BACKGROUND:Subdural haematoma (SDH) is an increasingly common neurosurgical condition, particularly in aging and at-risk populations. In the Northern Territory, the burden of neurotrauma is compounded by geographic remoteness and disparities in access to care. This study aimed to describe the incidence, management and outcomes of SDH at Royal Darwin Hospital. METHODS:A retrospective cohort study was conducted of all adults (≥ 18 years) admitted to Royal Darwin Hospital with convexity SDH between June 2014 and May 2020. Clinical and radiological data were extracted from medical records. Incidence was calculated using 2016 Census data. Outcomes were assessed using the Glasgow Outcome Scale-Extended (GOSE) at discharge and 6 months. RESULTS:A total of 247 patients were included. The incidence of SDH was 23.4 per 100 000 person-years (95% CI: 17.3-31.7), higher than national estimates. Patients travelled a mean distance of 121 km to access care, highlighting geographic barriers. Most patients (67%) presented with acute SDH, and 44% underwent surgical intervention, with burrhole drainage being the most common procedure. Functional outcomes were favourable in 65.2% at discharge and 70.5% at 6 months. Initial Glasgow Coma Scale scores strongly predicted outcomes. The 30-day mortality rate was 16.9%. CONCLUSION:SDH represents a significant burden on regional neurosurgical services in Northern Australia. The findings underscore the challenges of delivering timely care across vast distances and the need for improved service models to support neurotrauma care in rural and remote settings.

OBJECTIVE:The authors' goal was to perform a retrospective audit of all emergency cranial neurosurgery performed at the Royal Darwin Hospital in the first 5 years of the unit and to compile their data in a similar fashion to an earlier study titled "Emergency Neurosurgery in Darwin: Still the Generalist Surgeons' Responsibility," which was published in 2015. METHODS:All emergency cranial neurosurgery performed by a neurosurgeon between 2017 and 2021 was identified. Data were extracted from the National Critical Care and Trauma Response Centre database. Statistical analyses were descriptive logistic regression performed using Stata version 15.1 software to examine factors associated with death. RESULTS:A total of 320 patients (42% Indigenous) underwent 427 emergency neurosurgeries. There were 35 emergency neurosurgeries in 2017 and 82 in 2021. The most common procedure performed was insertion of an external ventricular drain, followed by craniotomy and removal of intracranial hematoma. Mortality was 7.5% overall and 8.4% among patients with trauma. Only age proved to be a statistically significant independent risk factor for death (t = -2.95, p < 0.0041; OR 1.06, p = 0.02). Location, sex, injury severity, and presenting Glasgow Coma Scale score were not associated with death. Indigenous and non-Indigenous patients had similar outcomes. CONCLUSIONS:The data illustrate the importance of developing small but sustainable neurosurgical units in rural and remote areas. A dedicated neurosurgical unit at the Royal Darwin Hospital has led to an increase in the amount and variety of emergency neurosurgery performed in Darwin. Interstate transfers have reduced. This has tangible lifesaving and economic advantages.

Objective Non-neurosurgeons in regional and rural hospitals may be required to operate on patients presenting with a traumatic brain injury where timely transfer to a tertiary hospital is not possible. Confidence and experience can vary significantly due to limited access to hands-on training. Increasing availability to advanced 3D printed models opens new opportunities to provide accurate head models suitable for this purpose. This study evaluated the experience of regional clinicians and nurses following a neurotrauma workshop where 3D printed head models were used to provide training in burr hole and craniotomy procedures. Methods A neurotrauma seminar and workshop was hosted at the Sunshine Coast Health Institute, in the state of Queensland, Australia. The workshop component allowed 26 local clinicians and nurses to gain hands-on experience with a 3D printed head model, guided by neurosurgeons from the closest tertiary hospital. Following training, participants completed a short survey. Results Prior to this workshop, most participants had never performed a burr hole (58%, n=15) or interacted with a 3D printed model (69%, n=18). Overall, most participants indicated that the 3D printed model performed better (58%, n=15) and much better (15%, n=4) than their expectations. 81% (n=21) left the workshop with improved confidence in performing burr hole and craniotomy procedures. Despite some melting of the plastic, 96% (n=25) of participants would recommend this model to their colleagues.

