Towards understanding the presence/absence of Human African Trypanosomosis in a focus of Côte d'Ivoire: a spatial analysis of the pathogenic system

BACKGROUND: This study aimed at identifying factors influencing the development of Human African Trypanosomosis (HAT, or sleeping sickness) in the focus of Bonon, located in the mesophile forest of Côte d'Ivoire. A previous study mapping the main daytime activity sites of 96 patients revealed an important disparity between the area south of the town- where all the patients lived- and the area north of the town, apparently free of disease. In order to explain this disparity, we carried out a spatial analysis of the key components of the pathogenic system, i.e. the human host, the tsetse vector and the trypanosomes in their environment using a geographic information system (GIS). RESULTS: This approach at the scale of a HAT focus enabled us to identify spatial patterns which linked to the transmission and the dissemination of this disease. The history of human settlement (with the rural northern area exploited much earlier than the southern one) appears to be a major factor which determines the land use pattern, which itself may account for differences found in vector densities (tsetse were found six times more abundant in the southern rural area than in the northern). Vector density, according to the human and environmental context in which it is found (here an intense mobility between the town of Bonon and the rural areas), may explain the observed spatial differences in HAT prevalence. CONCLUSION: This work demonstrates the role of GIS analyses of key components of the pathogenic system in providing a better understanding of transmission and dissemination of HAT. Moreover, following the identification of the most active transmission areas, and of an area unfavourable to HAT transmission, this study more precisely delineates the boundaries of the Bonon focus. As a follow-up, targeted tsetse control activities starting north of Bonon (with few chances of reinvasion due to very low densities) going south, and additional medical surveys in the south will be proposed to the Ivoirian HAT control program to enhance the control of the disease in this focus. This work also shows the evolution of HAT regarding time and environment, and the methodology used may be able to predict possible sleeping sickness development/extinction in areas with similar history and space organization

Evaluation of a virtual agent to train medical students conducting psychiatric interviews for diagnosing major depressive disorders

Background: A psychiatric diagnosis involves the physician's ability to create an empathic interaction with the patient in order to accurately extract semiology (i.e., clinical manifestations). Virtual patients (VPs) can be used to train these skills but need to be evaluated in terms of accuracy, and to be perceived positively by users. Methods: We recruited 35 medical students who interacted in a 35-min psychiatric interview with a VP simulating major depressive disorders. Semiology extraction, verbal and non-verbal empathy were measured objectively during the interaction. The students were then debriefed to collect their experience with the VP. Results: The VP was able to simulate the conduction of a psychiatric interview realistically, and was effective to discriminate students depending on their psychiatric knowledge. Results suggest that students managed to keep an emotional distance during the interview and show the added value of emotion recognition software to measure empathy in psychiatry training. Students provided positive feedback regarding pedagogic usefulness, realism and enjoyment in the interaction. Limitations: Our sample was relatively small. As a first prototype, the measures taken by the VP would need improvement (subtler empathic questions, levels of difficulty). The face-tracking technique might induce errors in detecting non-verbal empathy. Conclusion: This study is the first to simulate a realistic psychiatric interview and to measure both skills needed by future psychiatrists: semiology extraction and empathic communication. Results provide evidence that VPs are acceptable by medical students, and highlight their relevance to complement existing training and evaluation tools in the field of affective disorders.Bordeaux Region Aquitaine Initiative for NeurosciencePhénotypage humain et réalité virtuelleInitiative d'excellence de l'Université de Bordeau

Prediction of Clinical Deep Brain Stimulation Target for Essential Tremor From 1.5 Tesla MRI Anatomical Landmarks

International audienceBackground: Deep brain stimulation is an efficacious treatment for refractory essential tremor, though targeting the intra-thalamic nuclei remains challenging. Objectives: We sought to develop an inverse approach to retrieve the position of the leads in a cohort of patients operated on with optimal clinical outcomes from anatomical landmarks identifiable by 1.5 Tesla magnetic resonance imaging. Methods: The learning database included clinical outcomes and post-operative imaging from which the coordinates of the active contacts and those of anatomical landmarks were extracted. We used machine learning regression methods to build three different prediction models. External validation was performed according to a leave-one-out cross-validation. Results: Fifteen patients (29 leads) were included, with a median tremor improvement of 72% on the Fahn-Tolosa-Marin scale. Kernel ridge regression, deep neural networks, and support vector regression (SVR) were used. SVR gave the best results with a mean error of 1.33 ± 1.64 mm between the predicted target and the active contact position. Conclusion: We report an original method for the targeting in deep brain stimulation for essential tremor based on patients' radio-anatomical features. This approach will be tested in a prospective clinical trial

Short and long term outcome of bilateral pallidal stimulation in chorea-acanthocytosis

