Comprehensive literature review on the application of the otological surgical planning software OTOPLAN® for cochlear implantation.

BACKGROUND: The size of the human cochlear, measured by the diameter of the basal turn, varies between 7 and 11 mm. For hearing rehabilitation with cochlear implants (CI), the size of the cochlear influences the individual frequency map and the choice of electrode length. OTOPLAN® (CAScination AG [Bern, Switzerland] in cooperation with MED-EL [Innsbruck, Austria]) is a software tool with CE marking for clinical applications in CI treatment which allows for precise pre-planning based on cochlear size. This literature review aims to analyze all published data on the application of OTOPLAN®. MATERIALS AND METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied to identify relevant studies published in the PubMed search engine between January 2015 and February 2023 using the search terms "otoplan" [title/abstract] OR "anatomy-based fitting" [title/abstract] OR "otological software tool" [title/abstract] OR "computed tomography-based software AND cochlear" [title/abstract]. RESULTS: The systematic review of the literature identified 32 studies on clinical use of OTOPLAN® in CI treatment. Most studies were reported from Germany (7 out of 32), followed by Italy (5), Saudi Arabia (4), the USA (4), and Belgium (3); 2 studies each were from Austria and China, and 1 study from France, India, Norway, South Korea, and Switzerland. In the majority of studies (22), OTOPLAN® was used to assess cochlear size, followed by visualizing the electrode position using postoperative images (5), three-dimensional segmentation of temporal bone structures (4), planning the electrode insertion trajectory (3), creating a patient-specific frequency map (3), planning of a safe drilling path through the facial recess (3), and measuring of temporal bone structures (1). CONCLUSION: To date, OTOPLAN® is the only DICOM viewer with CE marking in the CI field that can process pre-, intra-, and postoperative images in the abovementioned applications.

[Comprehensive literature review on the application of the otological-surgical planning software OTOPLAN® for cochlear implantation. German version]. / Umfassender Literaturüberblick über die Anwendung der otologisch-chirurgischen Planungssoftware OTOPLAN® bei der Cochleaimplantation.

BACKGROUND: The size of the human cochlear, measured by the diameter of the basal turn, varies between 7 and 11 mm. For hearing rehabilitation with cochlear implants (CI), the size of the cochlear influences the individual frequency map and the choice of electrode length. OTOPLAN® (CAScination AG [Bern, Switzerland] in cooperation with MED-EL [Innsbruck, Austria]) is a software tool with CE marking for clinical applications in CI treatment which allows for precise pre-planning based on cochlear size. This literature review aims to analyze all published data on the application of OTOPLAN®. MATERIALS AND METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied to identify relevant studies published in the PubMed search engine between January 2015 and February 2023 using the search terms "otoplan" [title/abstract] OR "anatomy-based fitting" [title/abstract] OR "otological software tool" [title/abstract] OR "computed tomography-based software AND cochlear" [title/abstract]. RESULTS: The systematic review of the literature identified 32 studies on clinical use of OTOPLAN® in CI treatment. Most studies were reported from Germany (7 out of 32), followed by Italy (5), Saudi Arabia (4), the USA (4), and Belgium (3); 2 studies each were from Austria and China, and 1 study from France, India, Norway, South Korea, and Switzerland. In the majority of studies (22), OTOPLAN® was used to assess cochlear size, followed by visualizing the electrode position using postoperative images (5), three-dimensional segmentation of temporal bone structures (4), planning the electrode insertion trajectory (3), creating a patient-specific frequency map (3), planning of a safe drilling path through the facial recess (3), and measuring of temporal bone structures (1). CONCLUSION: To date, OTOPLAN® is the only DICOM viewer with CE marking in the CI field that can process pre-, intra-, and postoperative images in the abovementioned applications.

Species delimitation, discovery and conservation in a tiger beetle species complex despite discordant genetic data.

In an age of species declines, delineating and discovering biodiversity is critical for both taxonomic accuracy and conservation. In recent years, there has been a movement away from using exclusively morphological characters to delineate and describe taxa and an increase in the use of molecular markers to describe diversity or through integrative taxonomy, which employs traditional morphological characters, as well as genetic or other data. Tiger beetles are charismatic, of conservation concern, and much work has been done on the morphological delineation of species and subspecies, but few of these taxa have been tested with genetic analyses. In this study, we tested morphologically based taxonomic hypotheses of polymorphic tiger beetles in the Eunota circumpicta (LaFerté-Sénectère, 1841) species complex using multilocus genomic and mtDNA analyses. We find multiple cryptic species within the previous taxonomic concept of Eunota circumpicta, some of which were historically recognized as subspecies. We found that the mtDNA and genomic datasets did not identify the same taxonomic units and that the mtDNA was most at odds with all other genetic and morphological patterns. Overall, we describe new cryptic diversity, which raises important conservation concerns, and provide a working example for testing species and subspecies validity despite discordant data.

