Search

Background: Balance control performance after vestibular schwannoma surgical removal follows a course that is characterised by a deterioration in postural performance immediately after unilateral vestibular deafferentation (uVD) and a recovery process (vestibular compensation). However, sensory strategies for balance vary during tumoral growth, which could lead to differences in the preferential use of sensory afferences. This longitudinal study aimed to assess the post-operative sensorimotor strategies of postural regulation according to sensory preference of balance control before surgery. Methods: Twenty-two patients with vestibular schwannoma (11 relying less on vision (61), 11 relying more on vision (62), to control balance before surgery), underwent vestibular, subjective visual vertical (SW), static posturography and sensory organisation (SOT) tests, before and 8 days, 1 and 3 months after surgery. Results: In 61 patients, little static posturographic and SOT performance deterioration after uVO was observed, despite vestibular test and SW modifications. In 62 patients, uVD-related modifications followed a time-course characterised by a degradation in posturographic and SOT, vestibular and SW performances immediately after uVO and a progressive restoration and even improvement 1 month and particularly 3 months after surgery. Conclusions: High preference for vision before surgery intervenes in postural degradation immediately after surgery, thus delaying the short-term effects of vestibular compensation on postural control. Long-term performance being similar whatever the visual status before surgery, the time-dependent implementation of the central adaptive mechanisms due to neuroplasticity leads to a modification of neurosensory information hierarchy, allowing reliance on appropriate information, the gain varying according to the postural task to be performed. [ABSTRACT FROM AUTHOR]

Fractures of the distal extremity of the tibia include physeal injuries among teenagers and more complex fractures among adults. Displacement causes the compression of the muscles located between the distal tibia and the superior extensor retinaculum (SER). Among the muscles of anterior compartment of the leg, the extensor hallucis longus (EHL) is particularly vulnerable due to the amount of muscle fibers extending under the SER. Consequently, a partial anterior compartment syndrome could result, affecting only the distal portion located under the SER. In clinical practice, Mubarak measured the intramuscular pressure isolated under the SER and suggested the physio-pathological hypothesis of a compression of distal muscle fibers. The aim of this study is to compare the ratios of anterior compartment muscle fibers extending under the SER. Twenty legs were dissected in order to study how much of these muscles extend under the SER, their passages possibly dividing into two of the SER, as well as their vascularization and their innervation. On the last seven legs, the engagement of the muscles were measured in the spontaneous position and with a dorsal flexion of 0°. The posterior muscle fibers of this compartment always descend lower than the anterior fibers. EHL muscle fibers and those of the inconsistent fibularis tertius always extend under the retinaculum, unlike those of the tibialis anterior and of the extensor digitorum longus. The EHL muscle extends under the SER more than the other muscles. Its posterior fibers are longer when this muscle goes through a dividing into two of the retinaculum. Its vascularization seems lesser, which could explain why this muscle tends to suffer more. The deep fibular nerve innervates the anterior compartment of the leg, yet no nerve branches can be found under the upper edge of the retinaculum. In all cases, the muscle fibers do not extend as much under the SER in a 0° of dorsal flexion. This anatomical study allows us to explain why the EHL is more likely to suffer from this partial compartment syndrome and confirms that when the latter occurs it is necessary, in all cases, to do emergency surgery opening the distal crural fascia and necessarily including the SER. [ABSTRACT FROM AUTHOR]

Background: Parkinson's disease (PD), the most common basal ganglia degenerative disease, affects balance control, especially when patients change balance strategy during postural tasks. Bilateral chronic stimulation of the subthalamic nucleus (STN) is therapeutically useful in advanced PD, and reduces the motor signs of patients. Nevertheless, the effects of STN stimulation on postural control are still debatable.Aims: To assess the impact of bilateral STN stimulation on balance control in PD and to determine how basal ganglia related sensorimotor modifications act on neurosensorial organisation of balance and motor postural programming.Methods: Twelve subjects aged 45-70 years underwent unified Parkinson's disease rating scale motor (part III) clinical tests, static and dynamic posturography, including sensory organisation and adaptation tests, shortly before and six months after bilateral implantation of electrodes into the STN.Results: The postoperative static test showed an improvement in postural control precision both in eyes open and eyes closed conditions. The dynamic test highlighted the decreased number of falls and the ability of the patients to develop more appropriate sensorimotor strategies when stimulated. The sensory organisation test showed an improvement of equilibrium score and, thus, a better resolution of sensorial conflicts.Conclusions: STN stimulation allowed a reduction in rigidity and therefore an improvement in the ability to use muscular proprioception as reliable information, resulting in vestibulo-proprioceptive conflict suppression. STN stimulation has a synergistic effect with levodopa for postural control. Accordingly, non-dopaminergic pathways could be involved in postural regulation and STN stimulation may influence the functioning of these pathways. [ABSTRACT FROM AUTHOR]

