Kinematics and muscle activity of individuals with incomplete spinal cord injury during treadmill stepping with and without manual assistance

Background  

Treadmill training with bodyweight support and manual assistance improves walking ability of patients with neurological injury. The purpose of this study was to determine how manual assistance changes muscle activation and kinematic patterns during treadmill training in individuals with incomplete spinal cord injury.     

The effects of powered ankle-foot orthoses on joint kinematics and muscle activation during walking in individuals with incomplete spinal cord injury

Background  

Powered lower limb orthoses could reduce therapist labor during gait rehabilitation after neurological injury. However, it is not clear how patients respond to powered assistance during stepping. Patients might allow the orthoses to drive the movement pattern and reduce their muscle activation. The goal of this study was to test the effects of robotic assistance in subjects with incomplete spinal cord injury using pneumatically powered ankle-foot orthoses.     

Quantifying muscle coactivation in individuals with incomplete spinal cord injury using wavelets

BackgroundIndividuals with incomplete spinal cord injury often have decreased gait function and coactivation of antagonistic muscle pairs. Common ways of quantifying coactivation using electromyographic signals do not consider frequency information in the signal. As electromyographic signals from different motor unit types have different frequency components and muscle fiber type can change in individuals with spinal cord injury, it may be beneficial to consider frequency components. The aims were to demonstrate the utility of using a method which considers temporal and frequency components of the electromyographical signal to quantify coactivation in lower extremity muscles in individuals with incomplete spinal cord injury through 1) comparison with able-bodied individuals and 2) comparison before and after body weight supported treadmill training.MethodsFrequency decomposition techniques were applied to electromyographical signals to consider the temporal and frequency components of the electromyographical signals to quantify coactivation over a range of frequencies.ResultsOur main findings show that correlation coefficients between total EMG intensities of rectus femoris-biceps femoris and medial gastrocnemius-tibialis anterior were significantly different between able-bodied individuals and those with incomplete spinal cord injury (p = 0006, p = 0.01). The correlation spectra of medial gastrocnemius-tibialis anterior of the spinal cord injury group were substantially different than those the able-bodied group, while the EMG normalcy score was significantly different (p = 0.002). We also found that there was a change in coactivation of ankle muscles after body weight supported treadmill training.InterpretationOur findings indicate that there may be frequency specific differences in muscle coactivation between able-bodied individuals and those with incomplete spinal cord injury. Changes in coactivation were also observed before and after body weight supported treadmill training. These differences may reflect the changes in recruitment patterns of different motor unit types.     

Robotic-assisted, body-weight-supported treadmill training in individuals following motor incomplete spinal cord injury

BACKGROUND AND PURPOSE: Performance of therapist-assisted, body-weight-supported treadmill training (BWSTT) to enhance walking ability of people with neurological injury is an area of intense research. Its application in the clinical setting, however, is limited by the personnel and labor requirements placed on physical therapists. Recent development of motorized ("robotic") rehabilitative devices that provide assistance during stepping may improve delivery of BWSTT. CASE DESCRIPTION: This case report describes the use of a robotic device to enhance motor recovery and ambulation in 3 people following motor incomplete spinal cord injury. INTERVENTIONS: Changes in motor impairment, functional limitations, and locomotor disability were monitored weekly during robotic-assisted BWSTT and following transition to therapist-assisted BWSTT with the assistance of one therapist. OUTCOMES: Following this training, 2 patients recovered independent over-ground walking and another improved his gait speed and endurance. DISCUSSION: The use of robotic devices may assist physical therapists by providing task-specific practice of stepping in people following neurological injury.     

