Rise in complications of acute otitis media during and after the COVID-19 pandemic.

PURPOSE: After the lifting of nonpharmaceutical interventions (NPIs) during the COVID-19 pandemic, clinical observation showed an increase in complications of acute otitis, followed by a rise in the number of mastoidectomies performed. The aim of this study was to record the number of mastoidectomies performed before, during and after the COVID-19 pandemic as an indicator for complications of acute otitis media. METHODS: Data were collected from a tertiary hospital in a university setting, as well as from four major public health insurance companies in Germany. The data of 24,824,763 German citizens during a period from 2014 until 2023 were analyzed. RESULTS: According to the data, during the COVID-19 pandemic, the number of mastoidectomies performed dropped by 54% for children aged 0-6 and by 62% for children aged 7-18. For adults, there were 30% fewer mastoidectomies performed between 2020 and 2022. After the lifting of most NPI's in the season from July 2022 to June 2023, there was a sharp increase in the number of mastoidectomies performed on patients of all ages. CONCLUSIONS: During the COVID-19 pandemic, a decrease in the number of mastoidectomies performed was seen, suggesting a lower incidence of complicated acute otitis, most likely linked to the general decrease of upper airway infections due to NPI's. In contrast, a sharp increase in the incidence of complicated otitis occurred after the hygiene measures were lifted. The current development causes a more frequent performance of mastoidectomies, thus entailing a change in the challenges for everyday clinical practice.

[Interactive electronic visualization formats in student teaching]. / Interaktive elektronische Visualisierungsformate in der studentischen Ausbildung.

BACKGROUND: In the context of contact restrictions, conventional teaching is currently in need of optimization and expansion. The range of digital teaching formats in student training is very heterogeneous and their effectiveness uncertain. This study aims to investigate the extent to which an electronic ward round can be used as an alternative to the conventional ENT attendance practical course, and whether the use of electronic teaching formats has an influence on the quality of teaching. MATERIALS AND METHODS: Instead of regular attendance practicals, bedside teaching took place once a week in real time as a video stream via tablet. A total of 43 students in the seventh semester (winter semester 2020/2021) were included in the prospective study. Evaluation forms were used to examine the subjective didactic value of different visualization formats for the students. Examination results from previous years were used for comparison. RESULTS: The majority of students reported knowledge gain from the electronic rounds (93.02%) and that they were a good alternative to the traditional attendance clerkship (69.77%). The quality of the video and audio transmission as well as the comprehensibility of the case studies presented were consistently rated as good to very good. The students' examination results tended to be slightly worse in the test group compared to the control students of previous years. CONCLUSION: Integration of innovative interactive visualization options into teaching shows promising prospects as a supplement to conventional face-to-face teaching. The results of this study can contribute to the further expansion of digital teaching. Scaling up this model could be considered especially in countries with limited availability of face-to-face teaching.

[Multidimensional formats of surgical anatomy in otorhinolaryngology student teaching-a comparison of effectivity]. / Multidimensionale Formate chirurgischer Anatomie in der studentischen Ausbildung der HNO-Heilkunde ­ ein Effektivitätsvergleich.

BACKGROUND: Technological change in healthcare and the digital transformation of teaching require innovations in student teaching in medicine. New technologies are needed to enable the delivery and use of diverse teaching and learning formats by educational institutions independent of time and place. The aim of this study is to analyze the effectiveness of different multidimensional formats in student teaching in surgical ENT medical anatomy. MATERIALS AND METHODS: During the summer semester 2022 and winter semester 2022/2023, the digital teaching and learning program was expanded by testing different visualization formats (3D glasses, cardboards, or VR glasses) with students in the context of a highly standardized surgical procedure, namely cochlear implantation. A pre- and post-intervention knowledge assessment was carried out in all groups, followed by an evaluation. RESULTS: Of 183 students, 91 students fully participated in the study. The post-intervention knowledge assessment showed a significant increase in correct answers regardless of visualization format. In a direct comparison, the operating room (OR) group answered correctly significantly more often than the cardboard group (p = 0.0424). The majority of students would like to see 3D teaching as an integral part of the teaching program (87.9%) and more streaming of live surgeries (93.4%). They see the use of the various technologies as a very good addition to conventional surgical teaching (72.5%), as good visualization (89%) increases retention (74.7%) and motivation (81.3%). CONCLUSION: Application and use of new visualization technologies in everyday clinical practice is a promising approach to expanding student training. Mobile, interactive, and personalized technical formats can be adapted to the learning behavior of students. Last but not least, the use of new media influences learning motivation. An expansion of digital teaching and learning formats can be expressly recommended on the basis of this study.

