Neuronavigation in endoscopic skull base surgery and the accuracy of different MRI sequences.

OBJECTIVE: Neuronavigation is common technology used by skull base teams when performing endoscopic endonasal surgery. A common practice of MRI imagining is to obtain 3D isotopic gadolinium enhanced T1W magnetisation prepared rapid gradient echo (MPRAGE) sequences. These are prone to distortion when undertaken on 3 T magnets. The aim of this project is to compare the in vivo accuracy of MRI sequences between current and new high resolution 3D sequences. The goal is to determine if geometric distortion significantly affects neuronavigation accuracy. METHODS: Patients were scanned with a 3D T1 MPRAGE sequence, 3D T1 SPACE sequence and a CT stereotactic localisation. Following general anaesthesia, patients were registered on the Stealth Station (Medtronic, USA) using a side mount emitter for Electromagnetic navigation. A variety of surgically relevant anatomical landmarks in the sagittal and coronal plane were selected with real and virtual data points measured. RESULTS: A total of 10 patients agreed be enrolled in the study with datapoints collected during surgery. The distance between real and virtual datapoints trended to be lower in SPACE sequences compared to MPRAGE. Paired t test did not demonstrate a significant difference. CONCLUSION: We have demonstrated that navigational accuracy is not significantly affected by the type of MRI sequence selected and that current corrective algorithms are sufficient. Navigational accuracy is affected by many factors, with registration error likely playing the most significant role. Further research involving real time imaging such as endoscopic ultrasound may hopefully address this potential error.

A Novel Model of Staphylococcus aureus-Induced Lymphoplasmacytic Rhinosinusitis in Rats.

Chronic rhinosinusitis (CRS) is characterized by sinonasal mucosal inflammation. Staphylococcus aureus (S. aureus) is associated with severe CRS phenotypes. Different animal models have been proposed to study the association of CRS and S. aureus. However, current animal models are expensive due to the use of large animals, have high barriers to ethics approval, or require invasive surgical intervention, necessitating a need for a model that can overcome these limitations. This study aimed at establishing a reliable and efficient rat lymphoplasmacytic inflammatory model for rhinosinusitis. Sprague Dawley rats received a daily intranasal application of 20 µL of saline, S. aureus CI-182 exoprotein (250 µg/mL), or exoprotein CI-182 in combination with S. aureus clinical isolate (CI-908 or CI-913) 108 colony-forming unit (CFU)/mL. The rats' sinuses were harvested at 1 and 2 weeks post-intervention. The CFU and histopathologic examination of inflammation were evaluated. S. aureus clinical isolates CI-908 or CI-913 in combination with the exoprotein (CI-182) had higher CFUs and caused persistently higher inflammation at both the 1 and 2-week post-intervention compared to the exoprotein and saline group. The observed inflammatory cell type was lymphoplasmacytic. This study provided evidence that the combination of a S. aureus exoprotein with S. aureus induces inflammation that persists for a minimum of two weeks post-intervention. This model is the first known animal model to create the lymphoplasmacytic inflammation subtype seen in CRS patients. This offers a cost-effective, accessible, non-invasive, and easy-to-replicate model to study the causes and treatment of such inflammation.

An In Vitro Study Evaluating the Safety of Mesalazine on Human Nasoepithelial Cells.

Chronic rhinosinusitis (CRS) is a disease characterised by the inflammation of the nasal and paranasal cavities. It is a widespread condition with considerable morbidity for patients. Current treatment for chronic rhinosinusitis consists of appropriate medical therapy followed by surgery in medically resistant patients. Although oral steroids are effective, they are associated with significant morbidity, and disease recurrence is common when discontinued. The development of additional steroid sparing therapies is therefore needed. Mesalazine is a commonly used therapeutic in inflammatory bowel disease, which shares a similar disease profile with chronic rhinosinusitis. This exploratory in vitro study aims to investigate whether mesalazine could be repurposed to a nasal wash, which is safe on human nasoepithelial cells, and retains its anti-inflammatory effects. CRS patients' human nasal epithelial cells (HNECs) were collected. HNECs were grown at an air-liquid interface (ALIs) and in a monolayer and challenged with mesalazine or a non-medicated control. Transepithelial electrical resistance, paracellular permeability, and toxicity were measured to assess epithelial integrity and safety. The anti-inflammatory effects of mesalazine on the release of interleukin (IL)-6 and tumour necrosis factor alpha (TNF-α) were analysed using human leukemia monocytic cell line (THP-1). mesalazine did not impact the barrier function of HNEC-ALIs and was not toxic when applied to HNECs or THP-1 cells at concentrations up to 20 mM. mesalazine at 0.5 and 1 mM concentrations significantly inhibited TNF-α release by THP-1 cells. mesalazine effectively decreases TNF-α secretion from THP-1 cells, indicating the possibility of its anti-inflammatory properties. The safety profile of mesalazine at doses up to 20 mM suggests that it is safe when applied topically on HNECs.