脊髓损伤患者与健康人步行时躯干肌肌肉利用率的对照研究

目的观察和比较脊髓损伤患者与健康人步行时躯干肌的肌肉利用率（MUR）。 方法选取20例T11完全性脊髓损伤患者（病例组）及健康志愿者（对照组）,每组10例,采用表面电极和同步摄像技术对2组受试者步行时躯干肌表面肌群（胸大肌、腹直肌、腹外斜肌、斜方肌、背阔肌、竖脊肌）的肌电活动情况进行测试和分析,以最大用力收缩的百分比表示MUR。用独立样本t检验分析比较组间MUR的差异,用单因素方差分析比较组内MUR的差异。 结果①站立相时,病例组胸大肌、腹外斜肌和竖脊肌的MUR分别为（24.93±17.22）%、（30.38±13.92）%和（15.54±5.02）%,均大于对照组［(7.54±3.84)%、(10.48±6.02)%及(10.85±4.61)%］,且组间差异有统计学意义（P<0.05）。迈步相时,病例组腹外斜肌和竖脊肌的MUR［（29.11±24.62）%和（19.57±11.15）%］大于对照组［（8.20±4.23）%和（8.54±3.95）%］,组间差异亦有统计学意义（P<0.05）。②站立相时,病例组组内比较,腹外斜肌的MUR大于其它肌肉（胸大肌除外）,而胸大肌的MUR［（24.93±17.22）%］大于斜方肌［（10.88±9.28）%］,差异均有统计学意义（P<0.05）;对照组组内比较,各肌肉的MUR差异无统计学意义（P>0.05）。迈步相时,病例组内比较,腹外斜肌的MUR大于斜方肌（P<0.05）;对照组内斜方肌的MUR［（13.09±9.17）%］大于胸大肌［（7.90±4.06）%］和腹直肌［（5.76±4.21）%］,背阔肌的MUR［（11.06±6.52）%］大于腹直肌［（5.76±4.21）%］,且差异均有统计学意义（P<0.05）。 结论T11完全性脊髓损伤患者步行时胸大肌、腹外斜肌及竖脊肌的肌肉利用率高于健康人,可为优化步行训练方案提供参考。     

Combined use of body weight support, functional electric stimulation, and treadmill training to improve walking ability in individuals with chronic incomplete spinal cord injury

OBJECTIVE: To assess the effect of an intervention combining body weight support (BWS), functional electric stimulation (FES), and treadmill training on overground walking speed (OGWS), treadmill walking speed, speed and distance, and lower extremity motor scores (LEMS). DESIGN: Before and after comparison. SETTING: Miami Project to Cure Paralysis. PARTICIPANTS: Nineteen subjects with American Spinal Injury Association class C injury who were at least 1 year postinjury and had asymmetrical lower extremity function. INTERVENTION: Subjects trained 1.5 hours per day, 3 days per week, for 3 months. The training consisted of body weight-supported treadmill walking assisted by electric stimulation. Stimulation was applied to common peroneal nerve of the weaker lower extremity (LE) and timed to assist with the swing phase of the step cycle. MAIN OUTCOME MEASURES: OGWS in the absence of both BWS and FES; LEMS, and treadmill training parameters of speed and distance. RESULTS: Over the course of training, there was a significant increase in OGWS (from.12 +/- 0.8m/s to .21 +/- .15m/s, p = .0008), treadmill walking speed (from .23 +/- .12m/s to.49 +/- .20m/s, p = .00003), and treadmill walking distance (from 93 +/- 84m to 243 +/- 139m, p = .000001). The median LEMS increased significantly for both the stimulated and nonstimulated leg (from 8 to 11 in the FES-assisted leg, from 15 to 18 in the nonassisted leg, p < .005 for each). CONCLUSIONS: All subjects showed improvement in OGWS and overall LE strength. Further research is required to delineate the essential elements of these particular training strategies.     

Comparison of soleus H-reflex modulation after incomplete spinal cord injury in 2 walking environments: treadmill with body weight support and overground

Phadke CP, Wu SS, Thompson FJ, Behrman AL. Comparison of soleus H-reflex modulation after incomplete spinal cord injury in 2 walking environments: treadmill with body weight support and overground.

Objective

To investigate a walking environment effect on soleus H-reflex modulation during walking in persons with motor incomplete spinal cord injury (SCI) and noninjured controls.

Design

Pretest and posttest repeated-measures quasi-experimental controlled design.

