Surgical training strategies for physicians practicing in an isolated environment: an example from Antarctica. International survey of 13 countries with active winter stations.

For 60 years, human presence in Antarctica has required particularly demanding medical skills. Nevertheless, the preparation of physicians working in this extreme environment remains unknown and deserves clarification. This study aimed to summarise data on the surgical training given to physicians by different countries. In April 2020, we conducted a questionnaire-based study of 14 countries wintering in Antarctica. Responses were descriptively analysed. Regarding the profiles of physicians recruited by the wintering countries, 30% to 55% were non-surgeon doctors compared with 45% to 70% for surgeons depending on the year. Of the 13 countries answering the questionnaire, nine organised practical surgical training and six used theoretical material. All countries reported practical training for dental surgery, while only five countries provided training in four other surgical specialities (orthopaedic, digestive, thoracic, and ear, throat, and nose). All 13 countries reported using a telemedicine system. These results revealed heterogeneous training strategies among the recruited physicians, reflecting the difficulties of practice on this extreme continent. Future work may assess the effectiveness of each strategy. A better understanding of surgical epidemiology and a detailed referencing of the equipment available at the bases would help better define the contours of surgical care in Antarctica.

Surgical epidemiology of Antarctic stations from 1904 to 2022: A scoping review.

In Antarctica, it is extremely difficult to organise medical evacuations in winter. Antarctic physicians are often alone and must be prepared to perform surgery and dentistry, even if they are not specialists. This scoping review summarises epidemiological data on the types of surgical procedures performed in Antarctica and identifies gaps in the literature in this area. We searched PubMed and Google Scholar, without language restriction, for papers published between 1 January 1904, and 1 February 2022. Of the 35 papers on 12 Antarctic programs, very few were retrospective observational epidemiological studies; the majority were medical reports. The search identified 41 surgical procedures or reasons for surgical consultation, 19 different reasons for medical evacuations, and 12 causes of death that may have required surgical management. The diagnostic classifications used and the prevalence of each reported surgical speciality were heterogeneous. The most cited specialities were orthopaedics, dentistry, and digestive surgery. Telemedicine was integrated into on-site care or medical evacuation decisions. The current literature is poor, and most studies do not apply to surgical issues. The heterogeneous data collection methodologies limit their interpretation. A standardised diagnostic classification and detailed and systematic epidemiological registers will help define the contours of surgical management in Antarctica.

Radiological relationship of the ethmoid slit with the frontal sinus and the anterior ethmoidal artery and applications to the frontal sinus drillout.

PURPOSE: To compare two types of CT acquisition parameters: CT scan of the facial bone and CT scan of the sinuses, for studying the ethmoidal slit and its relationship with the frontal sinus and anterior ethmoidal artery. MATERIALS AND METHODS: Retrospective study of 145 scans of the sinuses and 79 of the facial bones performed between 2012 and 2016. On each scan, the visibility of the ethmoidal slits, their length, their distance from the ethmoidal artery, and their relationship with the anterior and posterior wall of the frontal sinus were studied. RESULTS: The ethmoidal slit was better visualized on CT scans of the facial bone (58.2%) than on those of the sinuses (43.1%) (p = 0.02). The distance between the anterior ethmoidal artery and the anterior part of the cribriform plate was 9.3 mm for CT scans of the facial bone and 8.4 mm for CT scans of the sinuses. The theoretical risk of damaging the glabellar soft tissue and that of damaging the meninges during a frontal sinusotomy was evaluated, respectively, at 9.6% and 26.1% for CT scans of the facial bone, and at 6.2% and 21.5% for sinus scans. CONCLUSIONS: CT scans of the facial bone are better than CT scans of the sinuses for identifying ethmoidal slits and their distance from the canal of the anterior ethmoidal artery. The identification of these elements is relevant for the surgeon during frontal sinus surgery and makes it possible to assess the risk of damaging the glabellar soft tissue or meninges. Performing a CT scan of the facial bone seems preferable to that of a CT scan of the sinuses in certain pathological situations, such as cerebrospinal rhinorrhea or revision surgeries of the frontal sinus.

The advantages of modified Thiel technique in head and neck surgical anatomy teaching.