Imaging Features of Invasive Fungal Rhinosinusitis: A Systematic Review.

Fungal rhinosinusitis (FRS) includes non-invasive and invasive subtypes with the latter having significant morbidity and mortality. This systematic review aims to identify the imaging features most correlated with invasive fungal rhinosinusitis (IFRS) and present a checklist of these features to aid diagnosis. PubMed, Embase, CENTRAL, and Science Direct were searched from inception to May 2023, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Primary research articles published in English describing the imaging features of IFRS were included. The systematic review was conducted in accordance with the PRISMA guidelines. Forty-eight articles were identified for inclusion. Six studies examined radiological features in acute invasive fungal rhinosinusitis (AIFRS), and 9 studies of chronic invasive fungal rhinosinusitis (CIFRS). A majority of studies did not specify whether IFRS cases were acute or chronic. On CT, bony erosion and mucosal thickening were the most common features. Other features include nasal soft tissue thickening, nasal cavity opacification, opacification of the affected sinus, and perisinus soft tissue infiltration. Extra-sinus extension was commonly observed on MRI, most often invading intraorbitally and intracranially. Other sites of extra-sinus extension included the cavernous sinus, pterygopalatine fossa, infratemporal fossa, masticator space, and facial soft tissue. IFRS is a condition with potential for high morbidity and mortality. Several radiological features are highly suggestive of IFRS. Early identification of high-risk radiological features using a checklist may aid prompt diagnosis and early treatment. Future research investigating the radiological differentiation between IFRS and other significant pathology including bacterial orbital cellulitis would be beneficial.

Inferior orbital fissure release to access the inferolateral orbital apex.

OBJECTIVE: To describe release of the inferior orbital fissure (IOF) as a novel surgical technique that will improve access to the inferior and inferolateral orbital apex. DESIGN: Laboratory investigation. PARTICIPANTS: Human cadaver heads. METHODS: Cadaveric dissection study whereby the technique of an IOF release was performed. A swinging eyelid preseptal approach was used to enable a subperiosteal dissection to the orbital floor without obstruction from orbital fat prolapse. A plane was dissected between periorbita and Muller's muscle, the smooth muscle that overlies the entire length of the IOF. Measurements were taken in the sagittal plane from a point on the inferior orbital rim directly above the infraorbital foramen to the most posterior aspect of the orbital floor. RESULTS: Fifteen orbits from 8 cadaver heads were dissected with the aid of a rigid 0-degree endoscope and microsurgical instruments. This study demonstrated that an additional 10.93 ± 2.10 mm of access to the orbital apex was gained after the release of periorbita from the IOF. CONCLUSION: We propose that the IOF release can be adopted as an adjunctive technique to orbital surgery of the inferior and inferolateral orbital apex.

Transorbital Endoscopic Approach to the Foramen Rotundum for Infraorbital Nerve Stripping.