Setting

Locomotor training laboratory.

Participants

Eight adults with incomplete SCI and 8 noninjured age- and speed-matched controls.

Intervention

Walking overground with a customary assistive device and brace at a self-selected, comfortable walking speed was compared with walking on treadmill with 40% body weight support (BWS) and manual trainers for leg and trunk movement guidance.

Main Outcome Measure

Mean soleus H-reflex amplitude (H/M ratio) was recorded during midstance and midswing phases of walking.

Results

The H/M ratio was 33% smaller in stance phase (P=.078) and 56% smaller in the swing phase (P=.008) of walking on the treadmill with BWS and manual assistance compared with overground in the incomplete SCI group. The H/M ratio in the incomplete SCI group was significantly greater compared with noninjured controls in the stance and swing phases of overground walking (P=.001, P=.007, respectively). Soleus H-reflex modulation in the 2 walking environments did not differ significantly in the noninjured population.

Conclusions

Training walking on a treadmill with BWS and manual assistance to approximate the kinematics and spatiotemporal pattern of walking may be a more optimal environment to aid in normalizing reflex modulation after incomplete SCI when compared with conventional gait training overground.     

Speed impacts frontal-plane maneuver stability of individuals with incomplete spinal cord injury

BackgroundFollowing incomplete spinal cord injury, people often move slowly in an effort to maintain stability during walking maneuvers. Here we examine how maneuver speed impacts frontal-plane stability in people with incomplete spinal cord injury. We hypothesized that the challenge to control frontal-plane stability would increase with maneuver speed; specifically, the minimum lateral margin of stability would be smaller and the required coefficient of friction to avoid a slip would be greater during fast vs. preferred speed maneuvers.MethodsWe measured kinematics and ground reaction forces as 12 individuals with incomplete spinal cord injury performed side-step, lateral maneuvers at preferred and fast speeds. We examined four sequential steps: the Setup and Pushoff steps initiated the maneuver, and the Landing and Recovery steps arrested the maneuver.FindingsOur hypotheses were partially supported. Maneuver time was shorter during fast vs. preferred speed maneuvers (p = 0.003). Minimum lateral margin of stability was smaller during the Setup step of fast vs. preferred speed maneuvers (p = 0.026). We found no differences in minimum lateral margin of stability between speeds for the Landing and Recovery steps (p > 0.05). The required coefficient of friction was not different between fast and preferred speed maneuvers (p = 0.087).InterpretationThe greatest effect of increasing maneuver speed occurred during the Setup step; as speed increased, participants reduced their minimum lateral margin of stability ipsilateral to the maneuver direction. This action allowed maneuvers to be performed more quickly without requiring a greater lateral impulse during the Pushoff step. However, this strategy reduced passive stability.     

Lower-extremity muscle cross-sectional area after incomplete spinal cord injury

OBJECTIVES: (1) To quantify skeletal muscle size in lower-extremity muscles of people after incomplete spinal cord injury (SCI), (2) to assess differences in muscle size between involved lower limbs, (3) to determine the impact of ambulatory status (using wheelchair for community mobility vs not using a wheelchair for community mobility) on muscle size after incomplete SCI, and (4) to determine if differential atrophy occurs among individual muscles after incomplete SCI. DESIGN: Case-control study. SETTING: University research setting. PARTICIPANTS: Seventeen people with incomplete SCI and 17 age-, sex-, weight-, and height-matched noninjured controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Maximum cross-sectional area (CSA) of individual lower-extremity muscles (soleus, medial gastrocnemius, lateral gastrocnemius, tibialis anterior, quadriceps femoris, hamstrings) as assessed by magnetic resonance imaging. RESULTS: Overall, subjects with incomplete SCI had significantly smaller (24%-31%) average muscle CSA in affected lower-extremity muscles as compared with control subjects (P<.05). Mean differences were highest in the thigh muscles ( approximately 31%) compared with the lower-leg muscles ( approximately 25%). No differences were noted between the self-reported more- and less-involved limbs within the incomplete SCI group. Dichotomizing the incomplete SCI group showed significantly lower muscle CSA values in both the wheelchair (range, 21%-39%) and nonwheelchair groups (range, 24%-38%). In addition, the wheelchair group exhibited significantly greater plantarflexor muscle atrophy compared with the dorsiflexors, with maximum atrophy in the medial gastrocnemius muscle (39%). CONCLUSIONS: Our results suggest marked and differential atrophic response of the affected lower-extremity muscles that is seemingly affected by ambulatory status in people with incomplete SCI.     