Objectives. Musculoskeletal disorders (MSDs) represent a prevalent global occupational health concern, primarily associated with high biomechanical solicitations, mental workload and work pace. Although cobots have shown promise in reducing risks of MSDs, a question of interest still persists as to how the pace in hybrid human–machine collaboration will affect the operator, in terms of both physical and cognitive health and the production.Methods. This study aimed to analyse the impact of pace on productivity, operators’ posture and mental workload in a human–cobot collaboration. The study, involving 20 participants engaged in a collaborative task with a cobot under three cobot-led paces, assessed productivity rapid upper limb assessment (RULA) scores (posture), dual task performance (cognitive resources) and NASA task load index (NASA-TLX) scores (workload).Results. The findings revealed that an excessively high pace had counterproductive effects, leading to reduced efficiency and increased susceptibility to MSDs, both in terms of physical and mental workloads.Conclusion. In the context of a human–cobot collaboration, it is imperative to adapt the pace to operators’ abilities in order to ensure optimal productivity while preserving their health, emphasizing the need for a balanced approach to pace management in such collaborative work scenarios. [ABSTRACT FROM AUTHOR]

Objectives: T2*‐weighted magnetic resonance imaging (MRI) sequences have been identified as non‐invasive tools with which to study placental oxygenation in vivo. This study aimed to use these to investigate both static and dynamic responses to hyperoxia of the normal placenta across gestation. Methods: We conducted a single‐center prospective study including 52 uncomplicated pregnancies. Two T2*‐weighted sequences (T2* relaxometry) were performed, one before and one after maternal hyperoxia. The distribution of placental T2* values was modeled by fitting a gamma probability density function (T2* ~Γαβ), describing the structure of the histogram using the mean T2* value, the shape parameter (α) and the rate (β). A dynamic acquisition (blood‐oxygen‐level‐dependent (BOLD) MRI) was also performed before and during maternal oxygen supply, until placental oxygen saturation had been achieved. The signal change over time was modeled using a sigmoid function, to determine the intensity of enhancement (ΔBOLD (% with respect to baseline)), a temporal variation coefficient (λ (min–1), controlling the slope of the curve) and the maximum steepness (Vmax (% of placental enhancement/min)). Results: The histogram analysis of the T2* values in normoxia showed a whole‐placenta variation, with a decreasing linear trend in the mean T2* value (Pearson's correlation coefficient (R) = −0.83 (95% CI, −0.9 to −0.71), P < 0.001), along with an increasingly peaked and narrower distribution of T2* values with advancing gestation. After maternal hyperoxia, the mean T2* ratios (mean T2*hyperoxia/mean T2*baseline) were positively correlated with gestational age, while the other histogram parameters remained stable, suggesting a translation of the histogram towards higher values with a similar appearance after maternal hyperoxia. ΔBOLD showed a non‐linear increase across gestation. Conversely, λ showed an inverted trend across gestation, with a weaker correlation (R = −0.33 (95% CI, −0.58 to −0.02), P = 0.04, R2 = 0.1). As a combination of ΔBOLD and λ, the changes in Vmax throughout gestation were influenced mainly by the changes in ΔBOLD and showed a positive non‐linear correlation with gestational age. Conclusions: Our results suggest that the decrease in the T2* placental signal as gestation progresses does not reflect placental dysfunction. The BOLD dynamic signal change is representative of a free‐diffusion model of oxygenation and highlights the increasing differences in oxygen saturation between mother and fetus as gestation progresses (ΔBOLD) and in the placental permeability to oxygen (λ). © 2024 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Objectives: It has been suggested previously that the presence of Probst bundles (PB) in cases with a short corpus callosum (SCC) on diffusion tensor imaging (DTI) may help to differentiate between corpus callosal (CC) dysplasia and a variant of normal CC development. The objectives of this study were to compare DTI parameters between cases of SCC vs normal CC and between cases of SCC with PB (SCC‐PB+) vs SCC without PB (SCC‐PB–). Methods: This was a retrospective study of patients referred to the Necker Hospital in Paris, France, for magnetic resonance imaging (MRI) evaluation of an apparently isolated SCC detected by sonography between November 2016 and December 2022 (IRB: 00011928). MRI was performed using a 1.5‐Tesla Signa system. T2‐weighted axial and sagittal sequences of the fetal brain were used to measure the length and thickness of the CC. 16‐direction DTI axial brain sequences were performed to identify the presence of PB and to generate quantitative imaging parameters (fractional anisotropy (FA) and apparent diffusion coefficient (ADC)) of the entire CC, genu, body and splenium. Cases in which other associated brain abnormalities were detected on MRI were excluded. Cases were matched for fetal gender and gestational age with controls in a 1:3 ratio. Control cases were normal fetuses included in the LUMIERE on