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1.
Eur Arch Otorhinolaryngol ; 275(12): 2947-2956, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30302574

RESUMEN

PURPOSE: Latest research on cochlear implantations focuses on hearing preservation during insertion of the implant's electrode array by reducing insertion trauma. One parameter which may influence trauma is insertion speed. The objective of this study was to extend the range of examined insertion speeds to include ultra-low velocities, being lower than manually feasible, and investigate whether these reduce insertion forces. METHODS: 24 custom-made cochlear implant test samples were fabricated and inserted into an artificial scala tympani model using 12 different insertion speeds while measuring the resulting insertion forces. Three commercially available slim straight electrode carriers were inserted using the same setup to analyze whether the results are comparable. RESULTS: Insertions of the test samples using high insertion speeds (2.0/2.8 mm/s) showed significantly higher insertion forces than insertions done with low insertion speeds (0.2 mm/s) or ultra-low insertion speeds (< 0.1 mm/s). The insertions with commercial slim straight electrode arrays showed significantly reduced insertion forces when using a low insertion speed as well. CONCLUSIONS: Slow insertions showed significantly reduced insertion forces. Insertion speeds which are lower than manually feasible showed even lower insertion forces.


Asunto(s)
Implantación Coclear/métodos , Implantes Cocleares , Humanos , Modelos Anatómicos
2.
Eur Arch Otorhinolaryngol ; 274(5): 2131-2140, 2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-28238160

RESUMEN

The aim of the study was to evaluate insertion forces during manual insertion of a straight atraumatic electrode in human temporal bones, and post-implantation histologic evaluation of the samples to determine whether violation of intracochlear structures is related to insertion forces. In order to minimize intracochlear trauma and preserve residual hearing during cochlear implantation, knowledge of the insertion forces is necessary. Ten fresh frozen human temporal bones were prepared with canal wall down mastoidectomy. All samples were mounted on a one-axis force sensor. Insertion of a 16-mm straight atraumatic electrode was performed from different angles to induce "traumatic" insertion. Histologic evaluation was performed in order to evaluate intracochlear trauma. In 4 of 10 samples, dislocation of the electrode into scala vestibuli was observed. The mean insertion force for all 10 procedures was 0.003 ± 0.005 N. Insertion forces measured around the site of dislocation to scala vestibuli in 3 of 4 samples were significantly higher than insertion forces at the same location of the cochleae measured in samples without trauma (p < 0.04). Mean force during the whole insertion process of the straight atraumatic electrode is lower than reported by other studies using longer electrodes. Based on our study, insertion forces leading to basilar membrane trauma may be lower than the previously reported direct rupture forces.


Asunto(s)
Membrana Basilar , Implantación Coclear , Implantes Cocleares/efectos adversos , Complicaciones Intraoperatorias , Hueso Temporal , Membrana Basilar/lesiones , Membrana Basilar/patología , Implantación Coclear/efectos adversos , Implantación Coclear/métodos , Humanos , Complicaciones Intraoperatorias/patología , Complicaciones Intraoperatorias/prevención & control , Modelos Anatómicos , Rotura/etiología , Rotura/patología , Rotura/prevención & control , Hueso Temporal/patología , Hueso Temporal/cirugía
3.
Biomolecules ; 12(4)2022 04 17.
Artículo en Inglés | MEDLINE | ID: mdl-35454178

RESUMEN

Cochlear hair cell damage and spiral ganglion neuron (SGN) degeneration are the main causes of sensory neural hearing loss. Cochlear implants (CIs) can replace the function of the hair cells and stimulate the SGNs electrically. The condition of the SGNs and their spatial distance to the CI are key factors for CI-functionality. For a better performance, a high number of neurons and a closer contact to the electrode are intended. Neurotrophic factors are able to enhance SGN survival and neurite outgrowth, and thereby might optimize the electrode-nerve interaction. This would require chronic factor treatment, which is not yet established for the inner ear. Investigations on chronic drug delivery to SGNs could benefit from an appropriate in vitro model. Thus, an inner ear inspired Neurite Outgrowth Chamber (NOC), which allows the incorporation of a mini-osmotic pump for long-term drug delivery, was designed and three-dimensionally printed. The NOC's function was validated using spiral ganglion explants treated with ciliary neurotrophic factor, neurotrophin-3, or control fluid released via pumps over two weeks. The NOC proved to be suitable for explant cultivation and observation of pump-based drug delivery over the examined period, with neurotrophin-3 significantly increasing neurite outgrowth compared to the other groups.


