined. Materials and Methods The intraoperative impedances and neural response telemetry (NRT) data of 23 patients implanted with a Nucleus Advance Contour (Cochlear Pty, Sydney, Australia) electrode were recorded. One CI surgeon and two radiologists evaluated the electrode array’s position independently radiologically by flat-panel tomography. Results from 17 patients with the electrode positioned in the scala tympani and six patients with the electrode changing intraoperatively from the tympanic into the vestibular scala were retrospectively analyzed. Results We found a statistically significant difference with an NRT threshold–based ratio for the groups. An estimation of the (radiologically confirmed) scalar position based on the NRT ratio was possible retrospectively. Conclusion The evaluation of specific intraoperative electrophysiologic data allowed separating between a regular and an irregular (i.e., scalar changing) position of CI electrodes. This noninvasive methodology can support the postoperative radiologic evaluation of the CI electrode array position.

Effects of Round Window Opening Size and Moisturized Electrodes on Intracochlear Pressure Related to the Insertion of a Cochlear Implant Electrode

Intracochlear pressure changes during the cochlear implant insertion are assumed to be an important contributor to hearing preservation. The aim was to observe intracochlear pressure changes by different round window opening sizes and different hydrophilic electrode conditions. The experiments were performed in a cochlear model with a micropressure sensor in the helicotrema area. Different artificial round window membrane and different moisturized electrode conditions were compared. A punctured round window causes a significantly higher and an indirect moisturized electrode condition a significantly lower intracochlear pressure change. The degree of round window opening and the hydrophilic character of an electrode during insertion affect the intracochlear pressure significantly in a model.

Prevalence and complications of MRI scans of cochlear implant patients

BackgroundCochlear implants (CI) are the preferred method of treatment for patients with severe to profound bilateral sensorineural hearing loss and unilateral deafness. For many years, because of the magnetic field applied during magnetic resonance imaging (MRI) examinations, MRI examinations were contraindicated for CI patients or feasible only under specific circumstances. MRI examinations of CI recipients entail complications and therefore preventive measures have to be considered. The aim of this study was to evaluate the prevalence of MRI scans in CI recipients and the occurrence of complications and furthermore to investigate the preventive measures taken in radiological daily routine.Materials and methodsAxa0retrospective questionnaire was sent to 482xa0patients that received CIs from 1999–2013. Details of the MRI examination and subjective and objective incidents during and after the MRI scan were evaluated.ResultsA total of 204 CI recipients answered the retrospective questionnaire (42.3u2009%). Twenty patients (9.8u2009%) with 23xa0implants underwent axa0total of 33xa0MRI scans with their cochlear implant in place. In 16xa0cases the scanned region was the head (49u2009%). Preventive measures in the form of head bandages were taken in 20xa0cases (61u2009%). The most common complication was pain in 23xa0cases (70u2009%) and the most serious complication was the dislocation of the internal magnet in 3xa0cases (9u2009%).ConclusionsThe number of CI recipients undergoing MRI scans is high. Possible complications and preventive measures attract too little attention in radiological daily routine.

Simultaneous Labyrinthectomy and Cochlear Implantation for Patients with Single-Sided Ménière’s Disease and Profound Sensorineural Hearing Loss

Objective. To investigate the treatment outcome of a simultaneous labyrinthectomy and cochlear implantation in patients with single-sided Ménières disease and profound sensorineural hearing loss. Study Design. Prospective study. Method. Five patients with single-sided Ménières disease with active vertigo and functional deafness were included. In all cases, simultaneous cochlear implantation combined with labyrinthectomy surgery was performed. The outcome has been evaluated by the Dizziness Handicap Inventory (DHI) and speech recognition. Results. The combined labyrinthectomy and cochlear implantation led in all patients to a highly significant reduction of dizziness up to a restitutio ad integrum. After activation of the cochlear implant and rehabilitation, a mean monosyllabic speech understanding of 69% at 65u2009dB was observed. Conclusion. For patients with single-sided Ménières disease and profound sensorineural hearing loss the simultaneous labyrinthectomy and cochlear implantation are efficient method for the treatment of vertigo as well as the rehabilitation of the auditory system.

Optimisation of the round window opening in cochlear implant surgery in wet and dry conditions: impact on intracochlear pressure changes.

To preserve residual hearing in cochlear implant candidates, the atraumatic insertion of the cochlea electrode has become a focus of cochlea implant research. In a previous study, intracochlear pressure changes during the opening of the round window membrane were investigated. In the current study, intracochlear pressure changes during opening of the round window membrane under dry and transfluid conditions were investigated. Round window openings were performed in an artificial cochlear model. Intracochlear pressure changes were measured using a micro-optical pressure sensor, which was placed in the apex. Openings of the round window membrane were performed under dry and wet conditions using a cannula and a diode laser. Statistically significant differences in the intracochlear pressure changes were seen between the different methods used for opening of the round window membrane. Lower pressure changes were seen by opening the round window membrane with the diode laser than with the cannula. A significant difference was seen between the dry and wet conditions. The atraumatic approach to the cochlea is assumed to be essential for the preservation of residual hearing. Opening of the round window under wet conditions produce a significant advantage on intracochlear pressure changes in comparison to dry conditions by limiting negative outward pressure.

Electrophysiological Detection of Intracochlear Scalar Changing Perimodiolar Cochlear Implant Electrodes: A Blinded Study.

Objective To investigate whether a previous established neural response telemetry (NRT) ratio corresponds with the scalar position of the CI electrode. Study Design Retrospective blinded controlled study. Setting Tertiary referral center. Patients The electrophysiological data sets of 85 patients with measured intraoperative NRTs were evaluated. All patients were implanted with the same CI system. Using a flat panel tomography system, the position of the electrode array was confirmed radiologically. Interventions The radiological results were blindly compared with the intraoperatively obtained electrophysiological data (NRT ratio) and statistically evaluated. In a second step, irregularities between the NRT ratios and the radiologically confirmed electrode positions were determined and the entire study material was investigated deeper. Main Outcome Measures Correlation of the NRT ratio with the intracochlear position of the CI electrode. Results By electrophysiological evaluation only, 69 patients were detected without a scalar change at first. In 16 patients, a scalar change was probable. A significant correlation between the radiological results and the NRT ratios was found. Secondly, additional patient characteristics were identified which influences the electrode’s position. Excluding those patients, the selectivity and specificity of the NRT ratio could be increased to a higher level. Conclusion Evidenced by a blinded group of patients, we are able to show that the electrode array position within the cochlea could be predicted using the NRT ratio.