scholarly journals A reduced somatosensory gating response in individuals with multiple sclerosis is related to walking impairment

2017 ◽  
Vol 118 (4) ◽  
pp. 2052-2058 ◽  
Author(s):  
David J. Arpin ◽  
James E. Gehringer ◽  
Tony W. Wilson ◽  
Max J. Kurz
Keyword(s):  
Multiple Sclerosis ◽  
Sensory Gating ◽  
Healthy Controls ◽  
Neural Responses ◽  
Neural Basis ◽  
Tactile Discrimination ◽  
Mobility Impairments ◽  
Gait Kinematics ◽  
Walking Performance ◽  
Somatosensory Gating

When identical stimuli are presented in rapid temporal succession, neural responses to the second stimulation are often weaker than those observed for the first. This phenomenon is termed sensory gating and is believed to be an adaptive feature that helps prevent higher-order cortical centers from being flooded with unnecessary information. Recently, sensory gating in the somatosensory system has been linked to deficits in tactile discrimination. Additionally, studies have linked poor tactile discrimination with impaired walking and balance in individuals with multiple sclerosis (MS). In this study, we examine the neural basis of somatosensory gating in patients with MS and healthy controls and assess the relationship between somatosensory gating and walking performance. We used magnetoencephalography to record neural responses to paired-pulse electrical stimulation applied to the right posterior tibial nerve. All participants also walked across a digital mat, which recorded their spatiotemporal gait kinematics. Our results showed the amplitude of the response to the second stimulation was sharply reduced only in controls, resulting in a significantly reduced somatosensory gating in the patients with MS. No group differences were observed in the amplitude of the response to the first stimulation nor the latency of the neural response to either the first or second stimulation. Interestingly, the altered somatosensory gating responses were correlated with aberrant spatiotemporal gait kinematics in the patients with MS. These results suggest that inhibitory GABA circuits may be altered in patients with MS, which impacts somatosensory gating and contributes to the motor performance deficits seen in these patients. NEW & NOTEWORTHY We aimed to determine whether somatosensory gating in patients with multiple sclerosis (MS) differed compared with healthy controls and whether a relationship exists between somatosensory gating and walking performance. We found reduced somatosensory gating responses in patients with MS, and these altered somatosensory gating responses were correlated with the mobility impairments. These novel findings show that somatosensory gating is impaired in patients with MS and is related to the mobility impairments seen in these patients.

scholarly journals Effects of Walking Direction and Cognitive Challenges on Gait in Persons with Multiple Sclerosis

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Douglas A. Wajda ◽  
Brian M. Sandroff ◽  
John H. Pula ◽  
Robert W. Motl ◽  
Jacob J. Sosnoff
Keyword(s):  
Multiple Sclerosis ◽  
Stride Length ◽  
Cognitive Task ◽  
Cognitive Test ◽  
Control Group ◽  
Healthy Controls ◽  
Backward Walking ◽  
Gait Parameters ◽  
Walking Performance ◽  
Testing Condition

Declines in walking performance are commonly seen when undergoing a concurrent cognitive task in persons with multiple sclerosis (MS). The purpose of this study was to determine the effect of walking direction and simultaneous cognitive task on the spatiotemporal gait parameters in persons with MS compared to healthy controls. Ten persons with MS (Median EDSS, 3.0) and ten healthy controls took part in this pilot study. Participants performed 4 walking trials at their self-selected comfortable pace. These trials included forward walking, forward walking with a cognitive task, backward walking, and backward walking with a cognitive task. Walking performance was indexed with measures of velocity, cadence, and stride length for each testing condition. The MS group walked slower with significantly reduced stride length compared to the control group. The novel observation of this investigation was that walking differences between persons with MS and healthy controls were greater during backward walking, and this effect was further highlighted during backward walking with added cognitive test. This raises the possibility that backward walking tests could be an effective way to examine walking difficulties in individuals with MS with relatively minimal walking impairment.

scholarly journals Motor Imagery of Walking in People Living with and without Multiple Sclerosis: A Cross-Sectional Comparison of Mental Chronometry

2021 ◽  
Vol 11 (9) ◽  
pp. 1131
Author(s):  
Douglas A. Wajda ◽  
Tobia Zanotto ◽  
Jacob J. Sosnoff
Keyword(s):  
Multiple Sclerosis ◽  
Motor Imagery ◽  
Well Being ◽  
Cross Sectional Study ◽  
Walking Ability ◽  
Healthy Controls ◽  
Cross Sectional ◽  
Actual Performance ◽  
Mental Chronometry ◽  
Walking Performance