PURPOSE: To develop and evaluate a transorbital endoscopic approach to the foramen rotundum to excise the maxillary nerve and infraorbital nerve branch. METHODS: Cadaveric dissection study of 10 cadaver heads (20 orbits). This technique is predicated upon 1) an inferior orbital fissure release to facilitate access to the orbital apex and 2) the removal of the posterior maxillary wall to enter the pterygopalatine fossa (PPF). Angulations along the infraorbital nerve were quantified as follows: the first angulation was measured between the orbitomaxillary segment within the orbital floor and the pterygopalatine segment suspended within the PPF, while the second angulation was taken between the pterygopalatine segment and maxillary nerve as it exited the foramen rotundum. With refinement of the technique, the minimum amount of posterior maxillary wall removal was quantified in the final 5 cadaver heads (10 orbits). RESULTS: The mean distance from the inferior orbital rim to the foramen rotundum was 45.55 ± 3.24 mm. The first angulation of the infraorbital nerve was 133.10 ± 16.28 degrees, and the second angulation was 124.95 ± 18.01 degrees. The minimum posterior maxillary wall removal to reach the PPF was 11.10 ± 2.56 mm (vertical) and 11.10 ± 2.08 mm (horizontal). CONCLUSIONS: The transorbital endoscopic approach to an en bloc resection of the infraorbital nerve branch up to its maxillary nerve origin provides a pathway to the PPF. This is relevant for nerve stripping in the context of perineural spread. Other applications include access to the superior portion of the PPF in selective biopsy cases or in concurrent orbital pathology.

The Learning Curve for Endoscopic Endonasal Transsphenoidal Pituitary Surgery: Evaluating Endocrine Outcomes.

OBJECTIVE: In South Australia endoscopic endonasal approach (EEA) pituitary surgery has been practiced since 2006, largely by two neurosurgeons with a small fellowship-trained otolaryngology team. The aim of this cohort study was to determine if a "learning curve" can be established over this time period, as represented by structural and endocrine patient outcomes. METHOD: Retrospective cohort study of patients undergoing EEA surgery between 2006 and 2021 in Adelaide, South Australia at three tertiary teaching hospitals.. Cases were divided by each surgeon and split into groups of sequential 40 cases. Endocrine assessment pre- and post-operatively involved static pituitary and end-organ hormones, with dynamic tests as required, assessed by an pituitary endocrinologist. Each hormonal axis (gonadal, cortisol, thyroid, prolactin and growth hormone) was documented preoperatively and at an early and long term follow up at 1-2 and 12 months, respectively. RESULTS: The study included a cohort of 443 pituitary adenomas managed with endoscopic endonasal transsphenoidal surgery in a consecutive fashion between two neurosurgeons over 16-years. Gross tumour resection but not visual visual outcomes improved with surgical experience but this outcome may be neurosurgeon dependent. Endocrine outcomes were not consistently improved with experience, but lower rates of hypopituitarism were seen with experience with one neurosurgeon. Average follow up was approximately 5 years, and a minimum follow up of 12 months for all patients. CONCLUSIONS: We present long term endocrine follow up for patients with functional and non-functional adenomas. Improved rates of gross tumour resection were evident with with surgical experience. However, there was no apparent change in post-operative endocrine outcomes.

The learning curve for endoscopic endonasal pituitary surgery: a systematic review.

Recent literature demonstrates that a learning curve exists for endoscopic pituitary surgery. However, there is significant variability in the way these studies report their outcomes. This study aims to systematically review the literature regarding outcomes for endoscopic pituitary surgery and how this may be related to a surgical learning curve. An electronic search of the databases Medline, Scopus, Embase, Web of Science and Cochrane Library databases was performed and data extracted according 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. Ten articles were included in the review as they examined the following: rates of gross total resection, average operative time, CSF leak rate, visual outcomes, endocrine outcomes and how these results were influenced by surgical experience. We have demonstrated that a learning curve exists for some outcome variables for endoscopic pituitary surgery. However, there is significant heterogeneity in the current body of literature which makes clear comparisons difficult.

Deferiprone-gallium-protoporphyrin (IX): A promising treatment modality against Mycobacterium abscessus.

Non-Tuberculous Mycobacterial Pulmonary Disease (NTM-PD) caused by Mycobacterium abscessus is a frequent complication in patients with cystic fibrosis (CF) that worsens lung function over time. Currently, there is no cure for NTM-PD, hence new therapies are urgently required. Disrupting bacterial iron uptake pathways using gallium-protoporphyrin (IX) (GaPP), a heme analog, has been proposed as a novel antibacterial approach to tackle multi-drug resistant M. abscessus. However, the antibacterial activity of GaPP has been tested only in iron-deficient media, which cannot accurately mirror the potential activity in vivo. Herein, we investigated the potential synergistic activity between GaPP and the iron-chelating agent deferiprone (Def) in regular media against M. abscessus-infected macrophages. The safety of the treatment was assessed in vitro using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in Nuli-1 and THP-1 cell lines. Def-GaPP had synergistic activity against M. abscessus-infected macrophages where 10 mM-12.5 mg/L of Def-GaPP reduced the viability by up to 0.9 log10. Furthermore, Def-GaPP showed no cytotoxicity to Nuli-1 and THP-1 cell lines at the effective antibacterial concentrations (10 mM-12.5 mg/L) of Def- GaPP. These data encourage future investigation of Def-GaPP as a novel antimicrobial against NTM-PD.

