Cognitive-motor dual task to reveal gait impairments in multiple sclerosis patients at an early stage: A systematic review

BACKGROUND

Multiple sclerosis can cause locomotor and cognitive impairments even at lower levels of disability, which can impact daily life. The cognitive-motor dual task is commonly used to assess everyday locomotion. Thus, this study aimed to examine the effect of cognitive-motor dual tasks on gait parameters among patients with multiple sclerosis in the early disease stages and to determine whether dual tasks could be used as a clinical test to detect locomotion impairments.

METHODS

A systematic search of five databases was conducted in May 2024. The population of interest was patients with multiple sclerosis with an Expanded Disability Status Scale score of 4 or less. The following outcome measures were examined: spatiotemporal and kinematic parameters. The Newcastle-Ottawa Scale was used to assess the quality of the studies.

FINDINGS

Eleven studies including 270 patients with multiple sclerosis and 221 healthy controls. Three spatiotemporal parameters were modified both in patients with multiple sclerosis and healthy controls during dual-task performance: gait speed, stride length and the double support phase. No spatiotemporal parameter was affected during dual-task performance in patients with multiple sclerosis alone.

INTERPRETATION

Dual-task performance could be useful for assessing gait impairments in patients with multiple sclerosis provided that assessments and protocols are standardized. Nevertheless, the spatiotemporal parameters did not allow discrimination between patients with multiple sclerosis at an early stage and healthy controls. Three-dimensional gait analysis during dual-task performance could be a useful approach for detecting early gait impairments in patients with multiple sclerosis, assessing their progression and adjusting rehabilitation programs.

Center of pressure palindromes reveals a wobbling standing balance in scoliotic girls

BACKGROUND

This study characterized the center of pressure planar displacement by palindromic strings. The objective is to test if the center of pressure pathway of able-bodied girls and those with a moderate and severe scoliosis displayed similar palindromic tendencies.

METHODS

The center of pressure excursions of 21 able-bodied girls were compared to 14 girls with a moderate scoliosis and 14 girls with severe one. Each girl was asked to stand upright on a force platform for 64 s. A crisscross grid of nine areas was centered around the mean center of pressure position (G) to define three other zones to use the MATLAB built-in nucleotide sequence analysis function. These were the antero-posterior extremities A, the coronal extremities C and the tilted or the four corners of the crisscross grid, T. The center of pressure positions were associated to any of the 4 zones using the GATC acronym.

FINDINGS

For all groups center of pressure pattern in decreasing order was A, G, T and C. Able-bodied girls favored the A zones. Girls with moderate scoliosis displaced their center of pressure mostly in the A zones with shifts in the T sections (P ≤ 0.001). Girls with severe scoliosis, additionally displaced their center of pressure in the C zones (P ≤ 0.001).

INTERPRETATION

An ankle modality characterized able-bodied girl's standing balance. Girls with a moderate scoliosis privilege the palindromic zones in the antero-posterior extremities with excursions in the corners of the base of support, girls with severe scoliosis further relied on the medio-lateral zones, suggesting a wobbling standing balance.

Time-delay estimation in biomechanical stability: a scoping review

Despite its high-level of robustness and versatility, the human sensorimotor control system regularly encounters and manages various noises, non-linearities, uncertainties, redundancies, and delays. These delays, which are critical to biomechanical stability, occur in various parts of the system and include sensory, signal transmission, CNS processing, as well as muscle activation delays. Despite the relevance of accurate estimation and prediction of the various time delays, the current literature reflects major discrepancy with regards to existing prediction and estimation methods. This scoping review was conducted with the aim of characterizing and categorizing various approaches for estimation of physiological time delays based on PRISMA guidelines. Five data bases (EMBASE, PubMed, Scopus, IEEE and Web of Science) were consulted between the years of 2000 and 2022, with a combination of four related categories of keywords. Scientific articles estimating at least one physiological time delay, experimentally or through simulations, were included. Eventually, 46 articles were identified and analyzed with 20 quantification and 16 qualification questions by two separate reviewers. Overall, the reviewed studies, experimental and analytical, employing both linear and non-linear models, reflected heterogeneity in the definition of time delay and demonstrated high variability in experimental protocols as well as the estimation of delay values. Most of the summarized articles were classified in the high-quality category, where multiple sound analytical approaches, including optimization, regression, Kalman filter and neural network in time domain or frequency domain were used. Importantly, more than 50% of the reviewed articles did not clearly define the nature of the estimated delays. This review presents and summarizes these issues and calls for a standardization of future scientific works for estimation of physiological time-delay.

