Stefan Hansen

The collagen receptor DDR1 co-localizes with the non-muscle myosin IIA in mice inner ear and contributes to the cytoarchitecture and stability of motile cells.

Discoidin domain receptor 1 (DDR1) is a tyrosine kinase receptor activated by native collagen. DDRs regulate cell adhesion, migration and various other cell functions. Deletion of the DDR1 gene in mice is associated with a severe decrease in auditory function and substantial structural alterations in a heterogeneous group of cells, including cells containing actin/myosin contractile elements, e.g., outer hair cells (OHCs) (Meyer zum Gottesberge et al. Lab Invest, 88: 27–37, 2008). The non-muscle myosin heavy chain isoform IIA (NM-IIA), encoded by MYH9, is implicated in the regulation of cell spreading, cellular reshaping and movement and cell migration and adhesion. In this study, we identify DDR1 and NM-IIA co-localization in the type III fibrocytes (tension fibrocytes) of the spiral ligament, the OHCs and the stereocilia of both OHCs and inner hair cells. We show for the first time that DDR1 malfunction causes OHC deformation and the separation of the lateral wall, the location of the cellular motor responsible for the electromotile property, explicitly in those regions showing DDR1 and NM-IIA co-localization. On the basis of our results, we propose that DDR1 acts in concert with proteins of the actin/myosin complex to maintain mechanical forces in the inner ear and to stabilize OHC cellular shape for proper auditory signal transduction.

Minimally Invasive Multiport Surgery of the Lateral Skull Base

Objective. Minimally invasive procedures minimize iatrogenic tissue damage and lead to a lower complication rate and high patient satisfaction. To date only experimental minimally invasive single-port approaches to the lateral skull base have been attempted. The aim of this study was to verify the feasibility of a minimally invasive multiport approach for advanced manipulation capability and visual control and develop a software tool for preoperative planning. Methods. Anatomical 3D models were extracted from twenty regular temporal bone CT scans. Collision-free trajectories, targeting the internal auditory canal, round window, and petrous apex, were simulated with a specially designed planning software tool. A set of three collision-free trajectories was selected by skull base surgeons concerning the maximization of the distance to critical structures and the angles between the trajectories. Results. A set of three collision-free trajectories could be successfully simulated to the three targets in each temporal bone model without violating critical anatomical structures. Conclusion. A minimally invasive multiport approach to the lateral skull base is feasible. The developed software is the first step for preoperative planning. Further studies will focus on cadaveric and clinical translation.

Quality Assurance of Multiport Image-Guided Minimally Invasive Surgery at the Lateral Skull Base

For multiport image-guided minimally invasive surgery at the lateral skull base a quality management is necessary to avoid the damage of closely spaced critical neurovascular structures. So far there is no standardized method applicable independently from the surgery. Therefore, we adapt a quality management method, the quality gates (QG), which is well established in, for example, the automotive industry and apply it to multiport image-guided minimally invasive surgery. QG divide a process into different sections. Passing between sections can only be achieved if previously defined requirements are fulfilled which secures the process chain. An interdisciplinary team of otosurgeons, computer scientists, and engineers has worked together to define the quality gates and the corresponding criteria that need to be fulfilled before passing each quality gate. In order to evaluate the defined QG and their criteria, the new surgery method was applied with a first prototype at a human skull cadaver model. We show that the QG method can ensure a safe multiport minimally invasive surgical process at the lateral skull base. Therewith, we present an approach towards the standardization of quality assurance of surgical processes.

Path Planning for Multi-port Lateral Skull Base Surgery Based on First Clinical Experiences

Our research project investigates a multi-port minimally-traumatic approach for lateral skull base surgery, where the surgical target shall be reached through up to three drill canals. For this purpose, an accurate path planning is crucial. In the present work, we propose a semi-automatic path planning approach for multi-port minimally-traumatic lateral skull base surgery. The best path combinations are automatically determined by optimizing the angles and distance buffers of the drill canals. We compare the automatically computed path combinations for 20 data sets to those selected manually by two different clinicians. The experiments prove that we can adequately reproduce the clinicians’ choice.