Influence of tonotopic cochlear stimulation on subjective visual vertical - a pilot study.

OBJECTIVE: This pilot study aimed at evaluating the effect of tonotopic (basal) stimulation on the Subjective Visual Vertical (SVV) in patients unilaterally treated with a Cochlear Implant (CI). MATERIALS AND METHODS: Ten adult subjects with severe to profound sensorineural hearing loss, who were implanted with a CI from Advanced Bionics (AB, Stäfa, Switzerland), model HiRes 90KTM or newer, were included in this prospective pilot study between September and December 2020. A specific CI processor (Naída CI Q90) was used to generate five different stimulation modes: simulation of either basal, medial, or apical electrodes, all electrodes on and all electrodes off. The examination of the verticality was carried out by means of SVV goggles both in the upright body position (head position 0 degrees) and with the head tilted sideways (-30°, -15°, +15°, +30°). RESULTS: In each stimulation mode, there was a significant difference (p < 0.05) in SVV between the straight head orientation and the tilted head position. There were, however, no significant differences between the five CI settings in any given head position (p > 0.05). No significant differences could be found regarding the direction of SVV deviation relative to the operated ear (p > 0.05). CONCLUSIONS: SVV could not be influenced by tonotopic CI stimulation. Different stimulation settings, patterns and intensity other than the auditory strategy may have to be developed to provide an adequate stimulus to the otolith organs.

Electrophysiological detection of electrode fold-over in perimodiolar cochlear implant electrode arrays: a multi-center study case series.

PURPOSE: It is important for the surgeon to determine the position of the CI electrode array during and after its placement within the cochlea. Most preferably, this should be within the scala tympani to obtain the best audiological outcome. Thus, misplacement into the scala vestibuli or tip fold-over should be prevented. Since there are different ways to ensure proper positioning of the electrode array within the scala tympani (e.g., intraoperative radiography, electrophysiological recordings), our study was aimed at detecting intraoperative electrophysiologic characteristics to better understand the mechanisms of those electrode tip fold-overs. MATERIAL AND METHODS: In a multi-centric, retrospective case-control series, patients with a postoperatively by radiography detected tip fold-over in perimodiolar electrodes were included. The point of fold-over (i.e., the electrode position) was determined and the intraoperative Auto-NRT recordings were analysed and evaluated. RESULTS: Four patients were found to have an electrode tip fold-over (out of 85 implantees). Significant changes of the Auto-NRT recordings were not detected. All tip fold-overs occurred in the most apical part of the electrodes. DISCUSSION: Cochlear implantation for hearing impaired patients plays a decisive role in modern auditory rehabilitation. Perimodiolar electrode arrays may fold over during the insertion and, hence, could have a negative impact on audiological outcome. Characteristic electrophysiologic changes to possibly predict this were not found in our series.

Electric compound action potentials (ECAPs) and impedances in an open and closed operative site during cochlear implantation.

INTRODUCTION: In patients undergoing cochlear implantation, intraoperative measures of impedance and electrically evoked compound action potentials (ECAPs) are used to confirm device integrity and electrode array position. However, these electrophysiological parameters have been shown to decrease over time, with a small decrement observable as early as 24 h post implantation and becoming more apparent after 6 months. Whether the intraoperatively measured impedances and ECAPs recorded immediately after electrode insertion versus later in the operation or in an open versus closed operative site vary has not been documented. Such variation in measurement procedure may affect the ultimate operative outcome. PATIENTS AND METHODS: Between February and October 2016, 38 patients received a cochlear implant (Cochlear®), with half receiving a CI 522 device and the other half receiving a CI 512 device. These patients were distributed into three groups. In the first (group A; n = 21), the impedance and threshold neural response telemetry (tNRT) measures were taken before (M1) and after cutaneous suture (M2), whereas in the second group (group B; n = 11) they were taken twice in the open operative site, once at the time of electrode insertion (M1) and then again 10 min later (M2). The last group (group C; n = 6) was measured only once after a 10 min waiting time before closing the operative site. RESULTS: tNRTs of both group A and B were significantly higher at M1 than measured at M2. The magnitude of change in tNRT did vary significantly by group (P = .027) with group A having a bigger decrease than group B. For impedances there was evidence for a significant difference in M2 between the three groups (P = .012), with group C having significantly higher values compared to group A and B. CONCLUSION: Intraoperative tNRT measures change significantly over time, including within the first 10 min of implantation. One underlying etiology of this phenomenon for tNRTs seems to be the condition of the surgical site whereas changes of impedances can be best explained by the 'electrochemical cleaning' theory associated with the first stimulation of the electrode. However, for both impedances and tNRTs there also is an important impact of time as well as of acute perioperative changes in electrical conductivity.

