Toward an interoperable, intraoperative situation recognition system via process modeling, execution, and control using the standards BPMN and CMMN.

PURPOSE: For the modeling, execution, and control of complex, non-standardized intraoperative processes, a modeling language is needed that reflects the variability of interventions. As the established Business Process Model and Notation (BPMN) reaches its limits in terms of flexibility, the Case Management Model and Notation (CMMN) was considered as it addresses weakly structured processes. METHODS: To analyze the suitability of the modeling languages, BPMN and CMMN models of a Robot-Assisted Minimally Invasive Esophagectomy and Cochlea Implantation were derived and integrated into a situation recognition workflow. Test cases were used to contrast the differences and compare the advantages and disadvantages of the models concerning modeling, execution, and control. Furthermore, the impact on transferability was investigated. RESULTS: Compared to BPMN, CMMN allows flexibility for modeling intraoperative processes while remaining understandable. Although more effort and process knowledge are needed for execution and control within a situation recognition system, CMMN enables better transferability of the models and therefore the system. Concluding, CMMN should be chosen as a supplement to BPMN for flexible process parts that can only be covered insufficiently by BPMN, or otherwise as a replacement for the entire process. CONCLUSION: CMMN offers the flexibility for variable, weakly structured process parts, and is thus suitable for surgical interventions. A combination of both notations could allow optimal use of their advantages and support the transferability of the situation recognition system.

Continuous Feature-Based Tracking of the Inner Ear for Robot-Assisted Microsurgery.

Robotic systems for surgery of the inner ear must enable highly precise movement in relation to the patient. To allow for a suitable collaboration between surgeon and robot, these systems should not interrupt the surgical workflow and integrate well in existing processes. As the surgical microscope is a standard tool, present in almost every microsurgical intervention and due to it being in close proximity to the situs, it is predestined to be extended by assistive robotic systems. For instance, a microscope-mounted laser for ablation. As both, patient and microscope are subject to movements during surgery, a well-integrated robotic system must be able to comply with these movements. To solve the problem of on-line registration of an assistance system to the situs, the standard of care often utilizes marker-based technologies, which require markers being rigidly attached to the patient. This not only requires time for preparation but also increases invasiveness of the procedure and the line of sight of the tracking system may not be obstructed. This work aims at utilizing the existing imaging system for detection of relative movements between the surgical microscope and the patient. The resulting data allows for maintaining registration. Hereby, no artificial markers or landmarks are considered but an approach for feature-based tracking with respect to the surgical environment in otology is presented. The images for tracking are obtained by a two-dimensional RGB stream of a surgical microscope. Due to the bony structure of the surgical site, the recorded cochleostomy scene moves nearly rigidly. The goal of the tracking algorithm is to estimate motion only from the given image stream. After preprocessing, features are detected in two subsequent images and their affine transformation is computed by a random sample consensus (RANSAC) algorithm. The proposed method can provide movement feedback with up to 93.2 µm precision without the need for any additional hardware in the operating room or attachment of fiducials to the situs. In long term tracking, an accumulative error occurs.

Retrospective in silico evaluation of optimized preoperative planning for temporal bone surgery.

PURPOSE: Robot-assisted surgery at the temporal bone utilizing a flexible drilling unit would allow safer access to clinical targets such as the cochlea or the internal auditory canal by navigating along nonlinear trajectories. One key sub-step for clinical realization of such a procedure is automated preoperative surgical planning that incorporates both segmentation of risk structures and optimized trajectory planning. METHODS: We automatically segment risk structures using 3D U-Nets with probabilistic active shape models. For nonlinear trajectory planning, we adapt bidirectional rapidly exploring random trees on Bézier Splines followed by sequential convex optimization. Functional evaluation, assessing segmentation quality based on the subsequent trajectory planning step, shows the suitability of our novel segmentation approach for this two-step preoperative pipeline. RESULTS: Based on 24 data sets of the temporal bone, we perform a functional evaluation of preoperative surgical planning. Our experiments show that the automated segmentation provides safe and coherent surface models that can be used in collision detection during motion planning. The source code of the algorithms will be made publicly available. CONCLUSION: Optimized trajectory planning based on shape regularized segmentation leads to safe access canals for temporal bone surgery. Functional evaluation shows the promising results for both 3D U-Net and Bézier Spline trajectories.

i3PosNet: instrument pose estimation from X-ray in temporal bone surgery.