Overground walking with a robotic exoskeleton elicits trunk muscle activity in people with high-thoracic motor-complete spinal cord injury

Background

The trunk muscles are critical for postural control. Recent neurophysiological studies have revealed sparing of trunk muscle function in individuals with spinal cord injury (SCI) classified with thoracic or cervical motor-complete injuries. These findings raise the possibility for recruiting and retraining this spared trunk function through rehabilitation. Robotic gait training devices may provide a means to promote trunk muscle activation. Thus, the objective of this study was to characterize and compare the activation of the trunk muscles during walking with two robotic gait training devices (Ekso and Lokomat) in people with high thoracic motor-complete SCI.

Methods

Participants with chronic motor-complete paraplegia performed 3 speed-matched walking conditions: Lokomat-assisted walking, Ekso-assisted walking overground, and Ekso-assisted walking on a treadmill. Surface electromyography (EMG) signals were recorded bilaterally from the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles.

Results

Greater recruitment of trunk muscle EMG was elicited with Ekso-assisted walking compared to the Lokomat. Similar levels of trunk EMG activation were observed between Ekso overground and Ekso on the treadmill, indicating that differences between Ekso and Lokomat could not be attributed to the use of a hand-held gait aid. The level of trunk EMG activation during Lokomat walking was not different than that recorded during quiescent supine lying.

Conclusions

Ekso-assisted walking elicits greater activation of trunk muscles compared to Lokomat-assisted walking, even after controlling for the use of hand-held assistive devices. The requirement of the Ekso for lateral weight-shifting in order to activate each step could lead to better postural muscle activation.

     

Mechanomyography responses characterize altered muscle function during electrical stimulation-evoked cycling in individuals with spinal cord injury

BackgroundInvestigation of muscle fatigue during functional electrical stimulation (FES)-evoked exercise in individuals with spinal cord injury using dynamometry has limited capability to characterize the fatigue state of individual muscles. Mechanomyography has the potential to represent the state of muscle function at the muscle level. This study sought to investigate surface mechanomyographic responses evoked from quadriceps muscles during FES-cycling, and to quantify its changes between pre- and post-fatiguing conditions in individuals with spinal cord injury.MethodsSix individuals with chronic motor-complete spinal cord injury performed 30-min of sustained FES-leg cycling exercise on two days to induce muscle fatigue. Each participant performed maximum FES-evoked isometric knee extensions before and after the 30-min cycling to determine pre- and post- extension peak torque concomitant with mechanomyography changes.FindingsSimilar to extension peak torque, normalized root mean squared (RMS) and mean power frequency (MPF) of the mechanomyography signal significantly differed in muscle activities between pre- and post-FES-cycling for each quadriceps muscle (extension peak torque up to 69%; RMS up to 80%, and MPF up to 19%). Mechanomyographic-RMS showed significant reduction during cycling with acceptable between-days consistency (intra-class correlation coefficients, ICC = 0.51–0.91). The normalized MPF showed a weak association with FES-cycling duration (ICC = 0.08–0.23). During FES-cycling, the mechanomyographic-RMS revealed greater fatigue rate for rectus femoris and greater fatigue resistance for vastus medialis in spinal cord injured individuals.InterpretationMechanomyographic-RMS may be a useful tool for examining real time muscle function of specific muscles during FES-evoked cycling in individuals with spinal cord injury.     