Motor imagery represents the ability to simulate anticipated movements mentally prior to their actual execution and has been proposed as a tool to assess both individuals’ perception of task difficulty as well as their perception of their own abilities. People with multiple sclerosis (pwMS) often present with motor and cognitive dysfunction, which may negatively affect motor imagery. In this cross-sectional study, we explored differences in motor imagery of walking performance between pwMS (n = 20, age = 57.1 (SD = 8.6) years, 55% female) and age- and sex-matched healthy controls (n = 20, age = 58.1 (SD = 7.0) years, 60% female). Participants underwent mental chronometry assessments, a subset of motor imagery, which evaluated the difference between imagined and actual walking times across four walking tasks of increasing difficulty (i.e., large/narrow-width walkway with/without obstacles). Raw and absolute mental chronometry (A-MC) measures were recorded in single- (ST) and dual-task (DT) conditions. In ST conditions, pwMS had higher A-MC scores across all walking conditions (p ≤ 0.031, η2 ≥ 0.119), indicating lower motor imagery ability compared to healthy controls. During DT, all participants tended to underestimate their walking ability (3.38 ± 6.72 to 5.63 ± 9.17 s). However, after physical practice, pwMS were less able to adjust their imagined walking performance compared to healthy controls. In pwMS, A-MC scores were correlated with measures of balance confidence (ρ = −0.629, p < 0.01) and the self-reported expanded disability status scale (ρ = 0.747, p < 0.01). While the current study revealed that pwMS have lower motor imagery of walking performance compared to healthy individuals, further work is necessary to examine how the disassociation between mental chronometry and actual performance relates to quality of life and well-being.

scholarly journals Evidence accumulation relates to perceptual consciousness and monitoring

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Michael Pereira ◽  
Pierre Megevand ◽  
Mi Xue Tan ◽  
Wenwen Chang ◽  
Shuo Wang ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Detection Threshold ◽  
Task Demands ◽  
Neuron Activity ◽  
Neural Responses ◽  
Neuronal Responses ◽  
Neural Basis ◽  
Perceptual Consciousness ◽  
Evidence Accumulation ◽  
Posterior Parietal

AbstractA fundamental scientific question concerns the neural basis of perceptual consciousness and perceptual monitoring resulting from the processing of sensory events. Although recent studies identified neurons reflecting stimulus visibility, their functional role remains unknown. Here, we show that perceptual consciousness and monitoring involve evidence accumulation. We recorded single-neuron activity in a participant with a microelectrode in the posterior parietal cortex, while they detected vibrotactile stimuli around detection threshold and provided confidence estimates. We find that detected stimuli elicited neuronal responses resembling evidence accumulation during decision-making, irrespective of motor confounds or task demands. We generalize these findings in healthy volunteers using electroencephalography. Behavioral and neural responses are reproduced with a computational model considering a stimulus as detected if accumulated evidence reaches a bound, and confidence as the distance between maximal evidence and that bound. We conclude that gradual changes in neuronal dynamics during evidence accumulation relates to perceptual consciousness and perceptual monitoring in humans.

Upper Extremity Motor Fatigability as an Early Indicator in Pediatric Onset Multiple Sclerosis

2021 ◽  
pp. 088307382199988
Author(s):  
Giuseppina Pilloni ◽  
Martin Malik ◽  
Raghav Malik ◽  
Lauren Krupp ◽  
Leigh Charvet
Keyword(s):  
Multiple Sclerosis ◽  
Grip Strength ◽  
Upper Extremity ◽  
Static Fatigue ◽  
Healthy Controls ◽  
Fatigue Index ◽  
Left Hand ◽  
Right Hand ◽  
Computer Based ◽  
Pediatric Onset

Aim: To adopt a computer-based protocol to assess grip fatigability in patients with pediatric-onset multiple sclerosis to provide detection of subtle motor involvement identifying those patients most at risk for future decline. Method: Pediatric-onset multiple sclerosis patients were recruited during routine outpatient visits to complete a grip assessment and compared to a group of healthy age- and sex-matched controls. All participants completed a computer-based measurement of standard maximal grip strength and repetitive and sustained grip performance measured by dynamic and static fatigue indices. Results: A total of 38 patients with pediatric-onset multiple sclerosis and 24 healthy controls completed the grip protocol (right-hand dominant). There were no significant group differences in maximal grip strength bilaterally (right: 21.8 vs 19.9 kg, P = .25; left: 20.4 vs 18.7 kg, P = .33), although males with pediatric-onset multiple sclerosis were significantly less strong than healthy controls (right: 26.53 vs 21.23 kg, P = .009; left; 25.13 vs 19.63 kg, P = .003). Both dynamic and static fatigue indices were significantly higher bilaterally in pediatric-onset multiple sclerosis compared with healthy control participants (left-hand dynamic fatigue index: 18.6% vs 26.7%, P = .003; right-hand static fatigue index: 28.3% vs 41.3%, P < .001; left-hand static fatigue index: 31.9% vs 42.6%, P < .001). Conclusion: Brief repeatable grip assessment including measures of dynamic and sustained static output can be a sensitive indicator of upper extremity motor involvement in pediatric-onset multiple sclerosis, potentially identifying those in need of intervention to prevent future disability.