PURPOSE: Accurate estimation of the position and orientation (pose) of surgical instruments is crucial for delicate minimally invasive temporal bone surgery. Current techniques lack in accuracy and/or line-of-sight constraints (conventional tracking systems) or expose the patient to prohibitive ionizing radiation (intra-operative CT). A possible solution is to capture the instrument with a c-arm at irregular intervals and recover the pose from the image. METHODS: i3PosNet infers the position and orientation of instruments from images using a pose estimation network. Said framework considers localized patches and outputs pseudo-landmarks. The pose is reconstructed from pseudo-landmarks by geometric considerations. RESULTS: We show i3PosNet reaches errors [Formula: see text] mm. It outperforms conventional image registration-based approaches reducing average and maximum errors by at least two thirds. i3PosNet trained on synthetic images generalizes to real X-rays without any further adaptation. CONCLUSION: The translation of deep learning-based methods to surgical applications is difficult, because large representative datasets for training and testing are not available. This work empirically shows sub-millimeter pose estimation trained solely based on synthetic training data.

Evolution and Stagnation of Image Guidance for Surgery in the Lateral Skull: A Systematic Review 1989-2020.

Objective: Despite three decades of pre-clinical and clinical research into image guidance solutions as a more accurate and less invasive alternative for instrument and anatomy localization, translation into routine clinical practice for surgery in the lateral skull has not yet happened. The aim of this review is to identify challenges that need to be solved in order to provide image guidance solutions that are safe and beneficial for use during lateral skull surgery and to synthesize factors that facilitate the development of such solutions. Methods: Literature search was conducted via PubMed using terms relating to image guidance and the lateral skull. Data extraction included the following variables: image guidance error, imaging resolution, image guidance system, tracking technology, registration method, study endpoints, clinical target application, and publication year. A subsequent search of FDA 510(k) database for identified image guidance systems and extraction of the year of approval, intended use, and indications for use was performed. The study objectives and endpoints were subdivided in three time phases and summarized. Furthermore, it was analyzed which factors correlated with the image guidance error. Factor values for which an error ≤0.5 mm (µerror + 3σerror) was measured in more than one study were identified and inspected for time trends. Results: A descriptive statistics-based summary of study objectives and findings separated in three time intervals is provided. The literature provides qualitative and quantitative evidence that image guidance systems must provide an accuracy ≤0.5 mm (µerror + 3σerror) for their safe and beneficial application during surgery in the lateral skull. Spatial tracking accuracy and precision and medical image resolution both correlate with the image guidance accuracy, and all of them improved over the years. Tracking technology with accuracy ≤0.05 mm, computed tomography imaging with slice thickness ≤0.2 mm, and registration based on bone-anchored titanium fiducials are components that provide a sufficient setting for the development of sufficiently accurate image guidance. Conclusion: Image guidance systems must reliably provide an accuracy ≤0.5 mm (µerror + 3σerror) for their safe and beneficial use during surgery in the lateral skull. Advances in tracking and imaging technology contribute to the improvement of accuracy, eventually enabling the development and wide-scale adoption of image guidance solutions that can be used safely and beneficially during lateral skull surgery.

Patient quality of life after vestibular schwannoma removal: possibilities and limits to measuring different domains of patients' wellbeing.

PURPOSE: Since the 1980s, health-related quality of life (HRQOL) has been recognized in the assessment of medical treatment. To determine the health-related quality of life (HRQOL) of vestibular schwannoma (VS) patients, a specific questionnaire that has been validated in different languages is essential. METHODS: The Short Form-36 Health Survey (SF-36) and PANQOL questionnaires in German were evaluated in patients after removal of a VS via the translabyrinthine approach. Descriptive statistics of a comparison of the SF-36 results to those of a normal sample are illustrated. Criterion validity was investigated using Spearman's rank test to correlate the PANQOL domains with the SF-36 domains. A confirmatory factor analysis of the PANQOL was performed to determine the stability of the factor structure of the PANQOL questionnaire for our cohort. RESULTS: The criterion validity of the German PANQOL questionnaire is comparable to that of the original English version. The SF-36 domains values ranged from 49.31/100 (role physical) to 66.46/100 (physical functioning). Compared to the normal population, patients who underwent surgical removal of a VS showed a significantly reduced quality of life, mainly in domains such as physical and social functioning, as well as psychological wellbeing. CONCLUSION: The German PANQOL has been validated and is now available. Post-surgical treatment should be focused not only on physiological rehabilitation but also on improving the quality of life, especially aspects of psychological and social wellbeing.

