Development and validation of a preclinical model for training and assessment of cerebrospinal fluid leak repair in endoscopic skull base surgery

Development and Validation of a Novel Human-Fixed Cadaveric Model Reproducing Cerebrospinal Fluid Circulation for Simulation of Endoscopic Endonasal Skull Base Surgery

BACKGROUND AND OBJECTIVES

Endoscopic endonasal surgery is a well-established surgical approach to the skull base. Surgeons need a reusable long-lasting tool to acquire the skills needed for skull base reconstruction. The aim of this study was to elaborate and validate a human formalin-fixed cadaveric model that reproduces a realistic cerebrospinal fluid (CSF) circulation and that adequately renders a CSF leak.

METHODS

An external ventricular drain that connects with a peristaltic pump is placed in the subarachnoid space, which allows a water circulation that reproduces CSF circulation. Intracranial pressure is measured in real time. Endoscopic endonasal skull base approaches are performed, to create different skull base openings and CSF leaks. Participants were tasked with reconstruction of the defects using a standardized multilayered approach, with the goal of obtaining a watertight closure under normal intracranial pressure ranges. Compiled data included time of reconstruction, years of experience of participants, and success/failure to achieve a watertight reconstruction. A Likert questionnaire was also used.

RESULTS

The cadaveric model reproduced CSF circulation in 4 types of dural defects: sellar, suprasellar, transcribriform, and transclival. Intracranial pressures were similar to physiological conditions and were reproducible. Each model was tested multiple times, over several months. Success rates concurred with training levels (r = .8282 and P = .0017). A strong inverse correlation was also found between years of experience and time of reconstruction (r = .4977 and P < .0001). Participants agreed that the model was realistic (median Likert score of 4), and they strongly agreed that it allowed for the improvement of their surgical skills (median Likert score of 5).

CONCLUSION

This novel human-fixed cadaveric model for CSF circulation is efficient and adequately reproduces surgical conditions for skull base approaches. The model is unique, easy to reproduce, and reusable. It can be used as a tool for teaching and for research purposes.

Training models and simulators for endoscopic transsphenoidal surgery: a systematic review

Endoscopic transsphenoidal surgery is a novel surgical technique requiring specific training. Different models and simulators have been recently suggested for it, but no systematic review is available. To provide a systematic and critical literature review and up-to-date description of the training models or simulators dedicated to endoscopic transsphenoidal surgery. A search was performed on PubMed and Scopus databases for articles published until February 2023; Google was also searched to document commercially available. For each model, the following features were recorded: training performed, tumor/arachnoid reproduction, assessment and validation, and cost. Of the 1199 retrieved articles, 101 were included in the final analysis. The described models can be subdivided into 5 major categories: (1) enhanced cadaveric heads; (2) animal models; (3) training artificial solutions, with increasing complexity (from "box-trainers" to multi-material, ct-based models); (4) training simulators, based on virtual or augmented reality; (5) Pre-operative planning models and simulators. Each available training model has specific advantages and limitations. Costs are high for cadaver-based solutions and vary significantly for the other solutions. Cheaper solutions seem useful only for the first stages of training. Most models do not provide a simulation of the sellar tumor, and a realistic simulation of the suprasellar arachnoid. Most artificial models do not provide a realistic and cost-efficient simulation of the most delicate and relatively common phase of surgery, i.e., tumor removal with arachnoid preservation; current research should optimize this to train future neurosurgical generations efficiently and safely.

Simulation training in endoscopic skull base surgery: A scoping review

Objective

Methods

Results

Conclusions

Additive Manufacturing for Personalized Skull Base Reconstruction in Endoscopic Transclival Surgery: A Proof-of-Concept Study

BACKGROUND

Endoscopic transnasal transclival intradural surgery is limited by a high postoperative cerebrospinal fluid leak rate. The aim of this study was to investigate the role of three-dimensional printing to create a personalized, rigid scaffold for clival reconstruction.