PurposeThree-dimensional (3D)printed skulls for neurosurgical training are increasingly being used due to the widespread access to 3D printing technology, their low cost and accuracy, as well as limitations and ethical concerns associated with using human cadavers. However, little is known about the risks of airborne particles or volatile organic compounds (VOCs) released while drilling into 3D-printed plastic models. The aim of this study is to assess the level of exposure to airborne contaminants while burr hole drilling.Design/methodology/approach3D-printed skull samples were produced using three different materials (polyethylene terephthalate glycol [PETG], white resin and BoneSTN) across three different 3D print processes (fused filament fabrication, stereolithography [SLA] and material jetting). A neurosurgeon performed extended burr hole drilling for 10 min on each sample. Spot measurements of particulate matter (PM2.5 and PM10) were recorded, and air samples were analysed for approximately 90 VOCs.FindingsThe particulate matter for PETG was found to be below the threshold value for respirable particles. However, the particulate matter for white resin and BoneSTN was found to be above the threshold value at PM10, which could be harmful for long periods of exposure without personal protective equipment (PPE). The VOC measurements for all materials were found to be below safety thresholds, and therefore not harmful.Originality/valueTo the best of the authors' knowledge, this is the first study to evaluate the safety of 3D-printed materials for burr hole surgical drilling. It recommends PETG as a safe material requiring minimal respiratory control measures, whereas resin-based materials will require safety controls to deal with airborne particles.

OBJECTIVE:Spine surgery addresses a wide range of spinal pathologies. Potential applications of 3-dimensional (3D) printed in spine surgery are broad, encompassing education, planning, and simulation. The objective of this study was to explore how 3D-printed spine models are implemented in spine surgery and their clinical applications.METHODS:Methods were combined to create a scoping review with meta-analyses. PubMed, EMBASE, the Cochrane Library, and Scopus databases were searched from 2011 to 7 September 2021. Results were screened independently by 2 reviewers. Studies utilizing 3D-printed spine models in spine surgery were included. Articles describing drill guides, implants, or nonoriginal research were excluded. Data were extracted according to reporting guidelines in relation to study information, use of model, 3D printer and printing material, design features of the model, and clinical use/patient-related outcomes. Meta-analyses were performed using random-effects models.RESULTS:Forty articles were included in the review, 3 of which were included in the meta-analysis. Primary use of the spine models included preoperative planning, education, and simulation. Six printing technologies were utilized. A range of substrates were used to recreate the spine and regional pathology. Models used for preoperative and intraoperative planning showed reductions in key surgical performance indicators. Generally, feedback for the tactility, utility, and education use of models was favorable.CONCLUSIONS:Replicating realistic spine models for operative planning, education, and training is invaluable in a subspeciality where mistakes can have devastating repercussions. Future study should evaluate the cost-effectiveness and the impact spine models have of spine surgery outcomes.

OBJECTIVE: 3D printing is increasingly used to fabricate three-dimensional neurosurgical simulation models, mak-ing training more accessible and economical. 3D printing includes various technologies with different capabilities for reproducing human anatomy. This study evaluated different materials across a broad range of 3D printing technologies to identify the combination that most pre-cisely represents the parietal region of the skull for burr hole simulation.METHODS: Eight different materials (polyethylene tere-phthalate glycol, Tough PLA, FibreTuff, White Resin, BoneSTN, SkullSTN, polymide [PA12], glass-filled polyamide [PA12-GF]) across 4 different 3D printing processes (fused filament fabrication, stereolithography, material jetting, selective laser sintering) were produced as skull samples that fit into a larger head model derived from computed tomography imaging. Five neurosurgeons conducted burr holes on each sample while blinded to the details of manufacturing method and cost. Qualities of mechanical drilling, visual appearance, skull exterior, and skull interior (i.e., diploe) and overall opinion were documented, and a final ranking activity was performed along with a semi -structured interview. RESULTS: The study found that 3D printed polyethylene terephthalate glycol (using fused filament fabrication) and White Resin (using stereolithography) were the best models to replicate the skull, surpassing advanced multi -material samples from a Stratasys J750 Digital Anatomy Printer. The interior (e.g., infill) and exterior structures strongly influenced the overall ranking of samples. All neurosurgeons agreed that practical simulation with 3D printed models can play a vital role in neurosurgical training.CONCLUSIONS: The study findings reveal that widely accessible desktop 3D printers and materials can play a valuable role in neurosurgical training.