PURPOSE: Thiel's body preservation method allows the donor body to retain color and soft tissue that are similar to those of a living individual. Since its initial description, the technique has not been developed much. Here, we propose a simpler protocol applied to the head and neck, making the technique easier, cheaper, and more accessible to a greater number of medical schools. METHODS: The modified Thiel technique was applied to three heads separated from the body, followed by 6 h of perfusion and 6 weeks of fixation. This technique was compared with formalin (three heads) and freeze (three heads) preservations during academic training in head and neck surgery. Anatomical dissections included a parotid gland dissection, a submandibular gland dissection, an otologic and an endonasal dissection. Twelve surgeons blindly assessed the three types of preservations using a standardized questionnaire. RESULTS: The modified Thiel technique made possible better quality of dissection and tissue identification, with the exception of endonasal dissection. Concerning the endonasal dissection, the modified Thiel technique ranked best for smell, but all other criteria ranked lower than the freezing method. For the submandibular and parotid gland dissections, the modified Thiel technique was ranked best, with statistically significant differences (p < 0.002) for all items. The modified Thiel technique also ranked significantly better during otologic surgery regarding the quality of the skin/eardrum, bone, and muscle, and the smell. CONCLUSION: This study demonstrated that the modified Thiel technique is an embalming technique which improves the quality of head and neck surgical anatomy education.

Motion Sickness Lessons from the Southern Ocean.

BACKGROUND: The objectives were to assess the prevalence, severity, and medication taken, and to look for predictive factors in order to better identify characteristics of passengers at risk of motion sickness during transport from Hobart in Tasmania to the French polar stations in Antarctica. METHODS: There were 239 passengers who were surveyed over 4 yr with 4 round trips per year using the Motion Sickness Susceptibility Questionnaire (MSSQ), Simulator Sickness Questionnaire (SSQ), state-trait anxiety test (STAI-Trait and STAI-State), and general parameters (age, gender, number of trips, jet-lag, direction of the trip), medication, calculation of the distance of each passengers cabin to the center of gravity (CoG). RESULTS: While the passengers had a low intrinsic sensitivity to motion sickness (MSSQ), 94 reported at least one SSQ symptom of motion sickness, and 38 vomited. Five associated factors were discovered: greater initial sensitivity (MSSQ), anticipation of being ill, younger age, higher level of anxiety at midtrip, and greater distance from the CoG. Of the passengers, there were 54 who took anti-motion sickness medication at different times of the trip, however, these passengers experienced more nausea. This could be due to self-selection since they were more sensitive to motion sickness. CONCLUSION: We identified three predictive factors of motion sickness (greater intrinsic susceptibility, younger age, and greater cabin distance from the CoG). For preventive purposes, two associated factors of MS (anticipation of being ill, MSSQ score) were determined to classify three groups of risk of MS to improve passenger care during the trip. Besnard S, Bois J, Hitier M, Vogt J, Laforet P, Golding JF. Motion sickness lessons from the Southern Ocean. Aerosp Med Hum Perform. 2021; 92(9):720727.

Impaired Attentional Processing During Parabolic Flight.

Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight experiments on attentional processes. To address this gap, we investigated the level of alertness, selective and sustained attention in 1 and 0 g using a Go/No-Go Continuous Performance Task. We also identified several parameters associated with the experimental set-up of a parabolic flight that could be expected to affect attentional processing. These included the use of scopolamine, sleep quality prior to the flight day, participant's stress level as well as mood and anxiety state before and after the parabolic flight. We observed a deterioration in attentional processing prior to the first parabola that was further aggravated in weightlessness and returned to baseline after the last parabola. Reaction Time, Hit and False Alarm Rate were moderately correlated with self-reported anxiety state, but not cortisol levels or emotional states. The use of scopolamine had minor effects on Reaction Time. Our results confirm previous studies reporting impairments of cognitive performance in 0 g, and highlight important aspects that should be considered for the design of behavioral research experiments in future parabolic flight campaigns.

Stratification of hippocampal electrophysiological activation evoked by selective electrical stimulation of different angular and linear acceleration sensors in the rat peripheral vestibular system.

