Development of a plant-based surgical training model for fluorescence-guided cancer surgery.

BACKGROUND: Fluorescence-guided surgery (FGS) can help surgeons to discriminate tumor tissue from adjacent normal tissues using fluorescent tracers. METHODS: We developed a surgical training model, manufactured using sustainable vegetable organic material with indocyanine green (ICG)-containing "tumor." Surgeons evaluated the model with both the closed-field and endoscopic fluorescence imaging devices and assessed its efficacy to identify residual tumor after enucleation using electrocautery. RESULTS: Strong correlations of fluorescence were obtained at all working distance (3, 5, 7, and 10 cm), showing the robustness of fluorescence signal for the closed-field and endoscopic fluorescence imaging devices. The higher fluorescence signals were obtained in the wound bed in the closed-field fluorescence imaging device and the residual tumor could be clearly identified by fluorescence endoscopy. CONCLUSIONS: Our FGS training model may provide experience for surgeons unfamiliar with optical surgery and subsequent tissue interactions. The model seemed particularly helpful in teaching surgeons the principles of FGS.

Simultaneous disturbance of NHE1 and LOXL2 decreases tumorigenicity of head and neck squamous cell carcinoma.

OBJECTIVE: Although there have been brilliant advancements in the practical application of therapies targeting immune checkpoints, achieving success in targeting the microenvironment remains elusive. In this study, we aimed to address this gap by focusing on Na+ / H+ exchanger 1 (NHE1) and Lysyl Oxidase Like 2 (LOXL2), which are upregulated in head and neck squamous cell carcinoma (HNSCC) cells. METHODS: The malignancy of a metastatic human HNSCC cell line was assessed in a mouse tongue cancer xenograft model by knocking down (KD) NHE1, responsible for regulating intracellular pH, and LOXL2, responsible for extracellular matrix (ECM) reorganization via cross-linking of ECM proteins. In addition to assessing changes in PD-L1 levels and collagen accumulation following knockdown, the functional status of the PD-L1 / PD-1 immune checkpoint was examined through co-culture with NK92MI, a PD-1 positive phagocytic human Natural Killer (NK) cell line. RESULTS: The tumorigenic potential of each single KD cell line was similar to that of the control cells, whereas the potential was attenuated in cells with simultaneous KD of both factors (double knockdown [dKD]). Additionally, we observed decreased PD-L1 levels in NHE1 KD cells and compromised collagen accumulation in LOXL2 KD and dKD cells. NK92MI cells exhibited phagocytic activity toward HNSCC cells in co-culture, and the number of remaining dKD cells after co-culture was the lowest in comparison to the control and single KD cells. CONCLUSION: This study demonstrated the possibility of achieving efficient anti-tumor effects by simultaneously disturbing multiple factors involved in the modification of the tumor microenvironment.

Development of a proficiency-based training curriculum for beginners in endoscopic endonasal surgery.

OBJECTIVE: Precise endoscopic skills are critical for endoscopic endonasal surgery (EES) to ensure patient safety, as well as to succeed as a surgeon. Among these skills, basic skills such as hand-eye coordination and bimanual dexterity are the most important skills for novice surgeons. However, there is no proficiency-based training for the basic skills in EES. In this study, we aimed to develop a proficiency-based training curriculum for beginners in EES using tractable tasks and to assess the curriculum's validity and educational benefits. METHODS: Training tasks for basic surgical skills of EES were created by experts, using a low-cost and simple simulator. Subsequently, a proficiency-based training curriculum was developed through a preliminary study. The face and content validity of the curriculum was evaluated by expert surgeons. The construct validity was confirmed by comparing the scores of the medical students with those of the experts. In addition, the educational benefits of the curriculum were assessed by comparing the scores of the medical students before and after the implementation of the curriculum. RESULTS: A proficiency-based training curriculum using six tractable tasks was developed in the preliminary study. Replication of real surgical situation, camera navigation, and instrument operability under endoscopy were all highly appreciated (4.6, 4.6, and 4.8 out of 5 points, respectively), which indicates face validity. The content validity of the curriculum was demonstrated by the results of the questionnaire (4.4 out of 5 points). The curriculum was implemented by 12 medical students. The initial student scores were significantly lower than the expert scores (mean score: 61.9 vs. 100.0, p < 0.001), and each coefficient of variation of the student scores was higher than that of the expert scores (p < 0.01), supporting the construct validity of the curriculum. The mean student composite scores were statistically improved after the training (61.9 vs. 93.3, p < 0.0001). In addition, improvement of five other medical students' EES skills through this training curriculum was confirmed in cadaver dissection (1.7 vs. 3.7, p < 0.0001). CONCLUSION: The validity of the proficiency-based training curriculum developed through the preliminary study was established based on the questionnaire of experts and the difference between student and expert scores. In addition, the educational benefits were demonstrated by the students' learning curves. The low-cost and simple simulator seems appropriate as an entry model for beginners in EES, and this curriculum can provide rapid intervention and objective assessment of basic skills in EES.

