A step toward restoring hand functions in patients with multiple sclerosis—a study protocol

Multiple sclerosis (MS) is a chronic autoimmune disease characterized by inflammation, demyelination of axons, and oligodendrocyte loss in the central nervous system. This leads to neurological dysfunction, including hand impairment, which is prevalent among patients with MS. However, hand impairment is the least targeted area for neurorehabilitation studies. Therefore, this study proposes a novel approach to improve hand functions compared to current strategies. Studies have shown that learning new skills in the motor cortex (M1) can trigger the production of oligodendrocytes and myelin, which is a critical mechanism for neuroplasticity. Transcranial direct current stimulation (tDCS) has been used to enhance motor learning and function in human subjects. However, tDCS induces non-specific effects, and concurrent behavioral training has been found to optimize its benefits. Recent research indicates that applying tDCS during motor learning can have priming effects on the long-term potentiation mechanism and prolong the effects of motor training in health and disease. Therefore, this study aims to assess whether applying repeated tDCS during the learning of a new motor skill in M1 can be more effective in improving hand functions in patients with MS than current neurorehabilitation strategies. If this approach proves successful in improving hand functions in patients with MS, it could be adopted as a new approach to restore hand functions. Additionally, if the application of tDCS demonstrates an accumulative effect in improving hand functions in patients with MS, it could provide an adjunct intervention during rehabilitation for these patients. This study will contribute to the growing body of literature on the use of tDCS in neurorehabilitation and could have a significant impact on the quality of life of patients with MS. 2023 Zoghi and Jaberzadeh

An integrated computer-based system to study neuromuscular disorders of the upper limb

A multi-channel computer-based clinical instrument was developed to simultaneously acquire, process, display, quantify and correlate electromyographic (EMG) activity, resistive torque, range of motion (ROM), and pain levels in the upper limbs of humans. Each channel consisted of a time and frequency domain block, a torque and angle measurement block, an experiment number counter block and a data storage and retrieval block. The study showed that there was increased level of EMG activity prior to pain onset (P<0.05). There was also clear evidence that elevated perception of pain and elevated levels of resistive torque (P<0.05) were positively correlated with the EMG activity in the muscles responsible for antalgic posture of the upper limb (P<0.05)

Computer-based clinical instrumentation for processing and analysis of mechanically evoked electromyographic signals in the upper limb

A computer-based clinical instrument was developed to simultaneously acquire, process, display, quantify and correlate electromyographic (EMG) activity, resistive torque, range of motion (ROM), and pain responses evoked by mechanical stimuli (i.e. passive elbow extensions) in humans. This integrated multichannel system was designed around AMLAB® analog modules and software objects called ICAMs. Although this system was designed to specifically study the patterns and nature of evoked motor responses in Carpal Tunnel Syndrome (CTS) patients, it could equally well be modified to allow acquisition, processing and analysis of EMG signals in other studies and applications. In this paper, we describe an integrated system to simultaneously study and analyze the mechanically evoked electromyographic, torque and ROM signals and correlate various levels of pain to these signals

Computer-based clinical instrumentation for processing and analysis of electroneuromyographic signals in the upper limb

A computer-based clinical instrument was developed to simultaneously acquire, process, display, quantify and correlate electroneuromyographic (ENMG) activity in the upper limb in humans. This system was designed around AMLAB® analog modules and software objects called ICAMs. The system consists of a nerve stimulator block, a time domain, EMG block with evoked response averaging capability, a counter block and a data storage and retrieval block. This system has been designed to study the H-reflex and M-response in the upper limb of normal subjects and Carpal Tunnel Syndrome (CTS) patients. It could be easily modified to acquire, process and analyze the ENMG signals in other parts of the human body to assess the continuity and function of the sensory and motor pathways. In this paper, we present an integrated system to simultaneously measure and analyze the electroneuromyographic activities in the upper limb

Does the longer application of anodal-transcranial direct current stimulaton increase corticomotor excitability further? A pilot study