It has become well established that vestibular information is important for hippocampal function and spatial memory. However, as yet, relatively little is known about how different kinds of vestibular information are 'represented' in different parts of the hippocampus. This study used selective electrical stimulation of each of the 5 vestibular sensors (the horizontal (HC), anterior (AC) and posterior (PC) semi-circular canals, and the utricle and saccule) in the rat and recorded local field potentials (LFPs) across the hippocampus, using a 16 electrode microarray. We found that stimulation of any vestibular sensor in the left labyrinth evoked triphasic LFPs in both hippocampi, although it was clear that, in general, the amplitudes were greater for the right, contralateral side. This was particularly true for Phase 1 for the HC, AC, utricle and saccule, Phase 2 for the HC, PC, utricle and saccule, and Phase 3 for the AC, PC and saccule. Overall, our results suggest that vestibular input to the hippocampus is bilateral, preferentially contralateral, but highly stratified in that stimulation of the same vestibular sensor results in activation of different specific areas of the hippocampus, with different LFP amplitudes and latencies. This suggests the possibility that different regions of the hippocampus use different kinds of vestibular information for different purposes and that there may be a high degree of redundancy in the representation of vestibular input, perhaps ensuring that the hippocampus is more robust to the partial loss of vestibular information.

The effects of selective electrical stimulation of the rat cochlea on hippocampal field potentials.

The hippocampus is a brain structure well known for its importance to spatial learning and memory. As such it is assumed to use multisensory integration in order to generate mathematical maps of the spatial environment. Auditory inputs to the hippocampus have been described to a limited extent. Although it has been demonstrated that natural auditory stimulation can evoke local field potentials (LFPs) and single neuron responses in the hippocampus, and that noise trauma and tinnitus can cause maladaptive hippocampal plasticity, to the best of our knowledge no one has selectively, electrically stimulated the cochlea and recorded electrophysiological responses in the hippocampus. Here, we used unilateral electrical cochlear stimulation in rats while recording LFPs in the hippocampus bilaterally, with a multi-electrode array. We observed triphasic LFP responses bilaterally from unilateral stimulation, but with larger amplitudes on the contralateral side, especially for Phase 1 and 3 of the LFP, for which the latencies were also longer. The latencies under urethane anaesthesia were consistent with auditory information from the cochlea travelling across approximately 6-7 synapses. These data demonstrate that the cochlea contributes a powerful auditory input to the hippocampus, which is also lateralized, and may have implications for spatial cognition in cochlear implant patients.

New landmarks in endonasal surgery: from nasal bone to anterior cribriform plate including branches of anterior ethmoidal artery and nerve and terminal nerve.

BACKGROUND: Despite the development of anterior skull base surgery, the anatomy of the nasal bone and anterior cribriform plate remains unclear. A recent study confirmed 2 distinct foramina in the anterior part of cribriform plate: the ethmoidal slit (ES) and the cribroethmoidal foramen (CF). The aim of this study was to specify their content, their anatomic relationship to the frontal sinus and skull base, and their potential value in skull base surgery. METHODS: Dissections were performed on 36 cadaver heads. Macro- and microscopic examinations were carried out. Microcomputed tomography scans contrasted with osmium were performed to identify vessels and nerves. Histology with neural, meningeal, or luteinizing hormone-releasing hormone immunomarkers was performed on the content of the foramina. Finally, endonasal surgical dissections were carried out. RESULTS: The ES and the CF were observed in all cases. They measured a mean of 4.2 and 1.6 mm, respectively. The ES contained dura mater, arachnoid tissues, lymphatics, and the terminal nerve. The CF contained the anterior ethmoidal nerve and artery. This foramen continued forward with the cribroethmoidal groove, which measured a mean of 2.5 mm. This groove was under the frontal sinus and in front of the skull base. We also described a "cribroethmoidal canal" and a "nasal bone foramen." CONCLUSION: The clinical applications of this new anatomic description concern both cribriform plate and frontal sinus surgeries. Identifying the terminal nerve passing through the ES is a step forward in understanding pheromone recognition in humans.

New detailed description of the anterior part of the cribriform plate using anatomic specimens and computed tomography.

