3D analysis of gerbil cochlea with cochlear implant.

OBJECTIVES: To assess a clearing protocol using ethyl cinnamate, an organic substance which is non-toxic for humans, and its value in light-sheet microscopy study of post-implantation cochlear damage in the Mongolian gerbil. MATERIAL AND METHODS: The animals underwent right cochlear implantation in the round window by a retroauricular approach. They were then euthanized 10 weeks after implantation (electrode array in place). The cochleae were prepared according to a 29-day protocol including steps of fixation, microdissection, decalcification, permeabilization, blocking, fluorescent immunolabeling, dehydration and finally clearing in ethyl cinnamate solution. Acquisition of transparent cochleae was performed by light-sheet microscopy. Imaris software was then used for 3D analysis. RESULTS: The transparent cochleae had not undergone any shrinkage or any significant architectural changes. Six cochleae were acquired by light-sheet microscopy, allowing good visibility of the whole cochlea. 3D immunofluorescence analysis of the cochlea provided sufficient image resolution for analysis of the spiral ganglion neurons and assessment of the fibrotic tissue reaction surrounding the electrode array. CONCLUSION: The ethyl cinnamate clearing protocol was effective for light-sheet microscopy analysis of the whole Mongolian gerbil cochlea with the implant left in situ. This technique is suitable for the study of post-implantation cell and tissue damage in the same sample, without the potential toxicity of other methods described to date.

The French Cochlear Implant Registry (EPIIC): General indicators.

Cochlear and brainstem implants have been included on the list of reimbursable products (LPPR) in France since March of 2009. The implants were initially inscribed for 5 years, after which an application for renewal with the French National Commission for the Evaluation of Medical Devices and Health Technologies (Commission Nationale d'évaluation des dispositifs médicaux et des technologies de santé - CNEDiMTS) was required [Haute Autorité de santé, 2009]. Upon registration to the list of reimbursable products, the companies and the reference centers for cochlear and brainstem implants were asked to set up a post-registration registry called EPIIC. This article reports the evolution in the EPIIC registry of the general indicators for 5051 patients over the five years from 2012-2016.

Optimised immunofluorescence method on cleared intact Mongolian gerbil cochlea.

Immunofluorescence on cleared intact cochlea allows detailed analysis of the cochlear ultrastructure, while avoiding the problems of dissection and serial sections. Protocols have been developed for mice and Mongolian gerbils. This technical note proposes a detailed and optimised immunofluorescence protocol in the Mongolian gerbil comprising significant quantitative and qualitative improvements. This protocol sequentially comprises: fixation (1 day), decalcification (6 days), pre-treatment (7.5hours), immunolabelling (42hours), dehydration and clearing (23hours), followed by mounting and laser scanning confocal microscopy acquisition. This protocol has been optimised in terms of duration (10 days versus 13 days) with a reduction of the number of steps, improvement of the specificity of immunolabelling and optimisation of the quality of the results obtained. This technical note provides a detailed description of this protocol.

Azimuthal sound source localization of various sound stimuli under different conditions.

AIM: To evaluate azimuthal sound-source localization performance under different conditions, with a view to optimizing a routine sound localization protocol. MATERIAL AND METHOD: Two groups of healthy, normal-hearing subjects were tested identically, except that one had to keep their head still while the other was allowed to turn it. Sound localization was tested without and then with a right ear plug (acute auditory asymmetry) for each of the following sound stimuli: pulsed narrow-band centered on 250Hz, continuous narrowband centered on 2000Hz, 4000Hz and 8000Hz, continuous 4000Hz warble, pulsed white noise, and word ("lac" (lake)). Root mean square error was used to calculate sound-source localization accuracy. RESULTS: With fixed head, localization was significantly disturbed by the earplug for all stimuli (P<0.05). The most discriminating stimulus was continuous 4000Hz narrow-band: area under the ROC curve (AUC), 0.99 [95% CI, 0.95-1.01] for screening and 0.85 [0.82-0.89] for diagnosis. With mobile head, localization was significantly better than with fixed head for 4000 and 8000Hz stimuli (P<0.05). The most discriminating stimulus was continuous 2000Hz narrow-band: AUC, 0.90 [0.83-0.97] for screening and 0.75 [0.71-0.79] for diagnosis. In both conditions, pulsed noise (250Hz narrow-band, white noise or word) was less difficult to localize than continuous noise. CONCLUSION: The test was more sensitive with the head immobile. Continuous narrow-band stimulation centered on 4000Hz most effectively explored interaural level difference. Pulsed narrow-band stimulation centered on 250Hz most effectively explored interaural time difference. Testing with mobile head, closer to real-life conditions, was most effective with continuous narrow-band stimulation centered on 2000Hz.