Upper limb contribution during tandem gait in multiple sclerosis: An early marker of balance impairments

Tandem gait is widely used during clinical exams to evaluate dynamic balance in chronic diseases, such as multiple sclerosis (MS). The early detection of balance impairments in MS is challenging to improve the understanding of patients' complaints. The objective was to propose two indexes to quantify the contributions and inefficiency of limb and trunk movements during tandem gait in early-stage MS patients. Fifteen patients with remitting-relapsed MS, with a median Expanded Disability Status Scale of 2.5 [0-4] were compared to 15 matched healthy participants. Three-dimensional motion analysis was performed during tandem gait to calculate spatiotemporal parameters, contribution and inefficiency indexes, based on the linear momentum of body segments. Compared to healthy participants, MS patients at the early stage of disease executed tandem gait with higher speed (p = 0.03) and increased step length (p = 0.03). The contribution indexes of upper limbs were significantly decreased during swing phase in MS patients. The inefficiency index for the upper limbs were around twice higher for MS patients compared to healthy participants. Since the additional movements concerned only light body segments and not contribute to the whole-body forward progression during tandem gait, they could reflected more both upper limb movements alterations and restoring movements to avoid loss of balance during tandem gait around swing phase in MS. These quantified indexes could be used as physical markers to quantify both the balance deterioration and the efficiency of rehabilitation program during the follow up of MS from the early stage of their disease.

Sensorimotor Time Delay Estimation by EMG Signal Processing in People Living with Spinal Cord Injury

Neuro mechanical time delay is inevitable in the sensorimotor control of the body due to sensory, transmission, signal processing and muscle activation delays. In essence, time delay reduces stabilization efficiency, leading to system instability (e.g., falls). For this reason, estimation of time delay in patients such as people living with spinal cord injury (SCI) can help therapists and biomechanics to design more appropriate exercise or assistive technologies in the rehabilitation procedure. In this study, we aim to estimate the muscle onset activation in SCI people by four strategies on EMG data. Seven complete SCI individuals participated in this study, and they maintained their stability during seated balance after a mechanical perturbation exerting at the level of the third thoracic vertebra between the scapulas. EMG activity of eight upper limb muscles were recorded during the stability. Two strategies based on the simple filtering (first strategy) approach and TKEO technique (second strategy) in the time domain and two other approaches of cepstral analysis (third strategy) and power spectrum (fourth strategy) in the time-frequency domain were performed in order to estimate the muscle onset. The results demonstrated that the TKEO technique could efficiently remove the electrocardiogram (ECG) and motion artifacts compared with the simple classical filtering approach. However, the first and second strategies failed to find muscle onset in several trials, which shows the weakness of these two strategies. The time-frequency techniques (cepstral analysis and power spectrum) estimated longer activation onset compared with the other two strategies in the time domain, which we associate with lower-frequency movement in the maintaining of sitting stability. In addition, no correlation was found for the muscle activation sequence nor for the estimated delay value, which is most likely caused by motion redundancy and different stabilization strategies in each participant. The estimated time delay can be used in developing a sensory motor control model of the body. It not only can help therapists and biomechanics to understand the underlying mechanisms of body, but also can be useful in developing assistive technologies based on their stability mechanism.

Simplified stance limb kinetics patterns revealed during gait initiation in early stage of multiple sclerosis

BACKGROUND

Although patients with an early stage of Multiple Sclerosis (MS) commonly complain about balance and gait impairments, their troubles remain misunderstood. The objective was to compare body kinematics and lower limb kinetics during gait initiation between patients with MS with an EDSS score ≤ 4 and healthy participants.