A genomic test of subspecies in the Eunota togata species group (Coleoptera: Cicindelidae): Morphology masks evolutionary relationships and taxonomy.

Most of the world's biodiversity is described primarily or exclusively using morphological traits that may not always reflect the true evolutionary units. Accurate taxonomy is critical for conservation efforts and re-evaluation of traditional taxonomy may often be warranted since species and subspecies are frequently the focus of conservation and faunistic studies. Here, we test comprehensive taxonomic hypotheses of morphologically defined subspecies in the tiger beetle, Eunota togata (LaFerté-Sénectère, 1841). The four recognized subspecies were delineated based mainly on the dorsal coloration and extent of white markings termed maculations. We combine inferences from mtDNA genealogies and genome-wide multilocus data to elucidate the evolutionary relationships within the group and assess the taxonomic implications. Three of the four subspecific taxa delineated by morphology were not supported by the genomic or mtDNA data. In fact, the species-level diversity in this group was underestimated, as E. togata was found to represent three well-supported distinct species in all genetic analyses. Emerging from these analyses, we also document an intriguing example of convergent evolution in lighter colored E. togata adapting to similar white saline backgrounds. Our collective work underscores the importance of using molecular methods to reevaluate morphological based taxonomy for species and subspecies delimitation and conservation.

Intra-cochlear differences in the spread of excitation between biphasic and triphasic pulse stimulation in cochlear implants: A modeling and experimental study.

Triphasic pulse stimulation can prevent unpleasant facial nerve stimulation in cochlear implant users. Using electromyographic measurements on facial nerve effector muscles, previous studies have shown that biphasic and triphasic pulse stimulations produce different input-output functions. However, little is known about the intracochlear effects of triphasic stimulation and how these may contribute to the amelioration of facial nerve stimulation. The present study used a computational model of implanted human cochleae to investigate the effect of pulse shape on the intracochlear spread of excitation. Biphasic and triphasic pulse stimulations were simulated from three different cochlear implant electrode contact positions. To validate the model results, experimental spread of excitation measurements were conducted with biphasic and triphasic pulse stimulation from three different electrode contact positions in 13 cochlear implant users. The model results depict differences between biphasic and triphasic pulse stimulations depending on the position of the stimulating electrode contact. While biphasic and triphasic pulse stimulations from a medial or basal electrode contact caused similar extents of neural excitation, differences between the pulse shapes were observed when the stimulating contact was located in the cochlear apex. In contrast, the experimental results showed no difference between the biphasic and triphasic initiated spread of excitation for any of the tested contact positions. The model was also used to study responses of neurons without peripheral processes to mimic the effect of neural degeneration. For all three contact positions, simulated degeneration shifted the neural responses towards the apex. Biphasic pulse stimulation showed a stronger response with neural degeneration compared to without degeneration, while triphasic pulse stimulation showed no difference. As previous measurements have demonstrated an ameliorative effect of triphasic pulse stimulation on facial nerve stimulation from medial electrode contact positions, the results imply that a complementary effect located at the facial nerve level must be responsible for reducing facial nerve stimulation.

Application of intentional facial nerve stimulation during cochlear implantation as an electrophysiological tool to estimate the intracochlear electrode position.

This proof of concept describes the use of evoked electromyographic (EMG) activation of the facial nerve for intraoperative monitoring of the electrode insertion during cochlear implantation (CI). Intraoperative EMG measurements from the facial nerve were conducted in nine patients undergoing CI implantation. Electric current pulses were emitted from contacts on the CI array during and immediately after electrode insertion. For control, the results of EMG measurements were compared to postoperative flat panel volume computed tomography scans with secondary reconstruction (fpVCTSECO). During insertion, the EMG response evoked by the electrical stimulation from the CI was growing with the stimulating contact approaching the facial nerve and declined with increasing distance. After full insertion, contacts on the apical half of the CI array stimulated higher EMG responses compared with those on the basal half. Comparison with postoperative imaging demonstrated that electrode contacts stimulating high EMG responses had the shortest distances to the facial nerve. It could be demonstrated that electrically evoked EMG activation of the facial nerve can be used to monitor the progress during CI electrode insertion and to control the intracochlear electrode position after full insertion.

