The goal of this observational study is to learn how different cranio-spinal surgical approaches work and how much anatomical exposure each technique provides in donated human cadaver specimens. The study also aims to understand anatomical variations and to evaluate new surgical techniques and tools that may improve neurosurgical training and practice.

The main questions it aims to answer are:

• How much surgical exposure area and volume of work does each cranio-spinal approach allow?
• How do anatomical variations influence the effectiveness and feasibility of different approaches? Researchers will also compare results obtained using different surgical visualization methods (such as the surgical microscope approach or macroscopic evaluation) to see if any method improves visibility or operative efficiency.

Cadaveric specimens will undergo:

• Step-by-step cranio-spinal surgical approaches performed by trained neurosurgeons.
• Quantitative measurements of exposed anatomical areas using imaging software (BrainChop).
• Assessment of operative time, perceived difficulty by surgeons, and visibility of target anatomical structures.
• Testing of new surgical instruments or techniques when applicable, without involving any drugs or medical devices.

This study follows Italian regulations on post-mortem body donation for scientific research (Law No. 10/2020) and is conducted at a single research center recognized as an IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico-Scientific Institute for Hospitalization and Care).

This observational, monocentric, preclinical study. The main objective of this study is to conduct a systematic and quantitative preclinical analysis of multiple cranio-spinal surgical approaches, using both macroscopic and microscopic evaluation.

The study evaluates multiple surgical corridors to the cranial and spinal regions and involves detailed measurement of the volume of work and exposed anatomical area attainable with each approach. Additional technical objectives include the analysis of anatomical variations that may influence surgical execution, and the validation of new surgical techniques and instruments in a controlled laboratory environment.

All dissections will be carried out on cadaveric specimens voluntarily donated according to Italian legislation on post-mortem body donation (Law No. 10/2020). Procedures will be performed by trained neurosurgeons using standard microsurgical techniques. Quantitative measurements of exposure areas and operative volumes will be obtained using dedicated imaging software, including BrainChop.

The study also incorporates structured evaluations of technical difficulty and surgeon experience. After completing each approach, operating surgeons will provide standardized ratings of perceived difficulty, visibility of target structures, and usability of any new surgical tools or techniques tested. These assessments contribute to the systematic validation of surgical methods and instrumentation in the preclinical setting.

In addition, the study supports surgical education by integrating structured dissection sessions. Participants (surgeons or trainees) will complete pre- and post-training assessments to evaluate procedural understanding, anatomical knowledge, and perceived skill acquisition.

The study will enroll 35 cadaveric specimens over a three-year period. No drugs or implantable medical devices will be used. All specimens will be stored and handled according to institutional anatomical laboratory standards.

The statistical analysis plan includes descriptive and comparative analyses. Quantitative variables-such as exposure area, volume of work, and operative time-will be summarized as mean ± standard deviation (SD). Qualitative variables-such as visibility scores or difficulty ratings-will be reported as absolute and relative frequencies. For pre- and post-training comparisons, the paired t-test or Wilcoxon signed-rank test will be applied depending on data distribution. Comparisons of operative time or exposure metrics across techniques will be performed using Analysis of Variance (ANOVA) or the Kruskal-Wallis test. Statistical significance will be defined as p < 0.05. All analyses will be conducted using Stata statistical software (StataCorp LLC, College Station, TX, USA).

Inclusion Criteria

• Cadaveric specimens from individuals who provided informed consent for post-mortem donation of their body or tissues for scientific research.
• Specimens that meet all legal requirements for anatomical donation under Italian Law No. 10/2020 and Presidential Decree (DPR) No. 47/2023.
• Specimens that are available for the full duration of the study and suitable for performing multiple cranio-spinal surgical approaches.

Exclusion Criteria

• Specimens that do not meet the legal or ethical requirements for anatomical donation as defined by Italian regulations.
• Cadavers with major anatomical deformities, advanced tissue degradation, or pathological conditions that would interfere with surgical dissection or measurement accuracy.
• Specimens lacking adequate documentation or verified donor consent for post-mortem donation.

The study population consists of human cadaveric specimens voluntarily donated for scientific and educational purposes under Italian post-mortem donation regulations. Specimens are obtained through the anatomical donation program of the participating institution and represent a natural range of adult anatomical variability. These cadavers serve as preclinical anatomical models for evaluating cranio-spinal neurosurgical approaches in a controlled laboratory setting. The population provides diverse anatomical characteristics that allow systematic assessment of surgical exposure, feasibility, and technical performance across different surgical corridors.