METHODS

Sixteen patients with MS with a median EDSS score of 2.5 [0-4] and disease duration of 7.4 ± 4.2 years, as well as 16 healthy participants were included, and 3-D motion analysis was performed during gait initiation to calculate spatiotemporal, kinematic and kinetic parameters.

FINDINGS

The center of pressure position at the beginning of the gait initiation was more anterior (p = 0.02) in patients with MS than healthy participants. The kinetic parameters of the stance limb were highly affected in patients with MS compared to healthy participants during gait initiation. The net muscular moments for each joint were significantly different during the anticipatory postural adjustment phase with smoother variations for patients with MS compared to healthy participants.

INTERPRETATION

Early stage MS strongly affects the motor modulation of stance limb kinetics during the anticipatory postural adjustment of gait initiation, without alteration of the execution phase. The net muscular moments are sensitive in detecting unobservable balance impairments and can be used to assess disease progression at the early stage. These results suggest that early rehabilitation programs aimed at improving motor modulation and flexibility in gait initiation should be implemented.

Untreated adolescent idiopathic scoliotic girls display altered balance modalities during self-paced voluntary body sways compared to able-bodied girls

INTRODUCTION

This study investigated self-paced voluntary oscillations of scoliotic and non-scoliotic girls. Temporal variables and frequency coherence were calculated for the overall, low and high frequency bandwidths of the center of pressure excursions and free-moment to identify which variables best describe sway balance modalities in both groups.

METHODS

Twenty-three girls with adolescent idiopathic moderate scoliosis (spinal curves to the right) formed the scoliotic group and 19 matched able-bodied girls formed the non-scoliotic group. Each girl performed self-paced voluntary medio-lateral and antero-posterior sways while standing on a force platform. Center of pressure displacements, out of plane deviation and free-moment were measured and their frequency content calculated. The magnitude of the coherence was calculated for each signal pairs for three frequency ranges.

RESULTS

In both sway conditions, the center of pressure excursion parameters were on average 28% higher for the scoliotic group. Factor analysis revealed that balance modalities were essentially based on frequency coherence pair interactions whereas temporal parameters play a secondary role. However, these balance modalities were altered in the scoliotic group. They relied essentially on 2 additional principal components and 3 additional variables reflecting a fine tuning of the control mechanism to maintain dynamic balance.

INTERPRETATION

Scoliotic girls appear to be performing a wide ellipsoidal trajectory when performing whole body oscillations. Superfluous variables could be related to the difficulty in preserving balance during body sway tasks and could parasitize the scoliotic dynamic control balance modalities. Self-paced voluntary sways could be an appropriate complementary balance test for untreated scoliotic girls.

Determination of the internal piezoelectric potentials and indium concentration in InGaN based quantum wells grown on relaxed InGaN pseudo-substrates by off-axis electron holography

Micro light emitting diodes have been grown by metal organic vapor phase epitaxy on standard GaN and partly relaxed InGaNOS substrates with the purpose of incorporating higher concentrations of indium for identical growth conditions. Green emission has been demonstrated at wavelengths of 500 nm for the GaN template and 525 and 549 nm for the InGaNOS substrates, respectively. The structure, deformation, indium concentration and piezoelectric potentials have been measured with nm-scale spatial resolution in the same specimens by transmission electron microscopy. We show by off-axis electron holography that the piezoelectric potential and information about the indium concentration from the mean inner potential are obtained simultaneously. By separating the components using a model, we show that for higher concentrations of indium in the quantum wells (QWs) grown on InGaNOS substrates, the piezoelectric potentials are reduced. The measurements of the indium concentrations by electron holography have been verified by combining energy dispersive x-ray spectrometry, x-ray diffraction and from the tensile deformation made by precession electron diffraction. A discussion of the limitations of these advanced aberration-corrected transmission electron microscopy techniques when applied to nm-scale QW structures is given.

