[Outpatient Antibiotic Prescription Rates and Mastoiditis in Children and Adolescents, Saarland, 2014-2019]. / Ambulante Antibiotika-Verordnungsrate und Mastoiditis-Fälle bei Kindern und Jugendlichen im Saarland, 2014­2019.

BACKGROUND: Infections of the respiratory tract are the main indication for outpatient antibiotic therapy in children and adolescents. In recent years the antibiotic prescription rate (APR) in the pediatric population has decreased significantly. OBJECTIVES: The aim of the retrospective mastoiditis audit in the PaedineSaar network is to investigate the incidence of inpatient acute mastoiditis (AM) in Saarland (2014-2019) regarding to the decreasing APRs in children, as well as to gather data of the clinical course of AM. METHODS: All inpatient AM cases 2014-2019 were analyzed retrospectively from 6 hospitals for pediatrics and/or otorhinolaryngology in Saarland and Trier. Children and adolescents aged 0-17 years and residing in Saarland were included in the study. RESULTS: 2014-2019 53 inpatient treated AM cases have been recorded. During the study period there was no significant increase of AM incidence (mean incidence 2014-2019: 6.1/100,000). 34% (18/53) of the patients received prehospital antibiotic treatment (main indication: acute otitis media (AOM) 15/18, 83%). At least one complication occurred in 30% of the patients (16/53). There was a slight trend to more complications in children without oral antibiotic treatment before admission (14/35 (40%) vs. 2/18 (11%) p=0.056). CONCLUSIONS: The incidence of AM leading to inpatient treatment in children in Saarland did not increase 2014-2019 despite a significant and sustained decline in the outpatient APRs. The results of this audit should be used for the development of a more standardized approach concerning the diagnostics and treatment of children with AM.

[Prospektives Audit des Gentamicin Drug Monitorings in einem Kinderkrebszentrum]. / Prospective Audit of Gentamicin Drug Monitoring Practice in a Pediatric Cancer Center.

BACKGROUND: Many pediatric cancer centers still use Gentamicin as first line combination treatment in patients with fever and neutropenia. Since 2011, our center has implemented a dosing regimen with 250 mg/m2 BSA (max. 10 mg/kg, max. 400 mg) as a single daily infusion according to the German guideline. PATIENTS AND METHODS: In this prospective audit (February 2011 to December 2019), 105 Gentamicin treatment cycles were analyzed in 66 pediatric cancer patients, focusing on adherence to the dosing regimen and the drug monitoring results. RESULTS: Adherence to the dosing regimen was high (89%). In 64% of all cycles, the Cmax (drawn 1 h after the 2nd dose) reached the target of 10-20 µg/ml. Cmax significantly correlated with dosing in mg/m2 BSA (p=0,007), but not with dosing in mg/kg (p=0,366). Age below 6 years did not influence these results. The Gentamicin Ctrough (drawn 8-10 h after the second dose) was < 2 µg/ml in 93% of all cycles without any dose correlation. None of the patients experienced Gentamicin-associated nephrotoxicity. DISCUSSION AND CONCLUSION: This prospective audit of single daily infusion Gentamicin in pediatric cancer patients without impaired renal function elicits the feasibility and safety of the dosing regimen in mg/m2 BSA according to the German guideline. Since indications for first-line gentamicin are limited, a multicenter prospective study would be advantageous to confirm these observations.

Cytotoxicity studies of an optoacoustic stimulation strategy for the development of laser-based hearing aids.

SIGNIFICANCE: Worldwide, ∼460 million people suffer from disabling hearing impairment. Many of these patients are still not sufficiently supplied with currently available auditory technologies. Optical stimulation of the hearing organ offers a promising alternative for a new generation of auditory prostheses. AIM: To assess the biocompatibility margins of our laser pulse amplitude strategy in vitro, we designed a protocol and present the effects on normal human dermal fibroblasts, human chondrocytes, and human osteoblasts. APPROACH: Laser pulses of 532 nm were applied over 120 s using our laser pulse amplitude modulation strategy. We then assessed cell viability and cytotoxicity through fluorescence staining and quantitative polymerase chain reaction-analysis regarding 84 key player-genes for cytotoxicity and stress response. RESULTS: The first in vitro biocompatibility margins for our stimulation parameters applied to cells of the peripheral hearing organ were between 200 and 223 mW (3348 J/cm2). After irradiation with a subphototoxic laser power of 199 mW (2988 J/cm2), only the fibroblasts showed a significant upregulation of GADD45G. CONCLUSION: Further studies are underway to optimize parameters for the optoacoustic stimulation of the auditory system. Our protocol and results on laser-tissue interactions can be useful for translational laser applications in various other irradiated biological tissues.

