High-versus low-frequency stimulation effects on fine motor control in chronic hemiplegia: a pilot study

Effect of Neuromuscular Electrical Stimulation Training on Control of Involuntary Muscular Torque and Stimulation Intensity in Older Adults

The purpose of this study was to examine the effects of a 4-week neuromuscular electrical stimulation (NMES) training regimen on involuntary torque output and electrical stimulation intensity in older adults. Twelve older adults (ages: 68.4 ± 6.5 years; men: n = 6, women: n = 6; weight: 158.6 ± 27.3 lbs; height: 65.2 ± 2.1 in) received submaximal intensity NMES to the quadriceps for 4 weeks to determine training-related changes in stimulation intensity and involuntary control of muscular torque during the NMES protocol. Two-way repeated measures ANOVAs were used to compare torque parameters and stimulation intensity between days and across protocol time bins. After training, stimulation intensity and torque increased over the course of the NMES protocol, while torque decreased during the protocol pre-training. These results suggest that muscular endurance of involuntary muscle contraction is increased with NMES training, and that stimulation intensity should be increased throughout the course of training to augment muscular torque output.

Effectiveness and Electrophysiological Mechanisms of Focal Vibration on Upper Limb Motor Dysfunction in Patients with Subacute Stroke: A Randomized Controlled Trial

Upper limb motor dysfunction is a common complication after stroke, which has a negative impact on the daily life of patients. Focal vibration (FV) has been used to improve upper limb motor function in acute and chronic stroke patients, but its application in subacute stroke patients has not been extensively explored. Therefore, the purpose of this study was to explore the therapeutic effect of FV on upper limb motor function in subacute stroke patients and its underlying electrophysiological mechanism. Twenty-nine patients were enrolled and randomized into two groups: control group and vibration group. The control group were treated with conventional therapy including passive and active physical activity training, standing and sitting balance exercises, muscle strength training, hand extension and grasping exercises. The vibration group were given conventional rehabilitation and vibration therapy. A deep muscle stimulator (DMS) with a frequency of 60 Hz and an amplitude of 6 mm was used to provide vibration stimulation, which was sequentially applied along the biceps muscle to the flexor radialis of the affected limb for 10 minutes, once a day, and 6 times a week. Both groups received treatments for 4 consecutive weeks. In the vibration group, the motor evoked potential (MEP) latency and the somatosensory evoked potential (SEP) latency were significantly shortened (P<0.05) immediately after vibration and 30 minutes after vibration; the SEP amplitude and MEP amplitude were significantly increased (P<0.05) immediately after vibration and 30 minutes after vibration. The MEP latency (P=0.001) and SEP N20 latency (P=0.001) were shortened, and the MEP amplitude (P=0.011) and SEP N20 amplitude (P=0.017) were significantly increased after 4 weeks in the vibration group. After 4 consecutive weeks, the vibration group showed significant improvements in Modified Ashworth Scale (MAS) (P=0.037), Brunnstrom stage for upper extremity (BS-UE) (P=0.020), Fugl-Meyer assessment for upper extremity (FMA-UE) (P=0.029), Modified Barthel Index (MBI) (P=0.024), and SEP N20 (P=0.046) compared to the control group. The Brunnstrom stage for hand (BS-H) (P=0.451) did not show significant differences between the two groups. This study showed that FV was effective in improving upper limb motor function in subacute stroke patients. The underlying mechanism of FV may be that it enhances the efficacy of sensory pathways and induces plastic changes in the sensorimotor cortex.

Use of Neuromuscular Electrical Stimulation for Abdominal and Quadriceps Muscle Strengthening: A Randomized Controlled Trial

BACKGROUND

Radiographic imaging has demonstrated muscle hypertrophy after treatment with noninvasive body contouring devices that target skeletal muscles.

OBJECTIVE

This pilot study sought to evaluate whether increased muscle mass translated to improved functional strength and endurance.

METHODS

A prospective, single-center, randomized open-label controlled study included 26 subjects randomized into 3 groups: 2 treatment groups and 1 control group. Both treatment groups received 4 neuromuscular electrical stimulation (NMES) treatments over a 2-week period. Muscle performance testing was conducted at baseline and 2-week and 4-week posttreatment. Anthropometric measurements were assessed at baseline and at 4-week posttreatment. Study participants completed subject satisfaction surveys and a personal experience assessment.

RESULTS

Treatment with NMES resulted in statistically significant improvements in abdominal and quadriceps strength and endurance from baseline through 4-week posttreatment. Mean waist circumference decreased and quadriceps circumference increased, both nonsignificantly. Subject satisfaction regarding abdominal and quadriceps strength was reported as "satisfied or very satisfied" in 89% and 92% at 4-week and 8-week posttreatment, respectively.

CONCLUSION

Treatment of the abdomen and quadriceps with NMES leads to significant improvements in muscular strength and endurance.

