Prediction in forensic science: a critical examination of common understandings

In this commentary, we argue that the term 'prediction' is overly used when in fact, referring to foundational writings of de Finetti, the correspondent term should be inference. In particular, we intend (i) to summarize and clarify relevant subject matter on prediction from established statistical theory, and (ii) point out the logic of this understanding with respect practical uses of the term prediction. Written from an interdisciplinary perspective, associating statistics and forensic science as an example, this discussion also connects to related fields such as medical diagnosis and other areas of application where reasoning based on scientific results is practiced in societal relevant contexts. This includes forensic psychology that uses prediction as part of its vocabulary when dealing with matters that arise in the course of legal proceedings.

Comparison of electrical nerve stimulation, electrical muscle stimulation and magnetic nerve stimulation to assess the neuromuscular function of the plantar flexor muscles.

INTRODUCTION: As it might lead to less discomfort, magnetic nerve stimulation (MNS) is increasingly used as an alternative to electrical stimulation methods. Yet, MNS and electrical nerve stimulation (ENS) and electrical muscle stimulation (EMS) have not been formally compared for the evaluation of plantar flexor neuromuscular function. METHODS: We quantified plantar flexor neuromuscular function with ENS, EMS and MNS in 10 volunteers in fresh and fatigued muscles. Central alterations were assessed through changes in voluntary activation level (VAL) and peripheral function through changes in M-wave, twitch and doublet (PS100) amplitudes. Discomfort associated with 100-Hz paired stimuli delivered with each method was evaluated on a 10-cm visual analog scale. RESULTS: VAL, agonist and antagonist M-wave amplitudes and PS100 were similar between the different methods in both fresh and fatigued states. Potentiated peak twitch was lower in EMS compared to ENS, whereas no difference was found between ENS and MNS for any parameter. Discomfort associated with MNS (1.5 ± 1.4 cm) was significantly less compared to ENS (5.5 ± 1.9 cm) and EMS (4.2 ± 2.6 cm) (p < 0.05). CONCLUSION: When PS100 is used to evaluate neuromuscular properties, MNS, EMS and ENS can be used interchangeably for plantar flexor neuromuscular function assessment as they provide similar evaluation of central and peripheral factors in unfatigued and fatigued states. Importantly, electrical current spread to antagonist muscles was similar between the three methods while discomfort from MNS was much less compared to ENS and EMS. MNS may be potentially employed to assess neuromuscular function of plantar flexor muscles in fragile populations.

Fatal Cervical Spine Injury From Diving Accident.

Spinal cord injuries result after diving into shallow water, often after incautious jumps head first into water of unknown depth during recreational or sport activities. Mortality is generally due to upper cervical trauma. The authors present a case of a diving-related death in a young woman who underwent medicolegal investigations. The measured water depth at the supposed dive site was 1.40 m. Postmortem radiology and autopsy revealed fractures of the body and the posterior arch of the fifth cervical vertebra, a fracture of the right transverse process of the sixth cervical vertebra and hemorrhages involving the cervical paraspinal muscles. Neuropathology showed a posterior epidural hematoma involving the whole cervical region and a symmetric laceration of the spinal cord located at the fourth and fifth cervical vertebra level, surrounded by multiple petechial hemorrhages. Toxicology revealed the presence of ethanol in both blood and urine samples. The death was attributed to cervical spine fracture (C5-C6), spinal cord contusion, and subsequent drowning. This case highlights the usefulness of postmortem radiology, examination of the deep structures of the neck, toxicology, neuropathology, and a detailed research of signs of drowning to formulate appropriate hypotheses pertaining to the cause and mechanism of death.

Application of intravoxel incoherent motion perfusion imaging to shoulder muscles after a lift-off test of varying duration.

Intravoxel incoherent motion (IVIM) MRI is a method to extract microvascular blood flow information out of diffusion-weighted images acquired at multiple b-values. We hypothesized that IVIM can identify the muscles selectively involved in a specific task, by measuring changes in activity-induced local muscular perfusion after exercise. We tested this hypothesis using a widely used clinical maneuver, the lift-off test, which is known to assess specifically the subscapularis muscle functional integrity. Twelve shoulders from six healthy male volunteers were imaged at 3 T, at rest, as well as after a lift-off test hold against resistance for 30 s, 1 and 2 min respectively, in three independent sessions. IVIM parameters, consisting of perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient D* and blood flow-related fD*, were estimated within outlined muscles of the rotator cuff and the deltoid bundles. The mean values at rest and after the lift-off tests were compared in each muscle using a one-way ANOVA. A statistically significant increase in fD* was measured in the subscapularis, after a lift-off test of any duration, as well as in D. A fD* increase was the most marked (30 s, +103%; 1 min, +130%; 2 min, +156%) and was gradual with the duration of the test (in 10(-3) mm(2) /s: rest, 1.41 ± 0.50; 30 s, 2.86 ± 1.17; 1 min, 3.23 ± 1.22; 2 min, 3.60 ± 1.21). A significant increase in fD* and D was also visible in the posterior bundle of the deltoid. No significant change was consistently visible in the other investigated muscles of the rotator cuff and the other bundles of the deltoid. In conclusion, IVIM fD* allows the demonstration of a task-related microvascular perfusion increase after a specific task and suggests a direct relationship between microvascular perfusion and the duration of the effort. It is a promising method to investigate non-invasively skeletal muscle physiology and clinical perfusion-related muscular disorders.