The Dorsal Skinfold Chamber as a New Tympanic Membrane Wound Healing Model: Intravital Insights into the Pathophysiology of Epithelialized Wounds.

BACKGROUND: Tympanic membrane perforations (TMPs) are a common complication of trauma and infection. Persisting perforations result from the unique location of the tympanic membrane. The wound is surrounded by air of the middle ear and the external auditory canal. The inadequate wound bed, growth factor, and blood supply lead to circular epithelialization of the perforation's edge and premature interruption of defect closure. Orthotopic animal models use mechanical or chemical tympanic membrane laceration to identify bioactive wound dressings and overcome premature epithelialization. However, all orthotopic models essentially lack repetitive visualization of the biomaterial-wound interface. Therefore, recent progress in 3D printing of customized wound dressings has not yet been transferred to the unique wound setup of the TMP. Here, we present a novel application for the mice dorsal skinfold chamber (DSC) with an epithelialized full-thickness defect as TMP model. METHODS: A circular 2-mm defect was cut into the extended dorsal skinfold using a biopsy punch. The skinfold was either perforated through both skin layers without prior preparation or perforated on 1 side, following resection of the opposing skin layer. In both groups, the wound was sealed with a coverslip or left unclosed (n = 4). All animals were examined for epithelialization of the edge (histology), size of the perforation (planimetry), neovascularization (repetitive intravital fluorescence microscopy), and inflammation (immunohistology). RESULTS: The edge of the perforation was overgrown by the cornified squamous epithelium in all pre-parations. Reduction in the perforation's size was enhanced by application of a coverslip. Microsurgical preparation before biopsy punch perforation and sealing with a coverslip enabled repetitive high-quality intravital fluorescence microscopy. However, spontaneous reduction of the perforation occurred frequently. Therefore, the direct biopsy punch perforation without microsurgical preparation was favorable: spontaneous reduction did not occur throughout 21 days. Moreover, the visualization of the neovascularization was sufficient in intravital microscopy. CONCLUSIONS: The DSC full-thickness defect is a valuable supplement to orthotopic TMP models. Repetitive intravital microscopy of the epithelialized edge enables investigation of the underlying pathophysiology during the transition from the inflammation to the proliferation phase of wound healing. Using established analysis procedures, the present model provides an effective platform for the screening of bioactive materials and transferring progress in tissue engineering to the special conditions of tympanic membrane wound healing.

Smartphone-based nystagmus diagnostics: development of an innovative app for the targeted detection of vertigo.

BACKGROUND: In medicine, the symptom of dizziness is one of the most common multidisciplinary causes of emergency medical presentation. Attending physicians are often faced with difficult decisions when evaluating patients with dizziness. A rapid differential diagnostic decision must be made during the initial examination. The goal of this study, was to develop a smartphone-based app that can diagnose and qualify nystagmus. The app should enable differentiation between acute emergencies such as strokes ("central vertigo") and vestibular disorders ("peripheral vertigo") using and recognizing or analyzing the accompanying symptom "nystagmus". MATERIALS AND METHODS: This prospective study was conducted at the Department of Otolaryngology, Head and Neck Surgery "Otto Körner", Rostock (Germany). The experimental study design consisted of two test runs and two control runs. In the two test runs, nystagmus was tracked and evaluated by caloric and optokinetic stimulation, respectively, through a custom-developed app. Sensitivity and correlation were calculated for the app's application performance and compared under different experimental conditions. RESULTS: The patient sample included twenty healthy participants with a mean age of 25.6 years (± 2.2 SD) who participated in the study. The overall sensitivity of detection of nystagmus averaged 82.14% in the optokinetic stimulation test trials. There is no correlation regarding specific subject data and sensitivity. CONCLUSIONS: The results of our experimental validation study show that a smartphone-based nystagmus app is a useful tool for vertigo diagnosis. The results of our analyses show that it is possible to diagnose nystagmus and determine shape or direction with the app.