BACKGROUND: Chorea-acanthocytosis (ChAc) is a neuroacanthocytosis syndrome presenting with severe movement disorders poorly responsive to drug therapy. Case reports suggest that bilateral deep brain stimulation (DBS) of the ventro-postero-lateral internal globus pallidus (GPi) may benefit these patients. To explore this issue, the present multicentre (n=12) retrospective study collected the short and long term outcome of 15 patients who underwent DBS. METHODS: Data were collected in a standardized way 2-6 months preoperatively, 1-5 months (early) and 6 months or more (late) after surgery at the last follow-up visit (mean follow-up: 29.5 months). RESULTS: Motor severity, assessed by the Unified Huntington's Disease Rating Scale-Motor Score, UHDRS-MS), was significantly reduced at both early and late post-surgery time points (mean improvement 54.3% and 44.1%, respectively). Functional capacity (UHDRS-Functional Capacity Score) was also significantly improved at both post-surgery time points (mean 75.5% and 73.3%, respectively), whereas incapacity (UHDRS-Independence Score) improvement reached significance at early post-surgery only (mean 37.3%). Long term significant improvement of motor symptom severity (≥ 20 % from baseline) was observed in 61.5 % of the patients. Chorea and dystonia improved, whereas effects on dysarthria and swallowing were variable. Parkinsonism did not improve. Linear regression analysis showed that preoperative motor severity predicted motor improvement at both post-surgery time points. The most serious adverse event was device infection and cerebral abscess, and one patient died suddenly of unclear cause, 4 years after surgery. CONCLUSION: This study shows that bilateral DBS of the GPi effectively reduces the severity of drug-resistant hyperkinetic movement disorders such as present in ChAc

Utilisation du test de concordance de script au cours du deuxième cycle des études médicales : expérience dans l’enseignement de la neurochirurgie

Contexte. Le test de concordance de script, largement diffusé en troisième cycle et en formation médicale continue, n’est en revanche pas utilisé au cours du deuxième cycle des études médicales. Objectifs. Le but de ce travail est d’évaluer si le test de concordance de script peut être utilisé pour classer les étudiants en formation initiale de médecine. Matériel et méthodes. Un test constitué de trente items de neurochirurgie est soumis à 75 étudiants à l’issue d’un stage hospitalier de neurochirurgie (43 étudiants de deuxième année – DCEM2 –, 20 de troisième année – DCEM3 – et 12 de quatrième année – DCEM4 – du deuxième cycle des études médicales). Résultats. Les scores moyens (sur 100 points) étaient de 51,84±8,22, 54,94±7,30 et 59,78±6,08 respectivement pour les trois groupes d’étudiants. L’analyse de variance mettait en évidence une différence globalement significative entre les groupes (p = 0,0076). Les tests post-hoc réalisés avec le test t de Student n’ont mis en évidence qu’une différence significative 2 à 2 entre les groupes DCEM2 vs: DCEM4 (p = 0,003). Conclusion. Nos résultats suggèrent que le test de concordance de script peut montrer une progression des capacités de raisonnement clinique au cours du deuxième cycle. Cela pose la question de son utilisation éventuelle dans le cadre des épreuves classantes nationales françaises

Comparison of two segmentation software tools for deep brain stimulation of the subthalamic and ventro-intermedius nuclei

International audiencePurpose: Deep brain stimulation (DBS) relies on precise targeting of key structures such as the subthalamic nucleus (STN)for Parkinson’s disease (PD) and the ventro-intermedius nucleus of the thalamus (Vim) for essential tremor (ET). Segmentation software, such as GuideXT© and Suretune©, are commercially available for atlas-based identification of deep brain structures. However, no study has compared the concordance of the segmentation results between the two software.Methods: We retrospectively compared the concordance of segmentation of GuideXT© and Suretune© software by comparing the position of the segmented key structures with clinically predicted targets obtained using the newly developed RebrAIn© software as a reference.Results: We targeted the STN in 44 MRI from PD patients (88 hemispheres) and the Vim in 31 MRI from ET patients (62 hemispheres) who were elected for DBS. In 22 STN targeting (25%), the target positioning was not correlating between GuideXT© and Suretune©. Regarding the Vim, targets were located in the segmented Vim in 37%, the posterior subthalamic area (PSA) in 60%, and the STN in 3% of the cases using GuideXT©; the proportions were 34%, 60%, and 6%, respectively, using Suretune©. The mean distance from the centre of the RebrAIn© targeting to the segmented Vim by Suretune© was closer (0.64 mm) than with GuideXT© (0.96 mm; p = 0.0004).Conclusion: While there is some level of concordance in the segmentation results of key structures for DBS treatment among software models, differences persist. Therefore, such software should still be considered as tools and should not replace clinician experience in DBS planning