Improved Cholesteatoma Removal with CADISS: A Quantitative Ultrastructural Comparison Using VP-SEM

Abstract

Background: Cholesteatoma is a destructive middle ear pathology requiring precise surgical removal to prevent recurrence and preserve auditory function. The chemically assisted dissection (CADISS) system (AuXin Surgery, Ottignies-Louvain-la-Neuve, Belgium), based on Mesna (5%), was introduced to enhance tissue separation and minimize residual disease. Objective: This study aimed to compare the cleaning efficiency of CADISS-assisted dissection versus the conventional manual dissection of cholesteatoma from incus bone surfaces using quantitative ultrastructural analysis. Methods: This retrospective study evaluated 67 human incus samples collected during cholesteatoma surgery-35 treated with manual dissection and 32 with CADISS. Samples were imaged using variable pressure scanning electron microscopy (VP-SEM) in hydrated conditions. Clean area/total area ratios were calculated and analyzed statistically using non-parametric tests. Postoperative MRI follow-up at 1 month was conducted to assess residual disease. Results: CADISS-assisted samples demonstrated significantly higher clean area/total area ratios (mean: 0.2095 vs. 0.0478, p < 0.0001). Qualitative imaging showed fewer residuals > 1 mm in the CADISS group (9% vs. 77%). MRI follow-up revealed a lower recurrence rate in the CADISS group (3.1%) compared to manual dissection (11.4%). Conclusions: CADISS-assisted dissection provides superior cholesteatoma debris removal compared to manual methods, as evidenced by VP-SEM imaging and clinical follow-up. This technique may improve surgical outcomes and reduce recurrence risk in middle ear surgery.

Keywords: VP-SEM imaging; chemical-assisted dissection; cholesteatoma surgery; residual disease.

Figure 1

The CADISS^® System kit used in this study.

Figure 2

Qualitative evaluation at low magnification of a sample treated with a conventional surgical technique: VP-SEM (A) magnification 13×; (B) 3D reconstruction; (C) the false color image emphasizes the presence of cholesteatoma residues.

Figure 3

(A,B) The sample was treated with conventional surgical technique (control VP-SEM): (A) magnification 100× secondary electrons and (B) 100× backscattered electrons; the white area is indicative of exposed bone surface. (C,D) The sample was treated with the CADDIS technique (CADISS VP-SEM): (C) magnification 100× secondary electrons and (D) 100× backscattered electrons; the white area is indicative of exposed bone surface. Note the larger area compared with the control sample.

Figure 4

Area measurement results automatically acquired using the Hitachi Mountains Map software on BSE mode images.

Figure 5

Distribution of clean area and total area values in the manual dissection group.

Figure 6

Distribution of clean and total area values in the CADISS-assisted group.

Figure 7

Box plot comparing clean area/total area ratios. Orange circles are outliers.