the FETUS trial (NCT04142606) that underwent the same DTI evaluation of the brain. Comparisons between SCC and normal CC cases, and between SCC‐PB+ and SCC‐PB– cases were performed using ANOVA and adjusted for potential confounders using ANCOVA. Results: Twenty‐two SCC cases were included and compared with 66 fetuses with a normal CC. In 10/22 (45.5%) cases of SCC, PB were identified. As expected, dimensions of the CC were significantly smaller in SCC compared with normal CC cases (all P < 0.01). In SCC‐PB+ vs SCC‐PB– cases, FA values were significantly lower in the entire CC (median, 0.21 (range, 0.19–0.24) vs 0.24 (range, 0.22–0.28); P < 0.01), genu (median, 0.21 (range, 0.15–0.29) vs 0.24 (range, 0.17–0.29); P = 0.04), body (median, 0.21 (range, 0.18–0.23) vs 0.23 (range, 0.21–0.27); P = 0.04) and splenium (median, 0.22 (range, 0.16–0.30) vs 0.25 (range, 0.20–0.29); P = 0.03). ADC values were significantly higher in the entire CC, genu and body in SCC‐PB+ vs SCC‐PB– cases (all P < 0.05). In SCC‐PB+ cases, all FA values were significantly lower, and ADC values in the CC body were significantly higher compared with normal CC cases (all P < 0.05). In SCC‐PB– cases, there was no significant difference in FA and ADC compared with normal CC cases (all P > 0.05). Conclusions: Fetal DTI evaluation of the CC showed that FA values were significantly lower and ADC values tended to be significantly higher in SCC‐PB+ compared with normal CC cases. This may highlight alterations of the white matter microstructure in SCC‐PB+. In contrast, isolated SCC‐PB– did not demonstrate significant changes in DTI parameters, strengthening the possibility that this is a normal CC variant. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Objectives: Diffusion tensor imaging (DTI) of the fetal brain is a relatively new technique that allows evaluation of white matter tracts of the central nervous system throughout pregnancy, as well as in certain pathological conditions. The objectives of this study were to evaluate the feasibility of DTI of the spinal cord in utero and to examine gestational‐age (GA)‐related changes in DTI parameters during pregnancy. Methods: This was a prospective study conducted between December 2021 and June 2022 in the LUMIERE Platform, Necker–Enfants Malades Hospital, Paris, France, as part of the LUMIERE SUR LE FETUS trial. Women with a pregnancy between 18 and 36 weeks of gestation without fetal or maternal abnormality were eligible for inclusion. Sagittal diffusion‐weighted scans of the fetal spine were acquired, without sedation, using a 1.5‐Tesla magnetic resonance imaging scanner. The imaging parameters were as follows: 15 non‐collinear direction diffusion‐weighted magnetic‐pulsed gradients with a b‐value 700 s/mm2 and one B0 image without diffusion‐weighting; slice thickness, 3 mm; field of view (FOV), 36 mm; phase FOV, 1.00; voxel size, 4.5 × 2.8 × 3 mm3; number of slices, 7–10; repetition time, 2800 ms; echo time, minimum; and total acquisition time, 2.3 min. DTI parameters, including fractional anisotropy (FA) and apparent diffusion coefficient (ADC), were extracted at the cervical, upper thoracic, lower thoracic and lumbar levels of the spinal cord. Cases with motion degradation and those with aberrant reconstruction of the spinal cord on tractography were excluded. Pearson's correlation analysis was performed to evaluate GA‐related changes of DTI parameters during pregnancy. Results: During the study period, 42 pregnant women were included at a median GA of 29.3 (range, 22.0–35.7) weeks. Five (11.9%) patients were not included in the analysis because of fetal movement. Two (4.8%) patients with aberrant tractography reconstruction were also excluded from analysis. Acquisition of DTI parameters was feasible in all remaining cases (35/35). Increasing GA correlated with increasing FA averaged over the entire fetal spinal cord (r, 0.37; P < 0.01), as well as at the individual cervical (r, 0.519; P < 0.01), upper thoracic (r, 0.468; P < 0.01), lower thoracic (r, 0.425; P = 0.02) and lumbar (r, 0.427; P = 0.02) levels. There was no correlation between GA and ADC averaged over the entire spinal cord (r, 0.01; P = 0.99) or at the individual cervical (r, −0.109; P = 0.56), upper thoracic (r, −0.226; P = 0.22), lower thoracic (r, −0.052; P = 0.78) or lumbar (r, −0.11; P = 0.95) levels. Conclusions: This study shows that DTI of the spinal cord is feasible in normal fetuses in typical clinical practice and allows extraction of DTI parameters of the spinal cord. There is a significant GA‐related change in FA in the fetal spinal cord during pregnancy, which may result from decreasing water content as observed during myelination of fiber tracts occurring in utero. This study may serve as a basis for further investigation of DTI in the fetus, including research into its potential in pathological conditions that impact spinal cord development. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Diffusion tensor Imaging (DTI) and tractography offer a unique possibility to visualise and evaluate the developing white matter in fetal brain. DTI could be used to explore the normal spinal cord development and to study pathological development of the spinal cord. The aim of this preliminary study was to assess the feasibility of DTI and tractography in the evaluation of the fetal spinal cord. [Extracted from the article]

