A modified pull-through approach with a pedicled bone flap for oral and oropharyngeal cancer resection: a feasibility study.

PURPOSE: Compromised swallowing, speaking, and local complications are the major disadvantages of established approaches to the posterior tongue and oropharynx. The mandibular split involves an esthetically unpleasant bipartition of the lower lip and is prone to bony non-union or sequestration. The conventional pull-through technique on the other hand lacks the secure reattachment of the lingually released soft tissues. METHODS: The feasibility of a new modified pull-through approach was tested on three anatomical specimens. CAD/CAM cutting guides were used to design a retentive bone flap to properly refixate the genioglossus and geniohyoid muscles after the procedure. The radiographic assessment and treatment planning was performed on 12 cadavers. The entire procedure was tested surgically via dissection in three of those cases. This procedure was then applied in a clinical case. RESULTS: Precise repositioning and dynamic compression of bony segments was possible reproducibly and without injury to adjacent structures. In all dissected cases, a median lingual foramen was found and in two cases vessels entering it could be dissected Radiologic anatomical landmarks were sufficient in all 12 cases to perform the clinical planning procedure. Clinically, the osteotomized segment demonstrated good blood supply and plateless repositioning was verified postoperatively via cone beam scan. CONCLUSION: The method presented is safe and easy to perform. Individual cutting guides improve the safety and accuracy of the procedure, potentially eliminating the need for osteosynthesis. We provide the anatomical and radiologic basis for clinical evaluation of this pedicled bone flap procedure and present the clinical application of this modified pull-through approach.

Spatial gene expression profile of Wnt-signaling components in the murine enteric nervous system.

Introduction: Wnt-signaling is a key regulator of stem cell homeostasis, extensively studied in the intestinal crypt and other metazoan tissues. Yet, there is hardly any data available on the presence of Wnt-signaling components in the adult enteric nervous system (ENS) in vivo. Methods: Therefore, we employed RNAscope HiPlex-assay, a novel and more sensitive in situ hybridization technology. By amplifying target specific signals, this technique enables the detection of low abundance, tightly regulated RNA content as is the case for Wnt-signaling components. Additionally, we compared our data to previously published physiological single cell RNA and RiboTag-based RNA sequencing analyses of enteric gliosis using data-mining approaches. Results: Our descriptive analysis shows that several components of the multidi-mensional regulatory network of the Wnt-signaling pathway are present in the murine ENS. The transport and secretion protein for Wnt-ligands Wntless as well as canonical (Wnt3a and Wnt2b) and non-canonical Wnt-ligands (Wnt5a, Wnt7a, Wnt8b and Wnt11) are detectable within submucosal and myenteric plexus. Further, corresponding Frizzled receptors (Fzd1, Fzd3, Fzd6, and Fzd7) and regulatory signaling mediators like R-Spondin/DKK ligands are present in the ENS of the small and large intestine. Further, data mining approaches revealed, that several Wnt-related molecules are expressed by enteric glial cell clusters and are dynamically regulated during the inflammatory manifestation of enteric gliosis. Discussion: Our results suggest, that canonical and non-canonical Wnt-signaling has a much broader impact on the mature ENS and its cellular homeostasis in health and inflammation, than previously anticipated.

Flat panel CT versus multidetector CT in skull base imaging: are there differences in image quality?

BACKGROUND: Purpose of this study was to compare image quality of the skull base in standard 20s protocol flat panel computed tomography (FPCT) with the new time and dose improved 10s protocol as well as with 128 slice multidetector computed tomography (MDCT). METHODS: 10 whole skull preparations were scanned with either 128 slice MDCT(SOMATOM Definition AS+, Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10s or 20s protocol. RESULTS: FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the anterior, temporal and posterior skull base compared to 128 slice MDCT. The 20s FPCT protocol yielded best delimitability of evaluated skull base structures. However, the shorter, dose saving 10s FPCT protocol was still significantly superior to 128 slice MDCT regarding delimitability of skull base structures and additionally showed no significant inferiority compared with the 20s FPCT protocol. CONCLUSIONS: The 10s FPCT protocol yields a significantly better image quality at a comparable radiation dose exposure in imaging skull base structures compared to MDCT. TRIAL REGISTRATION: 371/2017BO2.

