Static and dynamic responses to hyperoxia of normal placenta across gestation with T2*-weighted sequences.

OBJECTIVES: T2*-weighted sequences have been identified as non-invasive tools to study the placental oxygenation in-vivo. This study aims 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 were performed: T2*-relaxometry was performed before and after maternal hyperoxia. The histogram distribution of T2* values was assessed by fitting a gamma distribution as T2*~Γ(αß). A dynamic acquisition (BOLD protocol) was also performed before and during oxygen supply, until placental oxygen saturation. The signal change over time was modeled using a sigmoid function, used to determine the intensity of enhancement (∆BOLD,%), a temporal variation coefficient (λ,min-1 , controlling the slope of the curve), and the maximal steepness (Vmax, ∆BOLD.min-1 ) of placental enhancement. 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 (R= -0.83, 95% CI [-0.9, -0.71], p<0.001) along with a more peaked and narrower distribution of T2* values across 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 aspect. The ∆BOLD showed a non-linear increase across gestation. Conversely, the λ(min-1 ) parameter, showed an inverted trend across gestation, with a significantly weaker correlation (R = -0.33, 95% CI [-0.58, -0.02], p=0.04, R2 = 0.1). As a combination of ∆BOLD and λ, the changes in Vmax throughout gestation were mainly influenced by the changes in ∆BOLD and resulted in a positive non-linear correlation with gestational age. CONCLUSION: Our results suggest that the decrease in the T2* placental signal over gestation does not reflect a dysfunction. The BOLD effect, representative of a free-diffusion model of oxygenation, highlights the growing differences in oxygen saturation between mother and fetus across gestation (∆BOLD), and placental permeability to oxygen (λ). This article is protected by copyright. All rights reserved.

Quantitative fetal MRI with diffusion tensor imaging in cases with 'short' corpus callosum.

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.

Diffusion tensor imaging of fetal spinal cord: feasibility and gestational-age-related changes.

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.

Styrene alters potassium endolymphatic concentration in a model of cultured utricle explants.

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 high­potassium (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.

Visuo-proprioceptive interactions in degenerative cervical spine diseases requiring surgery.

Cervical proprioception plays a key role in postural control, but its specific contribution is controversial. Postural impairment was shown in whiplash injuries without demonstrating the sole involvement of the cervical spine. The consequences of degenerative cervical spine diseases are underreported in posture-related scientific literature in spite of their high prevalence. No report has focused on the two different mechanisms underlying cervicobrachial pain: herniated discs and spondylosis. This study aimed to evaluate postural control of two groups of patients with degenerative cervical spine diseases with or without optokinetic stimulation before and after surgical treatment. Seventeen patients with radiculopathy were recruited and divided into two groups according to the spondylotic or discal origin of the nerve compression. All patients and a control population of 31 healthy individuals underwent a static posturographic test with 12 recordings; the first four recordings with the head in 0° position: eyes closed, eyes open without optokinetic stimulation, with clockwise and counter clockwise optokinetic stimulations. These four sensorial situations were repeated with the head rotated 30° to the left and to the right. Patients repeated these 12 recordings 6weeks postoperatively. None of the patients reported vertigo or balance disorders before or after surgery. Prior to surgery, in the eyes closed condition, the herniated disc group was more stable than the spondylosis group. After surgery, the contribution of visual input to postural control in a dynamic visual environment was reduced in both cervical spine diseases whereas in a stable visual environment visual contribution was reduced only in the spondylosis group. The relative importance of visual and proprioceptive inputs to postural control varies according to the type of pathology and surgery tends to reduce visual contribution mostly in the spondylosis group.

Management of postural sensory conflict and dynamic balance control in late-stage Parkinson's disease.

Parkinson's disease (PD) is known to affect postural control, especially in situations needing a change in balance strategy or when a concurrent task is simultaneously performed. However, few studies assessing postural control in patients with PD included homogeneous population in late stage of the disease. Thus, this study aimed to analyse postural control and strategies in a homogeneous population of patients with idiopathic advanced (late-stage) PD, and to determine the contribution of peripheral inputs in simple and more complex postural tasks, such as sensory conflicting and dynamic tasks. Twenty-four subjects with advanced PD (duration: median (M)=11.0 years, interquartile range (IQR)=4.3 years; Unified Parkinson's Disease Rating Scale (UPDRS): M "on-dopa"=13.5, IQR=7.8; UPDRS: M "off-dopa"=48.5, IQR=16.8; Hoehn and Yahr stage IV in all patients) and 48 age-matched healthy controls underwent static (SPT) and dynamic posturographic (DPT) tests and a sensory organization test (SOT). In SPT, patients with PD showed reduced postural control precision with increased oscillations in both anterior-posterior and medial-lateral planes. In SOT, patients with PD displayed reduced postural performances especially in situations in which visual and vestibular cues became predominant to organize balance control, as was the ability to manage balance in situations for which visual or proprioceptive inputs are disrupted. In DPT, postural restabilization strategies were often inefficient to maintain equilibrium resulting in falls. Postural strategies were often precarious, postural regulation involving more hip joint than ankle joint in patients with advanced PD than in controls. Difficulties in managing complex postural situations, such as sensory conflicting and dynamic situations might reflect an inadequate sensory organization suggesting impairment in central information processing.