Curve walking is not better than straight walking in estimating ambulation-related domains after incomplete spinal cord injury

Labruyère R, van Hedel HJ. Curve walking is not better than straight walking in estimating ambulation-related domains after incomplete spinal cord injury.ObjectivesTo investigate whether a figure-of-8–shaped walking test can estimate various domains of walking in subjects with incomplete spinal cord injury (iSCI) better than the 10-meter walk test (10MWT), and to explore similarities and differences between the 2 tests and between subjects with iSCI and age-matched, healthy controls.DesignCase-control study.SettingSpinal cord injury center of a university hospital.ParticipantsA convenience sample of subjects with iSCI (n=15; mean age, 50y; 40% women; neurologic level from C3 to L5; median time since injury, 5mo) was compared with an age-matched control group (47% women).InterventionsNot applicable.Main Outcome MeasuresThe figure-of-8 test (FET) included 6 conditions to test the subjects' ability to adapt their gait to several circumstances. These conditions covered normal and maximal walking speed, constrained vision, obstacles, foamed soles, and a dual task. Additionally, subjects were tested for lower extremity muscle strength, gait capacity (10MWT) and balance, independence, and fear of falling.Results(1) Preferred straight-walking speed correlated with the different FET conditions in both groups; (2) if normalized to preferred straight-walking speed, FET conditions showed significant differences between both groups; (3) if normalized to preferred curve-walking speed, these differences seemed to disappear; and (4) the 10MWT appeared superior to the different conditions of the FET in estimating various walking-related functions.ConclusionsSubjects with iSCI seem to have difficulties with curve walking compared with straight walking. We therefore recommend the implementation of curve walking into rehabilitation training programs. However, the FET did not provide a better estimate of functional ambulation performance after an iSCI compared with the 10MWT.     

Long-term body-weight-supported treadmill training for incomplete cervical spinal cord injury: a case report

[Purpose] To investigate the effects of long-term body-weight-supported treadmill training on walking ability and physical function in an elderly individual with incomplete cervical spinal cord injury. [Participant and Methods] The patient was a 68 year-old male with an incomplete spinal cord injury at the C3/C4 level, incurred when he was 56 years old. He initiated home-based body-weight-supported treadmill training using a body-weight-supported treadmill installed at his home. His walking ability was measured as the percentage of body weight load reduction, and his physical function was evaluated using manual muscle testing and measuement of the range of motion of his lower limbs. [Results] The physical function of the lower limbs was improved, maintained, or showed delayed decline until 9.5 years post-injury. [Conclusion] Long-term body-weight-supported treadmill training may improve, maintain, or at least delay the decline of the physical function of participants for several years, without causing any remarkable complications.     

Reactive balance responses to an unexpected slip perturbation in individuals with incomplete spinal cord injury

BackgroundFrequent falls while walking among individuals with incomplete spinal cord injury may suggest impairments in reactive balance control; however, reactive balance control during walking has not been studied in this population. The objective was to compare reactive balance control with respect to changes in margin of stability, onset of arm and heel responses, and onset and magnitude of muscle activity following an unexpected slip perturbation in individuals with incomplete spinal cord injury and able-bodied individuals.MethodsKinematic and electromyography data were obtained during normal walking and one unexpected slip. Changes in margin of stability following a compensatory or aborted step, onset of arms and trail heel responses, and onset and magnitude of activation of the tibialis anterior, soleus and gluteus medius were calculated. Multivariate analyses compared responses between incomplete spinal cord injury and able-bodied groups.FindingsData from 16 participants with incomplete spinal cord injury (all American Spinal Injury Association Impairment Scale Grade D, 8 with tetraplegia) and 13 age-and-sex matched able-bodied individuals were included. Individuals with incomplete spinal cord injury demonstrated limited ability to increase margin of stability in the lateral direction during a compensatory or aborted step, and a smaller magnitude of soleus activity compared to able-bodied individuals.InterpretationThere are limitations in reactive balance control of individuals with incomplete spinal cord injury, which may be a reason for the high frequency of falls in this population. Reactive balance assessment should be included as a component of routine balance assessment and fall avoidance strategies in this population.     