A randomised clinical trial comparing 35 Hz versus 50 Hz frequency stimulation effects on hand motor recovery in older adults after stroke

More solid data are needed regarding the application of neuromuscular electrical stimulation (NMES) in the paretic hand following a stroke. A randomised clinical trial was conducted to compare the effects of two NMES protocols with different stimulation frequencies on upper limb motor impairment and function in older adults with spastic hemiparesis after stroke. Sixty nine outpatients were randomly assigned to the control group or the experimental groups (NMES with 50 Hz or 35 Hz). Outcome measures included motor impairment tests and functional assessment. They were collected at baseline, after 4 and 8 weeks of treatment, and after a follow-up period. NMES groups showed significant changes (p < 0.05) with different effect sizes in range of motion, grip and pinch strength, the Modified Ashworth Scale, and the muscle electrical activity in the extensors of the wrist. The 35 Hz NMES intervention showed a significant effect on Barthel Index. Additionally, there were no significant differences between the groups in the Box and Block Test. Both NMES protocols proved evidence of improvements in measurements related to hand motor recovery in older adults following a stroke, nevertheless, these findings showed that the specific stimulation frequency had different effects depending on the clinical measures under study.

Early-phase dose articulation trials are underutilized for post-stroke motor recovery: A systematic scoping review

BACKGROUND

To enable development of effective interventions, there is a need to complete systematic early-phase dose articulation research. This scoping review aimed to synthesize dose articulation research of behavioral motor interventions for stroke recovery.

METHODS

MEDLINE and EMBASE were systematically searched for dose articulation studies. Preclinical experiments and adult clinical trials were classified based on the discovery pipeline and analyzed to determine which dose dimensions were articulated (time, scheduling or intensity) and how they were investigated (unidimensional vs multidimensional approach). Reporting of dose, safety and efficacy outcomes were summarized. The intervention description, risk of bias, and quality was appraised.

RESULTS

We included 41 studies: 3 of preclinical dose preparation (93 rodents), 2 Phase I dose ranging (21 participants), 9 Phase IIA dose screening (198 participants), and 27 Phase IIB dose finding (1879 participants). All studies adopted a unidimensional approach. Time was the most frequent dimension investigated (53%), followed by intensity (29%), and scheduling (18%). Overall, 95% studies reported an efficacy outcome; however, only 65% reported dose and 45% reported safety. Across studies, 61% were at high risk of bias, and the average percentage reporting of intervention description and quality was 61% and 67%, respectively.

CONCLUSION

This review highlights a need to undertake more high-quality, early-phase studies that systematically articulate intervention doses from a multidimensional perspective in the field of behavioral motor stroke recovery. To address this gap, we need to invest in adapting early phase trial designs, especially Phase I, to support multidimensional dose articulation.

Skeletal muscle stiffness as measured by magnetic resonance elastography after chronic spinal cord injury: a cross-sectional pilot study

Skeletal muscle stiffness is altered after spinal cord injury (SCI). Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI. The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size, spasticity, and peak torque in persons with SCI. Previous studies examined the association between muscle stiffness and spasticity, however, we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI. Ten participants (one female) with chronic SCI and eight (one female) matched able-bodied controls participated in this cross-sectional study. Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation. Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion. Peak isometric and isokinetic torques were measured using a biodex dynamometer. Stiffness values were non-significantly lower (12.5%; P = 0.3) in the SCI group compared to able-bodied controls. Moreover, stiffness was positively related to vastus lateralis whole muscle cross-sectional area (CSA) (r² = 0.64, P < 0.005) and vastus lateralis absolute muscle CSA after accounting for intramuscular fat (r² = 0.78, P < 0.0007). Stiffness was also positively correlated to both isometric (r²= 0.55-0.57, P < 0.05) and isokinetic peak (r²= 0.46-0.48, P < 0.05) torques. Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls. Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles. The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities. All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center, USA (IRB #: 02314) on May 3, 2017.

Electrical Stimulation of Muscle: Electrophysiology and Rehabilitation

The generation of action potentials in intramuscular motor and sensory axons in response to an imposed external current source can evoke muscle contractions and elicit widespread responses throughout the nervous system that impact sensorimotor function. The benefits experienced by individuals exposed to several weeks of treatment with electrical stimulation of muscle suggest that the underlying adaptations involve several physiological systems, but little is known about the specific changes elicited by such interventions.

Reporting for Duty: The duty cycle in Functional Electrical Stimulation research. Part I: Critical commentaries of the literature

There are several parameters that can be modulated during electrical stimulation-induced muscle contraction to obtain external work, i.e., Functional Electrical Stimulation (FES). The literature has several reports of the relationships of parameters such as frequency, pulse width, amplitude and physiological or biomechanical outcomes (i.e., torque) when these parameters are changed. While these relationships are well-described, lesser known across the literature is how changing the duty cycle (time ON and time OFF) of stimulation affects the outcomes. This review provides an analysis of the literature pertaining to the duty cycle in electrical stimulation experiments. There are two distinct sections of this review - an introduction to the duty cycle and definitions from literature (part I); and contentions from the literature and proposed frameworks upon which duty cycle can be interpreted (part II). It is envisaged that the two reviews will highlight the importance of modulating the duty cycle in terms of muscle fatigue in mimicking physiological activities. The frameworks provided will ideally assist in unifying how researchers consider the duty cycle in electrical stimulation (ES) of muscles.