[Interactive intraoperative annotation of surgical landmarks in student education to support learning efficiency and motivation]. / Interaktive intraoperative Annotation chirurgischer Anatomie in der studentischen Ausbildung zur Unterstützung der Lerneffizienz und -motivation.

BACKGROUND: The development of technological innovations has not only changed social life and the healthcare system, but also affects medical education. The aim of this pilot study was to evaluate whether students, when observing a microsurgical procedure of the temporal bone, gain an additional understanding of the anatomical structures and surgical site when visualization is used that provides identical views for the surgeon and viewer in 3D. MATERIALS AND METHODS: During regular attendance tutorials, students were randomly assigned to three different groups: control group, 2D group, or 3D group. Evaluation questionnaires and intraoperative student annotation of the surgical view were used to assess the subjective didactic value of different visualization formats and resultant learning experiences for the students. RESULTS: A total of 47 students were included in the investigations during conventional attendance tutorials. The majority indicated a high added value of the 3D visualization in terms of method (70%) and vividness (80%) compared to the 2D group and self-study; 69% of the students fully agreed with the statement that 2D and 3D visualization increases learning motivation and is a very good way to improve recognition of anatomical topography and structures. CONCLUSION: New interactive visualization options in teaching promote learning efficiency and motivation among students. Especially 3D visualization and intraoperative annotation of the surgical view by the student is a useful didactic tool and increases the quality of clinical teaching. It supports the perception of anatomical topography and enables more focused surgical training.

Evaluating the didactic value of 3D visualization in otosurgery.

INTRODUCTION: Improvements of surgical visualization add value to the quality of clinical routine and offer the opportunity to improve surgical education of medical staff. The aim of this study was to determine whether otorhinolaryngology trainees gain additional comprehension of the anatomical structures and the surgical site when 3D visualization is used. METHODS: Data were collected from ENT trainees of microsurgical courses of the middle ear, inner ear and lateral skull base at four university ENT departments (Charité (Berlin), Martin Luther University Halle-Wittenberg (Halle/Saale), Ludwig Maximilian University (Munich) and Rostock University Medical Center). Participants were asked to complete a questionnaire assessing the subjective value of identical surgical field visualization in 3D for surgeon and observer. RESULTS: A total of 112 participants completed the questionnaire. The majority of participants stated a high additional value of 3D visualization compared to 2D visualization, with 75% fully agreeing to the statement that 3D visualization of the surgical field is superior to perceive the anatomical topography and structures compared to 2D representation. Participants encouraged the storage of data in online learning platforms. CONCLUSION: The results show that 3D visualization with identical imaging for surgeon and observer is a useful tool in teaching of microsurgery. It addresses perception of anatomical topography and structures as well as conception of the surgical workflow.

Neuromonitoring of the cochlear nerve during vestibular schwannoma resection and simultaneous cochlear implantation.

Vestibular schwannomas (VS) are benign tumors that originate from the nerve sheath of one of the two vestibular nerves. VS can have a severe impact on everyday life of the patient and may lead to symptoms such as vertigo, hearing loss (e.g., as sudden deafness), deafness, and tinnitus. Treatment concepts include observational waiting with regular imaging control ("wait and scan"), radiotherapy, or surgical resection. Depending on the size of the tumor and status of functional hearing, the surgical approach may be retrosigmoidal, transtemporal, retrolabyrinthine, or translabyrinthine. The translabyrinthine approach always results in complete deafness due to opening of the bony labyrinth. If the nerve structure of the cochlear nerve is preserved, hearing rehabilitation with a cochlear implant (CI) may be successful. In this article the surgical technique for microsurgical resection of VS using a translabyrinthine approach with simultaneous cochlear implantation under intraoperative monitoring of the cochlear nerve by electrical stimulation is presented.

[Skull and cervical spine fractures]. / Frakturen von Kopf und Halswirbelsäule.