PURPOSE: Ethmoidal slit (ES) and cribroethmoidal foramen (CF) have been poorly studied, without any radiological description. They may ease cribriform plate's diseases. The objective was to describe the frequency, size, and computed tomography (CT) appearance of these foramina. METHODS: A two-part anatomoradiological study was performed: first on dry skulls using a surgical microscope and CT, second on patients CT scans. For each, foramina were searched for, described, and measured when possible. RESULTS: Thirteen dry macerated skulls were studied. The orbitomeatal plane was relevant for studying ES. With microscope, ES and CF were identified in, respectively, 92% and 100% of cases. Using CT, all ES and CF were visible, with a mean length and width of, respectively, 3.9 ± 1.7 mm and 0.9 ± 0.3 mm for ES and 1.6 ± 1 mm and 0.9 ± 0.3 mm for CF. CT scans from 153 patients were reviewed. ES and CF were identified in, respectively, 80% and 91% of cases, with a mean length and width of, respectively, 3.9 ± 0.8 mm and 0.8 ± 0.2 mm for ES. CONCLUSION: Large-sized ES was found frequently, and were clearly visible in patients CT scans. CF was markedly smaller, but seen in most patient scans. ES and CF could be areas of least resistance in the anterior part of the cribriform plate. CT might be helpful in understanding their pathological implications.

The balance of sleep: Role of the vestibular sensory system.

The vestibular system encodes linear and angular head motion supporting numerous functions from gaze stabilization and postural control, to high-level cortical functions involving spatial cognition, including self-body perception, verticality perception, orientation, navigation and spatial memory. At the brainstem and mesencephalic levels, the vestibular organs also influence postural blood pressure regulation, bone density and muscle composition via specific vestibulo-sympathetic efferences and have been shown to act as a powerful synchronizer of circadian rhythms. Here, we review the evidence that sleep deprivation and sleep apnea syndrome alter vestibular-related oculo-motor and postural control, and that, in turn, vestibular pathologies induce sleep disturbances. We suggest that sleep-related neuroplasticity might serve the adaptation and compensation processes following vestibular lesions in patients. Interestingly, a reciprocal neuroanatomical route between the vestibular nuclei and the orexinergic neurons has been reported. While orexinergic modulation of the vestibular nuclei related to postural control has been suggested, we postulate that vestibular inputs might in turn influence the sleep-wake state switch, informing the brain about the daily quantity of motion.

Vestibular-related eye movements in the rat following selective electrical stimulation of the vestibular sensors.

Rats are the most commonly used species in the neurosciences; however, little is known about the effects of selective electrical stimulation of individual vestibular sensors, on their eye movements. This limits their use to study the effects of vestibular stimulation on the brain, and their use in further exploring novel technologies such as artificial vestibular implants. We describe the effects of electrical stimulation of each vestibular sensor on vestibular-related eye movement in rats and compared the results to other species. We demonstrated that each sensor is responsible for specific bilateral eye movements. We found that the eye movements in rats differed from other species. Although the results were similar when stimulating the horizontal canal ampulla, differences appeared when stimulating the vertical canal sensors. During utricular stimulation, the ipsilateral eye moved dorsally in most cases, while the contralateral eye usually moved either caudally, or in extorsion. Saccular stimulation usually moved the ipsilateral eye dorsally or ventrally, while the contralateral eye usually moved ventrally or caudally. This study provides the first data on the application of selective electrical vestibular stimulation in the rat to the study of vestibular-related eye movements.

Differential regulation of NMDA receptor-expressing neurons in the rat hippocampus and striatum following bilateral vestibular loss demonstrated using flow cytometry.

There is substantial evidence that loss of vestibular function impairs spatial learning and memory related to hippocampal (HPC) function, as well as increasing evidence that striatal (Str) plasticity is also implicated. Since the N-methyl-d-aspartate (NMDA) subtype of glutamate receptor is considered essential to spatial memory, previous studies have investigated whether the expression of HPC NMDA receptors changes following vestibular loss; however, the results have been contradictory. Here we used a novel flow cytometric method to quantify the number of neurons expressing NMDA receptors in the HPC and Str following bilateral vestibular loss (BVL) in rats. At 7 and 30 days post-op., there was a significant increase in the number of HPC neurons expressing NMDA receptors in the BVL animals, compared to sham controls (P ≤ 0.004 and P ≤ 0.0001, respectively). By contrast, in the Str, at 7 days there was a significant reduction in the number of neurons expressing NMDA receptors in the BVL group (P ≤ 0.05); however, this difference had disappeared by 30 days post-op. These results suggest that BVL causes differential changes in the number of neurons expressing NMDA receptors in the HPC and Str, which may be related to its long-term impairment of spatial memory.