This article discusses the potential of "black bone" (BB) MRI imaging sequences as an alternative to conventional radiography for examining the skeleton in fetuses during post-mortem MRI examinations. The study involved 60 fetuses, and skeletal abnormalities were found in 31.6% of cases. The overall sensitivity and specificity of BB MRI for skeletal pathology were 89.4% and 97.5% respectively. The main limitation of fetal BB MRI sequences was the diagnosis of craniosynostosis. The authors conclude that BB MRI imaging sequences offer a radiation-free method for imaging the fetal skeleton and could be a potential alternative to radiography for analyzing bone anomalies. [Extracted from the article]

Idiopathic scoliosis (IS) is correlated with a muscular disequilibrium of the spine and an alteration of balance control, efficient performance of the latter being necessary for physical and sporting activities (PSA). However, the type of the IS curve has different effects on muscle and on balance control according to the primary curve location. This study aimed to determine the relationships between IS type and PSA practice. One hundred and sixty-nine girl adolescents with IS [double major curve (DMC) scoliosis: n=74; single major curve (SMC) scoliosis: n=95] and 100 age-matched control girl adolescents completed an epidemiological questionnaire informing on curricular and extracurricular PSA. Adolescents with DMC scoliosis practised more PSA than those with SMC scoliosis. Moreover, among all PSA referenced, gymnastic activities are the most practiced PSA both in IS teenagers, whatever the curve type, and in controls. Besides, teenagers practising gymnastics were more numerous in those with DMC scoliosis than those with SMC scoliosis and controls. The highest proportion of adolescents with DMC scoliosis practising PSA, especially gymnastics, could be linked to the fact that they are less subject to scoliosis-related biomechanical repercussions leading to a better balance control, which is essential in these PSA. [ABSTRACT FROM AUTHOR]

Highlights: [•] Postural control in degenerative cervical spine diseases was analyzed. [•] Posture was analyzed in unperturbed and optokinetic stimulation situations. [•] Two groups were formed according to discal or spondylotic nature of the disease. [•] Sensorial strategies in posture depended on the type of cervical pathology. [•] Surgery seemed to reduce visual contribution mostly in patients with spondylosis. [Copyright &y& Elsevier]

