Changes in surface electromyography characteristics and foot-tapping rate of force development as measures of spasticity in patients with multiple sclerosis

Spasticity is a common symptom experienced by individuals with upper motor neuron lesions such as those with stroke, spinal cord injury, traumatic brain injury, cerebral palsy, amyotrophic lateral sclerosis, and multiple sclerosis. Although the etiology and progression of spasticity differs between these clinical populations, it shares many of the same consequences: muscle pain, weakness, fatigue, increased disability, depression, medication side effects, and a reduced quality of life. For this reason, there has been increased interest in the measurement and treatment of spasticity symptoms. Subjective measures of spasticity like the Modified Ashworth Scale (MAS) and Tardieu Scale have shown questionable validity/reliability and poorly correlate to functional outcome measures but continue to be used in clinical and research settings. Objective measures like myotonometry, electrogoniometry, and inertial sensors on the other hand provide much more reliable measures but at the expense of increased costs, time, and equipment. Therefore, to properly assess and treat spasticity symptoms, a timelier and cost-effective objective measure of spasticity is needed. PURPOSE: To reexamine a previously collected dataset from a sample of patients with multiple sclerosis before and after dry-needling and functional electrically stimulated walking spasticity treatments. Specifically, we wished to know whether there were: 1.) Acute (within visit) and chronic (between visit) changes in sEMG and Foot-tapping rate of force development measures after treatment, 2.) Between leg differences before and after treatments, 3.) significant correlations between EMG, foot-tapping, and functional outcome measures. METHODS: 16 MS patients (10 relapsing-remitting and 6 progressive MS) participated in the original study. The study consisted of 14 visits: 2 pre/post visits, 4 visits of dry-needling + functional electrically stimulated walking (FESW), and 8 visits with FESW only. The more spastic leg (involved leg) was given the treatment, making the other the control. Dry-needling was performed on the involved leg’s gastrocnemius medial and lateral heads by inserting monofilament needles and electrically stimming the muscles until visible twitches occurred. Dry-needling was done 30 seconds on and 30 seconds off for a total of 90 seconds of treatment. FESW was performed on the involved leg by attaching electrodes to the tibialis anterior and gastrocnemius muscles. Patients walked 20-minutes at a self-selected pace while the involved leg was stimmed. sEMG was collected before and after each treatment by having the patient perform a single maximal heel raise. Foot-tapping ability was assessed using the 10-second foot-tapping test (FTT) and a small force plate. Functional measures also included the 25-foot walk test (25FWT) 6-minute walk test (6MWT), modified fatigue impact score (MFIS), and number of heel raises performed. RESULTS: No significant between leg differences were noted for any of the sEMG measures (p>0.05). No significant chronic changes occurred in any of the sEMG measures. For the Dry-needling + FESW visits, sEMG sample entropy was significantly increased in the involved leg at post-needling (p = 0.035) and post-FESW (p = 0.027). The non-involved leg’s sample entropy was significantly higher at post-FESW only (p = 0.017). The non-involved leg’s, mean frequency was significantly higher at post-FESW compared pre-needling (p = 0.033) and post-needling (p = 0.032). For the FESW only visits, there were no significant changes in the involved leg. The Non-involved leg’s mean frequency was significantly higher at Post-FESW (p = 0.006). Median frequency was significantly higher at Post-FESW (p = 0.009). The number of foot-taps was significantly increased from Pre to Post-intervention in both the Involved (p = 0.006) and Non-involved legs (p 0.002). There was a significantly higher number of foot-taps in the Non-involved leg compared to the Involved leg at both Pre (p =0.008) and Post (p = 0.015) timepoints. AUC was significantly higher in the Involved leg at Post-treatment (p = 0.030). Time to peak was found to be higher in the Involved leg compared to the Non-involved leg at both Pre (p = 0.037) and Post-intervention (p = 0.019). Time to base was higher in the Involved leg compared to the Non-involved leg at both Pre (p = 0.031) and Post-intervention (p = 0.004). Total tap time was higher in the Involved leg at both Pre (p = 0.010) and Post-intervention (p = 0.007). Percent time to peak was significantly lower in the involved limb at Pre-intervention (p = 0.026) and Post intervention (p = 0.037). Percent time to base was significantly higher in the Involved leg at Pre-intervention (p = 0.026) and Post intervention (p = 0.037). The sEMG measures tended to poorly or non-significantly correlate with the functional outcome measures. The foot-tapping measures, especially the involved leg, tended to exhibit stronger correlations with the functional outcome measures. CONCLUSION: sEMG Sample entropy and foot-tapping ability are significantly improved by dry-needling treatments and walking. sEMG measures did not tend to correlate well with functional outcome measures but the foot-tapping measures did. This suggests that foot-tapping rate and related measures may be a useful measure of spasticity and treatment effects