The aim of this study was to prepare industrial design students for emerging roles in design and health through a 13-week, neurosurgery-centric design challenge. The study gathered survey data on their before and after perceptions on biomedical design, as well as their understanding of the role additive manufacturing plays in healthcare. At the conclusion of the project, nearly two-thirds of students had an interest in pursuing biomedical design after graduation. Prosthetics, implants and surgical planning aids were seen as the top applications of additive manufacturing in healthcare, while working with 3D models of human anatomy was seen as the biggest practical challenge. 3D printed prototypes exhibited at a major hospital showed a broad range of novel, modular, haptic and multi-material solutions that evidenced the value of biomedical design within healthcare, as well as the role advanced technology like additive manufacturing plays in solving real-world neurosurgical training challenges.

PurposeThis study aims to evaluate the color accuracy of HP Jet Fusion 580 3D printing, comparing 3D-printed outcomes against original digital input colors.Design/methodology/approachA custom cyan, magenta, yellow and black (CMYK) and red, green, blue (RGB) color chart was applied to the top, bottom and side surfaces of a 3D model. Four of each model were 3D-printed on a HP Jet Fusion 580, and half the samples were finished with a cyanoacrylate gloss surface finish, while half were left in raw form. A spectrophotometer was used to document CIELAB (L*a*b*) data, and comparisons made to the original input colors, including calculation of ΔE.FindingsThe CMYK samples were significantly more accurate than RGB samples, and grayscale samples in both color spaces were the most accurate of all. Typically, CMYK swatches were darker than the input values, and gloss samples were consistently darker than raw samples. The chromaticity (a*b*) range was found to be significantly smaller than what can be achieved digitally, with highly saturated colors unable to be produced by the printer.Originality/valueThis is the first study, to the best of the authors’ knowledge, to characterize the full color spectrum possible with the HP Jet Fusion 580, recommending that designers use the CMYK color space when applying colors and textures to 3D models. A quick-reference color chart has been provided; however, it is recommended that future research focus on developing a color management profile to better map digital colors to the capabilities of the printer.

Multicolour capability in additive manufacturing could play a key role in certain applications such as surgical training and consumer products. However, the ability to accurately 3D print colours is not well documented and could affect the realism of models produced through these technologies. As a recent system, the Stratasys J750 Digital Anatomy Printer has yet to be analyzed for its colour perception and accuracy, which is quantified through this study. This will allow users of this and similar material jetting systems with an improved understanding of the relationship between digitally applied colours and their result when 3D printed, as well as the influence of certain settings. Thirty-three rectangular prism models with different CMYK and RGB colours, as well as infill materials, were printed on a Stratasys J750 DAP printer. These were scanned on five faces using a Nix Mini 2 handheld colour sensor, documenting readings in CIELAB format. The data were analyzed using the CIEDE2000 colour difference formula, and its recent modifications for 3D printed objects. Results found statistically significant and perceptive differences in colour accuracy among different colours, core materials, and face orientations. It was also observed that the addition of VeroPureWhite as filler material instead of the default SUP706 support improved colour accuracy. The study recommends the following steps to improve colour accuracy: (i) avoid the addition of black (K) manually in CMYK colour space, (ii) use pure white as the base infill material instead of support material, (iii) add a little white (~ 10%–30%) to make samples opaque instead of translucent.

