**2. Computer-assisted training tools**

### **2.1 Ventricular drainage (VD) model**

Various VD training models have been developed, tested and published [13–15]. Recently, we performed another prospective study to evaluate practices, pitfalls and traceability in a realistic but virtual set-up for simulating ventricular drainage (VD) placement as a practicable training model using our navigation system (Brainlab, Munich, Germany), the navigation pointer functioning as a virtual VD catheter to be placed in the cMRI of a healthy subject (**Figure 1**). We evaluated accuracy by repeated virtual freehand VD placement on the prone subject using anatomical landmarks by neurosurgeons-in-training and non-neurosurgical staff. The influence of the level of neurosurgical knowledge and training level were of overall interest, especially in narrow ventricles. It was found that accurate VD placement correlated with neurosurgical experience (**Figures 2** and **3**). These initial results are not yet published, however.

This simple set-up is an easy model for continuous neurosurgical training, with the aim of optimizing the medical care of our patients and constantly improving the level of education. Its set-up could be varied further, for example, as a good training module for simulating an intraoperative emergency puncture of the ventricle, exemplary in an atypical pterional positioning of the head. This poses an unusual situation that requires high surgical skills with an excellent three-dimensional spatial concept.

#### **2.2 Augmented reality (AR) and virtual reality (VR) training tools**

Navigation systems offer a multitude of technical options that can be used for training and further education [16, 17]. Brainlab has been offering the function of transparent reflection in a superimposed display of previously segmented anatomical structures for over 20 years (**Figure 4**). This head-up display, as an early AR tool, in which the pre-planned and segmented structures are faded into the ocular of the operating microscope or onto the screen, allows optimal orientation and is didactically very valuable. However, the accusation is justified that we generally use these technical possibilities of virtual reality or augmented reality, offered as multiplanar visualization or as 3D reconstruction view, far too little for teaching and training purposes [17].

*Training Models for Skull-Base and Vascular Micro-Neurosurgery DOI: http://dx.doi.org/10.5772/intechopen.101924*

Recently, our department has been working with AR 3D models (UpSurgeOn S.r.l., Milan, Italy) to improve surgical and anatomical skills as well as presurgical positioning of the patient (**Figure 5**). For this, the department acquired partially reusable 3D models of the most common cranial neurosurgical approaches including certain pathologies (e.g., intracranial aneurysms) (**Figures 6**–**8**).

**Figure 1.** *Study set-up for virtual VD placement. The navigation pointer functions as a virtual VD catheter to be placed in the cMRI of a healthy subject.*

#### **Figure 2.**

*A selection of virtual VD trajectories by participants with neurosurgical experience including the 'ideal trajectory' in blue.*

#### **Figure 3.**

*A selection of virtual VD trajectories by participants without neurosurgical experience including the 'ideal trajectory' in blue.*

The 3D models are made of synthetic materials which render them extremely lifelike in haptics and handling. They can be used as are or in conjunction with an AR app (UpSurgeOn Neurosurgery S.r.l., Milan, Italy), which walks

*Training Models for Skull-Base and Vascular Micro-Neurosurgery DOI: http://dx.doi.org/10.5772/intechopen.101924*

#### **Figure 4.**

*Intraoperative screenshot during a skull base procedure performed on April 12, 2002, shows then state-ofthe-art technology with intraoperative AR tools that were already available at the time. The preoperatively segmented relevant anatomical structures are demonstrated and the navigation pointer shows the trajectory to the clival meningioma via a combined antero-sigmoidal/sub-temporal approach. The dominant sigmoid and transverse sinus (green) and the lateralized basilar artery (magenta) displaced by the tumor are visualized.*

#### **Figure 6.**

*Our setup for a cadaver-free manual training session with AR 3D models (UpSurgeOn S.r.l., Milan, Italy). The models can be reused by purchasing additional craniotomy covers as depicted here.*

the surgeon through the entire procedure by fusing a virtual image with the actual model, starting with optimal positioning of the patient for the specific surgery (**Figures 9**–**11**). The app also allows an image of the patient awaiting the planned procedure to be projected into any space, allowing the surgeon a 360° view. Training sessions were held for neurosurgery residents, offering them the opportunity to practice neurosurgical approaches safely, including craniotomies, drilling with various bits, brain retraction, basic intradural dissection and even aneurysm clip placement. We acquired a navigational data set for one of the models by placing it in a CT-scanner and uploading the data set it into our navigation system (Brainlab, Munich, Germany), thereby giving participants the additional chance to practice the procedure image-guided in a non-bloody and risk-free manner whilst getting more familiar with the navigation system itself (**Figure 12**). Our results concerning the efficacy of this kind of modern training model have yet to be published; however, anecdotally, residents report feeling more secure in their surgical approaches, in choosing and handling surgical drills as well as in the positioning of patients for surgery. Some residents now use the UpSurgeOn App to plan surgeries in advance or to double-check the preoperative positioning of the patient by overlaying the actual patient with an AR model.

#### **Figure 7.**

*Close-up of the 'aneurysm box' including the craniotomy model, the synthetic brain and vessels and the associated QR code for use in conjunction with the Upsurgeon App for an AR component. The right-sided aneurysm is partially visible through the Sylvian fissure.*

Due to the relative ease and cost-effectiveness of implementing the aforementioned tools, we consider simulation-based cadaver-free training with AR a promising option to bring skull-base surgery training to a new level.

The intense occupation with radiological images, necessary for the segmentation of a tumour or any other lesion and the marking of the anatomical structures, already brings great didactic benefit to the colleagues who are in training. During surgery, the recognition value of the anatomical structures rendered in the CT or MRT as a three-dimensional surgical site under the surgical microscope provides the greatest learning value. The use of navigation data for the dedicated operation planning and the daily discussion of the surgical cases are essential for this. Particularly, in the case of complex skull base operations, the position, craniotomy, microsurgical strategy and resulting operation-specific risks should routinely be discussed with the assistant physicians on the day before the surgical procedure in a pre-op conference. In particular, the discussion of surgery-specific anatomy on the basis of the 3D navigation data provides optimal preparation for

#### **Figure 8.**

*Retracting the synthetic brain to expose the right-sided MCA aneurysm. The materials used render the models extremely lifelike in haptics and handling.*

these complex neurosurgical interventions [17]. So the following day, the display of the operation-specific anatomical structures via the head-up display during surgery will provide a much higher didactic benefit for complex skull base procedures (**Figure 13**).