Validation of a surgical training model containing indocyanine green for near-infrared fluorescence imaging.

Objective: To determine the efficacy of a surgical training model for fluorescence-guided cancer surgery and validate its utility to detect any residual tumors after tumor resection using electrocautery. Methods: We developed surgical training models containing indocyanine green (ICG) for near-infrared (NIR) fluorescence imaging using a root vegetable organic material (konjac). After the fluorescence assessment for the models, the surgical simulation for fluorescence-guided cancer surgery using electrocautery was performed. ICG-containing tumors were divided into two surgical groups: "Enucleation" (removal of the entire visible tumor) and "Complete resection" (removal of the tumor with an appropriate 5-mm surgical margin). Results: All 12 ICG-containing tumors were clearly visible from the normal view but not from the flipped view. The tumor resection time was significantly longer in the "Complete resection" group than in the "Enucleation" group (p < .001). The ICG-containing tumors showed a high tumor-to background ratio from the normal (average = 45.8) and flipped (average = 19.2) views, indicating that the models including ICG-containing tumors were useful for a surgical simulation in fluorescence-guided surgery. The average mean fluorescence intensity of the wound bed was significantly higher in the "Enucleation" group than in the "Complete resection" group (p < .01). No decrease in fluorescence signal was found in the wound bed even at 2 days postresection. Conclusion: Our surgical training model containing a fluorescent agent is safe, inexpensive, not harmful for humans, and easy to dispose after use. Our model would be beneficial for surgeons to learn NIR fluorescence imaging and to accelerate fluorescence-guided cancer surgery into clinical application.

Intratympanic corticosteroid for Bell's palsy and Ramsay Hunt syndrome: Systematic review and meta-analysis.

OBJECTIVE: This study aimed to reveal the efficacy and safety of intratympanic steroid therapy (ITST) in patients with Bell's palsy and Ramsay Hunt syndrome. METHODS: A literature search was conducted in PubMed, Embase, Ichushi-Web, and Cochrane Central Register of Controlled Trials. Published randomized controlled trial and observational studies, which compared the combination of intratympanic corticosteroids with systemic corticosteroid versus systemic corticosteroid for Bell's palsy and Ramsay Hunt syndrome, were included for meta-analysis. The primary outcome was non-recovery at the end of the study follow-up. Data was analyzed using Review Manager software, and pooled odds ratio with 95% CI were calculated. RESULTS: Three randomized controlled trial and two cohort studies met the eligible criteria, and 350 individuals included for meta-analysis. The timing of intratympanic corticosteroid was varied from once or twice a week to consecutive 10-days. Patients treated with combination of systemic corticosteroids and intratympanic corticosteroids were likely to achieve recovery of normal facial function (OR = 0.36 [95% CI 0.12-1.14]). The subgroup analysis of the timing revealed that daily ITST reduced non-recovery (OR = 0.14 [95% CI 0.04-0.50). However, non-daily ITST did not reduced non-recovery (OR 0.93 [95% CI 0.37-2.34]). CONCLUSION: Intratympanic corticosteroid have a potential to reduce non-recovery in patients with Bell's palsy and Ramsay Hunt syndrome. The methods of intratympanic corticosteroid varied among included studies. Further well-designed randomized controlled trial is needed to confirm the effectiveness and to identify an adequate method of intratympanic corticosteroid in these patients.

Comparison of the Signal Intensity of Vestibular Schwannoma Between Growing and Nongrowing Tumors.