3D printing is increasingly used to fabricate medical devices and educational models, yet most studies to-date focus on a particular case study or training scenario. This study instead seeks to understand the relative importance of different qualities for 3D printed anatomical training models, including haptics, accuracy and costs. Clinicians at a major Australian hospital were presented with 24 3D printed prototypes for neurosurgical education in an interactive exhibition. These were produced by undergraduate industrial design students. A post-exhibition survey found that the top quality required in a 3D printed educational model was to feel realistic (33%), followed by accuracy to real anatomy (27%). A separate survey of other health professionals working within health-related disciplines and research also supported these two qualities as most important after attending the exhibition. 60% of clinicians left the exhibition believing that 3D printing plays a moderate or significant role in the hospital/health system, while 100% of other health professionals shared this same opinion. With a range of materials, 3D print and other technologies employed in the production of the models, this unique study helps clarify the core considerations when designing and 3D printing educational models for neurosurgery and other medical disciplines, and highlights some of the differences between clinicians and other health professionals in relation to the technology.

ANZ Journal of SurgeryVolume 93, Issue 5 p. 1408-1409 IMAGES FOR SURGEONS Chalk-stick fracture leading to rapid neurological decline and death Oleg Peselzon MCHD, Corresponding Author Oleg Peselzon MCHD [email protected] orcid.org/0000-0002-0570-0714 Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, ​Investigation, Writing - original draft, Writing - review & editingSearch for more papers by this authorMichael Redmond AM, RFD, FRACS, Michael Redmond AM, RFD, FRACS orcid.org/0000-0003-3494-9129 Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, Supervision, Writing - review & editingSearch for more papers by this authorAmeya Kamat MBBCh, FRACS, Ameya Kamat MBBCh, FRACS Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, Supervision, Writing - review & editingSearch for more papers by this authorRondhir Jithoo MBChB, FRACS, Rondhir Jithoo MBChB, FRACS Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, Supervision, Writing - review & editingSearch for more papers by this author Oleg Peselzon MCHD, Corresponding Author Oleg Peselzon MCHD [email protected] orcid.org/0000-0002-0570-0714 Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, ​Investigation, Writing - original draft, Writing - review & editingSearch for more papers by this authorMichael Redmond AM, RFD, FRACS, Michael Redmond AM, RFD, FRACS orcid.org/0000-0003-3494-9129 Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, Supervision, Writing - review & editingSearch for more papers by this authorAmeya Kamat MBBCh, FRACS, Ameya Kamat MBBCh, FRACS Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, Supervision, Writing - review & editingSearch for more papers by this authorRondhir Jithoo MBChB, FRACS, Rondhir Jithoo MBChB, FRACS Department of Neurosurgery, Royal Darwin Hospital, Darwin, Northern Territory, Australia Contribution: Conceptualization, Supervision, Writing - review & editingSearch for more papers by this author First published: 27 December 2022 https://doi.org/10.1111/ans.18240Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1Spiegl UJ, Holbing PL, Jarvers JS, Pieroh P, Osterhoff G et al. Midterm outcome after posterior stabilization of unstable midthoracic spine fractures in the elderly. BMC Musculoskelet. Disord. 2021; 22: 188. 2McLain RF. Functional outcomes after surgery for spinal fractures: return to work and activity. Spine (Phila Pa 1976) 2004; 29: 470–7. 3Schiefer TK, Milligan BD, Bracken CD et al. In-hospital neurologic deterioration following fractures of the ankylosed spine: a single-institution experience. World Neurosurg. 2015; 83: 775–83. 4Hunter T, Dubo H. Spinal fractures complicating ankylosing spondylitis. Ann. Intern. Med. 1978; 88: 546–9. 5Chaudhary SB, Hullinger H, Vives MJ. Management of acute spinal fractures in ankylosing spondylitis. ISRN Rheumatol. 2011; 2011: 150484. 6Lotan R, Prosso I, Klatzkin L, Hershkovich O. The COVID 19 pandemic effect on the epidemiology of thoracolumbar fractures presenting to the Emergency Department in patients above 65 years old. Geriatr. Orthop. Surg. Rehabil. 2022; 13: 21514593221098828. Volume93, Issue5May 2023Pages 1408-1409 ReferencesRelatedInformation