First biocompatibility margins for optical stimulation at the eardrum via 532-nm laser pulses in a mouse model.

Hearing impairment affects ∼460 million people worldwide. Conservative therapies, such as hearing aids, bone conduction systems, and middle ear implants, do not always sufficiently compensate for this deficit. The optical stimulation is currently under investigation as an alternative stimulation strategy for the activation of the hearing system. To assess the biocompatibility margins of this emerging technology, we established a method applicable in whole-mount preparations of murine tympanic membranes (TM). We irradiated the TM of anesthetized mice with 532-nm laser pulses at an average power of 50, 89, 99, and 125 mW at two different locations of the TM and monitored the hearing function with auditory brainstem responses. Laser-power-dependent negative side effects to the TM were observed at power levels exceeding 89 mW. Although we did not find any significant negative effects of optical stimulation on the hearing function in these mice, based on the histology results further studies are necessary for optimization of the used parameters.

Frequency-specific activation of the peripheral auditory system using optoacoustic laser stimulation.

Hearing impairment is one of the most common sensory deficits in humans. Hearing aids are helpful to patients but can have poor sound quality or transmission due to insufficient output or acoustic feedback, such as for high frequencies. Implantable devices partially overcome these issues but require surgery with limited locations for device attachment. Here, we investigate a new optoacoustic approach to vibrate the hearing organ with laser stimulation to improve frequency bandwidth, not requiring attachment to specific vibratory structures, and potentially reduce acoustic feedback. We developed a laser pulse modulation strategy and simulated its response at the umbo (1-10 kHz) based on a convolution-based model. We achieved frequency-specific activation in which non-contact laser stimulation of the umbo, as well as within the middle ear at the round window and otic capsule, induced precise shifts in the maximal vibratory response of the umbo and neural activation within the inferior colliculus of guinea pigs, corresponding to the targeted, modelled and then stimulated frequency. There was also no acoustic feedback detected from laser stimulation with our experimental setup. These findings open up the potential for using a convolution-based optoacoustic approach as a new type of laser hearing aid or middle ear implant.

Laser-induced tissue remodeling within the tympanic membrane.

The tympanic membrane (TM) separates the outer ear from the tympanic cavity. Repeated pathologies can permanently decrease its tension, inducing conductive hearing loss and adhesive processes up to cholesteatoma. The current main therapy is its surgical reconstruction. Even though lasers have been proposed to tighten atrophic TMs, details of this effect, specifically histological analyses, are missing. We therefore used laser pulses to induce TM collagen remodeling in an animal model to compare the histological and electrophysiological effects of different applied laser intensities before entering clinical studies. We irradiated Fuchsin-stained areas of the TM in anesthetized mice with 532-nm laser-pulses of 10 mW for 30 s (0.3 J), 25 mW for 30 s (0.75 J) or 50 mW for 30 s (1.5 J) monitoring hearing with auditory brainstem responses (ABRs). The mice were sacrificed after 2 to 8 weeks and histologically analyzed. An increase in the TM thickness within the defined, stained, and irradiated areas could be observed after 4 weeks. Polarized light microscopy and transmission electron microscopy demonstrated the tissue volume increase majorly due to new collagen-fibrils. Directly after irradiation, ABR thresholds did not increase. We herein demonstrate a controlled laser-induced collagen remodeling within defined areas of the TM. This method might be the prophylactic solution for chronic inflammatory ear pathologies related to decreased TM tension.

Non-penetrating round window electrode stimulation for tinnitus therapy followed by cochlear implantation.