Dickkopf1 induces enteric neurogenesis and gliogenesis in vitro if apoptosis is evaded.

Neurogenesis in the postnatal enteric nervous system (ENS) is controversially discussed. Yet, deciphering the regenerative potential of the ENS is essential for our understanding and therapy of human enteric neuropathies. Dickkopf1 (DKK1) is a Wnt-antagonist and involved in the homeostasis of various tissues. We hypothesize that DKK1 could function as a negative regulator on the proliferation of ENS-progenitors in the postnatal gut of mice and human infants. Here, we provide evidence that DKK1 is expressed in the murine and human ENS. If applied to ENS-progenitors in vitro, DKK1 leads to an increased proliferation, however, followed by extensive apoptosis. Yet, once we block apoptosis, DKK1-stimulation markedly increases enteric neurogenesis in murine and human ENS-progenitors. Thus, DKK1 is a strong, ambivalent regulator of the ENS-progenitor cell pool in mice and humans. These results are fundamental steps to reshaping our understanding of the homeostasis of the ENS in health and disease.

The chemicals between us-First results of the cluster analyses on anatomy embalming procedures in the German-speaking countries.

Hands-on courses utilizing preserved human tissues for educational training offer an important pathway to acquire basic anatomical knowledge. Owing to the reevaluation of formaldehyde limits by the European Commission, a joint approach was chosen by the German-speaking anatomies in Europe (Germany, Austria, Switzerland) to find commonalities among embalming protocols and infrastructure. A survey comprising 537 items was circulated to all anatomies in German-speaking Europe. Clusters were established for "ethanol"-, formaldehyde-based ("FA"), and "other" embalming procedures, depending on the chemicals considered the most relevant for each protocol. The logistical framework, volumes of chemicals, and infrastructure were found to be highly diverse between the groups and protocols. Formaldehyde quantities deployed per annum were three-fold higher in the "FA" (223 L/a) compared to the "ethanol" (71.0 L/a) group, but not for "other" (97.8 L/a), though the volumes injected per body were similar. "FA" was strongly related to table-borne air ventilation and total fixative volumes ≤1000 L. "Ethanol" was strongly related to total fixative volumes >1000 L, ceiling- and floor-borne air ventilation, and explosion-proof facilities. Air ventilation was found to be installed symmetrically in the mortuary and dissection facilities. Certain predictors exist for the interplay between the embalming used in a given infrastructure and technical measures. The here-established cluster analysis may serve as decision supportive tool when considering altering embalming protocols or establishing joint protocols between institutions, following a best practice approach to cater toward best-suited tissue characteristics for educational purposes, while simultaneously addressing future demands on exposure limits.

Aquaporin-1 and Aquaporin-4 Expression in Ependyma, Choroid Plexus and Surrounding Transition Zones in the Human Brain.

The choroid plexus (CP) is a structure in the brain ventricles that produces the main part of the cerebrospinal fluid (CSF). It is covered with specialized cells which show epithelial characteristics and are the site of the blood-CSF barrier. These cells form a contiguous cell sheet with ventricle-lining ependymal cells which are known to express aquaporin-4 (AQP4). In contrast, CP epithelial cells express aquaporin-1 (AQP1) apically. We investigated the expression patterns of aquaporins in the CP-ependyma transition from human body donors using immunofluorescence and electron microscopy. Ependymal cells and subependymal astrocytes at the base of the CP showed a particularly high AQP4 immunoreactivity. Astrocytic processes formed a dense meshwork or glial plate around the blood vessels entering the CP. Interestingly, some of these astrocytic processes were in direct contact with the CP stroma, which contains fenestrated blood vessels, separated only by a basal lamina. Electron microscopy confirmed the continuity of the subastrocytic basal lamina with the CP epithelium. We also probed for components of the AQP4 anchoring dystrophin-dystroglycan complex. Immunolabeling for dystrophin and AQP4 showed an overlapping staining pattern in the glial plate but not in previously reported AQP4-positive CP epithelial cells. In contrast, dystroglycan expression was associated with laminin staining in the glial plate and the CP epithelium. This suggests different mechanisms for AQP4 anchoring in the cell membrane. The high AQP4 density in the connecting glial plate might facilitate the transport of water in and out of the CP stroma and could possibly serve as a drainage and clearing pathway for metabolites.