OBJECTIVES/HYPOTHESIS: To determine the relationship between signal intensity on gadolinium (Gd)-enhanced magnetic resonance images and growth of vestibular schwannomas (VSs). STUDY DESIGN: Cross-sectional study. METHODS: In this cross-sectional study, we retrospectively reviewed the data of 31 patients with VSs who underwent magnetic resonance imaging (MRI). The mean signal intensities within the regions of interest in the tumor, pons, and temporal muscles were measured on Gd-enhanced T1-weighted MRI. Relative intensity ratios were calculated as follows: T/N pons ratio (T/Np) is the tumor signal intensity/pons signal intensity and T/N muscle ratio (T/Nm) is the tumor signal intensity/temporal muscle signal intensity. Volume measurements were used to assess the tumor size. Growth rate was determined by assessing previous imaging studies. Growing VS was defined as a tumor with a growth rate >100 mm3 /year. RESULTS: The mean (standard deviation) T/Np and T/Nm were 1.47 (0.27) and 1.50 (0.24), respectively, in nongrowing tumors and 1.78 (0.17) and 1.90 (0.12), respectively, in growing tumors. The T/Np and T/Nm differed significantly between the two groups (T/Np, P < .001; T/Nm, P < .001). Receiver operating characteristic curve analysis showed that cutoffs of 1.56 and 1.76 for T/Np (93.33% sensitivity, 75.00% specificity) and T/Nm (100.00% sensitivity, 93.75% specificity), respectively, could be used to diagnose a growth rate of >100 mm3 /year. The area under the curve was 0.85 (95% confidence interval, 0.70-1.00) for T/Np and 0.94 (0.82-1.00) for T/Nm. CONCLUSION: Growing VSs show higher signal intensities on Gd-enhanced MRI. Thus, measuring the signal intensity of VS on Gd-enhanced MRI may aid in predicting VS growth. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:198-203, 2022.

Using deep learning to identify the recurrent laryngeal nerve during thyroidectomy.

Surgeons must visually distinguish soft-tissues, such as nerves, from surrounding anatomy to prevent complications and optimize patient outcomes. An accurate nerve segmentation and analysis tool could provide useful insight for surgical decision-making. Here, we present an end-to-end, automatic deep learning computer vision algorithm to segment and measure nerves. Unlike traditional medical imaging, our unconstrained setup with accessible handheld digital cameras, along with the unstructured open surgery scene, makes this task uniquely challenging. We investigate one common procedure, thyroidectomy, during which surgeons must avoid damaging the recurrent laryngeal nerve (RLN), which is responsible for human speech. We evaluate our segmentation algorithm on a diverse dataset across varied and challenging settings of operating room image capture, and show strong segmentation performance in the optimal image capture condition. This work lays the foundation for future research in real-time tissue discrimination and integration of accessible, intelligent tools into open surgery to provide actionable insights.

Case-specific three-dimensional hologram with a mixed reality technique for tumor resection in otolaryngology.

OBJECTIVE: We report our first experience of using a case-specific three-dimensional (3D) hologram for tumor resection in otolaryngology to show the proof of concept. In addition, a questionnaire was administered to assess the usefulness of the mixed reality technique in otolaryngology. METHODS: A case-specific 3D hologram was developed from enhanced images of dynamic computed tomography, with reference to contrast-enhanced magnetic resonance images, and used for preoperative planning and intraoperative image reference. To evaluate the usefulness of the 3D hologram with head mount displays (HMDs), 18 attendings and resident otolaryngologists completed a questionnaire with the Likert scale. RESULTS: The case-specific 3D hologram on HMDs was successfully used by means of easy gesture-handling without any monitors preoperatively and intraoperatively. The experience of picturing the tumor localization and evaluating the surgical approach was statistically better using the 3D hologram on HMDs than using the computer images (P < .01). Similarly, the holograms were observed to be better for intraoperative application and surgical education than computer images (P < .01). CONCLUSION: We demonstrated the use of a case-specific 3D hologram for tumor resection in otolaryngology. The technology may be useful for preoperative planning and intraoperative image reference, especially for challenging cases, and surgical education. LEVEL OF EVIDENCE: NA.

Verbalization, Categorization, and Evaluation of Fundamental Surgical Skills: An Expert Consensus in Open Head and Neck Surgery.