Automatic Registration for Navigation at the Anterior and Lateral Skull Base.

OBJECTIVE: Navigation systems create a connection between imaging data and intraoperative situs, allowing the surgeon to consistently determine the location of instruments and patient anatomy during the surgical procedure. The best results regarding the target registration error (measurement uncertainty) are normally demonstrated using fiducials. This study aimed at investigating a new registration strategy for an electromagnetic navigation device. METHODS: For evaluation of an electromagnetic navigation system and comparison of registration with screw markers and automatic registration, we are calculating the target registration error in the region of the paranasal sinuses/anterior and lateral skull base with the use of an electromagnetic navigation system and intraoperative digital volume tomography (cone-beam computed tomography). We carried out 10 registrations on a head model (total n = 150 measurements) and 10 registrations on 4 temporal bone specimens (total n = 160 measurements). RESULTS: All in all, the automatic registration was easy to perform. For the models that were used, a significant difference between an automatic registration and the registration on fiducials was evident for just a limited number of screws. Furthermore, the observed differences varied in terms of the preferential registration procedure. CONCLUSION: The automatic registration strategy seems to be an alternative to the established methods in artificial and cadaver models of intraoperative scenarios. Using intraoperative imaging, there is an option to resort to this kind of registration as needed.

High-precision evaluation of electromagnetic tracking.

PURPOSE: Navigation in high-precision minimally invasive surgery (HP-MIS) demands high tracking accuracy in the absence of line of sight (LOS). Currently, no tracking technology can satisfy this requirement. Electromagnetic tracking (EMT) is the best tracking paradigm in the absence of LOS despite limited accuracy and robustness. Novel evaluation protocols are needed to ensure high-precision and robust EMT for navigation in HP-MIS. METHODS: We introduce a novel protocol for EMT measurement evaluation featuring a high-accuracy phantom based on LEGO[Formula: see text], which is calibrated by a coordinate measuring machine to ensure accuracy. Our protocol includes relative sequential positions and an uncertainty estimation of positioning. We show effects on distortion compensation using a learned interpolation model. RESULTS: Our high-precision protocol clarifies properties of errors and uncertainties of EMT for high-precision use cases. For EMT errors reaching clinically relevant 0.2 mm, our design is 5-10 times more accurate than previous protocols with 95% confidence margins of 0.02 mm. This high-precision protocol ensures the performance improvement in compensated EMT by 0.05 mm. CONCLUSION: Our protocol improves the reliability of EMT evaluations because of significantly lower protocol-inherent uncertainties. To reduce patient risk in HP-MIS and to evaluate magnetic field distortion compensation, more high-accuracy protocols such as the one proposed here are required.

Cochlear Implantation in Patients With Single-sided Deafness After the Translabyrinthine Resection of the Vestibular Schwannoma-Presented at the Annual Meeting of ADANO 2016 in Berlin.

OBJECTIVE: To evaluate effectiveness of the cochlear implant (CI) to facilitate single-sided deafness (SSD) rehabilitation following translabyrinthine resection of the vestibular schwannoma. STUDY DESIGN: Retrospective patient review. SETTING: Single center, University hospital. PATIENTS: Patients with SSD who underwent translabyrinthine resection of a vestibular schwannoma with anatomical preservation of the cochlear nerve and subsequent CI on the same ear. INTERVENTIONS: CI at post-translabyrinthine resection of the acoustic neuroma to treat SSD, and evaluation by retrospective individual case review in a period from 2009 to 2016. MAIN OUTCOME MEASURES: Individual patients' clinical outcome and speech understanding. RESULTS: Thirteen patients were provided CI. In all cases, complete removal of the tumor was achieved and the cochlear nerve was preserved; in one case, the CI was implanted simultaneously. In most cases, the follow-up interval was 2 years. In 9 of 13 cases, the implanted ear achieved capability to understand and discriminate monosyllabic words at 65 dB. Level of speech understanding of over 50% at 65 dB was possible in 7 patients at 12 months after the first fitting of CI. CONCLUSIONS: Under certain conditions, CI was an effective solution to restore hearing in patients with SSD following translabyrinthine access to the skull base. Study with prospective design is required to provide more significant results.