The use of functional electrical stimulation to improve upper limb function in children with hemiplegic cerebral palsy: A feasibility study

Background

Grasping and manipulating objects are common problems for children with hemiplegic cerebral palsy. Multichannel-functional electrical stimulation may help facilitate upper limb movements and improve function.

Objective

To evaluate the feasibility of multichannel-functional electrical stimulation to improve grasp and upper limb function in children with hemiplegic cerebral palsy to inform the development of a clinical trial.

Methods

A prospective pre-/post-test/follow-up (six months) design with three children, aged 6–13 years, was used. Multichannel-functional electrical stimulation (mFES) was applied to the hemiplegic upper limb for up to 48 sessions over 16 weeks. Feasibility indicators included recruitment of participants and adherence rates, safety, and discomfort/pain. Effectiveness was assessed using the grasp domain of the Quality of Upper Extremity Skills Test, and other secondary clinical outcome measures with “success” criteria set a priori.

Results

Participant recruitment target was not met but adherence was high, and multichannel-functional electrical stimulation was found to be safe and comfortable. Of the three participants, two improved in grasp at post-test, whereas one child’s ability deteriorated. Only one child met success criteria on most outcomes at post-test.

Conclusions

Feasibility indicators met success criteria, except for participant recruitment. Treatment effectiveness was mixed. A future case comparison investigation with a larger but more selected sample is suggested.

Efficacy of mechano-acoustic vibration on strength, pain, and function in poststroke rehabilitation: a pilot study

BACKGROUND

Vibration therapy may be used to help cortical reorganization after stroke as it can cause different adaptive metabolic and mechanical effects.

OBJECTIVE

This study examined whether the application of mechano-acoustic vibration on upper limb muscles could induce changes in range of motion (ROM), function, pain, and grip strength in individuals with chronic stroke.

METHODS

Out of 52 individuals post stroke with upper limb spasticity who were eligible,16 received mechano-acoustic vibration therapy (ViSS device) 3 times weekly for 12 sessions. The frequency of vibration was set to 300 Hz for 30 minutes. The treated muscles were the extensor carpi radialis longus and brevis and triceps brachii during voluntary contraction. All participants were evaluated in both upper limbs before (T0) and at the end (T1) of treatment with a dynamometer (hand grip strength), Modified Ashworth Scale, QuickDASH, FIM score, Fugl-Meyer scale, Verbal Numerical Rating Scale of pain, and Jebsen-Taylor Hand Function Test.

RESULTS

After 4 weeks, hand grip power had improved and pain and spasticity had decreased. Improvements were recorded for all parameters and were considered statistically significant.

CONCLUSIONS

Application of vibratory stimuli to a muscle can increase the motor-evoked potential recorded from the muscle, suggesting an enhancement of corticospinal excitability. Low amplitude, high-frequency vibration treatment (300 Hz) can significantly decrease tone and pain and improve strength in upper limb of hemiplegic individuals, when applied for 30 minutes, 3 times a week over 4 weeks.

Neuromuscular Electrical Stimulation for Treatment of Muscle Impairment: Critical Review and Recommendations for Clinical Practice

Purpose: In response to requests from physiotherapists for guidance on optimal stimulation of muscle using neuromuscular electrical stimulation (NMES), a review, synthesis, and extraction of key data from the literature was undertaken by six Canadian physical therapy (PT) educators, clinicians, and researchers in the field of electrophysical agents. The objective was to identify commonly treated conditions for which there was a substantial body of literature from which to draw conclusions regarding the effectiveness of NMES. Included studies had to apply NMES with visible and tetanic muscle contractions. Method: Four electronic databases (CINAHL, Embase, PUBMED, and SCOPUS) were searched for relevant literature published between database inceptions until May 2015. Additional articles were identified from bibliographies of the systematic reviews and from personal collections. Results: The extracted data were synthesized using a consensus process among the authors to provide recommendations for optimal stimulation parameters and application techniques to address muscle impairments associated with the following conditions: stroke (upper or lower extremity; both acute and chronic), anterior cruciate ligament reconstruction, patellofemoral pain syndrome, knee osteoarthritis, and total knee arthroplasty as well as critical illness and advanced disease states. Summaries of key details from each study incorporated into the review were also developed. The final sections of the article outline the recommended terminology for describing practice using electrical currents and provide tips for safe and effective clinical practice using NMES. Conclusion: This article provides physiotherapists with a resource to enable evidence-informed, effective use of NMES for PT practice.