Drug-resistant temporal lobe epilepsy is associated with postural control abnormalities.

Epilepsy is responsible for falls that are not systematically associated with seizures and that therefore suggest postural impairment. There are very few studies of postural control in patients with epilepsy and none of them focus on temporal lobe epilepsy (TLE), although part of the vestibular cortex is located in the temporal cortex. The aim of this study was to evaluate the characteristics of postural control in a homogeneous population of patients with complex partial TLE. Twenty-six patients with epilepsy and 26 age-matched healthy controls underwent a sensory organization test combining six conditions, with and without sensory conflicting situations. Patients with epilepsy displayed poorer postural control, especially in situations where vestibular information is necessary to control balance. In addition to potential antiepileptic drug side effects, vestibular dysfunction could be related to the temporal pathology. Our study allows for a better understanding of the mechanism underlying falls in this population of patients.

Pre-operative vestibular pattern and balance compensation after vestibular schwannoma surgery.

This longitudinal study aimed to assess the sensorimotor balance strategies before and after vestibular schwannoma (VS) surgery according to the degree of pre-operative vestibular lesion. Thirty-eight VS patients were split in three groups according to caloric vestibular test results before surgery; nine had a symmetrical vestibular response (vestibular normoreflexy), 19 with a decreased response of more than 20% of the affected side (vestibular hyporeflexy) and 10 with an absent caloric response on the side of the affected labyrinth (vestibular areflexy). They underwent pendular rotary vestibular testing (RVT), allowing to evaluate gain and directional preponderance of the vestibulo-ocular reflex, and a sensory organisation test (SOT), evaluating balance control in six conditions (C1 to C6). These tests were performed shortly before, and 8 and 90 days after surgery. Directional preponderance performances of patients with vestibular normoreflexy or hyporeflexy followed a classical time-course with a huge asymmetry just after surgery and a recovery to pre-operative performances at 90 days; patients with vestibular areflexy were relatively stable in time. Variation in SOT performances of patients with vestibular normoreflexy, especially in the more complex C4 to C6, followed a classical time-course with an important postural degradation just after surgery and a recovery to pre-operative performances at 90 days. Patients with vestibular areflexy showed no balance degradation just after surgery and a marked increase in performances at 90 days after surgery, especially in C5 and C6. Performances of patients with vestibular hyporeflexy were intermediate, close to performances of patients with vestibular normoreflexy before surgery and close to performances of patients with vestibular areflexy at 8 and 90 days after surgery. Pre-operative vestibular function alteration triggers an adaptive process, characterized by a restoration of the symmetry of the vestibular nuclei activity and by sensory substitution and new behavioural strategies, allowing the anticipation of unilateral vestibular deafferentation effects.

Visual sensorial preference delays balance control compensation after vestibular schwannoma surgery.

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 (G1), 11 relying more on vision (G2), to control balance before surgery), underwent vestibular, subjective visual vertical (SVV), static posturography and sensory organisation (SOT) tests, before and 8 days, 1 and 3 months after surgery. RESULTS: In G1 patients, little static posturographic and SOT performance deterioration after uVD was observed, despite vestibular test and SVV modifications. In G2 patients, uVD-related modifications followed a time-course characterised by a degradation in posturographic and SOT, vestibular and SVV performances immediately after uVD 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.

The practice of physical and sporting activity in teenagers with idiopathic scoliosis is related to the curve type.

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.

Extensor retinaculum syndrome after distal tibial fractures: anatomical basis.

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 degrees . 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 degrees 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.

Current physical activity improves balance control during sensory conflicting conditions in older adults.

Aging process is characterized by difficulties in ensuring balance control, especially in conditions of reduced or conflicting sensory information, leading to an increased risk of falling. Conversely, the practise of physical activities (PA) has been recognized as a good approach to improve the quality of balance control. This study aimed to investigate the influence of current and/or past PA on balance-related neurosensorial organization in older adults on the maintenance of the upright stance, especially during sensory conflicting situations. Postural control was evaluated by means of the Sensory Organization Test on 130 healthy noninstitutionalized volunteers aged over 65, split into four groups according to the presence or absence of PA before or after retirement. Subjects who practised PA for a long time (Gr1) and subjects who started PA after retirement (Gr2) displayed the best postural performances and better managed sensory conflicting situations compared to subjects who had stopped PA for many years (Gr3) and subjects who had never practised PA (Gr4). Multiple regression analyses revealed that current PA was the major determinant for postural parameters during sensorial conflict compared to age, gender, body mass index and past PA. Regular PA, even when started late in life, allows appropriate reorganization of the different components of postural control during sensory conflicting situations. Indeed, active subjects were more able to compensate for suppressed or perturbed sensory information by an increased usage of another referential and so to correct their posture by adopting a more appropriate balance strategy. Thus, PA counteracts the age-related decline of postural control and could consequently reduce the risk of falling.