Introduction: Anodal transcranial direct current stimulation (a-tDCS) of the primary motor cortex (M1) has been shown to be effective in increasing corticomotor excitability.　Methods: We investigated whether longer applications of a-tDCS coincide with greater increases in corticomotor excitability compared to shorter application of a-tDCS. Ten right-handed healthy participants received one session of a-tDCS (1mA current) with shorter (10 min) and longer (10+10 min) stimulation durations applied to the left M1 of extensor carpi radialis muscle (ECR). Corticomotor excitability following application of a-tDCS was assessed at rest with transcranial magnetic stimulation (TMS) elicited motor evoked potentials (MEP) and compared with baseline data for each participant.　Results: MEP amplitudes were increased following 10 min of a-tDCS by 67% (p = 0.001) with a further increase (32%) after the second 10 min of a-tDCS (p = 0.005). MEP amplitudes remained elevated at 15 min post stimulation compared to baseline values by 65% (p = 0.02).　Discussion: The results demonstrate that longer application of a-tDCS within the recommended safety limits, increases corticomotor excitability with after effects of up to 15 minutes post stimulation.<br /

What is the Effect of Motor Level Peripheral Electrical Stimulation on Corticospinal Excitability and Functional Outcome Measures in Both Healthy Participants and those with Neurological Disorders? A Systematic Review and Meta-Analysis

Introduction: To explore the effect of Motor Level peripheral Stimulation (MLS) on Corticospinal Excitability (CSE) in healthy participants and those with neurological disorders, and to establish stimulation parameters best suited to this purpose. Methods and Materials: A comprehensive search strategy was developed for identification of papers answering the review question. The studies identified were used to do meta-analyses. Results: Following motor-level stimulation, there was a significant change in CSE from baseline: 57.66% (95% CI). Subgroup analysis showed that there was a significant change in the 100Hz subgroup: 68.31% (95% CI) and the 20-50Hz subgroup: 80.14% (95% CI), but not in the &lt;10Hz subgroup: 9.97% (95% CI). In addition, CSE changes was greater where intervention time = 30mins: 83.19% (95% CI), then where intervention time &gt;30mins: 53.14% (95% CI). CSE showed no significant changes following ‘no stimulation”: 69.61% (95% CI). Conclusions: The findings indicate that MLS leads to increases in CSE; however, magnitude of change depends on the stimulation frequency and the area stimulated. It also appears that stimulation durations of longer than 30mins do not result in greater changes. Significance: The present review article hopes to catalyze further research into the determination of appropriate MLS treatment parameters for specific muscle groups.Key words: Motor level stimulation, corticospinal excitability, functional electrical stimulation, associative stimulation, transcranial magnetic stimulation, motor evoked potential

Mental fatigue does not affect static balance under both single and dual task conditions in young adults

The ability to control balance and prevent falls while carrying out daily life activities may require a predominantly controlled (cognitive) or automatic processing depending on the balance challenge, age, or other factors. Consequently, this process may be affected by mental fatigue which has been shown to impair cognitive abilities. Controlling static balance in young adults is a relatively easy task that may proceed automatically with minimal cognitive input making it insusceptible to mental fatigue. To investigate this hypothesis, static single and dual task (while concurrently counting backward by seven) balance was assessed in 60 young adults (25.2 ± 2.4 years) before and after 45 min of Stroop task (mental fatigue condition) and watching documentary (control), presented in a randomized counterbalanced order on separate days. Moreover, because mental fatigue can occur due to task underload or overload, participants carried out two different Stroop tasks (i.e., all congruent, and mainly incongruent trials) on separate days in the mental fatigue condition. Results of the study revealed a significantly higher feeling of mental fatigue after the mental fatigue conditions compared to control (p 0.05) indicating lack of effect of mental fatigue on static balance in this population. Therefore, future studies investigating this phenomenon in occupational or sport settings in similar population should consider using more challenging balance tasks. © 2023, The Author(s)

Measurement of superficial and deep abdominal muscle thickness: an ultrasonography study