BACKGROUND: Injuries of the skull and the cervical spine are common trauma sequelae and prompt diagnosis is of utmost importance to prevent neurologic complications. OBJECTIVES: The different imaging modalities for the diagnosis of skull and cervical spine fractures are presented and discussed in the context of the current literature. MATERIALS AND METHODS: Common fractures of the skull and cervical spine and their classification systems are described. Indications for imaging are discussed within the context of the literature. RESULTS: Fractures of the head can affect the cranial vault, the base of the skull, and the petrous bone. Injuries to the dura are associated with an open craniocerebral trauma. Fractures of the cervical spine can be subdivided into fractures of the craniocervical junction and subaxial fractures. CONCLUSIONS: The imaging modality of choice in the acute setting is computed tomography (CT). Skull fractures can be differentiated into open and closed craniocerebral traumas and accompanying intracranial trauma sequelae must be recognized. In the case of petrous bone fractures, attention must always be paid to the middle and inner ear structures. In cervical spine fractures, decisive is whether the fracture is stable or unstable and whether there has been an accompanying injury to the myelon.

Stapes surgery leads to significant improvement in quality of life, independently from the surgical method: evaluation of stapes surgery using different prostheses and different quality of life measurements.

OBJECTIVES: To compare quality-of-life (QoL) measurements with audiological results after stapes surgery with two different prostheses. METHODS: This is a retrospective longitudinal study. All patients required stapes surgery for otosclerosis and ossicular chain reconstruction with either a titanium band prothesis (TBP) or receiving a nitinol head prosthesis (NHP). Intervention was between January 2011 and March 2017 patients received stapes-surgery with either TBP (n = 95) or NHP (n = 50). Audiological measurements at three different time points (preoperatively, early follow up < 3 months, late follow-up > 3 months) were compared and two different QoL-inventories, the Glasgow-Benefit-Inventory (GBI) and the Stapes-Plasty-Outcome-Test-25 (SPOT-25) were investigated postoperatively. The main outcome measures were Pure tone average (PTA) at 0.5, 1, 2, 3 kHz at early and late follow up after stapes surgery were compared and correlated with the subjective benefit on the QoL inventories. The perforation method and the type of surgery were analyzed as potentially influencing factors. RESULTS: All patients showed a significantly reduced air bone gap (ABG 0.5, 1, 2, 3) at the two follow-up visits (visit 2: mean: 13.6 dB, SD 7.7; visit 3: mean: 12.7 dB SD 8.1) compared to preoperative measurements (mean: 28.9 dB, SD 9.9) and subjectively benefitted from stapes surgery (mean GBI score: 21.55; SD 20.60, mean SPOT-25 score: 28.03; SD 18.53). The outcome of the two questionnaires correlated with each other. Neither the hearing-outcome nor the subjective benefit was significantly influenced by the prosthesis, the perforation method or the type of anesthesia. CONCLUSIONS: Both prostheses were safe and led to comparable hearing results as well as to subjective benefits in the Health-related-Quality-of-Life (HrQoL). A combination of the two questionnaires is recommendable for postoperative quality control.

Evaluation of Multicenter Registry Data. / Register ­ Auswertung von multizentrischen Daten.

A registry actively documents and standardizes patient data on pre-defined questions. The term "register" emphasizes the data-holding aspect with the aim of describing epidemiological relationships and differences, supporting quality assurance and improvement, as well as clinical research. The evaluation of efficacy in the medical care routine, the monitoring of patient safety as well as economic evaluation and minimum quantity research are further tasks of registries. Patients and reporting institutions determine the quality of registries through completeness and high data validity. This must be taken into account when designing, financing and operating a registry. The analysis of potentially confounding or effect modifying variables is of significant importance for the evaluation of multi-center data from registers. Regular feedback to reporting institutions, patient information, public announcements and scientific publications as well as compliance with data protection regulations increase the transparency of the register. Otorhinolaryngology has few points of contact with registries. An exception is the integration into the cancer registry and the newborn hearing screening registry, which is currently under construction. The great variety of measurable outcome parameters in otorhinolaryngology, such as in otology, phoniatrics, rhinology, allergology, etc., forms the basis for various potential registers. Clinical questions, prevention measures, quality assurance, health care research and recommendations for health policy would be scientifically sound and evidence-based.

Minimal Reporting Standards for Active Middle Ear Hearing Implants.