Background Large skull defects present a reconstructive challenge. Conventional cranioplasty options include autologous bone grafts, vascularized bone, metals, synthetic ceramics, and polymers. Autologous options are affected by resorption and residual contour deformities. Synthetic materials may be customized via digital planning and 3D printing, but they all carry a risk of implant exposure, failure, and infection, which increases when the defect is large. These complications can be a threat to life. Without reconstruction, patients with cranial defects may experience headaches and stigmatization. The protection of the brain necessitates lifelong helmet use, which is also stigmatizing. Objective Our clinical trial will formally study a hybridized technique's capacity to reconstruct large calvarial defects. Methods A hybridized technique that draws on the benefits of autologous and synthetic materials has been developed by the research team. This involves wrapping a biodegradable, ultrastructured, 3D-printed scaffold made of medical-grade polycaprolactone and tricalcium phosphate in a vascularized, autotransplanted periosteum to exploit the capacity of vascularized periostea to regenerate bone. In vitro, the scaffold system supports cell attachment, migration, and proliferation with slow but sustained degradation to permit host tissue regeneration and the replacement of the scaffold. The in vivo compatibility of this scaffold system is robust—the base material has been used clinically as a resorbable suture material for decades. The importance of scaffold vascularization, which is inextricably linked to bone regeneration, is underappreciated. A variety of methods have been described to address this, including scaffold prelamination and axial vascularization via arteriovenous loops and autotransplanted flaps. However, none of these directly promote bone regeneration. Results We expect to have results before the end of 2023. As of December 2020, we have enrolled 3 participants for the study. Conclusions The regenerative matching axial vascularization technique may be an alternative method of reconstruction for large calvarial defects. It involves performing a vascularized free tissue transfer and using a bioresorbable, 3D-printed scaffold to promote and support bone regeneration (termed the regenerative matching axial vascularization technique). This technique may be used to reconstruct skull bone defects that were previously thought to be unreconstructable, reduce the risk of implant-related complications, and achieve consistent outcomes in cranioplasty. This must now be tested in prospective clinical trials. Trial Registration Australian New Zealand Clinical Trials Registry ACTRN12620001171909; https://tinyurl.com/4rakccb3 International Registered Report Identifier (IRRID) DERR1-10.2196/36111

Largely attributed to the tyranny of distance, timely transfer of patients with major traumatic brain injuries (TBI) from rural or regional hospitals to metropolitan trauma centres is not always feasible. This has warranted emergent craniotomies to be undertaken by non-neurosurgeons at their local hospitals with previous acceptable results reported in regional Australia. Our institution endorses this ongoing potentially life-saving practice when necessary and emphasize the need for neurosurgical units to provide ongoing TBI education to peripheral hospitals. In this first of a two-part narrative review, the authors describe the recommended diagnostic pathway for patients with a suspected TBI presenting to rural or regional hospitals and discuss local surgical management options in the presence or absence of a CT scanner.

ObjectivesResults Delayed inter-hospital transfers of deteriorating neurotrauma patients from rural and regional hospitals to tertiary centres have seen the need for non-neurosurgeons to undertake emergency intracranial haematoma evacuation surgery locally. In the present study, the authors contributed to the paucity in the literature regarding the widespread availability of cranial access equipment in non-tertiary centres and patient outcomes in Queensland. Methods We surveyed delegates (senior theatre nurses or surgical service directors) from rural and regional Queensland hospitals if they were located outside the local catchment of a tertiary centre and had a CT scanner. Questions regarded availability, location and storage conditions of mechanical cranial access kits, as well as last usage, and associated patient outcomes. Twenty-six delegates from eligible hospitals responded. Eighteen hospitals offered surgical services. Eleven hospitals housed complete mechanical cranial access kits. Five hospitals housed incomplete kits. Thirteen hospitals housed their equipment sterile in the operating theatre or ED. Eleven hospitals reported using the equipment, with last usage ranging from 4 months to over 30 years. Two hospitals reported using the equipment within 12 months while a further five reported using it within 10 years. Two hospitals reported 'good' outcomes, two 'ok' and one 'poor'. Conclusions The availability of cranial access equipment outside Queensland tertiary centres has been limited. Inter-hospital transfers are likely to persist in Queensland and haematoma evacuation surgery has been a life-saving endeavour, so improving access to cranial access equipment in hospitals where it is currently lacking is highly warranted.