Less Than One Millimeter Under the Great Toe is Enough to Change Balance Ability in Elite Women Handball Players

Team handball is a complex intermittent sport game, which requires several motor abilities and effective postural control. Objective evaluation of stabilometric variables may be interesting to assess and improve functional parameters by postural control management. The purpose of the study was to evaluate the effects of a small additional thickness placed under the great toe (TUGT) on the Centre of Pressure (CoP) parameters in elite women handball players. Fourteen elite women handball players voluntarily participated in this study. Two conditions were compared: TUGT 0 (control) and TUGT 0.8 mm; four variables were computed from the CoP displacements. A paired T-test was performed for each variable. This study concludes that a low focal additional thickness placed under both great toes has an effect on the CoP measures used to assess postural control during an unperturbed stance. These results suggest that a low TUGT could contribute to a change in balance ability, and may be of clinical interest. This brings new perspectives in the management of athletes to prevent injury risk and optimize performance.

Determination of optimal shoe fitting for children tennis players: Effects of inner-shoe volume and upper stiffness

The purpose of this study was to determine the optimal inner-shoe volume for children tennis players. Sixteen participants, aged from 8 to 12 years old assessed comfort of 6 shoes, which were a combination of 3 lasts (thin, medium and wide) and 2 upper constructions (flexible and stiff), while a sock equipped with textile sensors was measuring the pressure applied on their foot. The thin last was based on the proportion of an adult last. The widest shoes produced the lowest pressure on the 1st and 5th metatarsal heads, the medial midfoot and the medial and lateral heel (p < 0.05), whilst they were perceived the most comfortable for the 3rd and 5th metatarsal heads, the 5th metatarsal base and the medial and lateral heel (p < 0.05). These outcomes indicated that footwear manufacturers should design wider shoes for children than for adults.

[Associations working to combat HIV/AIDS]

Numerous associations play an essential role in the fight against the AIDS epidemic. Today, they continue to support patients with the human immunodeficiency virus (HIV). They work to provide support, fight against exclusion and to ensure patients' rights are respected. Communication between patients and health professionals is essential for the construction of projects optimising patient care.

Functional outcomes in adult patients with herpes simplex encephalitis admitted to the ICU: a multicenter cohort study

PURPOSE

We aimed to study the association of body temperature and other admission factors with outcomes of herpes simplex encephalitis (HSE) adult patients requiring ICU admission.

METHODS

We conducted a retrospective multicenter study on patients diagnosed with HSE in 47 ICUs in France, between 2007 and 2017. Fever was defined as a body temperature higher or equal to 38.3 °C. Multivariate logistic regression analysis was used to identify factors associated with poor outcome at 90 days, defined by a score of 3-6 (indicating moderate-to-severe disability or death) on the modified Rankin scale.

RESULTS

Overall, 259 patients with a score on the Glasgow coma scale of 9 (6-12) and a body temperature of 38.7 (38.1-39.2) °C at admission were studied. At 90 days, 185 (71%) patients had a poor outcome, including 44 (17%) deaths. After adjusting for age, fever (OR = 2.21; 95% CI 1.18-4.16), mechanical ventilation (OR = 2.21; 95% CI 1.21-4.03), and MRI brain lesions > 3 lobes (OR = 3.04; 95% CI 1.35-6.81) were independently associated with poor outcome. By contrast, a direct ICU admission, as compared to initial admission to the hospital wards (i.e., indirect ICU admission), was protective (OR = 0.52; 95% CI 0.28-0.95). Sensitivity analyses performed after adjustment for functional status before admission and reason for ICU admission yielded similar results.

CONCLUSIONS

In HSE adult patients requiring ICU admission, several admission factors are associated with an increased risk of poor functional outcome. The identification of potentially modifiable factors, namely, elevated admission body temperature and indirect ICU admission, provides an opportunity for testing further intervention strategies.

Do Older People Accurately Estimate the Length of Their First Step during Gait Initiation?