Hybrid Ear Cubes for local controlled dexamethasone delivery to the inner ear.

A new type of miniaturized implants for local controlled drug delivery to the inner ear is proposed: Hybrid Ear Cubes. They are composed of two main parts: (i) a cylinder, which is placed into a tiny hole (<0.4 mm) drilled into (or close to) the oval (or round) window, and (ii) a cuboid, which is placed into the middle ear. The drug is released at a pre-programmed rate into the perilymph: (i) via the cylindrical part of the implant, which is in direct contact with this liquid, and (ii) via diffusion from the cuboid through the oval/round window. Importantly, the cylindrical part assures a reliable fixation of the drug delivery system at the site of administration. Furthermore, the cuboid provides a relatively "large" drug reservoir, without expulsing perilymph from the cochlea. The required surgery is minimized compared to the placement of an intracochlear implant. In contrast to previously proposed Ear Cubes, which are mono-block systems, Hybrid Ear Cubes consist of two halves, which can: (i) be loaded with different drugs, (ii) be loaded with the same drug at different concentrations, and/or (iii) be based on two different matrix formers. This offers a substantially increased formulation flexibility. Different types of silicone-based Hybrid Ear Cubes were prepared, loaded with 10% dexamethasone in one half and 0-60% dexamethasone in the other half. Importantly, tiny drug crystals were homogeneously distributed throughout the respective implant halves. The observed drug release rates were very low (e.g., <0.5% after 2 months), which can be attributed to the type of drug and silicone as well as to the very small surface area exposed to the release medium. Importantly, no noteworthy implant swelling was observed.

Sound source localization.

Sound source localization is paramount for comfort of life, determining the position of a sound source in 3 dimensions: azimuth, height and distance. It is based on 3 types of cue: 2 binaural (interaural time difference and interaural level difference) and 1 monaural spectral cue (head-related transfer function). These are complementary and vary according to the acoustic characteristics of the incident sound. The objective of this report is to update the current state of knowledge on the physical basis of spatial sound localization.

Imaging and cell count in cleared intact cochlea in the Mongolian gerbil using laser scanning confocal microscopy.

OBJECTIVES: To draw up a clearing protocol for Mongolian gerbil cochlea, and to assess the feasibility of quantifying and analyzing 3D cell architecture in the transparent cochleae. MATERIALS AND METHODS: Freshly dissected inner ears were prepared on a 13-day protocol: fixation, microdissection, post-fixation, decalcification, pretreatment (signal enhancement, permeabilization and blocking), fluorescent labeling (indirect immunolabeling and direct labeling), dehydration, clearing in Spalteholz solution (MSBB: methyl salicylate and benzyl benzoate) and mounting. Image acquisition used laser scanning confocal microscopy. ImageJ software was used to measure the length of the organ of Corti thus available for analysis and to count inner and outer hair cells. RESULTS: Four cochleas underwent imaging. 3D reconstruction enabled organ of Corti length to be measured, at a mean 1269±346µm. Mean inner and outer hair-cell count per organ of Corti length was 142±44 and 400±122, respectively. CONCLUSION: Cochlear clearing by MSBB was feasible in Mongolian gerbils and provided high-resolution immunofluorescence-labeled inner-ear images. To our knowledge, this was the first application of the technique in this species. Cell count could thus be performed along the organ of Corti length without traumatic dissection.

Desmoid tumours of the head and neck in children: Review of management.

