Long-Term Preservation of Human Head and Neck Specimens for Neurosurgical Training: A Technical Note

Purpose: Cadaveric dissection is a cornerstone of neurosurgical education, providing trainees with a realistic 3D understanding of anatomy and a safe environment to practice surgical approaches. A preservation technique was developed that merges the advantages of fresh-frozen and embalmed cadavers, maintaining tissue realism while enhancing durability. This approach preserves flexibility and natural color, improves anatomical detail, and creates a safe, long-lasting model ideal for neurosurgical training. Methods: Four specimens were thawed, cannulated, and irrigated before implementing a protocol consisting of low concentration formaldehyde with glycerol and ethanol for extended preservation. The specimens were prepared for both neurosurgery training and educational purposes, and their condition was evaluated with a semi-quantitative scale. Each specimen was evaluated independently by two raters, blinded to the time-point, using a semi-quantitative scale anchored to predefined criteria (0-3 per domain). Inter-rater reliability was calculated using the intraclass correlation coefficient (ICC [2,k]) for continuous scores and Cohen's κ for categorical agreement. Results: Over nine years of intermittent use, the specimens remained in good condition: tissues retained sufficient softness for dissection, injected vessels stayed vivid in color, and no foul odor or microbial growth was observed. The evaluation employed a semi-quantitative scale, with results ranging from 11/14 to 14/14. The mean values demonstrate stable tissue quality over time, with only minor variations in color and perfusion. The inter-rater reliability was high (ICC = 0.91; κ = 0.88). Conclusions: The preservation method leverages the strengths of both fresh-frozen and embalmed models. The results suggest feasibility of long-term reuse, although further quantitative validation is needed.