Kenneth G Jamieson described the emergent craniotomy for traumatic brain injuries (TBI) in the rural and regional setting back in 1965 in his book 'A First Notebook Of Head Injury'. Since then, there has been successful use of the technique in peripheral hospitals prior to the safe transfer of patients to metropolitan trauma centres. Although the procedure can be daunting in inexperienced hands, our institution supports ongoing education to continue implementation of trauma craniotomies by non-neurosurgeons if it means another life is potentially saved. Here we describe the surgical technique for an emergent craniotomy and craniectomy. Although the surgical technique has been described elsewhere, we have done so in a simplified 10-step approach with consideration of available resources in the peripheral hospital setting and the added pearls from the experience of a metropolitan neurosurgical unit. We also discuss future prospects for undertaking neurosurgical operations in peripheral hospitals but with intra-operative tele-surgery monitoring and supervision.

-BACKGROUND: Intracranial surgery can be complex and high risk. Safety, ethical and financial factors make training in the area challenging. Head model 3-dimensional (3D) printing is a realistic training alternative to patient and traditional means of cadaver and animal model simulation. -OBJECTIVE: To describe important factors relating to the 3D printing of human head models and how such models perform as simulators. -METHODS: Searches were performed in PubMed, the Cochrane Library, Scopus, and Web of Science. Articles were screened independently by 3 reviewers using Covidence software. Data items were collected under 5 categories: study information; printers and processes; head model specifics; simulation and evaluations; and costs and production times. -RESULTS: Forty articles published over the last 10 years were included in the review. A range of printers, printing methods, and substrates were used to create head models and tissue types. Complexity of the models ranged from sections of single tissue type (e.g., bone) to high-fidelity integration of multiple tissue types. Some models incorporated disease (e.g., tumors and aneurysms) and artificial physiology (e.g., pulsatile circulation). Aneurysm clipping, bone drilling, craniotomy, endonasal surgery, and tumor resection were the most commonly practiced procedures. Evaluations completed by those using the models were generally favorable. -CONCLUSIONS: The findings of this review indicate that those who practice surgery and surgical techniques on 3D-printed head models deem them to be valuable assets in cranial surgery training. Understanding how surgical simulation on such models affects surgical performance and patient outcomes, and considering cost-effectiveness, are important future research endeavors.

The incidence of intracranial infected collections (IIC) ranges between 0.4 and 1.2/100 000 persons per year. There is anecdotal evidence that residents in Top End of the Northern Territory are at a greater risk of infections with protracted clinical presentations. To our knowledge, there is no study to date to explore IIC in the Top End.

The lack of radio navigational aids in early Royal Flying Doctor Service aircraft in Australia occasionally resulted in aircraft being stranded at a remote site with a critically injured patient due to weather and other conditions. For a brief period in the 1950s, at least one Royal Flying Doctor Service pilot was trained to administer anaesthesia to critically ill patients who could not be immediately evacuated. The aim of this paper is to describe the circumstances in which this arose and how it worked in practice. This is based largely on the recollections of pilot anaesthetist Captain Keith Galloway, who shared his recollections during interviews with the authors.

Intracranial schwannomas not originating from cranial nerves are rare. In this paper, we report a case of a 50-year-old male who presented with worsening headaches, diplopia and nausea over two years. Radiological imaging revealed a large tumour arising from the olfactory groove region with a preoperative diagnosis of olfactory groove meningioma (OGM). Intraoperatively, the tumour originated from the region of the attachment of the falx to the crista galli. The patient recovered without complication and histopathology reported an unexpected diagnosis of WHO Grade 1 schwannoma. However, as olfactory groove schwannomas (OGSs) cannot be distinguished from olfactory ensheathing cell tumours (OECTs), it is possible that the tumour could have been either an OGS or an OECT. Distinguishing between OGSs, OECTs and OGMs preoperatively is difficult. OGMs exhibit distinct histopathological features from OGSs/OECTs, however, OGSs and OECTs currently cannot be distinguished from each other. Here, we review the literature to discuss the differentiating features and cellular origins of these three tumours.