There is currently no standardized method for reporting audiological, surgical and subjective outcome measures in clinical trials with active middle ear implants (AMEIs). It is often difficult to compare studies due to data incompatibility and to perform meta-analyses across different centres is almost impossible. A committee of ENT and audiological experts from Germany, Austria and Switzerland decided to address this issue by developing new minimal standards for reporting the outcomes of AMEI clinical trials. The consensus presented here aims to provide a recommendation to enable better inter-study comparability.

Reinforced active middle ear implant fixation in incus vibroplasty.

OBJECTIVES: The active middle ear implant Vibrant Soundbridge® was originally designed to treat mild-to-severe sensorineural hearing losses. The floating mass transducer (FMT) is crimped onto the long incus process. The procedure is termed incus vibroplasty to distinguish from other attachment sites or stimulus modi for treating conductive and mixed hearing losses. Rare but possible complications are difficult incus anatomy, necrosis of the long incus process, secondary detachment, and loosening of the FMT with concomitant amplification loss. The aim of this study was to functionally evaluate reinforcement of the standard attachment of the FMT to the long incus process. The head of a Soft CliP® stapes prosthesis was used for reinforcement. Functional evaluation was performed in temporal-bone preparations and in clinical practice. DESIGN: A subtotal mastoidectomy and a posterior tympanotomy were performed in ten fresh human temporal bones. As a control for normal middle-ear function, the tympanic membrane was stimulated acoustically and the vibration of the stapes footplate and the round-window (RW) membrane, respectively, were measured by laser Doppler vibrometer (LDV). FMT-induced vibration responses of the stapes and RW were then measured for standard attachment and attachment reinforced with the head of a Soft CliP® stapes prosthesis. Additionally, the outcome in two groups of patients with incus vibroplasty using standard and the reinforced FMT attachment were compared. Eleven patients were treated by standard coupling; nine patients obtained reinforcement with the head of the Soft CliP® stapes prosthesis. Three to six months postoperatively, auditory thresholds for frequency-modulated (warble) tones and vibroplasty thresholds for pure tones were measured. RESULTS: In temporal bone, laser Doppler vibrometer measurements showed significantly enhanced vibration amplitudes of the stapes footplate and the RW membrane for the reinforced attachment compared with those for the standard attachment (on average, 5-10 dB at frequencies below 1 kHz and above 4 kHz). Interindividual amplitude variations were also smaller for reinforced attachment (on average, the standard deviation was 4-7 dB smaller). The clinical data showed lower vibroplasty thresholds for reinforced attachment compared with standard attachment, which amounted to, on average, 16 dB at 500 Hz and 12 dB at 4 kHz. CONCLUSION: Auxiliary fixation of the FMT by reinforcing the attachment to the long incus process, in these experiments with the head of a Soft CliP stapes prosthesis, leads to enhanced mechanical and functional coupling, evidenced by lower vibroplasty thresholds and increased bandwidth together with reduced variability of the vibrational frequency responses of the stapes footplate and RW membrane.

Alternative fixation of an active middle ear implant at the short incus process.

INTRODUCTION: Since 1996, the preferred approach for positioning the active middle-ear implant Vibrant Soundbridge© is a mastoidectomy and a posterior tympanotomy. With this device, placement of the floating mass transducer (FMT) on the long incus process is the standard method for treatment of mild-to-severe sensorineural hearing loss in the case of normal middle-ear anatomy. The aim of this study was to determine the vibrational effectiveness of FMT placement at the short incus process. MATERIALS AND METHODS: An extended antrotomy and a posterior tympanotomy were performed in 5 fresh human temporal bones. As a control for normal middle-ear function, the tympanic membrane was stimulated acoustically and the vibration of the stapes footplate and the round-window (RW) membrane were (sequentially) measured by laser Doppler vibrometry. Vibration responses for coupling of an FMT to the long incus process (standard coupling) were compared to those for coupling to the short incus process. RESULTS: Apart from narrow frequency bands near 3 and 9 kHz for the stapes footplate and RW membrane, respectively, the velocity responses presented no significant differences between standard coupling of the FMT and coupling to the short incus process. CONCLUSION: Coupling the FMT to the short incus process may be a viable alternative in cases where the surgical approach is limited to an extended antrotomy. A reliable technique for attachment to the short incus process has yet to be developed.

Transimpedance Matrix Can Be Used to Estimate Electrode Positions Intraoperatively and to Monitor Their Positional Changes Postoperatively in Cochlear Implant Patients.