Olfaction preservation in olfactory groove meningiomas: a systematic review.

Olfactory groove meningiomas (OGM) are a skull base neoplasm that represents between 8 and 13% of all intracranial meningiomas. Approach selection focuses on achieving frontal lobe decompression, gross total resection and vision preservation. Recently, there has been a focus on olfaction and considering its preservation as a quality-of-life outcome measure. An electronic search of the databases Medline, Scopus, Embase, Web of Science and Cochrane library databases was performed and data extracted according 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. Six articles were selected for inclusion mainly based due to reporting quantitative outcomes for olfaction assessed by a smell identification test (e.g. sniffin' sticks). Objective olfaction preservation can be achieved with a variety of surgical approaches. More research which includes objective assessment of olfactory function and ideally as well QoL outcome measures is needed to further optimize the treatment pathways in OGM patients.

Haemostatic efficacy and inflammatory response of a novel beta-chitin patch in a cerebral small vessel injury model - A pilot study.

OBJECTIVE: Rapid and efficacious haemostasis is paramount in neurosurgery. Assessing the efficacy and short- and long-term safety of haemostatic agents utilised within cerebral tissue is essential. This pilot study investigates the haemostatic efficacy and long-term safety of a novel beta-chitin patch against traditionally used agents, bipolar and Floseal, within cerebral tissue. METHODS: Eighteen Merino sheep underwent standardised distal cortical vessel injury via temporal craniotomy. Sheep were randomised to receive 2 mls Floseal, 2 cm novel beta-chitin patch, or bipolar cautery to manage bleeding. All sheep underwent cerebral magnetic resonance imaging (MRI) at three months, before euthanasia and brain harvesting for histological assessment. RESULTS: Beta-chitin demonstrated a trend towards a faster mean time to haemostasis (TTH) compared to Floseal (223.3 ± 199 s v. 259.8 ± 186.4 s), albeit non-significant (p = 0.234). Radiologically, cerebrocortical necrosis (p = 0.842) and oedema (p = 0.368) were noted slightly more frequently in the beta-chitin group. Histologically, severe fibrotic (p = 0.017) and granulomatous changes at the craniotomy sites were only present in the beta-chitin group (p = 0.002). Neuronal degeneration was seen in all with Floseal, but beta-chitin showed a trend towards more severe reaction when present. Bipolar use predominantly showed an inflammatory cortical reaction with substantial microvascular proliferation, and Floseal showed worse severity and depth of subpial oedema, however no statistical significance was reached. CONCLUSION: All haemostats controlled bleeding, with beta-chitin demonstrating a non-inferior TTH compared to Floseal. However, it resulted in intense granulomatous and fibrotic changes, including degenerative neuronal reactions. More extensive studies are needed to assess these trends, to make further clinical inferences.

Case Report: Late spontaneous orbital subperiosteal hematoma after endoscopic sinonasal tumor resection.

INTRODUCTION AND IMPORTANCE: We report a case of spontaneous subperiosteal orbital hematoma many years after endoscopic sinonasal resection of malignancy. CASE PRESENTATION: A 50-year-old female with a six-year history of endoscopic sinonasal resection of a poorly differentiated neuroendocrine tumor presented with two days of worsening frontal headache and left periocular swelling. A subperiosteal abscess was initially suspected on CT; however, MRI sequences revealed changes consistent with the diagnosis of hematoma. A conservative approach was justified based on the clinico-radiologic features. Progressive clinical resolution was noted over three weeks. Two monthly follow-up MRI revealed resolution of the orbital findings with no features to indicate recurrence of malignancy. CLINICAL DISCUSSION: Subperiosteal pathologies can be clinically challenging to differentiate. Differing radiodensities on CT may help differentiate between them but is not always reliable. MRI is more sensitive and is the preferred imaging modality. CONCLUSION: Spontaneous orbital hematomas are self-resolving, and surgical exploration may be avoided in the absence of complications. Therefore, it is beneficial to recognize it as a potential late complication of extensive endoscopic endonasal surgery. Characteristic features on MRI can aid diagnosis.

