Ziel dieses Forschungsprojekt ist es, zu untersuchen ob neuartige, computer- und robotergestützte Ansätze zu einem verbesserten und reproduzierbareren Operationsergebnis beitragen können. Hierbei wird in Computertomographiebildern des Patienten ein Tunnel mit einem Durchmesser von 1.8 bzw. 2.5 mm von hinter dem Ohr direkt bis in die Cochlea geplant, der unmittelbar zwischen dem Gesichtsnerv und dem Geschmacksnerv hindurchführt. Die Implantatelektrode kann darüber in einem definierten Eintrittswinkel in die Hörschnecke eingeführt werden. Diese geplante Trajektorie wird dann während der Operation mit einem Roboter gebohrt. Aufgrund der vorhandenen Größenverhältnisse im Schädel und Innenohr muss der Roboter auf wenige Zehntelmillimeter genau bohren können. Für den Chirurgen gibt es hier keine direkten visuellen Kontrollmöglichkeiten. Um beim Bohrvorgang die nötige Sicherheit für den Roboter zu gewährleisten, sind deshalb dezidierte und voneinander unabhängige Sicherheitsmechanismen erforderlich, die in diesem Verfahren erstmalig zur Anwendung kommen. Dies ist vergleichbar mit dem Instrumentenflugprinzip eines modernen Flugzeugs, das auch bei fehlenden Sichtverhältnissen eine sichere Flugzeugführung gewährleistet.
In diesem Projekt sollen Methoden und Ansätze zur Komplementierung des existierenden und klinisch erprobten robotischen Mittelohrzugangs um Elemente ergänzt werden, die eine vollständige robotische Cochleaimplantation ermöglichen könnten. Zum einen ist dies der Innenohrzugang, der zunächst bildbasiert geplant und dann sensor-geführt mit dem Robotersystem gebohrt werden muss. Zum Anderen soll ein klinisch nutzbarer Ansatz für eine robotische Elektrodeninsertion konzipiert und durchgesetzt werden. Beide Elemente werden präklinisch anhand von Phantomen und ex-vivo Modellen entwickelt.
The Cochlear implant (CI) is a neuroprosthetic that restores hearing in patients with severe-to-profound sensorineural hearing loss (Eshraghi et al. 2012) , high frequency hear-ing loss (Turner et al. 2008) and unilateral hearing loss (Boyd 2015). During the microsurgical CI implantation procedure, the otologist creates a cone-shaped access to the inner ear by passing through the mastoid bone, traversing past the facial nerve, the chorda tympani and ossicles. The otologist uses visual examination through the 20 mm opening to advance the drill either to the natural opening of the cochlea (round window) or an inci-sion into the cochlea (cochleostomy). Then the implant electrode is inserted into the cochlea with as much care as the tactile abilities of the otologist permit. Once the implant is functional, the electrode sends out electric impulses to stimulate the spiral ganglion cells that innervate the fibres of the auditory nerve to convert external sounds into electronic signatures that are interpreted as hearing by the brain’s auditory cortex.
CI implantation to date is a manual procedure in which variations in operator experience and skill are associated with inconsistent surgical and audiological outcomes. In particular trauma caused by the cochlear access, electrode insertion and electrode placement impact the effectiveness of hearing restoration (Lehnhardt 1993) (Roland 2005) (Pau et al. 2007). Limits of human tactile sensing, feedback and dexterity have proved a barrier to reduce procedural invasiveness and attempts to improve outcomes without computer assistance have been challenging (Coulson et al. 2007)(James et al. 2005). The investigation of augmenting tools for CI surgery has resulted in the concept of Robotic Cochlea Implantation (RCI), in which each stage of the manual procedure is superseded by sensor data-driven devices. They will replace:i)the surgeon’s “decide as you go” approach with patient-specific computer based planning (CAP, phase 1) of all relevant treatment aspects using preoperatively acquired 3D imaging, ii) the manual middle and inner ear access with a minimally invasive robotic approach access to the middle ear (RMA, phase 2) and inner ear (RIA, phase 3) subsequently; iii) free-hand manual electrode insertion with speed & force controlled robotic electrode insertion (REI, phase 4).
We have evolved the RCI model and demonstrated its feasibility for robotic middle ear access in patients (Weber et al. 2017). The work proposed herein focusses on the investigation of methods and approaches to complement our existing RCI model with clinically viable solutions for robotic inner ear access and robotic electrode insertion. The aim of this project is the investigation of an approach to inner ear access, including: aspects of geometric planning, multi sensor-based robotic control of the actual drilling process and investigation of tool-tissue interaction, all based on the development of suitable anatomical phantoms; as well as experimental investigation of efficiency and efficacy of the approach both in phantoms and in-vivo. Proposed research towards robotic electrode insertion encompasses the experimental investigation of different electrode insertion approaches through the combination of elements such as previously developed insertion guide tubes, manual insertion, motorized insertion, and the monitoring and feedback of applicable insertion forces. Additionally, the feasibility of a multi-port approach (i.e. several drill trajectories for multiple instrument placement) to support a controlled and reproducible insertion process will be investigated. An experimental technical model incorporating reproducible conditions, anatomical variability and sufficient complexity will be developed as part of the work.
The experimental work conducted for each of the treatment modules will aid in determining optimised technical and performance parameters that will underlie prototype components to be tested in in vitro and ex vivo pilot studies. Experimental results will also be used to investigate: i) the feasibility and benefits of performing all of the RCI modules in a robotic treatment model approach, and ii) the generalisability of a robotic treatment model for the development of novel skull-base applications for robotic surgery.
Last updated:24.05.2022