Electrophysiological detection of scalar changing perimodiolar cochlear electrode arrays: a long term follow-up study.

The position of the cochlear electrode array within the scala tympani is essential for an optimal hearing benefit. An intraoperative NRT-ratio was established, which can provide information about the intraoperative intracochlear electrode array position for perimodiolar electrodes. The aims of this study were to verify the longterm reliability for the NRT-ratio in perimodiolar electrodes. In a retrospective controlled study in a Tertiary Referral Center the electrophysiological data sets of 123 patients with implanted Nucleus Contour Advance electrodes were enclosed. Intraoperative and up to 1 year follow-up Auto-NRTs were evaluated. A NRT-ratio was calculated by dividing the average Auto-NRT data from electrode 16 to 18 with the average from electrode 5 to 7. Using a flat panel tomography system, the position of the electrode array was certified radiological. 31 patients with perimodiolar electrodes with 1 year follow-up data were included in the study. Eleven patients showed regular follow-up NRT-ratio with a correlated and radiologically confirmed electrode position. 20 patients showed mismatches between the NRT-ratio and the radiological position. These patients were highly variable in terms of duration of deafness and neural spectrum disorders. The NRT-ratio can be used to determine the intracochlear position of the electrode array for perimodiolar electrodes. Intraoperatively the NRT-ratio predicts the array position within the cochlea highly reliable for perimodiolar electrodes. We showed that after 6 months and a year, the NRT-ratio remains unchanged in most of the cases and shows a good correlation to the radiological determined position of the array. Nevertheless, the condition of the neural structures is highly important for reproducible responses. Limited validity is given in patients with degenerative and structural neural disorders.

ECAP analysis in cochlear implant patients as a function of patient's age and electrode-design.

INTRODUCTION: Electric compound action potentials (ECAPs) provide information about the nerve's and device's function in and after cochlear implantation. In general, lower ECAP values are expected to generate better results. Aim was an analysis of ECAPs in the course of time as a function of the patient's age and electrode design. PATIENTS AND METHODS: Between 2008 and 2013, 168 patients of eight defined age groups were included into the investigation. NRTs were measured intraoperatively, after 6 and after 12months. RESULTS: The intraoperative mean value of ECAP was 174.14CL (current level) and decreased after 6months to 156.38CL. Highest ECAPs were achieved intraoperatively in the clusters "younger than 18months" (181.04CL) and "older than 80 years" (190.45CL). CI 422 showed apparently higher ECAP thresholds (182.69) during surgery than CI 24 RE (171.47) and CI 512 (170.64). CONCLUSION: ECAPs are a well-established method to get information about the CI's and nerve's function during and after surgery. After initial higher values NRTs decrease after 6months and remain stable in the following controls. Very young and older patients tend to have higher thresholds than middle-aged groups. Perimodiolar electrodes are significantly attached to lower values because there is a closer nerve-electrode interaction.

[Treatment of recurrent epistaxis by artery ligation: up to date or old fashioned?]. / Behandlung rezidivierender Epistaxis durch Gefäßligatur: zeitgerecht oder überholt?

UNLABELLED: Treatment of Recurrent Epistaxis by Artery Ligation: Up to Date or Old Fashioned? BACKGROUND: Despite the ongoing development in the field of endoscopic treatment techniques, recurrent epistaxis remains a challenge for otolaryngologists. The aim of the present study was to compare our own results of various interventions for the treatment of recurrent epistaxis. MATERIALS AND METHODS: From 2007 to 2013 we performed surgical treatment of recurrent epistaxis under general anaesthesia in 148 cases. While the majority of causes were idiopathic (n=98), epistaxis also occurred postoperatively (n=30), post-traumatically (n=7) or as a result of M. Osler (n=12). In 141/148 cases the treatment was performed by mono- or bipolar coagulation in the area of the bleeding source - this required an ethmoidectomy in 17 cases. In 19 cases the intervention was combined with a septoplasty. In 4 patients with recurrent bleeding of unknown origin, where electrocoagulation under general anaesthesia failed, we performed a clipping of the ethmoid- and/or the maxillary arteries in the pterygopalatine fossa. Following this intervention no further bleeding episodes occured. In further 3 patients, neuroradiological embolization was successfully performed. CONCLUSION: If conservative measures fail in the treatment of epistaxis, surgical treatment by electrocoagulation of the bleeding site under general anaesthesia is an effective intervention in 95% of cases. However for the remaining 5% where these measures have been proven to be ineffective, clipping of the ipsilateral anterior and posterior ethmoid- and/or the maxillar artery provides a treatment option being equally efficient as neuroradiological interventions.