Intraoperative Auditory Brainstem Response Measurements via the Vibrant Soundbridge Active Middle Ear Implant: Comparison of Two Methods.

PURPOSE: The Vibrant Soundbridge (VSB) active middle ear implant can be used to treat adults and children with hearing loss. Intraoperative measurements based on auditory brainstem response (ABR) allow the determination of the implant's performance. Two methods for stimulus presentation during ABR measurements via VSB will be compared. METHOD: ABRs were measured in patients implanted with a VSB using a standard ABR system. The stimulus was transmitted directly to the VSB using a new transmission unit (AcoustiAP, MED-EL) and for comparison via a standard audio processor coupled to a wireless streaming device. The study included 10 subjects with mild-to-profound sensorineural, conductive, or mixed hearing loss. RESULTS: As opposed to the wireless method, the AcoustiAP transmits the ABR stimulus without additional signal processing. Therefore, only minor distortions of the transmitted signal are to be expected. There was no significant difference between the performance of the two methods (mean wave V amplitudes 313 [75.2] vs. 301 [88.2] nVpp). In addition, the new system allowed for a more stable connection to the implant system. CONCLUSION: The AcoustiAP is a valuable tool for performing ABR measurements in patients during VSB implantation using standard equipment, as it allows for easier and more controlled measurements of the coupling efficiency of the implant.

Effects of electrical pulse polarity shape on intra cochlear neural responses in humans: Triphasic pulses with anodic and cathodic second phase.

Modern cochlear implants employ charge-balanced biphasic and triphasic pulses. However, the effectiveness of electrical pulse shape and polarity is still a matter of debate. For this purpose, a previous study (Bahmer & Baumann, 2013) conducted electrophysiological and psychophysical measurements following triphasic pulse stimulation with constant cathodic second phase and varying anodic first and third phases. Pulse stimulation with constant anodic second phase was not investigated. Therefore, in this study, pulse stimulation with cathodic and anodic second phase was applied for the recording of electrically evoked compound action potentials (ECAPs) as well as for psychophysical thresholds in cochlear implant (CI) recipients. First it was investigated whether the temporal polarity distribution has a different effect on neuronal stimulation when the second phase is cathodic or anodic; second, whether the electrophysiological and psychophysical results show a comparable difference between triphasic stimulation with anodic and cathodic second phases. The results showed that variation of the temporal polarity distribution of the triphasic pulse had a smaller effect on the ECAP response when the second phase was anodic compared to when it was cathodic, whereas for psychophysical detection thresholds this variation had a similar effect for both polarities. While electrophysiological responses and psychophysical detection thresholds showed a high correlation for variations of the triphasic pulse with cathodic second phase, the results for variations of the triphasic pulse with anodic second phase showed only moderate correlation. Furthermore, the difference between triphasic stimulation with cathodic and anodic second phases did not correlate between the electrophysiological and psychophysical results. In summary, after stimulation with different configurations of triphasic pulses used in the present study, the polarity of the second phase has an effect on electrophysiological response at suprathreshold level but not on the psychophysical detection thresholds. Thus, at different stimulation levels a possible substitution of the psychophysical test by an electrophysiological measurement (e.g. neural health measurement of the cochlea) could not be corroborated by the present results.

Geographic Life History Differences Predict Genomic Divergence Better than Mitochondrial Barcodes or Phenotype.

Species diversity can be inferred using multiple data types, however, results based on genetic data can be at odds with patterns of phenotypic variation. Tiger beetles of the Cicindelidiapolitula (LeConte, 1875) species complex have been taxonomically problematic due to extreme phenotypic variation within and between populations. To better understand the biology and taxonomy of this group, we used mtDNA genealogies and multilocus nuclear analyses of 34,921 SNPs to elucidate its evolutionary history and evaluate the validity of phenotypically circumscribed species and subspecies. Genetic analyses recovered two divergent species that are also ecologically distinct, based on adult life history. These patterns are incongruous with the phenotypic variation that informed prior taxonomy, and most subspecies were not supported as distinct evolutionary lineages. One of the nominal subspecies was found to be a cryptic species; consequently, we elevate C. p.laetipennis (Horn, 1913) to a full species. Although nuclear and mtDNA datasets recovered broadly similar evolutionary units, mito-nuclear discordance was more common than expected, being observed between nearly all geographically overlapping taxonomic pairs. Additionally, a pattern of 'mitochondrial displacement' was observed, where mitochondria from one species unidirectionally displace others. Overall, we found that geographically associated life history factors better predict genomic divergence than phenotype and mitochondrial genealogies, and consequently taxon identifications based on mtDNA (e.g., DNA barcodes) may be misleading.