Colloidal silver against macrophage infections and biofilms of atypical mycobacteria.

Skin and soft tissue infection (SSTI) caused by atypical mycobacteria such as Mycobacterium abscessus and Mycobacterium avium intracellulare complex (MAIC) have increased in recent years. Current therapeutic options are limited, and hence new and better therapies are urgently required. Colloidal Silver (CS) has been identified for its widespread antibacterial properties and silver-impregnated dressings have been used for SSTIs caused by various pathogens. The efficacy of Green Synthesized Colloidal Silver (GSCS) was investigated for bacterial growth inhibition (BGI) using a microdilution method and minimum biofilm eradication concentration (MBEC) using resazurin assay and confocal scanning laser microscopy (CSLM) of M. abscessus (n = 5) and MAIC (n = 5). The antibacterial effect of GSCS against M. abscessus infected macrophages was also evaluated. The in vitro cytotoxicity of GSCS on a human keratinocyte cell line (HaCaT) and neonatal foreskin fibroblasts was analyzed by the crystal violet proliferation assay. Average BGI and MBEC of GSCS varied between 0.7 and 22 ppm for M. abscessus and MAIC. The concentration of 3 ppm reduced M. abscessus-infection in macrophages significantly. GSCS was not cytotoxic to HaCaT and neonatal foreskin fibroblast cells at concentrations < 3 ppm up to 2 h exposure time. GSCS therefore, has the potential for topical application against atypical mycobacterial SSTI.

Wound healing in endoscopic sinus surgery: Phase 1 clinical trial evaluating the role of Chitogel with adjuvants.

OBJECTIVES: This study aimed to determine the safety and efficacy of Chitogel, with and without Deferiprone (Def) and Gallium Protoporphyrin (GaPP), as a promoter of wound healing to improve surgical outcomes after endoscopic sinus susgery. DESIGN: A double-blinded, randomised control human clinical trial was conducted in patients undergoing ESS as a treatment for chronic rhinosinusitis. Participants underwent functional ESS or FESS with drill out as required and were randomised to receive test product Chitogel, Chitogel in combination with Def or Def-GaPP versus no packing (control). SETTING: Ostial stenosis and persistent inflammation are the main reasons for revision endoscopic sinus surgery (ESS). Post-operative (PO) dressings can improve PO wound healing and patient outcomes after ESS. PARTICIPANTS: Eighty two patients were included in this study with 79 patients completing the study with 40 undergoing full house FESS and 39 FESS plus frontal drillout. MAIN OUTCOME MEASURES: Patients were followed up at 2, 6 and 12 weeks PO, and outcome scores such as SNOT-22, VAS and LKS, pre and post-surgery (12 weeks) were compared. RESULTS: Seventy nine patients completed the study, there was a significant reduction in SNOT-22 score and improvement of VAS at 12 weeks in patients treated with Chitogel compared to control (p < .05). In those patients, the mean ostium area for the Chitogel and the Chitogel + Def + GaPP groups was higher across all three sinuses compared to the no-treatment control group, without statistical significance. Sphenoid sinus ostium was significantly more patent in patients treated with Chitogel compared to the control at the 12-week time point (p < .05). CONCLUSION: Chitogel as a PO dressing after ESS results in the best patient-reported symptom scores and objective measurements. The combination of Def and GaPP to Chitogel though proving safe, had no effect on the ostium patency or mucosal healing.

Staphylococcal protein A modulates inflammation by inducing interferon signaling in human nasal epithelial cells.