BACKGROUND: Real-time ultrasound imaging is a valid method in the field of rehabilitation. The ultrasound imaging allows direct visualization for real-time study of the muscles as they contract over the time. Measuring of the size of each abdominal muscle in relation to the others provides useful information about the differences in structure, as well as data on trunk muscle activation patterns. The purpose of this study was to assess the size and symmetry of the abdominal muscles at rest in healthy adults and to provide a reference range of absolute abdominal muscle size in a relatively large population. METHOD: A total 156 healthy subjects with the age range of 18–44 years were randomly recruited. The thickness of internal oblique, external oblique, transverse abdominis, and rectus abdominis muscles was measured at rest on both right and left sides using ultrasound. Independent t test was used to compare the mean thickness of each abdominal muscle between males and females. Differences on side-to-side thicknesses were assessed using paired t test. The association between abdominal muscle thicknesses with gender and anthropometric variables was examined using the Pearson correlation coefficient. RESULTS: A normal pattern of increasing order of mean abdominal muscle thickness was found in both genders at both right and left sides: transverse abdominis < external oblique < internal oblique < rectus abdominis. There was a significant difference on the size of transverse abdominis, internal oblique, and external oblique muscles between right and left sides in both genders. Males had significantly thicker abdominal muscles than females. Age was significantly correlated with the thickness of internal oblique, external oblique, and rectus abdominis muscles. Body mass index was also positively correlated with muscle thickness of rectus abdominis and external oblique. CONCLUSIONS: The results provide a normal reference range for the abdominal muscles in healthy subjects and may be used as an index to find out abnormalities and also to evaluate the effectiveness of different interventions

Different current intensities of anodal transcranial direct current stimulation do not differentially modulate motor cortex plasticity

Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates the excitability of neurons within the motor cortex (M1). Although the aftereffects of anodal tDCS on modulating cortical excitability have been described, there is limited data describing the outcomes of different tDCS intensities on intracortical circuits. To further elucidate the mechanisms underlying the aftereffects of M1 excitability following anodal tDCS, we used transcranial magnetic stimulation (TMS) to examine the effect of different intensities on cortical excitability and short-interval intracortical inhibition (SICI). Using a randomized, counterbalanced, crossover design, with a one-week wash-out period, 14 participants (6 females and 8 males, 22&ndash;45 years) were exposed to 10 minutes of anodal tDCS at 0.8, 1.0, and 1.2&thinsp;mA. TMS was used to measure M1 excitability and SICI of the contralateral wrist extensor muscle at baseline, immediately after and 15 and 30 minutes following cessation of anodal tDCS. Cortical excitability increased, whilst SICI was reduced at all time points following anodal tDCS. Interestingly, there were no differences between the three intensities of anodal tDCS on modulating cortical excitability or SICI. These results suggest that the aftereffect of anodal tDCS on facilitating cortical excitability is due to the modulation of synaptic mechanisms associated with long-term potentiation and is not influenced by different tDCS intensities

The Effect of Unihemispheric Concurrent Dual-Site Transcranial Direct Current Stimulation of Primary Motor and Dorsolateral Prefrontal Cortices on Motor Function in Patients With Sub-Acute Stroke

It is believed that unihemispheric concurrent dual-site transcranial direct current stimulation (tDCSUHCDS) of the primary motor cortex (M1) and the dorsolateral prefrontal cortex (DLPFC) causes an increase in motor cortex excitability. However, the clinical effect of this type of stimulation on patients with neurological conditions is not yet known. The aim of the present study was to assess the effect of anodal-tDCSUHCDS (a-tDCSUHCDS) on upper limb motor function in subacute stroke patients. Fifteen patients participated in this sham-controlled crossover study. The main outcome measures were the reaction time (RT) to visual stimuli, completion time of a nine-pin pegboard (9-PPB), and the scores from the Fugl–Meyer assessment (FMA) for the upper limb of the involved side before and after three brain stimulation conditions. For a-tDCSUHCDS, the anodal electrodes were placed on the M1 and the DLPFC, while for a-tDCS, the anodal electrode was placed on the M1. For the sham stimulation, the tDCS was turned off after 30 s. For brain stimulation, the selected current was 1 mA for 20 min. After a-tDCSUHCDS, there was a significant reduction in the RT and completion time of the 9-PPB compared with the times after a-tDCS and the sham stimulation: p = 0.013 and p = 0.022, respectively). However, there was no significant difference in the FMA scores after the three types of stimulations (p = 0.085). Compared with a-tDCS, a-tDCSUHCDS temporarily improved the RT and dexterity of the involved hand in subacute stroke patients.Clinical Trial Registration: Iranian Registry of Clinical Trials (IRCT), identifier IRCT2015012520787N1