Effects of electrical stimulation of the rat vestibular labyrinth on c-Fos expression in the hippocampus.

Several studies have demonstrated that electrical activation of the peripheral vestibular system can evoke field potential, multi-unit neuronal activity and acetylcholine release in the hippocampus (HPC). However, no study to date has employed the immediate early gene protein, c-Fos, to investigate the distribution of activation of cells in the HPC following electrical stimulation of the vestibular system. We found that vestibular stimulation increased the number of animals expressing c-Fos in the dorsal HPC compared to sham control rats (P ≤ 0.02), but not in the ventral HPC. c-Fos was also expressed in an increased number of animals in the dorsal dentate gyrus (DG) compared to sham control rats (P ≤ 0.0001), and to a lesser extent in the ventral DG (P ≤ 0.006). The results of this study show that activation of the vestibular system results in a differential increase in the expression of c-Fos across different regions of the HPC.

Extended endonasal approach versus maxillary swing approach to the parapharyngeal space.

BACKGROUND: The nasopharyngeal and parapharyngeal spaces are difficult for surgeons to access. Of the various external routes described, the maxillary swing has emerged as the gold standard because of its simplicity. However, its morbidity has led to the development of less invasive techniques. The purpose of our study was to compare the surgical anatomy of the maxillary swing with that of the endoscopic endonasal approach. METHODS: Each procedure was performed on 10 anatomic specimens. The exposure and the limits obtained were evaluated. A CT scan analysis was performed. RESULTS: The endoscopic endonasal approach extended the limits, offering wider exposure. The endoscopic endonasal approach made possible better visualization of deep structures and precise dissection of the parapharyngeal spaces. However, the maxillary swing provided better access to the oropharynx and could be completed 3 times faster. CONCLUSION: The endoscopic endonasal approach provides excellent exposure, a wide dissection range, and precise definition of anatomic structures, making it an alternative of choice rather than the maxillary swing approach.

Celio-mesenteric trunk associated with giant omphalocele: surgical consequences / Tronco celíaco-mesentérico asociado con onfalocele gigante: consecuencias quirúrgicas

We report the first case of a newborn presenting with a celio-mesenteric trunk variation associated with a giant omphalocele. The celio-mesenteric trunk was unexpected and unseen during the staged surgical closure. After partial reintegration of the liver, the newborn presented refractory hypovolemia with anuria, leading to redo surgery. This procedure revealed ischemia of the liver and necrosis of the entire gastrointestinal tract except the colon. Despite treatment, including liver externalization, the infant did not survive. The autopsy revealed a celio-mesenteric trunk, a rare anomaly characterized by a common origin of the celiac axis and the superior mesenteric artery from the aorta. This association may explain the dramatic consequences of the staged closure procedure. Awareness of the association of celio-mesenteric trunk and omphalocele would allow the surgeon to take extra care during this delicate surgery.

Presentamos el primer caso de un recién nacido que presenta una variación del tronco celíaco-mesentérico asociada con un onfalocele gigante. El tronco celíaco-mesentérico fue inesperado y no se vio durante las etapas del cierre quirúrgico. Después de la reintegración parcial del hígado, el recién nacido presentó hipovolemia refractaria con anuria, lo que condujo a la repetición de la cirugía. Este procedimiento reveló isquemia del hígado y necrosis de todo el tracto gastrointestinal excepto el colon. A pesar del tratamiento, incluyendo la externalización hepática, el bebé no sobrevivió. La autopsia reveló un tronco celíaco-mesentérico, una rara anomalía caracterizada por un origen común del tronco celíaco y la arteria mesentérica superior, a partir de la aorta. Esta asociación puede explicar las dramáticas consecuencias del procedimiento durante las etapas del cierre. El conocimiento de la asociación de tronco celíaco-mesentérico y onfalocele permitiría al cirujano tomar especial cuidado durante esta delicada cirugía.