The influence of physical and sporting activities (PSA) on idiopathic scoliosis (IS) is still obscure. The aim of this study was to investigate whether such an influence exists and if so, to determine its characteristics. Two hundred and one teenagers with IS and a control group of 192 adolescents completed an epidemiological questionnaire. Those practising gymnastics were more numerous in the IS group than in the control group. Moreover, the practice of gymnastics was chosen before IS was diagnosed. As gymnastic activities are considered neither as a therapy nor as a precursor of IS, the distribution observed could be linked to a common factor that both increases the likelihood of IS and favors the practice of gymnastics. Joint laxity (JL) may be such a common factor, and was therefore tested (wrist and middle finger) on 42 girls with IS and 21 girls of a control group. IS patients, practising gymnastics or not, showed a higher JL than the control group practising gymnastics or not. Furthermore, the groups practising gymnastic activities did not show higher JL levels than the other groups. Children with a high JL could be drawn toward gymnastics because of their ability to adapt to the constraints of this sport. Girls with a high JL may therefore be prone to developing IS. The fact that most teenagers with IS practise gymnastics could be related to a higher JL. [ABSTRACT FROM AUTHOR]

Background: Ageing is associated with a reduction in balance, in particular through dysfunction of each level of postural control, which results in an increased risk of falling. Conversely, the practice of physical activities has been shown to modulate postural control in elderly people.Objective: This study examined the potential positive effects of two types of regular physical and sporting activities on vestibular information and their relation to posture.Methods: Gaze and postural stabilisation was evaluated by caloric and rotational vestibular tests on 18 healthy subjects over the age of 60 who regularly practised low-energy or bioenergetic physical activities and on 18 controls of a similar age who only walked on a regular basis. These subjects were also submitted to static and dynamic posturographic tests.Results: The control group displayed less balance control, with a lower vestibular sensitivity and a relatively high dependency on vision compared to the group practising low-energy physical activities, which had better postural control with good vestibular sensitivity and less dependency on vision. The postural control and vestibular sensitivity of subjects practising bioenergetic activities was average, and required higher visual afferent contribution.Conclusion: Low-energy exercises, already shown to have the most positive impact on balance control by relying more on proprioception, also appear to develop or maintain a high level of vestibular sensitivity allowing elderly people practising such exercises to reduce the weight of vision. [ABSTRACT FROM AUTHOR]

Despite well-documented neurotoxic and ototoxic properties, styrene remains commonly used in industry. Its effects on the cochlea have been extensively studied in animals, and epidemiological and animal evidence indicates an impact on balance. However, its influence on the peripheral vestibular receptor has yet to be investigated. Here, we assessed the vestibulotoxicity of styrene using an in vitro model, consisting of three-dimensional cultured newborn rat utricles filled with a high‑potassium (K+) endolymph-like fluid, called "cysts". K+ entry in the cyst ("influx") and its exit ("efflux") are controlled by secretory cells and hair cells, respectively. The vestibular epithelium's functionality is thus linked to K+ concentration, measured using a microelectrode. Known inhibitors of K+ efflux and influx validated the model. Cysts were subsequently exposed to styrene (0.25; 0.5; 0.75 and 1 mM) for 2 h or 72 h. The decrease in K+ concentration measured after both exposure durations was dose-dependent, and significant from 0.75 mM styrene. Vacuoles were visible in the cytoplasm of epithelial cells from 0.5 mM after 2 h and from 0.25 mM after 72 h. The results presented here are the first evidence that styrene may deregulate K+ homeostasis in the endolymphatic space, thereby altering the functionality of the vestibular receptor. • Styrene vestibulotoxicity was assessed in vitro with cultured rat utricles. • This model forms a sphere filled with high-K+ endolymph-like fluid. • Styrene causes a decrease of K+ concentration as soon as 2 h after treatment. • The decrease of K+ level was significant from 0.75 mM of styrene • Histopathological effects of styrene may appear prior to the decrease of K+ concentration. [ABSTRACT FROM AUTHOR]

The article presents a study aimed to define a model that is able to explain raw measurement data in the Closed-Loop ‘Perception–Cognition–Decision-Action' and to predict an increase in the falling risk. It mentions that the study is a biomechanical and human behavior assessment using virtual reality to challenge balance and posture for the elderly and patients with Parkinson's disease.