OBJECTIVE: Accurate positioning of the electrode array during cochlear implant (CI) surgery is crucial for achieving optimal hearing outcomes. Traditionally, postoperative radiological imaging has been used to assess electrode position. Transimpedance matrix (TIM) measurements have also emerged as a promising method for assessing electrode position. This involves utilizing electric field imaging to create an electric distance matrix by analyzing voltage variations among adjacent electrodes. This study aimed to investigate the feasibility of using intraoperative TIM measurements to estimate electrode position and monitor postoperative changes. STUDY DESIGN: Retrospective cohort study. SETTING: University Medical center, tertiary academic referral center. PATIENTS: Patients undergoing CI (CI622) surgery between January 2019 and June 2022. INTERVENTION: CI electrode positions and maximal angular insertion depths (maxAID) were determined using X-ray imaging according to Stenvers' projection. The mean gradient phase (MGP) was extracted from the TIM, and a correlation between the MGP and maxAID was examined. A model was then built to estimate the maxAID using the MGP, and changes in electrode location over time were assessed using this model. MAIN OUTCOME MEASURES: Twenty-four patients were included in this study. A positive correlation between the maxAID and the MGP ( R = 0.7, p = 0.0001) was found. The established model was able to predict the maxAID with an accuracy of 27.7 ± 4.4°. Comparing intraoperative and postoperative TIM measurements, a decrease of 24.1° ± 10.7° in maxAID over time was observed. CONCLUSION: TIM measurements are useful for estimating the insertion depth of the electrode and monitoring changes in the electrode's position over time.

Head and Neck Cancer: A Study on the Complex Relationship between QoL and Swallowing Function.

Head and neck squamous cell carcinoma (HNSCC) is linked to significant morbidity, adversely affecting survival and functional capacity. Post-treatment challenges such as pain, dysphonia, and dysphagia are common, prompting increased attention in survivorship research. Quality of Life (QoL) questionnaires, especially the MD Anderson Dysphagia Inventory (MDADI), are prevalent outcome measures in clinical studies but often lack parallel objective swallowing function evaluations, leading to potential outcome discrepancies. This study aimed to illuminate the relationship between subjective QoL (EQ-5D-5L and MDADI) measures and objective swallowing function (evaluated via Fiberoptic Endoscopic Evaluation of Swallowing, FEES) in patients with HNSCC. The analysis revealed a notable discordance between objective measures of swallowing function, such as the Penetration-Aspiration Scale (PAS) and residue ratings in the vallecula or piriform sinus, and patients' subjective QoL assessments (p = 0.21). Despite the lack of correlation, swallowing-related QoL, as measured by the MDADI, was more indicative of disease severity than generic QoL assessments. Generic QoL scores did not demonstrate substantial variation between patients. In contrast, MDADI scores significantly declined with advancing tumor stage, multimodal therapy, and reliance on feeding tubes. However, the clinical significance of this finding was tempered by the less than 10-point difference in MDADI scores. The findings of this study underline the limitations of QoL measures as standalone assessments in patients with HNSCC, given their reliance on patient-perceived impairment. While subjective QoL is a crucial aspect of evaluating therapeutic success and patient-centric outcomes, it may fail to capture critical clinical details such as silent aspirations. Consequently, QoL assessments should be augmented by objective evaluations of swallowing function in clinical research and practice to ensure a holistic understanding of patient well-being and treatment impact.

Continuous intraoperative perfusion monitoring of free microvascular anastomosed fasciocutaneous flaps using remote photoplethysmography.

Flap loss through limited perfusion remains a major complication in reconstructive surgery. Continuous monitoring of perfusion will facilitate early detection of insufficient perfusion. Remote or imaging photoplethysmography (rPPG/iPPG) as a non-contact, non-ionizing, and non-invasive monitoring technique provides objective and reproducible information on physiological parameters. The aim of this study is to establish rPPG for intra- and postoperative monitoring of flap perfusion in patients undergoing reconstruction with free fasciocutaneous flaps (FFCF). We developed a monitoring algorithm for flap perfusion, which was evaluated in 15 patients. For 14 patients, ischemia of the FFCF in the forearm and successful reperfusion of the implanted FFCF was quantified based on the local signal. One FFCF showed no perfusion after reperfusion and devitalized in the course. Intraoperative monitoring of perfusion with rPPG provides objective and reproducible results. Therefore, rPPG is a promising technology for standard flap perfusion monitoring on low costs without the need for additional monitoring devices.