Surgical Approach for Rapid and Minimally Traumatic Recovery of Human Inner Ear Tissues From Deceased Organ Donors.

OBJECTIVE: To develop a surgical approach for rapid and minimally traumatic recovery of inner ear tissue from human organ and tissue donors to provide fresh tissue for use in inner ear research. STUDY DESIGN: Exploration of novel surgical methodology and evaluation of the steps necessary for obtaining specimens from donors during the procurement of organs for transplantation. SETTING: Donor procurement locations across multiple local hospitals and tissue processing at the microsurgical temporal bone laboratory. PATIENTS TISSUE SOURCE: Human organ and tissue donors. INTERVENTIONS: Dissection and procurement of the inner ear tissue. MAIN OUTCOME MEASURES: Development of rapid and minimally traumatic inner ear tissue recovery. Primarily, establishing an efficient process which includes collaboration with transplant network, implementing a consent protocol, developing and training an on-call recovery team, and designing a portable surgical kit suitable for use in a variety of settings. RESULTS: The extraction procedure is described in three consecutive steps: the trans-canal exposure, the approach to the vestibule with extraction of the vestibular organs; and the approach to extract inner ear tissues from the cochlear duct. CONCLUSIONS: Organ and tissue donors are a promising and underutilized resource of inner ear organs for purposes of research and future translational studies. Using our modified technique through the trans-canal/trans-otic approach, we were able to extract tissues of the vestibular and auditory end organs in a timely manner.

Robotic-assisted plate osteosynthesis of the anterior pelvic ring and acetabulum: an anatomical feasibility study.

Pelvic ring injuries or acetabular fractures present a challenge to trauma surgeons. Recently, endoscopic dissection techniques for visualization of the anterior pelvic ring and acetabulum have been presented. Robotic-assisted surgical systems offer advantages in terms of improved visualization and easier instrument handling. The aim of this pilot anatomic study was to verify the feasibility of robotic-assisted plate osteosynthesis on the anterior pelvic ring and acetabulum. The experiment was performed on a human whole body specimen. The DaVinci system with standard instruments as used in RARP was used. After docking the system, the anterior pelvic ring was first prepared as previously described for the endoscopic techniques. This was followed by dissection of both acetabula analogous to pelvic lymphadenectomy as performed during RARP. After the dissection was performed along the pelvic brim up to the iliosacral joint, the complete anterior column of the acetabulum including quadrilateral surface and incisura ischiadica major could be visualized. Finally, robotic-assisted endoscopic plate osteosynthesis was performed on the symphysis and anterior acetabular column as previously described in the endoscopic techniques. Robotic-assisted plate osteosynthesis of the anterior pelvic ring and acetabulum is feasible with the available robotic-assisted systems. Due to the excellent freedom of movement of the robotic arms, combined with the magnifying 3D visualization of the system, highly accurate preparation of the situs in preparation for plate osteosynthesis can be performed. The question of reduction of dislocated fractures remains open and is the subject of further investigation. Compared with conventional laparoscopy, robotic-assisted preparation nevertheless appears to offer an advantage in view of the complexity of the operation.

Aquaporin-4 expression in the human choroid plexus.