The new final Clinical Skills examination in human medicine in Switzerland: Essential steps of exam development, implementation and evaluation, and central insights from the perspective of the national Working Group.

OBJECTIVE: Since 2011, the new national final examination in human medicine has been implemented in Switzerland, with a structured clinical-practical part in the OSCE format. From the perspective of the national Working Group, the current article describes the essential steps in the development, implementation and evaluation of the Federal Licensing Examination Clinical Skills (FLE CS) as well as the applied quality assurance measures. Finally, central insights gained from the last years are presented. METHODS: Based on the principles of action research, the FLE CS is in a constant state of further development. On the foundation of systematically documented experiences from previous years, in the Working Group, unresolved questions are discussed and resulting solution approaches are substantiated (planning), implemented in the examination (implementation) and subsequently evaluated (reflection). The presented results are the product of this iterative procedure. RESULTS: The FLE CS is created by experts from all faculties and subject areas in a multistage process. The examination is administered in German and French on a decentralised basis and consists of twelve interdisciplinary stations per candidate. As important quality assurance measures, the national Review Board (content validation) and the meetings of the standardised patient trainers (standardisation) have proven worthwhile. The statistical analyses show good measurement reliability and support the construct validity of the examination. Among the central insights of the past years, it has been established that the consistent implementation of the principles of action research contributes to the successful further development of the examination. CONCLUSION: The centrally coordinated, collaborative-iterative process, incorporating experts from all faculties, makes a fundamental contribution to the quality of the FLE CS. The processes and insights presented here can be useful for others planning a similar undertaking.

The analgesic efficacy of ultrasound-guided transversus abdominis plane block (TAP Block) in adult patients : a meta-analysis

Introduction : Le bloc transverse de l'abdomen (bloc TAP, Transversus Abdominis Plane) échoguidé consiste en l'injection d'anesthésique local dans la paroi abdominale entre les muscles oblique interne et transverse de l'abdomen sous contrôle échographique. Ceci permet de bloquer l'innervation sensitive de la paroi antérolatérale de l'abdomen afin de soulager la douleur après des interventions chirurgicales. Auparavant, cette procédure reposait sur une technique dite « à l'aveugle » qui utilisait des repères anatomiques de surface. Depuis quelques années, cette technique est effectuée sous guidage échographique ; ainsi, il est possible de visualiser les structures anatomiques, l'aiguille et l'anesthésique local permettant ainsi une injection précise de l'anesthésique local à l'endroit désiré. Les précédentes méta- analyses sur le bloc TAP n'ont inclus qu'un nombre limité d'articles et n'ont pas examiné l'effet analgésique spécifique de la technique échoguidée. L'objectif de cette méta-analyse est donc de définir l'efficacité analgésique propre du bloc TAP échoguidé après des interventions abdominales chez une population adulte. Méthode : Cette méta-analyse a été effectuée selon les recommandations PRISMA. Une recherche a été effectuée dans les bases de donnée MEDLINE, Cochrane Central Register of Controlled Clinical Trials, Excerpta Medica database (EMBASE) et Cumulative Index to Nursing and Allied Health Literature (CINAHL). Le critère de jugement principal est la consommation intraveineuse de morphine cumulée à 6 h postopératoires, analysée selon le type de chirurgie (laparotomie, laparoscopie, césarienne), la technique anesthésique (anesthésie générale, anesthésie spinale avec/ou sans morphine intrathécale), le moment de l'injection (début ou fin de l'intervention), et la présence ou non d'une analgésie multimodale. Les critères de jugement secondaires sont, entre autres, les scores de douleur au repos et à l'effort à 6 h postopératoires (échelle analogique de 0 à 100), la présence ou non de nausées et vomissements postopératoires, la présence ou non de prurit, et le taux de complications de la technique. Résultats : Trente et une études randomisées contrôlées, incluant un total de 1611 adultes ont été incluses. Indépendamment du type de chirurgie, le bloc TAP échoguidé réduit la consommation de morphine à 6 h postopératoires (différence moyenne : 6 mg ; 95%IC : -7, -4 mg ; I =94% ; p<0.00001), sauf si les patients sont au bénéfice d'une anesthésie spinale avec morphine intrathécale. Le degré de réduction de consommation de morphine n'est pas influencé par le moment de l'injection (I2=0% ; p=0.72) ou la présence d'une analgésie multimodale (I2=73% ; p=0.05). Les scores de douleurs au repos et à l'effort à 6h postopératoire sont également réduits (différence moyenne au repos : -10 ; 95%IC : -15, -5 ; I =92% ; p=0.0002; différence moyenne en mouvement : -9 ; 95%IC : -14, -5 ; I2=58% ; p<0. 00001). Aucune différence n'a été retrouvée au niveau des nausées et vomissements postopératoires et du prurit. Deux complications mineures ont été identifiées (1 hématome, 1 réaction anaphylactoïde sur 1028 patients). Conclusions : Le bloc TAP échoguidé procure une analgésie postopératoire mineure et ne présente aucun bénéfice chez les patients ayant reçu de la morphine intrathécale. L'effet analgésique mineure est indépendant du moment de l'injection ou de la présence ou non d'une analgésie multimodale.