OBJECTIVE: Desmoid tumours of the head and neck in children are rare, local invasive and potentially fatal tumours. The purpose of this review is to discuss the management of these tumours in the light of a case series and a review of the literature. MATERIAL AND METHODS: This retrospective study summarised the medical data of children treated for desmoid tumours of the head and neck between 1976 and 2014. RESULTS: Five of the 6 children were treated by radical surgical resection, with positive surgical margins (R1) in 2 cases, followed by recurrence requiring further resection. One child with a very advanced lesion was treated by weekly methotrexate and vinorelbine chemotherapy for 18months, allowing 93% reduction of tumour volume without recurrence. CONCLUSIONS: Desmoid tumours of the head and neck in children are more aggressive than their adult counterparts and are associated with high morbidity and mortality and a high recurrence rate. CT and MRI imaging assessment should preferably be performed before biopsy. External beam radiotherapy must be avoided in children as it is less effective than in adults, and is responsible for long-term cosmetic and functional sequelae and even a risk of second tumours. Treatment is surgical whenever radical resection is possible. In patients presenting an excessive risk of morbidity and mortality, chemotherapy devoid of long-term adverse effects (such as methotrexate in combination with a Vinca alkaloid) can be proposed. Long-term follow-up must be ensured due to the risk of recurrence.

How to perform 3D reconstruction of skull base tumours.

The surgical management of skull base lesions is difficult due to the complex anatomy of the region and the intimate relations between the lesion and adjacent nerves and vessels. Minimally invasive approaches are increasingly used in skull base surgery to ensure an optimal functional prognosis. Three-dimensional (3D) computed tomography (CT) reconstruction facilitates surgical planning by visualizing the anatomical relations of the lesions in all planes (arteries, veins, nerves, inner ear) and simulation of the surgical approach in the operating position. Helical CT angiography is performed with optimal timing of the injection in terms of tumour and vessel contrast enhancement. 3D definition of each structure is based on colour coding by automatic thresholding (bone, vessels) or manual segmentation on each slice (tumour, nerves, inner ear). Imaging is generally presented in 3 dimensions (superior, coronal, sagittal) with simulation of the surgical procedure (5 to 6 reconstructions in the operating position at different depths).

Atypical Lemierre syndrome.

INTRODUCTION: Lemierre syndrome is a complication of oropharyngeal infection and consists of a combination of internal jugular vein septic thrombophlebitis with septicaemia and distant septic emboli (mainly in the lungs). We describe an atypical case with facial vein and anterior jugular vein thrombophlebitis. CASE SUMMARY: A 34-year-old woman attended the emergency room with tonsillitis, left head and neck cellulitis, left facial vein thrombosis and lung abscesses. A diagnosis of atypical Lemierre syndrome was proposed and the patient was treated surgically (neck incision and tonsillectomy) and medically (antibiotics, hyperbaric oxygen therapy and anticoagulation) allowing cure without sequelae. DISCUSSION: Lemierre syndrome, a rare but serious complication requiring immediate treatment, should be investigated (by blood cultures and chest CT scan) in the presence of neck vein thrombosis complicating oropharyngeal infection.

Long-term sequelae treatment of peripheral facial paralysis with botulinum toxin type A: Repartition and kinetics of doses used.

STUDY OBJECTIVES: Botulinum toxin is a key therapeutic tool in the comprehensive treatment of peripheral facial paralysis. It fights spasms, synkinesis and overactivity of the different skin muscles responsible of facial expressions. Even though injection techniques as well as target muscles have been well identified, doses used remain quite imprecise and often not detailed muscle by muscle, further more dosage progression has not been monitored over time. Our retrospective study is the first one to refine the repartition of botulinum toxin doses on each of the relevant skin muscles and assess dosage kinetics. PATIENTS AND METHODS: Thirty patients were included since 2008 with a mean follow-up of 2.3years. Each patient had at least 3 injections, with a delay of 4 to 6months between each injection. RESULTS: Mean doses are indicated for each muscle injected on the paralyzed and healthy sides. Dose kinetics suggests an initial dosage increase after the first injection followed by a decrease over time. No treatment resistance was observed. CONCLUSION: Our study represents a didactic help in using botulinum toxin for sequelae of peripheral facial paralysis by providing more details on the effective mean doses for each muscle and their progression over time.