Conditions for highly efficient and reproducible round-window stimulation in humans.

Round-window stimulation is a new clinical approach for the application of active middle-ear implants. To investigate factors influencing the efficiency of round-window stimulation, experiments in 6 human temporal bones were performed with different actuator geometries and coupling conditions. The experiments show that the amplitude ratio between stapes and round-window actuator vibration is most efficient when using a 1.0-mm diameter rod with a 30° inclined tip geometry and an attached silicone pad. In this case, the amplitude ratio is 0.34 for frequencies up to 1.5 kHz and 0.27 for frequencies up to 20 kHz, with a standard deviation of only 4-6 dB at most frequencies. The analysis of data presented here and in a companion paper suggests that control of proper round-window membrane pretension as well as the inclined tip geometry are the major requirements for maximal performance.

A PLLA Coating Does Not Affect the Insertion Pressure or Frictional Behavior of a CI Electrode Array at Higher Insertion Speeds.

To prevent endocochlear insertion trauma, the development of drug delivery coatings in the field of CI electrodes has become an increasing focus of research. However, so far, the effect of a polymer coating of PLLA on the mechanical properties, such as the insertion pressure and friction of an electrode array, has not been investigated. In this study, the insertion pressure of a PLLA-coated, 31.5-mm long standard electrode array was examined during placement in a linear cochlear model. Additionally, the friction coefficients between a PLLA-coated electrode array and a tissue simulating the endocochlear lining were acquired. All data were obtained at different insertion speeds (0.1, 0.5, 1.0, 1.5, and 2.0 mm/s) and compared with those of an uncoated electrode array. It was shown that both the maximum insertion pressure generated in the linear model and the friction coefficient of the PLLA-coated electrode did not depend on the insertion speed. At higher insertion speeds above 1.0 mm/s, the insertion pressure (1.268 ± 0.032 mmHg) and the friction coefficient (0.40 ± 0.15) of the coated electrode array were similar to those of an uncoated array (1.252 ± 0.034 mmHg and 0.36 ± 0.15). The present study reveals that a PLLA coating on cochlear electrode arrays has a negligible effect on the electrode array insertion pressure and the friction when higher insertion speeds are used compared with an uncoated electrode array. Therefore, PLLA is a suitable material to be used as a coating for CI electrode arrays and can be considered for a potential drug delivery system.

Intrathecal Application of a Fluorescent Dye for the Identification of Cerebrospinal Fluid Leaks in Cochlear Malformation.

In cases of cerebrospinal fluid (CSF) leaks, reliable detection of their origins is needed to seal the leak sufficiently and prevent complications, such as meningitis. A method is presented here using intrathecal administered fluorescein in a clinical case of bilateral congenital ear malformation. A fluorescent dye is administered intrathecally to achieve intraoperative visualization of CSF leaks. The dye is applied 20 min before surgery, and concentration of 5% is used. Per every 10 kg of body weight, 0.1 mL of the fluid is applied intrathecally. The fluorescein is visualized using a fully digital microscope. The origin of the fluid leak is identified in the stapes footplate. During primary surgery, it is sealed, and cochlea implantation is performed for hearing restoration. In this specific case, 6 weeks later, the implant was explanted due to acute meningitis, and the electrode array was left as a spacer. Postoperatively, in the aural smear, ß-transferrin was detected. During a revision mastoidectomy, dislocated coverage of the leak was found. The stapes was removed and oval window sealed. Five days after revision surgery, no ß-transferrin was detected in the aural smear. During the revision of cochlea implantation 6 months later, intact coverage of the oval niche was observed. Thus, intrathecal fluorescein application proves to be a reliable tool for the detection of CSF leaks. It facilitates the orientation in malformations and complicated or unknown surgical situs. In the literature, its use is described for CSF fistulas in endonasal surgery but is rarely described in skull base and mastoid surgeries. The method has been used successfully in several cases with CSF leaks, and the results confirm the feasibility of safely accessing the origin of the leak.