Asunto(s)
Técnicas de Cultivo de Célula , Ganglio Espiral de la Cóclea , Factores de Crecimiento Nervioso/farmacología , Neuronas , Impresión Tridimensional , Ganglio Espiral de la Cóclea/fisiología
4.
Otol Neurotol ; 42(8): e1013-e1021, 2021 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-33883518

RESUMEN

OBJECTIVE: The present study sought to 1) characterize insertion forces resulting from a flexible straight electrode array (EA) inserted at slow and ultra-slow insertion velocities, and 2) evaluate if ultra-slow velocities decrease insertion forces independent of other variables. BACKGROUND: Low insertion forces are desirable in cochlear implant (CI) surgery to reduce trauma and preserve hearing. Recently, ultra-slow insertion velocities (lower than manually feasible) have been shown to produce significantly lower insertion forces using other EAs. METHODS: Five flexible straight EAs were used to record insertion forces into an inelastic artificial scala tympani model. Eleven trial recordings were performed for each EA at five predetermined automated, continuous insertion velocities ranging from 0.03 to 1.6 mm/s. RESULTS: An ultra-slow insertion velocity of 0.03 mm/s resulted in a median insertion force of 0.010 N at 20 mm of insertion depth, and 0.026 N at 24.3 mm-the final insertion depth. These forces represent only 24 to 29% of those measured using 1.6 mm/s. After controlling for insertion depth of the EA into the artificial scala tympani model and trial insertion number, decreasing the insertion velocity from 0.4 to 0.03 mm/s resulted in a 50% decrease in the insertion forces. CONCLUSION: Using the tested EA ultra-slow velocities can decrease insertion forces, independent of variables like insertion depth. Our results suggest ultra-slow velocities can reduce insertion forces at least 60%, compared with humanly feasible continuous velocities (≥0.9 mm/s).


Asunto(s)
Implantación Coclear , Implantes Cocleares , Audición , Humanos , Fenómenos Mecánicos , Rampa Timpánica/cirugía
5.
J Mech Behav Biomed Mater ; 97: 90-98, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31102984

RESUMEN

Long-term drug delivery to the inner ear for neuroprotection might improve the outcome for hearing disabled patients treated with a cochlear implant (CI). Neurotrophic factor (NTF) producing cells encapsulated in an alginate-matrix, to shield them from the host immune system and to avoid migration, and applied as viscose solution or electrode coating could address this requirement. Both application methods were tested for their feasibility in an artificial human cochlea model. Since both strategies potentially influence the electrode implantability, insertion forces and coating stability were analyzed on custom-made electrode arrays. Both, injection of the alginate-cell solution into the model and a manual dip coating of electrode arrays with subsequent insertion into the model were possible. The insertion forces of coated arrays were reduced by 75% of an uncoated reference. In contrast, filling of the model with non-crosslinked alginate-cell solution slightly increased the insertion forces. A good stability of the coating was observed after first insertion (85%) but abrasion increased after multiple insertions (50%). Both application strategies are possible options for cell-induced drug-delivery to the inner ear, but an alginate-cell coating of CI-electrodes has a great potential to combine an endogenous NTF-source with a strong reduction of insertion forces.


Asunto(s)
Alginatos/química , Implantación Coclear/instrumentación , Implantes Cocleares , Sistemas de Liberación de Medicamentos , Electrodos , Células de la Médula Ósea/citología , Materiales Biocompatibles Revestidos , Oído Interno , Humanos , Fenómenos Mecánicos , Células Madre Mesenquimatosas/citología , Viscosidad
6.
Comput Med Imaging Graph ; 77: 101655, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31539862

RESUMEN

Surgical treatment with a cochlear implant (CI) for hearing rehabilitation requires a highly accurate and personalized opening of the inner ear (cochlea) to protect the delicate intra-cochlear fine structures, whose functional integrity needs to be maintained to preserve residual hearing. Spatial orientation within the complex anatomy of the lateral skull base during the procedure is a highly demanding task for the surgeon. In order to reduce risk of facial nerve palsy and loss of residual hearing as well as to establish minimally invasive CI surgery (minCIS), image-guided procedures incorporating surgical assistance systems are under development. However, there is a lack of an accuracy threshold value or range that such a system needs to fulfill to be considered sufficiently accurate for atraumatic opening of the inner ear. In this study, high resolution three-dimensional (3D) morphological images of eight human temporal bone specimens were manually segmented to build anatomical models of the human inner ear including all surgically relevant intra-cochlear structures as well as the facial recess. These 3D models were used to plan the surgical access path to the basal turn of the cochlea using the mastoidectomy posterior tympanotomy approach (MPTA). Therefore, custom-made image-processing software was developed to perform both path planning and identification of the valid target region- i.e., the largest possible region for atraumatic opening of the scala tympani. The developed 3D models provide visualization of the complex and variable anatomy of the basal portion of the human cochlear duct (also known as cochlear "hook region") as well as its spatial relationship to the facial recess. Their spatial arrangement directly impacts the accessibility of the hook region and limits the entry direction into scala tympani. The average diameter of the target region was found to be 1.56 mm ±â€¯0.10 mm (range: 1.43 to 1.72 mm). The anatomic variability and the need for a high safety level of at least 95% for hearing preservation CI surgery lead to a remaining safety margin of approximately 0.3 mm. In the future, this accuracy threshold value can serve as benchmark during the pre-clinical evaluation of image-guidance technologies to allow for highly accurate CI surgery.


Asunto(s)
Cóclea/diagnóstico por imagen , Cóclea/cirugía , Implantación Coclear , Procesamiento de Imagen Asistido por Computador/métodos , Modelos Anatómicos , Cirugía Asistida por Computador/métodos , Hueso Temporal/diagnóstico por imagen , Puntos Anatómicos de Referencia , Humanos , Imagenología Tridimensional , Procedimientos Quirúrgicos Mínimamente Invasivos , Programas Informáticos
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