METHODS

Two different types of clivectomy were performed in 5 specimens with the aid of neuronavigation, and 11 clival reconstructions were simulated. They were repaired with polylactide, three-dimensional-printed scaffolds that were manually designed in a computer-aided environment based either on the real or on the predicted defect. Scaffolds were printed with a fused filament fabrication technique and different offsets. They were positioned and fixed either following the gasket seal technique or with screws. Postdissection radiological evaluation of scaffold position was performed in all cases. In 3 specimens, the cerebrospinal fluid leak pressure point was measured immediately after reconstruction.

RESULTS

The production process took approximately 30 hours. The designed scaffolds were satisfactory when no offset was added. Wings were added during the design to allow for screw positioning, but broke in 30% of cases. Radiological assessment documented maximal accuracy of scaffold positioning when the scaffold was created on the real defect; accuracy was satisfactory when the predicted clivectomy was performed under neuronavigation guidance. The cerebrospinal fluid leak pressure point was significantly higher when the scaffold was fixed with screws compared with the gasket technique.

CONCLUSIONS

In this preclinical setting, additive manufacturing allows the creation of customized scaffolds that are effective in reconstructing even large and geometrically complex clival defects.

Management of cerebrospinal fluid leak: the importance of multidisciplinary approach

Cerebrospinal fluid (CSF) leak remains a rare condition, characterized by serious complications and potentially fatal. According to different etiologies, CSF leaks may be classified into two main categories: traumatic and spontaneous. Spontaneous fistulas seem to be mainly related to obesity and idiopathic intracranial hypertension. Diagnosis is both clinical and radiological. During the last three decades, surgical treatment has mostly shifted to endonasal endoscopic approach, which widely demonstrated to be more effective than invasive intracranial ones. Post-operative complications, long-term sequelae and hospital stay are strongly reduced thanks to endoscopic approach. The diagnosis and treatment of CSF leaks represent a difficult and challenge task. The main effort seems to be related to the precise localization of the leak. An accurate assessment of both predisposing factors and comorbidities is mandatory in case of spontaneous leaks. However, a clinical multidisciplinary evaluation as well as treatment, is essential to decrease the rate of failure of surgery. The presence of a dedicated instruments, the Skull Base Team, the knowledge of reconstructive materials and techniques represents a decisive result in therapeutical management even if for each patient an effective therapeutic algorithm can be obtained considering the correct leak detection and characteristics. In conclusion the strict teamwork with neurosurgeons, neuroradiologists, ophtalmologists will enable the development also of innovative biomaterials, which could spread and standardize multi-layer techniques, nowadays still related to surgeon preferences.

Cerebrospinal Fluid Leak Repair Simulation Model: Face, Content, and Construct Validation

Background

Cerebrospinal fluid leak (CSFL) repair simulation models are scarce; however, these models are valuable tools for skull base reconstruction surgery training.

Objectives

This study aims to assess the face, content, and construct validity of a CSFL repair simulation model.

Method

Eight novices (residents- PGY3) and eight experts have performed skull base reconstruction in multiple sites in twelve human cadaveric heads in simulated surgical environment. The experts completed a post-study 21-item questionnaire to assess the face and content validity. The performances of the participants were recorded and scored by two independent investigators who were blinded to the participant's level. Global Rating Scale of Operative Performance (GRSOP) and a Specific Skull Base Reconstruction Checklist (SBRC) were used to score the performances.

Results

The responses from the expert group for the 21-item questionnaire were high for all items (4.13–4.88 out of 5). The internal consistency reliability of the questionnaire and the intraclass correlation, which was derived by Cronbach’s Alpha, were 0.913 and 0.941 respectively. Differences in construct validity between the two groups were statistically significant for both the GRSOP and SBRS (P-value < 0.001).

Conclusion

We demonstrated the face, content, and construct validity of the CSFL repair simulation model, which facilitates the acquisition of technical skills necessary for skull base reconstruction surgery. The model includes realistic features that make it useful in educational courses.