Balance and ambulation improvements in individuals with chronic incomplete spinal cord injury using locomotor training-based rehabilitation

Harkema SJ, Schmidt-Read M, Lorenz DJ, Edgerton VR, Behrman AL. Balance and ambulation improvements in individuals with chronic incomplete spinal cord injury using locomotor training–based rehabilitation.ObjectiveTo evaluate the effects of intensive locomotor training on balance and ambulatory function at enrollment and discharge during outpatient rehabilitation after incomplete SCI.DesignProspective observational cohort.SettingSeven outpatient rehabilitation centers from the Christopher and Dana Reeve Foundation NeuroRecovery Network (NRN).ParticipantsPatients (N=196) with American Spinal Injury Association Impairment Scale (AIS) grade C or D SCI who received at least 20 locomotor training treatment sessions in the NRN.InterventionsIntensive locomotor training, including step training using body-weight support and manual facilitation on a treadmill followed by overground assessment and community integration.Main Outcome MeasuresBerg Balance Scale; Six-Minute Walk Test; 10-Meter Walk Test.ResultsOutcome measures at enrollment showed high variability between patients with AIS grades C and D. Significant improvement from enrollment to final evaluation was observed in balance and walking measures for patients with AIS grades C and D. The magnitude of improvement significantly differed between AIS groups for all measures. Time since SCI was not associated significantly with outcome measures at enrollment, but was related inversely to levels of improvement.ConclusionsSignificant variability in baseline values of functional outcome measures is evident after SCI in individuals with AIS grades C and D and significant functional recovery can continue to occur even years after injury when provided with locomotor training. These results indicate that rehabilitation, which provides intensive activity-based therapy, can result in functional improvements in individuals with chronic incomplete SCI.     

Reliability of daily step activity monitoring in adults with incomplete spinal cord injury

We determined the number of days of step activity monitoring required to establish stable measures of walking activity in adults with incomplete spinal cord injury (iSCI). Eleven individuals with iSCI (mean age 49 +/- 14 years) wore a StepWatch Activity Monitor during waking hours for 7 consecutive days. We used generalizability theory to identify sources of variance in daily step counts and determine the minimum number of days necessary to obtain a reliability coefficient (G-coefficient) greater than or equal to 0.80. Average daily step activity (DSA) was 1,281 +/- 1,594 steps. Participants and days accounted for 70.9% and 1.3% of total variance in DSA, respectively, while unidentifiable error accounted for 27.8% of the total variance in DSA. A minimum of 2 days was required to achieve a G-coefficient greater than or equal to 0.80. An acceptably stable measure of walking activity in adults with iSCI can be obtained by averaging step count values from any 2-day period in a week. Results from this investigation should be useful in evaluating the effect of activity-based programs designed to enhance locomotor function in persons with iSCI.     

Wheelchair marathon racing causes striated muscle distress in individuals with spinal cord injury

OBJECTIVE: To assess the effects of wheelchair marathon racing in individuals with spinal cord injury (SCI) on circulating muscle enzymes and myoglobin. SUBJECTS: Thirty-one men with SCI, including 25 wheelchair marathon athletes and 6 sedentary men. DESIGN: Serum myoglobin (Mb), creatine kinase (CK) activity, and lactate dehydrogenase (LDH) were measured in participants of the 1995 Oita International Wheelchair Marathon Race (42.195 km). Blood samples were obtained 24 hours before, immediately after, 24 hours after, and 7 days after the race. RESULTS: Marathon racing resulted in significant increases in serum Mb, total CK activity, and LDH (p<.01) after the race. The peak Mb and LDH levels occurred immediately after the race; total CK activity peaked 24 hours after the race. Evaluation of cardiac muscle enzymes showed no significant changes in two CK isoenzymes (CK-MM and CK-MB). CONCLUSIONS: Propulsion of the wheelchair in a marathon race induced muscle stress in athletes with SCI. Completion of the marathon race did not cause cardiac muscle damage, however. Elevated muscle enzyme levels likely resulted from muscle distress rather than from dehydration.