The choroid plexus (CP) consists of specialized ependymal cells and underlying blood vessels and stroma producing the bulk of the cerebrospinal fluid (CSF). CP epithelial cells are considered the site of the internal blood-cerebrospinal fluid barrier, show epithelial characteristics (basal lamina, tight junctions), and express aquaporin-1 (AQP1) apically. In this study, we analyzed the expression of aquaporins in the human CP using immunofluorescence and qPCR. As previously reported, AQP1 was expressed apically in CP epithelial cells. Surprisingly, and previously unknown, many cells in the CP epithelium were also positive for aquaporin-4 (AQP4), normally restricted to ventricle-lining ependymal cells and astrocytes in the brain. Expression of AQP1 and AQP4 was found in the CP of all eight body donors investigated (3 males, 5 females; age 74-91). These results were confirmed by qPCR, and by electron microscopy detecting orthogonal arrays of particles. To find out whether AQP4 expression correlated with the expression pattern of relevant transport-related proteins we also investigated expression of NKCC1, and Na/K-ATPase. Immunostaining with NKCC1 was similar to AQP1 and revealed no particular pattern related to AQP4. Co-staining of AQP4 and Na/K-ATPase indicated a trend for an inverse correlation of their expression. We hypothesized that AQP4 expression in the CP was caused by age-related changes. To address this, we investigated mouse brains from young (2 months), adult (12 months) and old (30 months) mice. We found a significant increase of AQP4 on the mRNA level in old mice compared to young and adult animals. Taken together, we provide evidence for AQP4 expression in the CP of the aging brain which likely contributes to the water flow through the CP epithelium and CSF production. In two alternative hypotheses, we discuss this as a beneficial compensatory, or a detrimental mechanism influencing the previously observed CSF changes during aging.

Accessing the Stapedius Muscle Via Novel Surgical Retrofacial Approach: A Cadaveric Feasibility Study.

HYPOTHESIS: Despite the complete embodiment of the stapedius muscle (SM) into the pyramidal eminence, it is possible to safely gain access to the SM belly via a retrofacial approach. This presents a novel approach to directly measure the electrically evoked stapedius reflex threshold (eSRT). BACKGROUND: Objective fitting of maximum comfortable loudness levels for cochlear implant users can improve the benefit introduced by the device. Sensing SM activity via direct surgical access represents a potential tool for objective eSRT fitting. METHODS: Eighteen human temporal bones (TBs) were used. Micro-computed tomography was performed for six TBs. Standard computed tomography for six TBs. Manual 3D-segmentation of the relevant middle and inner ear anatomy was performed on 12 TBs. Mastoidectomy and posterior tympanotomy allowed the access to middle ear of all 18 the TBs. Once identified the mastoidal segment of the facial nerve (FN), the retrofacial access to the SM was drilled. RESULTS: The total access rate was 72.2%. Only in the first three cases the posterior semi-circular canal was hit. The SM access was identified posterior to the FN at a 4 ±â€Š0.78 mm distance from the stapes' head, almost halfway to the chorda tympani's branching point along the FN direction. The drilling depth to access the SM posterior to the external surface of FN on average was 2 ±â€Š0.30 mm. The exposure took on average of 5 to 8 minutes. CONCLUSIONS: The retrofacial approach seems to offer a feasible and reproducible access to the SM belly opening an avenue to electromyographic sensing of eSRT.

Developing formalin-based fixative agents for post mortem brain MRI at 9.4 T.

PURPOSE: To develop fixative agents for high-field MRI with suitable dielectric properties and measure MR properties in immersion-fixed brain tissue. METHODS: Dielectric properties of formalin-based agents were assessed (100 MHz-4.5 GHz), and four candidate fixatives with/without polyvinylpyrrolidone (PVP) and different salt concentrations were formulated. B1 field and MR properties (T1 , R2∗ , R2 , R2' , and magnetic susceptibility [QSM]) were observed in white and gray matter of pig brain samples during 0.5-35 days of immersion fixation. The kinetics were fitted using exponential functions. The immersion time required to reach maximum R2∗ values at different tissue depths was used to estimate the Medawar coefficient for fixative penetration. The effect of replacing the fixatives with Fluoroinert and phosphate-buffered saline as embedding media was also evaluated. RESULTS: The dielectric properties of formalin were nonlinearly modified by increasing amounts of additives. With 5% PVP and 0.04% NaCl, the dielectric properties and B1 field reflected in vivo conditions. The highest B1 values were found in white matter with PVP and varied significantly with tissue depth and embedding media, but not with immersion time. The MR properties depended on PVP yielding lower T1 , higher R2∗ , more paramagnetic QSM values, and a lower Medawar coefficient (0.9 mm/h ; without PVP: 1.5). Regardless of fixative, switching to phosphate-buffered saline as embedder caused a paramagnetic shift in QSM and decreased R2∗ that progressed during 1 month of storage, whereas no differences were found with Fluorinert. CONCLUSION: In vivo-like B1 fields can be achieved in formalin fixatives using PVP and a low salt concentration, yielding lower T1 , higher R2∗ , and more paramagnetic QSM than without additives. The kinetics of R2∗ allowed estimation of fixative tissue penetration.