Toward an automatic preoperative pipeline for image-guided temporal bone surgery.

PURPOSE: Minimally invasive surgery is often built upon a time-consuming preoperative step consisting of segmentation and trajectory planning. At the temporal bone, a complete automation of these two tasks might lead to faster interventions and more reproducible results, benefiting clinical workflow and patient health. METHODS: We propose an automatic segmentation and trajectory planning pipeline for image-guided interventions at the temporal bone. For segmentation, we use a shape regularized deep learning approach that is capable of automatically detecting even the cluttered tiny structures specific for this anatomy. We then perform trajectory planning for both linear and nonlinear interventions on these automatically segmented risk structures. RESULTS: We evaluate the usability of segmentation algorithms for planning access canals to the cochlea and the internal auditory canal on 24 CT data sets of real patients. Our new approach achieves similar results to the existing semiautomatic method in terms of Dice but provides more accurate organ shapes for the subsequent trajectory planning step. The source code of the algorithms is publicly available. CONCLUSION: Automatic segmentation and trajectory planning for various clinical procedures at the temporal bone are feasible. The proposed automatic pipeline leads to an efficient and unbiased workflow for preoperative planning.

Robotic cochlear implantation: feasibility of a multiport approach in an ex vivo model.

PURPOSE: A recent clinical trial has shown the feasibility of robotic cochlear implantation. The electrode was inserted through the robotically drilled tunnel and an additional access through the external auditory canal was created to provide for means of visualization and manipulation. To obviate the need for this additional access, the utilization of multiple robotically drilled tunnels targeting the round window has been proposed. The objective of this study was to assess the feasibility of electrode insertion through a robotic multiport approach. METHODS: In four ex vivo human head specimens (left side), four trajectories through the facial recess (2x) and the retrofacial and suprameatal region were planned and robotically drilled. Optimal three-port configurations were determined for each specimen by analyzing combinations of three of the four trajectories, where the three trajectories were used for the electrode, endoscopic visualization and manipulative assistance. Finally, electrode insertions were conducted through the optimal configurations. RESULTS: The electrodes could successfully be inserted, and the procedure sufficiently visualized through the facial recess drill tunnels in all specimens. Effective manipulative assistance for sealing the round window could be provided through the retrofacial tunnel. CONCLUSIONS: Electrode insertion through a robotic three-port approach is feasible. Drill tunnels through the facial recess for the electrode and endoscope allow for optimized insertion angles and sufficient visualization. Through a retrofacial tunnel effective manipulation for sealing is possible.

Quality of Life After Translabyrinthine Vestibular Schwannoma Resection-Reliability of the German PANQOL Questionnaire.

OBJECTIVE: To quantify the postoperative quality of life (QOL) of patients after translabyrinthine surgery for vestibular schwannoma (VS) using the German version of the Penn acoustic neuroma quality-of-life questionnaire (PANQOL) in a university hospital. METHODS: The PANQOL questionnaire was administered to 72 patients who were treated in our department with translabyrinthine surgery for VS between January 2007 and January 2017. Descriptive evaluations of results were performed in addition to analyses of the reliability and convergent validity of the results and a subgroup analysis. RESULTS: For the first time, QOL was measured in German-speaking VS patients after translabyrinthine surgery. Cronbach's alpha for internal consistency and Guttman's split half, used as measures of reliability, showed values between 0.39 and 0.92 (raw alpha) and 0.58 and 0.98 (Lambda 4), respectively. DESCRIPTIVE STATISTICS: The mean total PANQOL score of patients after translabyrinthine VS resection was 61.96. The domain "hearing" had the lowest score (50.87), while "facial dysfunction" had the highest score (74.88). Subgroup analysis showed that neither preoperative tumor size nor elapsed time postoperatively significantly influenced QOL outcomes. CONCLUSIONS: Depending on the different domains the German PANQOL questionnaire showed poor to good internal consistency, reliability, and convergent validity. Moreover, some VS patients suffer from reduced QOL for a long time after the translabyrinthine procedure, thus psycho-oncological care should be recommended in these cases.