Objective: This study aimed to verbalize fundamental surgical skills required for open head and neck surgery (OHNS), to organize them by categorization, and to establish a consensus among surgeons regarding the importance and difficulty of each skill. Summary Background Data: Improvement of fundamental surgical skills is the core of surgical education; however, surgical skills are not yet organized, and consensus in any surgical field remains uncertain. Methods: Fundamental surgical skills during OHNS were collected from surgical textbooks, real surgeries, and expert interviews. The items were analyzed to calculate the frequency of words and were categorized by 2 expert surgeons. After consensus on the importance and difficulty of each item was established by 15 expert surgeons using a Delphi survey, principal component (PC) analysis was performed to integrate importance and difficulty into a single parameter. Results: Sixty skills were verbalized and categorized into 7 categories: "skin flap elevation (n = 6)," "vessel management (n = 9)," "nerve preservation (n = 8)," "instrument handling (n = 11)," "counter traction (n = 7)," "tissue exposure (n = 9)," and "flow and planning (n = 10)." In the Delphi survey, expert consensus was established after 2 voting rounds (Cronbach's α ≥ 0.80). The "counter traction" and "flow and planning" categories had high PC scores, which indicate priority in surgical education. Conclusion: Fundamental OHNS skills were verbalized, categorized, and evaluated via expert consensus. Assessment of surgeons' skills by the structured items hereby developed will help standardize the quality of OHNS and improve patient outcomes.

Development of proficiency-based knot-tying and suturing curriculum for otolaryngology residents: A pilot study.

OBJECTIVE: Basic surgical skills such as knot-tying and suturing are important for all otolaryngologists, regardless of subspecialty. The present study was undertaken in order to assess basic surgical techniques such as knot-tying and suturing required for novice otolaryngology residents with taking the variety of subspecialties into consideration, and evaluate the impact of a proficiency-based training curriculum based on these techniques. METHODS: A prospective study was performed for developing of proficiency-based knot-tying and suturing curriculum for otolaryngology residents in the third post-graduate year (PGY-3). The proficiency-based training curriculum was developed based on the tasks selected by RAND/UCLA method with expert panel, which is an iterative and anonymous survey used to establish consensus among participants. Expert panelists were selected from various divisions to reflect variety of their subspecialties. PGY-3 residents trained with the developed curriculum that included proctored pre-test, self-training to proficiency, and proctored post-test. Visual analogue scale (VAS) of trainees' overall competence in the operating room was self-assessed by each resident, before and after completing the training curriculum. RESULTS: Nine PGY-3 residents were enrolled as trainees. Eleven experts chosen as panelists had various subspecialty, including 2 from otology, 2 from rhinology, 2 from laryngology, 2 from head and neck surgery, and 3 from general otolaryngology. Seven tasks were selected from RAND/UCLA method and used to develop the curriculum. Trainee scores at pre-test were significantly lower than expert scores for all 7 tasks (p < 0.01) and each coefficient of variation of trainee score was larger than that of expert score (p < 0.05), supporting construct validity. The mean of composite scores between pre-test and post-test had statistical significance (68.6 ± 11.6 vs 95.9 ± 3.6, p < 0.01), documenting substantial improvement after training. Self-assessment VAS was also improved pre- to post-training (1.2 ± 0.9 vs 4.5 ± 1.4, p < 0.01). A follow-up questionnaire showed that trainees felt the educational curriculum to be beneficial. CONCLUSION: In the present study, seven basic technical skills were selected using the RAND/UCLA method and used to create a proficiency-based training curriculum. Our results indicate that this curriculum significantly improves proficiency of basic surgical skills of junior otolaryngology residents.

Anatomic Invasive Depth Predicts Delayed Cervical Lymph Node Metastasis of Tongue Squamous Cell Carcinoma.

Delayed cervical lymph node metastasis (CLNM) is the most negative prognostic factor of tongue squamous cell carcinoma (SCC). This study analyzed the relationship between clinicopathologic factors, including anatomic invasive depth (AID), and CLNM. A total of 212 patients with clinically node-negative (cN0) tongue SCC who had undergone partial glossectomy through the mouth were eligible for this retrospective study. The deepest portions where tongue SCC cells invaded as determined by microscopic analyses were classified into 5 categories, including epithelial and submucosal tissue, lateral extrinsic tongue muscle (ETM), intrinsic tongue muscles (ITM), paralingual and sublingual spaces, and medial ETM according to AID. We examined the relationship between clinicopathologic factors including AID and delayed CLNM. Multivariate analysis demonstrated that AID was an independent predictive factor for delayed CLNM (P=0.0022; odds ratio=7.1). Deeper invasion than ITM, including ITM, paralingual and sublingual spaces, and medial ETM, had high sensitivity and negative predictive value for delayed CLNM (94.4% and 95.7%, respectively). Precise elucidation of AID may be useful for the preoperative decision for performing elective neck dissection. None of 11 patients in whom the deepest portion where tumor invaded to lateral ETM (according to AID) showed delayed CLNM, although tongue SCC T4a tumor is defined by the presence of invasion of cancer cells to ETM. Tumors with invasion to lateral ETM might have to be excluded from the pathologic T4a category.