Background/Study Context: Advancing age is associated with a decrease in step length. In line with previous studies showing that older adults often overestimate their motor abilities, we investigate whether older adults overestimate the length of their first step during gait initiation. The underlying effect could be a failure to update the internal model of motor action as a function of age-related motor decline. Methods: Without taking a step, community-dwelling older women (n = 22, age range: 68-87 years) and younger women (n = 19, age range: 19-33 years) estimated the length of their first step for both preferred step length and largest step length, which were performed without endangerment. Thereafter, the participants performed real gait initiation for both types of steps. The estimated step lengths were compared to the actual step lengths. Results: Older adults judged their first step as larger than it was (mean error: 30% for the preferred step and 9% for the largest step). A fine-grained analysis showed that this effect mainly concerned those for whom an increased risk of falling was suspected. These older adults were also among those who performed the shortest steps, and they presented with a slight decrease in cognitive functioning. Younger participants underestimated their preferred step length. Overall, the estimates were more accurate for the largest steps than for the preferred-length steps. Conclusion: Step length estimation revealed powerful evidence for overestimation in older adults. Those who overestimated step length presented with more signs of motor decline. While this result sustains the idea of an insufficient actualization of the motor-action model, the explanation also refers to more global appraisal processes. Further research should explore the relevance of this task as a clinical laboratory tool for assessing gait capacity and the risk of falling.

How can the stimulation of plantar cutaneous receptors improve postural control? Review and clinical commentary

Postural control requires constant and subconscious postural sway to manage balance and achieve postural stability. These movements of regulation are based in particular on cutaneous plantar information. The foot constitutes a functional whole that participates in the mechanisms of postural control and regulation. It represents the direct interface between the body and the ground during quiet standing, and plantar cutaneous information contributes to postural control. Upright balance mechanically depends on the gravitational torque produced by the forces of gravity and reaction of the ground. In this context, the foot behaves like a sensory system for postural regulation whose objective is to maintain a state of stability within a changing and constraining environment. There is a relation between balance improvement and the facilitation of sensory feedback related to the activation of the plantar cutaneous mechanoreceptors. From a clinical point of view, the application of additional tactile cues may have therapeutic benefits in relation to fall prevention, or to improve specific types of chronic pain.

In Vitro Inhibition of Platelet Aggregation by Bile Salts

In a series of in vitro experiments, the influence of bile salts on platelet aggregation by ADP or by collagen and on serotonin-14C release by collagen, was studied.

Sodium salts of the following bile acids showed a clear inhibitory effect: glycochenodeoxycholic acid, taurochenodeoxycholic acid, glycocholic acid, taurocholic acid and cholic acid. Lowering the pH of the platelet-rich plasma resulted in decreased platelet aggregation by ADP and by collagen. Bile salts further enhanced the inhibitory effect of pH change. In contrast the sodium salt of chenodeoxycholic acid was the sole aggregation inducing bile salt we studied. Relating the above studies to the clinical situation of upper gastroduodenal mucosal haemorrhage, we suggest that biliary reflux as well as the acidic environment may contribute to a poor haemostatic response by impaired platelet aggregation in the upper gastrointestinal tract of otherwise normal human subjects.

Inhibitory Effect of Acetylsalicylic Acid on Human Platelet Function in Normal Volunteers and in Women Using a Combined Oral Contraceptive Regime

Six parameters related to the release reaction were measured simultaneously in 10 human volunteers prior to the intake of one single dose of 1 g acetylsalicylic acid and 1, 4, 5, 6 and 7 days later: ΔE5 with diluted collagen, ΔE10 with Thrombofax® and the serotonin-14C release by undiluted and diluted collagen, by Thrombofax and by bovine plasma. The duration of the inhibitory effect varied according to the test used. It was the most prolonged (through the 7th day) if serotonin-14C release by diluted collagen was measured.

A systematic investigation of the platelet release reaction in women taking a combined oral contraceptive was also performed. There were no statistically significant differences from a control group. No difference in acetylsalicylic acid sensitivity, measured 24 hours after intake of 1 g of aspirin, could be demonstrated.

Limitations of the Activated Partial Thromboplastin Time for Determination of Plasma Heparin Concentration and Half-Life in Human Subjects

In vivo heparin concentrations and half-life were estimated in 20 human subjects, after a single intravenous injection.