ENT Residents Benefit from a Structured Operation Planning Approach in the Training of Functional Endoscopic Sinus Surgery.

Background and Objectives: Preoperative planning utilizing computed tomographies (CT) is of utmost importance in functional endoscopic sinus surgery (FESS). Frequently, no uniform documentation and planning structures are available to residents in training. Consequently, overall completeness and quality of operation planning may vary greatly. The objective of the present study was to evaluate the impact of a structured operation planning (SOP) approach on the report quality and user convenience during a 4-day sinus surgery course. Materials and Methods: Fifteen participant were requested to plan a FESS procedure based on a CT scan of the paranasal sinuses that exhibited common pathological features, in a conventional manner, using a free text. Afterwards, the participants reevaluated the same scans by means of a specifically designed structured reporting template. Two experienced ENT surgeons assessed the collected conventional operation planning (COP) and SOP methods independently with regard to time requirements, overall quality, and legibility. User convenience data were collected by utilizing visual analogue scales. Results: A significantly greater time expenditure was associated with SOPs (183 s vs. 297 s, p = 0.0003). Yet, legibility (100% vs. 72%, p < 0.0001) and overall completeness (61.3% vs. 22.7%, p < 0.0001) of SOPs was significantly superior to COPs. Additionally, description of highly relevant variants in anatomy and pathologies were outlined in greater detail. User convenience data delineated a significant preference for SOPs (VAS 7.9 vs. 6.9, p = 0.0185). Conclusions: CT-based planning of FESS procedures by residents in training using a structured approach is more time-consuming while producing a superior report quality in terms of detailedness and readability. Consequently, SOP can be considered as a valuable tool in the process of preoperative evaluations, especially within residency.

Anatomical work-up of an individual with multiple muscular variants on both forearms.

Muscular variants of the forearm are common and frequently cause neurovascular compression syndromes, especially when interfering with the compact topography of the carpal tunnel or the Canalis ulnaris. Here, we report on a male body donor with multiple muscular normal variations on both forearms. The two main findings are (1) an accessory variant muscle (AVM) on the right forearm originating from the M. brachioradialis, the distal radius, and the M. flexor pollicis longus. It spanned the wrist beneath the Fascia antebrachia and inserted at the proximal phalanx of the digitus minimus. (2) Moreover, we found a three-headed palmaris longus variant on the left arm with proximal origin tendon and a distal, trifurcated muscle belly, with separated insertions at the palmar aponeurosis, the flexor retinaculum, and, in analogy to the accessory muscle on the contralateral arm, at the base of the proximal phalanx of the digitus minimus. We found a considerable thickening of the left-hand median nerve right before entering the carpal tunnel indicative of a possible chronic compression syndrome adding clinical relevance to this anatomical case. We also discuss the notion that both, the AVM and the contralateral three-headed palmaris variant are developmental descendants of the M. palmaris longus. Additionally, we found a previously not recorded variant of the M. palmaris brevis on the left hand.

Laparoscopic Acetabular Surgery (LASY) - vision or illusion?

Displaced acetabular fractures usually require open surgical approaches. Aim of this cadaver study was to evaluate a laparoscopic approach to prepare the anterior acetabular column and the quadrilateral plate in analogy to the laparoscopic pelvic lymphadenectomy. The laparoscopic preparation and anatomy is presented and illustrated step by step in a human cadaver followed by a modular plate osteosynthesis of the anterior column involving the quadrilateral plate is performed via a minimally invasive approach using standard laparoscopic instruments. In conclusion we could demonstrate that the laparoscopic preperitoneal preparation of the acetabulum according to the laparoscopic pelvic lymphadenectomy provides more free range for the surgical instruments compared to a previously described total extraperitoneal approach. The development of specific reduction tools and implants is under investigation. Until then, at least the laparoscopic preparation could be introduced in the clinical setting in the near future. TYPE OF STUDY: Technical note - Cadaver study.