Effect of bihemispheric transcranial direct current stimulation on distal upper limb function and corticospinal tract excitability in a patient with subacute stroke: a case study

IntroductionActivation of the unaffected hemisphere contributes to motor function recovery post stroke in patients with severe upper limb motor paralysis. Transcranial direct current stimulation (tDCS) has been used in stroke rehabilitation to increase the excitability of motor-related areas. tDCS has been reported to improve upper limb motor function; nonetheless, its effects on corticospinal tract excitability and muscle activity patterns during upper limb exercise remain unclear. Additionally, it is unclear whether simultaneously applied bihemispheric tDCS is more effective than anodal tDCS, which stimulates only one hemisphere. This study examined the effects of bihemispheric tDCS training on corticospinal tract excitability and muscle activity patterns during upper limb movements in a patient with subacute stroke.MethodsIn this single-case retrospective study, the Fugl–Meyer Assessment, Box and Block Test, electromyography, and intermuscular coherence measurement were performed. Intermuscular coherence was calculated at 15–30 Hz, which reflects corticospinal tract excitability.ResultsThe results indicated that bihemispheric tDCS improved the Fugl–Meyer Assessment, Box and Block Test, co-contraction, and intermuscular coherence results, as compared with anodal tDCS. Discussion: These results reveal that upper limb training with bihemispheric tDCS improves corticospinal tract excitability and muscle activity patterns in patients with subacute stroke

Sex differences in the neural control of muscle

Sex-differences in muscle strength have been linked to differences in muscle size, involved limb, and daily activities. Early work has shown that sex-differences are greater in the upper compared to lower limb, making the upper limb an ideal model to investigate the best statistical approaches for sex comparison. Large differences in the upper limb reveals how biomechanical factors may impact neural control. Since males and females are more comparable with respect to strength in the lower limb, it allows for a determination of whether potential sex-differences in neural control exist without large differences in biomechanics. Understanding sex-differences allows for prescription of rehabilitation and training modalities, taking into account potential specificities in sex-related neuromuscular and musculoskeletal factors. The overall purpose was to examine neural and biomechanical differences that would account for sex-differences in neural control of muscle. Manuscript 1 examined normalization versus an ANCOVA to assess sex-differences. Sex-differences were seen in elbow flexor strength and rate of force development (RFD). Normalization by either maximum strength or neural factors couldn’t account for all sex-differences in RFD, resulting in an ambiguous interpretation. In contrast, both variables were able to be incorporated in an ANCOVA to determine their relative contribution. Manuscript 2 examined the effect of task familiarization and the contribution of maximum strength, twitch contraction time, muscle fiber condition velocity, and rate of muscle activation to sex-differences in the RFD during dorsiflexion. There were no significant differences between the sexes in muscle properties, but there were differences in neural control. Additionally, across days females exhibited a neural adaptation leading to an improvement in the RFD. Manuscript 3 directly assessed potential sex-differences in neural control during force gradation by recording motor unit activity during maximal and submaximal contractions. Females had less force steadiness (FS), which may have resulted from neural compensation for a less optimal pennation angle or a tendency towards greater joint laxity. Higher motor unit discharge rates and incidence of doublets may increase twitch force summation leading to a reduction in FS. Thus, biomechanical, not inherent sex-differences in neural drive led to neural compensation strategies manifesting as a difference in FS