Central neuropathic pain in multiple sclerosis is associated with impaired innocuous thermal pathways and neuronal hyperexcitability

Pain Medicine ◽  
2021 ◽  
Author(s):  
Michal Rivel ◽  
Anat Achiron ◽  
Mark Dolev ◽  
Yael Stern ◽  
Gaby Zeilig ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Neuropathic Pain ◽  
Cross Sectional Study ◽  
Healthy Controls ◽  
Sectional Study ◽  
Sensory Testing ◽  
Cross Sectional ◽  
Central Neuropathic Pain ◽  
Body Regions ◽  
Thermal Grill Illusion

Abstract Objective About a third of patients with multiple sclerosis (MS) suffer from chronic and excruciating central neuropathic pain (CNP). The mechanism underlying CNP in MS is not clear, since previous studies are scarce and their results are inconsistent. Our aim was to determine whether CNP in MS is associated with impairment of the spinothalamic-thalamocortical pathways (STTCs) and/or increased excitability of the pain system. Design Cross sectional study Setting General hospital Subjects 47 MS patients with CNP, 42 MS patients without CNP, and 32 healthy controls. Methods Sensory testing included the measurement of temperature, pain, and touch thresholds and the thermal grill illusion (TGI) for evaluating STTCs function, and hyperpathia and allodynia as indicators of hyperexcitability. CNP was characterized using interviews and questionnaires. Results The CNP group had higher cold and warm thresholds (p &lt; 0.01), as well as higher TGI perception thresholds (p &lt; 0.05), especially in painful body regions compared to controls, whereas touch and pain thresholds values were normal. The CNP group also had a significantly greater prevalence of hyperpathia and allodynia. Regression analysis revealed that whereas presence of CNP was associated with a higher cold threshold, CNP intensity, and the number of painful body regions were associated with allodynia and hyperpathia, respectively. Conclusions CNP in MS is characterized by a specific impairment of STTC function; the innocuous thermal pathways, and by pain hyperexcitability. Whereas CNP presence is associated with STTC impairment, its severity and extent are associated with pain hyperexcitability. Interventions that reduce excitability level may therefore mitigate CNP severity.

Neuromuscular Electrical Stimulation Improves Walking Performance In People With Multiple Sclerosis

2017 ◽  
Vol 49 (5S) ◽  
pp. 632 ◽  
Author(s):  
Awad M. Almuklass ◽  
Leah Davis ◽  
Landon Hamilton ◽  
Jeffrey R. Hebert ◽  
Enrique Alvarez ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Electrical Stimulation ◽  
Neuromuscular Electrical Stimulation ◽  
Walking Performance

Baclofen increases the soleus stretch reflex threshold in the early swing phase during walking in spastic multiple sclerosis patients

2000 ◽  
Vol 6 (2) ◽  
pp. 105-114 ◽  
Author(s):  
Jørgen F Nielsen ◽  
Jacob B Anderson ◽  
Thomas Sinkjær
Keyword(s):  
Multiple Sclerosis ◽  
Stretch Reflex ◽  
Swing Phase ◽  
Modulation Index ◽  
Emg Activity ◽  
Walking Performance ◽  
Linear Fit ◽  
Reflex Threshold ◽  
Multiple Sclerosis Patients ◽  
Velocity Input

The effect of baclofen on walking performance was examined in nine spastic multiple sclerosis patient. In addition, nine healthy subjects were tested as controls. The modulation of the short latency soleus stretch reflex was closer to normal with baclofen compared to the recordings without baclofen, the modulation index being 74% (range: 60-100) with baclofen and 62% (range: 20 -100) without baclofen, P=0.03. In healthy subject the modulation index was 100% (range: 52 -100). In the early swing phase the threshold of the soleus stretch reflex was significantly higher during baclofen medication being 139 degls (range: 63 -302) compared with 93 degls (range: 37-187) with out baclofen, P=0.004. The relation between the stretch velocity (input) and the amplitude of the stretch reflex (output) in early swing phase was unchanged being 0.27 μVs/deg (range: 0.1-1.51) in patient with baclofen and 0.24 μVs/deg (range: 0.08-0.79) without baclofen, P=0.25. Baclofen induced no change in input-output properties of the stretch reflex during walking compared with findings in a sitting position at matched EMG activity. There was a significant correlation between clinical spasticity score and stretch reflex threshold in the early swing phase (p=-0.61, P=0.04) and between clinical spasticity score and the slope of the best linear fit in the early swing phase (p=0.72, P=0.009).

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