[Hearing rehabilitation with the cochlea implant following translabyrinthine CPA tumor removal ?] / Hörrehabilitation durch Cochlea-Implantation nach Vestibularisschwannom-Entfernung?

We present a quality analysis of 10 patients with an individual treatment trial for a simultaneous or consecutive cochlea implantation after translabyrinthine removal of a neurinoma at the cerebellopontine angle. The results show that most of the patients benefit from the cochlea implantation after unilateral deafness. Through a careful surgical preparation technique at the inner ear canal and its surroundings the morphological and functional integrity of the neurovascular structures can be guaranteed.

Multistep translation and cultural adaptation of the Penn acoustic neuroma quality-of-life scale for German-speaking patients.

BACKGROUND: Monitoring the health-related quality of life (HRQOL) for patients with vestibular schwannoma (VS) has garnered increasing interest. In German-speaking countries, there is no disease-specific questionnaire available similar to the "Penn Acoustic Neuroma Quality-of-life Scale" (PANQOL). METHOD: We translated the PANQOL for German-speaking patients based on a multistep protocol that included not only a forward-backward translation but also linguistic and sociocultural adaptations. The process consists of translation, synthesis, back translation, review by an expert committee, administration of the prefinal version to our patients, submission and appraisal of all written documents by our research team. The required multidisciplinary team for translation comprised head and neck surgeons, language professionals (German and English), a professional translator, and bilingual participants. A total of 123 patients with VS underwent microsurgical procedures via different approaches at our clinic between January 2007 and January 2017. Among these, 72 patients who underwent the translabyrinthine approach participated in the testing of the German-translated PANQOL. RESULT: The first German version of the PANQOL questionnaire was created by a multistep translation process. The responses indicate that the questionnaire is simple to administer and applicable to our patients. CONCLUSION: The use of a multistep process to translate quality-of-life questionnaires is complex and time-consuming. However, this process was performed properly and resulted in a version of the PANQOL for assessing the quality of life of German-speaking patients with VS.

Assessment of the endoscopic range of motion for head and neck surgery using the SOLOASSIST endoscope holder.

BACKGROUND: A 'third hand' is useful for holding the endoscope during surgery. The SOLOASSIST camera holder (AktorMed GmbH, Germany), which is used for abdominal surgery, is supposed to be modified for head and neck surgery. The aim of this study was to determine the intraoperative hand-held endoscopic range of motion for different surgical procedures and to define the required technical changes. METHODS: The intraoperative movements of the hand-held endoscope during sinus surgery, rigid laryngoscopy, and lateral skull base surgery were measured and calculated. RESULTS: The endoscopic range of motion during surgery revealed diverse geometric bodies and volumes. For use in the ENT area, the system must be expanded by a manual release function for the driven axes and two additional lockable axes at the distal end of the arm. CONCLUSION: Intraoperative endoscopic range of motions in head and neck surgery are highly specific and, as expected, differ from the endoscopic movements in abdominal surgery.

Development of a new endoscope holder for head and neck surgery--from the technical design concept to implementation.