The method, used for heparin determination, is based on the activated partial thromboplastin time. The test plasmas are diluted in plasma of the same subject obtained before heparin administration. In this way the heparin concentrations are reduced to measurable levels between 0.1 I. U./ml and 0.8 I. U./ml. Indeed a linear relationship between log activated partial thromboplastin time and heparin concentrations from 0.1 to 0.8 I. U./ml can be computed. Different half-lives were found in 13 of the 20 subjects examined when different dilution factors were used. This seems an important limitation for the examination of the pharmacokinetics of heparin.

Effect of natural sagittal trunk lean on standing balance in untreated scoliotic girls

BACKGROUND

Generally, scoliotic girls have a tendency to lean further back than a comparable group of non-scoliotic girls. To date, no study has addressed how standing balance in untreated scoliotic girls is affected by a natural backwardly or forwardly inclined trunk.

METHODS

27 able-bodied young girls and 27 young girls with a right thoracic curve were classified as leaning forward or backward according to the median of their trunk sagittal inclination. Participants stood upright barefoot. Trunk and pelvis orientations were calculated from 8 bony landmarks. Upright standing balance was assessed by 9 parameters calculated from the excursion of the center of pressure and the free moment.

FINDINGS

In the anterior-posterior direction, backward scoliotic girls had a greater center of pressure range (P=0.036) and speed (P=0.015) by 10.4mm and 2.8mm/s respectively than the forward scoliotic group. Compared to their matching non-scoliotic group, the backward scoliotic girls stood more on their heels by 14.6mm (P=0.017) and display greater center of pressure speed by 2.5mm/s (P=0.028). Medio-lateral center of pressure range (P=0.018) and speed (P=0.008) were statistically higher by 8.7mm and 3.6mm/s for the backward group. Only the free moment RMS was significantly larger (P=0.045) for the backward scoliotic group when compared to the forwardly inclined scoliotic group.

INTERPRETATION

Only those with a backward lean displayed statistically significant differences from both forward scoliotic girls and non-scoliotic girls. Untreated scoliotic girls with an exaggerated back extension could profit more from postural rehabilitation to improve their standing balance.

A simple ultra-high-performance liquid chromatography-high resolution mass spectrometry assay for the simultaneous quantification of 15 antibiotics in plasma

Antibiotic (ATB) treatment of critically ill patients with pathophysiological injuries remains a challenge due to the constant increase in antimicrobial resistance. Therapeutic drug monitoring (TDM) is advised for ATB dose adjustments to avoid suboptimal concentrations and dose-related adverse effects. Therefore, a single and reliable analytical method for a broad selection of ATBs was developed using a high-resolution mass spectrometry (HRMS) platform for frequent use in intensive care units. An UHPLC assay coupled to high resolution accurate mass acquisition has been developed for the quantification of penicillins (amoxicillin, oxacillin, piperacillin, and ticarcillin), cephalosporines (cefepime, cefotaxime, ceftazidime, and ceftriaxone), carbapenems (ertapenem, imipenem, and meropenem), lincosamide (clindamycin), quinolones (ofloxacin and ciprofloxacin) and tazobactam. Plasma samples (100μL) were spiked with an internal standard solution followed by protein precipitation. Separation was achieved on an Accucore C18 column, which enabled sample analysis every 9min. All compounds were detected in electrospray positive ion mode and quantified with a linear regression between 0.5 and 32mg/L (r2>0.998). Overall precision and accuracy did not exceed 15%. No significant matrix effect was observed for the studied ATBs. Stored stock solutions at -20°C were stable for 6 months, except for amoxicillin and imipenem. Analytes in plasma were stable for 24h under ambient conditions as well as in post-preparation in an autosampler, except for amoxicillin and imipenem. This HRMS assay provides the simultaneous quantification of 15 ATB; it fulfills the usual quality criteria and was successfully applied for routine TDM of ATBs. The method is based on a full scan acquisition, and it would be easy to add other compounds to the present panel in the future, as this assay has already been proven to be efficient for different classes of compounds.