Muscle activation patterns in shoulder impingement patients

Introduction: Shoulder impingement is one of the most common presentations of shoulder joint problems 1. It appears to be caused by a reduction in the sub-acromial space as the humerus abducts between 60o -120o – the 'painful arc'. Structures between the humeral head and the acromion are thus pinched causing pain and further pathology 2. Shoulder muscle activity can influence this joint space but it is unclear whether this is a cause or effect in impingement patients. This study aimed to observe muscle activation patterns in normal and impingement shoulder patients and determine if there were any significant differences. Method: 19 adult subjects were asked to perform shoulder abduction in their symptomatic arm and non-symptomatic. 10 of these subjects (age 47.9 ± 11.2) were screened for shoulder impingement, and 9 subjects (age 38.9 ± 14.3) had no history of shoulder pathology. Surface EMG was used to collect data for 6 shoulder muscles (Upper, middle and lower trapezius, serratus anterior, infraspinatus, middle deltoids) which was then filtered and fully rectified. Subjects performed 3 smooth unilateral abduction movements at a cadence of 16 beats of a metronome set at 60bpm, and the mean of their results was recorded. T-tests were used to indicate any statistical significance in the data sets. Significance was set at P<0.05. Results: There was a significant difference in muscle activation with serratus anterior in particular showing a very low level of activation throughout the range when compared to normal shoulder activation patterns (<30%). Middle deltoid recruitment was significantly reduced between 60-90o in the impingement group (30:58%).Trends were noted in other muscles with upper trapezius and infraspinatus activating more rapidly and erratically (63:25%; 60:27% respectively), and lower trapezius with less recruitment (13:30%) in the patient group, although these did not quite reach significance. Conclusion: There appears to be some interesting alterations in muscle recruitment patterns in impingement shoulder patients when compared against their own unaffected shoulders and the control group. In particular changes in scapula control (serratus anterior and trapezius) and lateral rotation (infraspinatus), which have direct influence on the sub-acromial space, should be noted. It is still not clear whether these alterations are causative or reactionary, but this finding gives a clear indication to the importance of addressing muscle reeducation as part of a rehabilitation programme in shoulder impingement patients

A Systematic Review and Meta-Analysis of the Incidence of Injury in Professional Female Soccer

The epidemiology of injury in male professional football is well documented and has been used as a basis to monitor injury trends and implement injury prevention strategies. There are no systematic reviews that have investigated injury incidence in women’s professional football. Therefore, the extent of injury burden in women’s professional football remains unknown. PURPOSE: The primary aim of this study was to calculate an overall incidence rate of injury in senior female professional soccer. The secondary aims were to provide an incidence rate for training and match play. METHODS: PubMed, Discover, EBSCO, Embase and ScienceDirect electronic databases were searched from inception to September 2018. Two reviewers independently assessed study quality using the Strengthening the Reporting of Observational Studies in Epidemiology statement using a 22-item STROBE checklist. Seven prospective studies (n=1137 professional players) were combined in a pooled analysis of injury incidence using a mixed effects model. Heterogeneity was evaluated using the Cochrane Q statistic and I2. RESULTS: The epidemiological incidence proportion over one season was 0.62 (95% CI 0.59 - 0.64). Mean total incidence of injury was 3.15 (95% CI 1.54 - 4.75) injuries per 1000 hours. The mean incidence of injury during match play was 10.72 (95% CI 9.11 - 12.33) and during training was 2.21 (95% CI 0.96 - 3.45). Data analysis found a significant level of heterogeneity (total Incidence, X2 = 16.57 P < 0.05; I2 = 63.8%) and during subsequent sub group analyses in those studies reviewed (match incidence, X2 = 76.4 (d.f. = 7), P <0.05; I2 = 90.8%, training incidence, X2 = 16.97 (d.f. = 7), P < 0.05; I2 = 58.8%). Appraisal of the study methodologies revealed inconsistency in the use of injury terminology, data collection procedures and calculation of exposure by researchers. Such inconsistencies likely contribute to the large variance in the incidence and prevalence of injury reported. CONCLUSIONS: The estimated risk of sustaining at least one injury over one football season is 62%. Continued reporting of heterogeneous results in population samples limits meaningful comparison of studies. Standardising the criteria used to attribute injury and activity coupled with more accurate methods of calculating exposure will overcome such limitations