One main theory behind the origin of tinnitus is based on the idea that alterations of the spontaneous electrical activity within the auditory system lead to abnormal firing patterns in the affected nervous structures [1]. A possible therapeutic option is the use of electrical stimulation of the auditory nerve for the recovery or at least limitation of the abnormal firing pattern to a level that can be easily tolerated by the patient. The Tinnelec Implant consists of a single non-penetrating stimulation electrode connected to a Neurelec cochlear implant system. As a first feasibility study, before starting implantations in hearing patients, we thought to assess the potential of the Tinnelec stimulation to treat tinnitus in unilateral deaf patients, analysing hereby its effectivity and risks. Three patients suffering from unilateral tinnitus resistant to pharmacological treatment and ipsilateral severe to profound sensorineural hearing loss/deafness were implanted with a Tinnelec system between September 2007 and July 2008, at the ENT Department of Hannover Medical School. The stimulation strategy was chosen to induce alleviation of the tinnitus through suppression, masking and/or habituation and the response of each patient on the treatment was monitored using a visual analogue scale (VAS) on loudness and annoyance of tinnitus, mood of the patient, as well as the tinnitus handicap inventory (THI). All patients had a benefit from the electrical stimulation for their tinnitus (THI-score improvement of 20-70), however, not all participants profited from the Tinnelec system in same way and degree. In one patient, despite good results, the device had to be replaced with a conventional cochlear implant because of Tinnelec-independent increase in hearing loss on the contralateral ear. Additionally, due to the extension of cochlear implant indications, the devices of the other two patients have been meanwhile replaced with a conventional cochlear implant to benefit additionally from hearing improvement. As demonstrated in the present study, sensorineural tinnitus in humans may be suppressed/masked/habituated by electrical stimulation. The main advantage of the Tinnelec implant would be the option to treat patients with normal and usable hearing, stimulating the affected ear with the cochlear non-penetrating stimulation electrode of the device, and extend the treatment in cases of progressive hearing loss by explanation and reimplantation with a penetrating electrode addressing tinnitus as well as the hearing impairment. The present study is the first report on a long-term follow-up on tinnitus patients implanted with Tinnelec. Further clinical studies to implant tinnitus patients with residual or normal hearing on the affected ear are on the way.

Optical cochlear implant: evaluation of insertion forces of optical fibres in a cochlear model and of traumata in human temporal bones.

Optical stimulation for hearing restoration is developing as an alternative therapy to electrical stimulation. For a more frequency-specific activation of the auditory system, light-guiding fibres need to be inserted into the coiled cochlea. To enable insertion with minimal trauma, glass fibres embedded in silicone were used as models. Thus, glass fibres of varying core/cladding diameter with and without silicon coating (single as well as in bundles) were inserted into a human scala tympani (ST) model. Insertion cochlear model force measurements were performed, and the thinner glass fibres that showed low insertion forces in the model were inserted into cadaveric human temporal bones. Silicone-coated glass fibres with different core/cladding diameters and bundle sizes could be inserted up to a maximum depth of 20 mm. Fibres with a core/cladding diameter of 50/55 µm break during insertion deeper than 7-15 mm into the ST model, whereas thinner fibres (20/25 µm) could be inserted in the model without breakage and in human temporal bones without causing trauma to the inner ear structures. The insertion forces of silicone-coated glass fibres are comparable to those measured with conventional cochlear implant (CI) electrodes. As demonstrated in human temporal bones, a minimal traumatic implantation of an optical CI may be considered feasible.

Stable release of BDNF from the fibroblast cell line NIH3T3 grown on silicone elastomers enhances survival of spiral ganglion cells in vitro and in vivo.

The treatment of choice for profound sensorineural hearing loss (SNHL) is direct electrical stimulation of spiral ganglion cells (SGC) via a cochlear implant (CI). The number and excitability of SGC seem to be critical for the success that can be achieved via CI treatment. However, SNHL is associated with degeneration of SGC. Long-term drug delivery to the inner ear for improving SGC survival may be achieved by functionalisation of CI electrodes with cells providing growth factors. Therefore, the capacity of brain-derived neurotrophic factor (BDNF)-secreting NIH3T3 cells grown on cylindrically shaped silicone elastomers (SE) to exert local and sustained neuroprotective effects was assessed in vitro and in vivo. An in vitro model to investigate adhesion and cell growth of lentivirally modified NIH3T3 cells synthesising BDNF on SE was established. The bioactivity of BDNF was characterised by co-cultivation of SGC with cell-coated SE. In addition, cell-coated SE were implanted into deafened guinea pigs. The recombinant NIH3T3 cells proliferated on silicone surfaces during 14 days of cultivation and expressed significantly increasing BDNF levels. Enhanced survival rates and neurite outgrowth of SGC demonstrated the bioactivity of BDNF in vitro. Implantation of SE with adhering BDNF-secreting NIH3T3 cells into the cochleae of systemically deafened guinea pigs induced a significant increase in SGC survival in comparison to SE without cell coating. Our data demonstrate a novel approach of cell-based long-term drug delivery to support SGC survival in vitro and in vivo. This therapeutic strategy--once transferred to cells suitable for clinical application--may improve CI performance.

Artemin improves survival of spiral ganglion neurons in vivo and in vitro.