Endoscope holders are utilized by a variety of surgeons but are not commonplace in head and neck surgery. The SOLOASSIST active camera holder, which is currently used for abdominal surgery, will soon be adapted for head and neck surgery in collaboration with AKTORmed GmbH SOLO SURGERY (Barbing, Germany). In our pre-feasibility study, we analyzed the use of the existing endoscope holder on anatomical specimens during head and neck surgery. Based on these results, we are proceeding towards the development of a new endoscope holder for head and neck surgery. First, we drafted the technical concepts and discussed the advantages and disadvantages of the system. Then, we used anatomic specimens to measure the forces that occur intraoperatively during sinus surgery. Next, we designed a computer-aided design (CAD) model. Finally, we developed the first production prototype and used it for a frontal skull base procedure on an anatomical specimen. We present the three most promising concepts for a new holder. The resulting total force (F res = √(X (2) + Y (2) + Z (2))) was calculated to be 3.2 N during sinus surgery. We could observe all necessary intraoperative landmarks with the endoscope and its holder in a sinus and frontal skull base surgery. We developed a production prototype of a new endoscope holder and demonstrate satisfactory results in the use of anatomic specimens for skull base surgery.

Cochlear obliteration after translabyrinthine vestibular schwannoma surgery.

The objective of the study was to determine the temporal occurrence of cochlear obliteration following translabyrinthine vestibular schwannoma resection. A retrospective chart review, cross-sectional study, and sequential analysis of the time series were performed. The retrospective study included patients undergoing translabyrinthine resection for stage T1-T2 vestibular schwannoma from 2007 to 2010 without prior therapy and postoperative follow-up including MRI of the brain and the cerebellopontine angle. Already 3 months after surgery a radiographic labyrinthine change was observed in 66.7 %, a partial obstruction in 50 %, and an obstruction limited to the saccule in 16.7 %. Only 33.3 % of the patients showed an unchanged inner ear. In consideration of early cochlear obstruction after translabyrinthine vestibular schwannoma resection, temporary follow-up is necessary. Since the indications for cochlear implantation (CI) have been extended, especially concerning patients with single-side deafness, a simultaneous or early second-stage CI after tumour removal should be discussed.

Taking a fresh look at the skull base in otorhinolaryngology with web-based simulation: Student's Interactive Skull-Base Trainer (SISTer).

IMPORTANCE: The increasing amount of medical knowledge and necessity for time-effective teaching and learning have given rise to emerging online, or e-learning, applications. The base of the skull is a challenging anatomic area in the otorhinolaryngology (ORL) department-for both students and lecturers. Technology-enhanced learning might be an expedient approach to benefit both learners and lecturers. OBJECTIVE: To investigate and create for advanced medical students a self-assessed adaptive e-learning application for the skull base within our curriculum of otolaryngology at the University Medical Center of Heinrich Heine University, Düsseldorf, Germany. DESIGN, SETTING, AND PARTICIPANTS: Pilot approach with prospective evaluation of a newly implemented web-based e-learning simulation. The e-learning application (Student's Interactive Skull-Base Trainer) was made accessible as an elective course to a total of 269 enrolled medical students during the first 2 semesters after web launch. INTERVENTIONS: Spatiotemporal independent e-learning application for the skull base. MAIN OUTCOMES AND MEASURES: Self-assessed evaluation with focus on general acceptance and personal value as well as usage data analysis. RESULTS: The application was well accepted by the learners. More than 80% of the participating students found the application to be a beneficial tool for enhancing their analytical and clinical problem-solving skills. Although the general matter of the skull base seemed to be of lesser interest, the concept of anchored instructions with the use of high-end, interactive, multimedia-based content was considered to be particularly suitable for this challenging topic. Most of the students would have appreciated an extension of optional e-learning modules. CONCLUSIONS AND RELEVANCE: With this pilot approach we were able to implement a useful and now well-accepted tool for blended learning. We showed that it is possible to raise interest even in this very specialized subspecialty of ORL with overall individual learning benefit for the students. There is a demand for more e-learning and web-based simulation to support the existing curricula in a hybrid, blended way.

Optical coherence tomography guided laser cochleostomy: towards the accuracy on tens of micrometer scale.

Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned based on the residual bone thickness distribution. OCT itself is also used as a highly accurate tracking system for motion compensation between the target area and the optics. During ex vivo experimental evaluation on fresh porcine cochleae, the ablation process terminated automatically when the thickness of the residual tissue layer uniformly reached a predefined value. The shape of the resulting channel bottom converged to the natural curvature of the endosteal layer without injuring the critical structure. Preliminary measurements in OCT scans indicated that the mean absolute accuracy of the shape approximation was only around 20 µm.

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.