OBJECTIVE AND DESIGN: Staphylococcus aureus (S. aureus) is one of the leading causes of human respiratory tract infections. The function of Staphylococcal protein A (SpA), expressed on the S. aureus bacterial membrane and released in the environment, on human nasal epithelial cells (HNECs) have not been fully elucidated. In this study, we tested the SpA expression in S. aureus from chronic rhinosinusitis patients and investigated the effects of SpA on HNECs inflammation through Interferon Gamma Receptor 1(IFNGR1)/phosphorylated Janus Kinase 2 (p-JAK2) pathway. METHODS: RNA profiling was performed to investigate inflammatory activation in a S. aureus chronic rhinosinusitis (CRS) mouse model. SpA release by S. aureus clinical isolates was determined using ELISA. The effect of purified SpA and SpA enriched conditioned media from S. aureus clinical isolates on HNECs cytotoxicity, apoptosis and release of inflammatory cytokines was evaluated using lactate dehydrogenase assays, and flow cytometry. SpA dependent IFNGR1 and p-JAK2 expression were assessed by qPCR, immunofluorescence and western blot in HNECs. RESULTS: 49 genes were significantly induced in S. aureus CRS mice indicative of activation of interferon signaling. SpA release was significantly higher in S. aureus clinical isolates from chronic rhinosinusitis with nasal polyps (CRSwNP) patients. Purified SpA significantly increased IFNGR1 mRNA and protein expression in HNECs. SpA induced cytotoxic effects and induced the release of Interleukin-6 (IL-6) and IL-8 in an IFNGR1 dependent way. CONCLUSION: SpA induces interferon signaling through activation of the IFNGR1-JAK-2 pathway, which provides an understanding of how S. aureus SpA affects the inflammatory process in the upper airways.

Unraveling the role of the microbiome in chronic rhinosinusitis.

Chronic rhinosinusitis (CRS) is a complex, heterogenous condition that is likely associated with infectious and inflammatory causative factors. Renewed interest in the role that microbes play in this condition has stemmed from advancements in microbe identification and parallel research implicating the microbiome as having a role in other chronic inflammatory conditions. This clinical commentary provides a review of the current literature relevant to chronic rhinosinusitis. Particular focus is placed on factors specific to investigation of the sinonasal microbiome, evidence for the role of dysbiosis in the disease state, and influences that may affect the microbiome. Possible mechanisms of disease and therapeutic implications through microbial manipulation are also reviewed, as are deficiencies and limitations of the current body of research.

Remote Training of Functional Endoscopic Sinus Surgery With Advanced Manufactured 3D Sinus Models and a Telemedicine System.

Objective: Traditionally, cadaveric courses have been an important tool in surgical education for Functional Endoscopic Sinus Surgery (FESS). The recent COVID-19 pandemic, however, has had a significant global impact on such courses due to its travel restrictions, social distancing regulations, and infection risk. Here, we report the world-first remote (Functional Endoscopic Sinus Surgery) FESS training course between Japan and Australia, utilizing novel 3D-printed sinus models. We examined the feasibility and educational effect of the course conducted entirely remotely with encrypted telemedicine software. Methods: Three otolaryngologists in Hokkaido, Japan, were trained to perform frontal sinus dissections on novel 3D sinus models of increasing difficulty, by two rhinologists located in Adelaide, South Australia. The advanced manufactured sinus models were 3D printed from the Computed tomography (CT) scans of patients with chronic rhinosinusitis. Using Zoom and the Quintree telemedicine platform, the surgeons in Adelaide first lectured the Japanese surgeons on the Building Block Concept for a three Dimensional understanding of the frontal recess. They in real time directly supervised the surgeons as they planned and then performed the frontal sinus dissections. The Japanese surgeons were asked to complete a questionnaire pertaining to their experience and the time taken to perform the frontal dissection was recorded. The course was streamed to over 200 otolaryngologists worldwide. Results: All dissectors completed five frontal sinusotomies. The time to identify the frontal sinus drainage pathway (FSDP) significantly reduced from 1,292 ± 672 to 321 ± 267 s (p = 0.02), despite an increase in the difficulty of the frontal recess anatomy. Image analysis revealed the volume of FSDP was improved (2.36 ± 0.00 to 9.70 ± 1.49 ml, p = 0.014). Questionnaires showed the course's general benefit was 95.47 ± 5.13 in dissectors and 89.24 ± 15.75 in audiences. Conclusion: The combination of telemedicine software, web-conferencing technology, standardized 3D sinus models, and expert supervision, provides excellent training outcomes for surgeons in circumstances when classical surgical workshops cannot be realized.