Why do idiopathic scoliosis patients participate more in gymnastics?

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.

Determinants of accident proneness: a case-control study in railway workers.

BACKGROUND: Accident proneness or workers who have more frequent occupational injuries is common but the role of occupational and individual factors has rarely been studied. AIM: To assess the relationships of certain occupational and individual characteristics with frequency of occupational injuries. METHOD: This case-control study included 1305 male workers with occupational injuries during 1999-2000 and 1305 controls from a railway company. A standardized questionnaire was completed by the occupational physician in the presence of the subject. The data were analysed using logistic regression. RESULTS: Having more than one injury was associated with short service in the present job, younger age, sleep disorders, smoking, requesting a job change, physical disability and lack of physical activity. Safety training was negatively related to injury frequency. Short service in the present job was the only significant factor for single injuries. CONCLUSION: This study identified a number of work and individual factors that predicted occupational injury frequency and may be useful in designing preventative measures. Occupational physicians could assist workers to be more aware of the risks and to find remedial measures.

Bilateral subthalamic nucleus stimulation improves balance control in Parkinson's disease.

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.

Individual characteristics in occupational accidents due to imbalance: a case-control study of the employees of a railway company.

BACKGROUND: Falls are frequent occupational accidents, and are responsible for a significant amount of lost working time and, more importantly, for a high mortality. The factors involved in falling mechanisms can be of external or individual origin, the latter being less well identified. AIMS: To assess the relations between certain individual characteristics and occupational accidents due to imbalance. METHODS: A total of 427 male employees, who had been victims of at least one occupational accident with sick leave due to imbalance (cases) and 427 controls were recruited among the employees of a large French railway company. A standardised questionnaire on life conditions and professional factors, and a description of the accidents was filled in by an occupational physician for each subject. RESULTS: Some job categories were more affected by a specific release mechanism of work related falls. Certain individual characteristics such as smoking, alcohol consumption, inactivity, sleep disorders, and request for a job change were correlated with the occurrence of occupational accidents. Sick leaves of eight days or over were more frequent in older and overweight injured workers. Some lesions were linked with the specific fall released mechanisms. CONCLUSIONS: Individual characteristics can increase the risk of occupational accidents, especially falling. This study identified subjects most at risk on whom prevention related to working conditions and falls could be focused.

Improved muscle strength and power in elderly exercising regularly.

Since the number of elderly people with a sedentary lifestyle is considerable and still growing, regular exercise could be an extra stimulant to compensate for the decrease in functional capacities. The potential positive effects of physical and sporting activities (PSA) on muscular function in relation to the period of practice were studied. Muscular strength and power were evaluated by dynamometric knee and ankle tests on 40 healthy subjects aged over 60 years old, split into four groups according to the period of practice. Higher muscular performance was obtained in subjects who had always practised PSA, whereas subjects who had always been inactive displayed the worst muscular performances. Subjects who had begun PSA practice lately had good muscular strength and power, close to those of the AA group, whereas the subjects who had stopped the practice at an early age did not perform as well. Life-long PSA attenuates the age-related loss of muscle function, and initiation at old age improves it. This, and the absence of any beneficial effects of PSA stopped when young, indicates that the actual activity level is an important determinant of skeletal muscle function at old age. Practicing PSA increases muscular strength and power and thus improves daily living activities in elderly people.

Physical and sporting activities improve vestibular afferent usage and balance in elderly human subjects.

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.

Influence of different types of progressive idiopathic scoliosis on static and dynamic postural control.

STUDY DESIGN: Balance control assessment of static and dynamic conditions was performed to study the effects of progressive idiopathic scoliosis on postural control in 102 adolescents. OBJECTIVE: To determine how the type and location of idiopathic scoliosis may affect global balance control. SUMMARY OF BACKGROUND DATA: Idiopathic scoliosis may impair postural control components, but the repercussions for global balance are relatively mild. METHODS: The following four different types of idiopathic scoliosis were compared: thoracic (n = 36), thoracolumbar (n = 22), lumbar (n = 23), and double major (n = 21) curves. Center of foot pressure displacements and electromyographic responses were recorded using static and dynamic posturographic tests (single and fast upward tilt, slow sinusoidal oscillations). RESULTS: The major criteria of postural control were better in the double major group for all the tests. In the static test, the patients with high major curves performed better than those with low major curves. In the fast dynamic test, similar latency values were observed in all the groups. In the slow dynamic test, better results were observed for the patients with low major curves. CONCLUSIONS: These data demonstrate that idiopathic scoliosis indeed alters balance control, with different hierarchies, from the best to the worst as follows: double major, thoracic, thoracolumbar, and lumbar curves in the static test and double major, lumbar, thoracolumbar, and thoracic curves in the slow dynamic test. The location of the major curve appeared to be important, with an effect on lateral disequilibrium and vestibular symmetry. The absence of anomaly in the fast dynamic test suggests that the type of scoliosis does not impair proprioception.