Applied anatomy and surgical technique of the lateral single-position L5-S1 fusion.

The latest development in the anterior lumbar interbody fusion (ALIF) procedure is its application in the lateral position to allow for simultaneous posterior percutaneous screw placement. The technical details of the lateral ALIF technique have not yet been described. To describe the surgical anatomy relevant to the lateral ALIF approach we performed a comprehensive anatomical study. In addition, the preoperative imaging, patient positioning, planning of the skin incision, positioning of the C-arm, surgical approach, and surgical technique are discussed in detail. The technique described led to the successful use of the lateral ALIF technique in our clinical cases. No lateral ALIF procedure needed to be aborted during these cases. Our present work gives detailed anatomical background and technical details for the lateral ALIF approach. This teaching article can provide readers with sufficient technical and anatomical knowledge to assist them in performing their first lateral ALIF procedure.

Anatomic landmarks for masseteric nerve identification: Anatomic study for a new reference point.

The masseteric nerve is often used as a donor nerve in the treatment of facial paralysis. Even if several anatomical studies described landmarks for its identification, their main disadvantages are the anatomical variability and the changes due to surgery. Sixteen dissections were performed on cadaveric specimens. The masseteric muscle (MM), the zygomatic arch (ZA), the masseteric nerve (MN) and the zygomatic branch of the facial nerve (ZB) were identified and their relationships were measured. The relationships between MN and ZB resulted to be constant, with MN intersecting ZB at a depth of 0,78 cm in the muscle, 1,6 cm below ZA and 0,8 cm from the posterior border of MM. The measures obtained demonstrated as the main zygomatic branch of the facial nerve can be a suitable landmark for the identification of the masseteric nerve, with no variations due to the surgical procedure or patient characteristics.

Observing Interprofessional Collaboration: Impact on Attitude and Knowledge Acquisition.

Interprofessional collaboration (IPC) in the medical field is an important factor for good clinical outcomes and should be taught as early as in undergraduate medical education. Since implementing IPC training is an organizational challenge, students are often limited in their opportunities to experience real-life IPC. Therefore, an approach where students observe successful IPC activities of role models in an applied anatomical format was proposed. It was studied whether observing IPC activities in undergraduate anatomical education has an impact on both students' attitude toward IPC and on knowledge acquisition. Further, it was examined whether the attitudes and knowledge of students from different medical disciplines were influenced in different ways. Therefore, 75 medical students and thirty-eight physiotherapy students participated in a study with the task of observing a live broadcast of an interprofessional teaching session. Participants were asked about their attitudes toward interprofessional learning, their evaluation of professional responsibilities, and their profession-specific knowledge before and after observing the IPC session. The participants' attitude toward interprofessional learning improved for both groups of students. Moreover, students of physiotherapy adjusted their evaluation of their own and others' professional responsibilities after observing IPC. In both student groups, knowledge increased, in particular, with respect to the field of knowledge in other professions. So, observing IPC can modify students' attitudes and support knowledge acquisition. The implementation of IPC observations provides students from various healthcare disciplines with a clearer impression of professionals' responsibilities and gives learners the opportunity to acquire knowledge from healthcare fields unfamiliar to them.

Observing Inter-Professional Videos: Impact of Collaboration Between Physicians and Psychologists on Attitude and Knowledge Acquisition.