Artemin and its receptors are upregulated in the auditory nerve of deafened rats as a possible intrinsic protective mechanism against ototoxicity-related apoptosis. Consequently, we examined the effect of artemin on spiral ganglion neurons in vitro and in vivo. Spiral ganglion neurons were isolated from neonatal rats and cultured in serum-free medium supplemented with artemin and/or brain-derived neurotrophic factor (BDNF). In vitro, the survival rate of spiral ganglion neurons cultivated with artemin or BDNF was significantly improved compared with negative controls. In addition, artemin was delivered to the inner ear of deafened guinea pigs for 28 days. In-vivo artemin was as effective as BDNF in spiral ganglion neuron protection. Therefore, artemin promotes the survival of spiral ganglion neurons in vitro and in vivo.

Contact endoscopy for the evaluation of the pharyngeal and laryngeal mucosa.

OBJECTIVES: Contact endoscopy is a noninvasive tool that allows in vivo and in situ examination of superficial mucosa. Its use for early diagnosis of cancerous lesions of the oropharynx and larynx has not been evaluated. The aim of the study was to validate contact endoscopy for the examination of pharyngeal and laryngeal mucosa. STUDY DESIGN: Prospective clinical study. METHODS: Superficial cells of the mucosa were stained with methylene blue and examined with contact endoscopes. The documented images were assessed by a cytopathologist and by an otolaryngologist independently for each patient. Biopsies for histopathological examination of the area were performed and correlated with contact endoscopic findings of both examiners. RESULTS: Of the 42 examined specimen, 32 (76.2%) showed benign changes in the histological analysis. Squamous cell carcinoma was revealed in 10 specimen (23.8%). Using contact endoscopy, the cytopathologist accurately identified 90.6% of the benign findings (29 of 32); however, only seven of 10 (70%) carcinomas were correctly categorized. In comparison, the otolaryngologist made a correct diagnosis in 93.75% (30 of 32) of the benign and in 90% (nine of 10) of the malignant cases. Thus, a sensitivity of 90% and a specificity of 93.75% can be achieved by contact endoscopy. CONCLUSIONS: Contact endoscopy offers valuable support for the evaluation of oropharyngeal, hypopharyngeal, and laryngeal mucosa. Contact endoscopy can be a useful contribution to rapid intraoperative evaluation of mucosal alterations for early diagnosis of tumors and might reduce diagnostic biopsy sampling. Even so, it does not replace biopsy sampling.

Green laser light activates the inner ear.

The hearing performance with conventional hearing aids and cochlear implants is dramatically reduced in noisy environments and for sounds more complex than speech (e. g. music), partially due to the lack of localized sensorineural activation across different frequency regions with these devices. Laser light can be focused in a controlled manner and may provide more localized activation of the inner ear, the cochlea. We sought to assess whether visible light with parameters that could induce an optoacoustic effect (532 nm, 10-ns pulses) would activate the cochlea. Auditory brainstem responses (ABRs) were recorded preoperatively in anesthetized guinea pigs to confirm normal hearing. After opening the bulla, a 50-microm core-diameter optical fiber was positioned in the round window niche and directed toward the basilar membrane. Optically induced ABRs (OABRs), similar in shape to those of acoustic stimulation, were elicited with single pulses. The OABR peaks increased with energy level (0.6 to 23 microJ/pulse) and remained consistent even after 30 minutes of continuous stimulation at 13 microJ, indicating minimal or no stimulation-induced damage within the cochlea. Our findings demonstrate that visible light can effectively and reliably activate the cochlea without any apparent damage. Further studies are in progress to investigate the frequency-specific nature and mechanism of green light cochlear activation.

HIV-associated cerebral lymphocyte infiltration mimicking vestibular schwannoma.

The association of unilateral, rapidly progressive hearing loss, tinnitus and vestibular dysfunction in combination with a contrast-enhancing mass within the internal auditory canal on MRI is suggestive of a vestibular schwannoma (VS). We report the rare finding of a HIV-associated cerebral lymphocyte infiltration, most probably malignant lymphoma, which was presumed initially to be a VS. A 36-year-old male presented with progressive unilateral hearing loss accompanied by acute, ipsilateral tinnitus. Interpreted first as sudden sensorineural hearing loss, his symptoms were treated with rheologic therapy. Ipsilateral facial palsy appeared. MRI with gadolininium disclosed a contrast-enhancing mass within the internal auditory meatus of the left side. Within five weeks an extended leptomeningeal lymphocyte infiltration evolved and the diagnosis of an underlying HIV infection was made. Unilateral, rapidly progressive hearing loss and a fast growing cerebello-pontine mass is atypical for VS and highly suspicious of malignant disease. To our knowledge we report the first case of an HIV-associated cerebral lymphocyte infiltration, mimicking a VS. In such cases the diagnostic work-up should include a HIV test.