BACKGROUND: Inter-professional collaboration (IPC) is an important prerequisite for successful patient care. Even though inter-professional education (IPE) is increasingly common in undergraduate medical education, few IPE approaches explicitly address the IPC among medical students and students of psychology. IPE videos can be used to give learners the opportunity to gather relevant knowledge from different professional perspectives. So far it has been unclear whether it is enough when the topic of the video itself is inter-professional or if it is necessary for experts from different professions explicitly to appear in the video. METHODS: In an online experiment, medical students watched 1 of 2 videos about Parkinson's disease (PD) and the care of PD patients. The information was either provided by protagonists from only 1 profession (ie, physicians; mono-professional condition) or provided by protagonists from 2 different professions (ie, physicians and a psychologist; inter-professional condition). Attitude toward inter-professional interaction and learning, evaluation of the entertaining and illustrative character of the video, attitude toward physicians and psychologists, importance of IPC, evaluation of psychological treatment support, and knowledge acquisition served as dependent variables. RESULTS: The analysis was based on 140 participants (74 in the mono-, 66 in the inter-professional condition). We found that the inter-professional video was perceived to be more entertaining than the mono-professional video (t (138) = -2.227; P = .028; d = 0.38). The inter-professional video was also considered to be more illustrative (t (138) = -6.269; P < .001; d = 1.06). Moreover, participants improved their attitude toward physicians by watching the video (F (1,138) = 4.860, P < .001, η 2 p = 0.11), but they did not change their attitude toward psychologists (P = .146). Participants who watched the inter-professional video considered IPC to be more important than participants who watched the mono-professional video (t (138) = -7.954; P < .001; d = 1.354). Finally, the inter-professional video led to better performance in the knowledge test (t (138) = -2.285; P = .024; d = 0.04). CONCLUSION: Inter-professional videos showing explicitly the appearance of experts from different professions come along with several advantages. We discuss the implications of their application in educational practice. TRIAL REGISTRATION: The study was pre-registered on the pre-registration platform AsPredicted (aspredicted.org) before we began data collection (registration number: #33143). The pre-registration document can be accessed via the following link: https://aspredicted.org/blind.php?x=gd5hd8.

Histological Evidence for the Enteric Nervous System and the Choroid Plexus as Alternative Routes of Neuroinvasion by SARS-CoV2.

Evidence is mounting that the novel corona virus SARS-CoV2 inflicts neurological symptoms in a subgroup of COVID-19 patients. While plenty of theories on the route of neuroinvasion have been proposed, little histological evidence has been presented supporting any of these hypotheses. Therefore, we carried out immunostainings for ACE2 and TMPRSS2, two proteinases crucial for the entry of SARS-CoV2 into host cells, in the human enteric nervous system (ENS), as well as in the choroid plexus of the lateral ventricles. Both of these sites are important, yet often neglected entry gates to the nervous system. We found that ACE2 and TMPRSS2 are expressed by enteric neurons and glial cells of the small and large intestine, as well as choroid plexus epithelial cells, indicating that these cells meet the molecular requirements for viral entry. Together, our results are fundamental histological evidence substantiating current theories of neuroinvasion by SARS-CoV2.

Feasibility of the Far Lateral Suboccipital Approach to the Retroodontoid Region. How Much Bone Removal Is Truly Needed?

OBJECTIVE: The posterolateral extradural suboccipital approach can be used to reach the anterior epidural space and the retro-odontoid regions. The extent of necessary bone removal of the atlas vertebra (C1) has not yet been defined. We studied the changes in the size of the horizontal and vertical surgical windows using stepwise bone removal of C1. A representative case is shown. METHODS: The anatomical study was performed bilaterally on five Thiel-fixed human cadavers (mean age, 83.7 years). The surgical window (horizontal × vertical) required to access the retro-odontoid region via a posterolateral approach was measured for an intact C1 posterior arch, after a semicircular inferior partial resection of the C1 arch, after resection of the unilateral hemiarch of C1, and finally after drilling approximately 3 mm from the medial aspect of the lateral mass of C1. RESULTS: The intact C1 resulted in a very narrow surgical window of 6.3 mm × 9.7 mm (horizontal × vertical). The vertical window increased to a 13 mm after the semicircular inferior partial resection of the C1 arch and to 17.3 mm in the case of removal of the ipsilateral C1 posterior arch. The bone removal from the medial aspect of the C1 lateral mass resulted in a widening of the horizontal surgical window to 10.3 mm. The final size of the surgical window was 10.3 mm × 17.3 mm. The patient with severe kyphoscoliosis of the craniocervical spine was successfully operated on using odontoid and C1-2 facet osteotomies. CONCLUSION: If only the anterior epidural space or the base of the odontoid needs to be reached, the semicircular inferior partial resection of the C1 arch allows for an adequate surgical window. The tip of the odontoid could only be reached if the ipsilateral posterior arch is resected.