Helper-dependent adenovirus-mediated gene transfer into the adult mouse cochlea.

BACKGROUND: Gene therapy may provide a way to restore cochlear function to deaf patients. The most successful techniques for cochlear gene therapy have been injection of early-generation adenoviral vectors into scala media in guinea pigs. However, it is important to be able to perform gene therapy research in mice because there is wide availability of transgenic strains with hereditary hearing loss. PURPOSE: We demonstrate our technique for delivery of a third-generation adenoviral vector, helper-dependent adenovirus (HDAd), to the adult mouse cochlea. METHODS: Mice were injected with an HDAd that contained a reporter gene for either beta-galactosidase or green fluorescent protein into scala media. After 4 days, the cochleae were harvested for analyses. Auditory brainstem response monitoring of cochlear function was performed before making a cochleostomy, after making a cochleostomy, and before killing the animal. RESULTS: Beta-galactosidase was identified in the spiral ligament, the organ of Corti, and spiral ganglion cells by light microscopy. Green fluorescent protein epifluorescence was assessed in whole-mount organ of Corti preparations using confocal microscopy. This demonstrated transduction of inner hair cells, outer hair cells, and supporting cells. Paraffin-embedded cross sections similarly revealed gene transduction within the organ of Corti. Threshold shifts of 39.8 +/- 5.4 and 37.7 +/- 5.5 dB were observed in mice injected with HDAd or control buffer, respectively. CONCLUSION: The technique of scala media HDAd injection reliably infects the adult mouse cochlea, including cells within the organ of Corti, although the procedure itself adversely affects hearing.

Laser-induced collagen remodeling and deposition within the basilar membrane of the mouse cochlea.

The cochlea is the mammalian organ of hearing. Its predominant vibratory element, the basilar membrane, is tonotopically tuned, based on the spatial variation of its mass and stiffness. The constituent collagen fibers of the basilar membrane affect its stiffness. Laser irradiation can induce collagen remodeling and deposition in various tissues. We tested whether similar effects could be induced within the basilar membrane. Trypan blue was perfused into the scala tympani of anesthetized mice to stain the basilar membrane. We then irradiated the cochleas with a 694-nm pulsed ruby laser at 15 or 180 Jcm(2). The mice were sacrificed 14 to 16 days later and collagen organization was studied. Polarization microscopy revealed that laser irradiation increased the birefringence within the basilar membrane in a dose-dependent manner. Electron microscopy demonstrated an increase in the density of collagen fibers and the deposition of new fibrils between collagen fibers after laser irradiation. As an assessment of hearing, auditory brainstem response (ABR) thresholds were found to increase moderately after 15 Jcm(2) and substantially after 180 Jcm(2). Our results demonstrate that collagen remodeling and new collagen deposition occurs within the basilar membrane after laser irradiation in a similar fashion to that found in other tissues.

Laser irradiation of the guinea pig basilar membrane.

BACKGROUND AND OBJECTIVES: The cochlea is the part of the inner ear that transduces sound waves into neural signals. The basilar membrane, a connective tissue sheet within the cochlea, is tonotopically tuned based on the spatial variation of its mass, stiffness, and damping. These biophysical properties are mainly defined by its constituent collagen fibers. We sought to assess the effect of laser irradiation on collagen within the basilar membrane using histological analysis. STUDY DESIGN/MATERIALS AND METHODS: Four excised guinea pig cochleae were stained with trypan blue. From these, two were irradiated with a 600 nm pulsed dye laser and two were used as controls. Collagen organization was visualized using polarization microscopy. RESULTS: Laser irradiation reduced the birefringence within the basilar membrane as well as within other stained collagen-containing structures. Larger reductions in birefringence were measured when more laser pulses were given. The effects were similar across all turns of each cochlea. CONCLUSIONS: Laser irradiation causes immediate alterations in collagen organization within the cochlea that can be visualized with polarization microscopy. These alterations may affect cochlear tuning. Ongoing research is aimed at analyzing the effect of laser irradiation on cochlear function. It is conceivable that this technique may have therapeutic benefits for patients with high-frequency sensorineural hearing loss.