Neuromuscular Electrical Stimulation for Motor Restoration in Hemiparesis

Stroke rehabilitation: from diagnosis to therapy

Stroke remains a significant global health burden, necessitating comprehensive and innovative approaches in rehabilitation to optimize recovery outcomes. This paper provides a thorough exploration of rehabilitation strategies in stroke management, focusing on diagnostic methods, acute management, and diverse modalities encompassing physical, occupational, speech, and cognitive therapies. Emphasizing the importance of early identification of rehabilitation needs and leveraging technological advancements, including neurostimulation techniques and assistive technologies, this manuscript highlights the challenges and opportunities in stroke rehabilitation. Additionally, it discusses future directions, such as personalized rehabilitation approaches, neuroplasticity concepts, and advancements in assistive technologies, which hold promise in reshaping the landscape of stroke rehabilitation. By delineating these multifaceted aspects, this manuscript aims to provide insights and directions for optimizing stroke rehabilitation practices and enhancing the quality of life for stroke survivors.

Effect of intensive functional electrical stimulation therapy on upper-limb motor recovery after stroke: case study of a patient with chronic stroke

PURPOSE

Motivated by a prior successful randomized controlled trial showing that functional electrical stimulation (FES) therapy can restore voluntary arm and hand function in people with severe stroke, this study was designed to examine neuromuscular changes in the upper limb following intensive FES therapy, consisting of task-specific upper-limb movements with a combination of preprogrammed FES and manual assisted motion.

METHODS

The patient was a 22-year-old woman who had suffered a haemorrhagic stroke 2 years earlier. FES therapy was administered for 1 hour twice daily for 12 weeks, for a total of 108 treatment sessions.

RESULTS

While maximal voluntary contraction level of the upper-limb muscles did not show significant improvement, the ability to initiate and stop the muscle contraction voluntarily was regained in several upper-limb muscles (approx. 5%-15% of the maximum voluntary contraction of the same muscle in the less-affected arm). A reduction in arm spasticity was also observed, as indicated by the reduction of H-reflex in the wrist flexor muscle (82.1% to 45.0% in Hmax/Mmax) and decreased Modified Ashworth Scale scores (from 3 to 2 for the hand and 4 to 3 for the arm). Coordination between shoulder and elbow joints during the circle-drawing test improved considerably over the course of FES therapy: the patient was unable to draw a circle at all at baseline but was able to do so proficiently at discharge.

CONCLUSION

Improvements in upper-limb function observed in people with severe stroke following intensive FES therapy can be attributed to (a) regained ability to voluntarily contract muscles of the affected arm, (b) reduced spasticity and improved muscle tone in the same muscles, and (c) increased range of motion of all joints.

Effects of repeated treadmill testing and electrical stimulation on post-stroke gait kinematics

Improvements in task performance due to repeated testing have previously been documented in healthy and patient populations. The existence of a similar change in performance due to repeated testing has not been previously investigated at the level of gait kinematics in the post-stroke population. The presence of such changes may define the number of testing sessions necessary for measuring a stable baseline of pre-training gait performance, which is a necessary prerequisite for determining the effectiveness of gait interventions. Considering the emergence of treadmills as a popular tool for gait evaluation and retraining and the common addition of functional electrical stimulation (FES) to gait retraining protocols, the stability of gait kinematics during the repeated testing of post-stroke individuals on a treadmill, either with or without FES, needs to be determined. Nine individuals (age: 58.1±7.3 years), with hemi-paresis secondary to a stroke (onset: 7.3±6.0 years) participated in this study. An 8-camera motion analysis system was used to measure sagittal plane knee and ankle joint kinematics. Gait kinematics were compared across two (N=9) and five (N=5) testing sessions. No consistent changes in knee or ankle kinematics were observed during repeated testing. These findings indicate that clinicians and researchers may not need to spend valuable time and resources performing multiple testing and acclimatization sessions when assessing baseline gait kinematics in the post-stroke population for use in determining the effectiveness of gait interventions.

Gait training after stroke: a pilot study combining a gravity-balanced orthosis, functional electrical stimulation, and visual feedback

RATIONALE

This case report describes the application of a novel gait retraining approach to an individual with poststroke hemiparesis. The rehabilitation protocol combined a specially designed leg orthosis (the gravity-balanced orthosis), treadmill walking, and functional electrical stimulation to the ankle muscles with the application of motor learning principles.

CASE

The participant was a 58-year-old man who had a stroke more than three years before the intervention. He underwent gait retraining over a period of five weeks for a total of 15 sessions during which the gravity compensation provided by the gravity-balanced orthosis and visual feedback about walking performance was gradually reduced.

OUTCOMES

At the end of five weeks, he decreased the time required to complete the Timed Up and Go test; his gait speed increased during overground walking; gait was more symmetrical; stride length, hip and knee joint excursions on the affected side increased. Except for gait symmetry, all other improvements were maintained one month post-intervention.

CONCLUSIONS

This case report describes possible advantages of judiciously combining different treatment techniques in improving the gait of chronic stroke survivors. Further studies are planned to evaluate the effectiveness of different components of this training in both the subacute and chronic stages of stroke recovery.

Abnormal joint torque patterns exhibited by chronic stroke subjects while walking with a prescribed physiological gait pattern

Background

It is well documented that individuals with chronic stroke often exhibit considerable gait impairments that significantly impact their quality of life. While stroke subjects often walk asymmetrically, we sought to investigate whether prescribing near normal physiological gait patterns with the use of the Lokomat robotic gait-orthosis could help ameliorate asymmetries in gait, specifically, promote similar ankle, knee, and hip joint torques in both lower extremities. We hypothesized that hemiparetic stroke subjects would demonstrate significant differences in total joint torques in both the frontal and sagittal planes compared to non-disabled subjects despite walking under normal gait kinematic trajectories.

Methods

A motion analysis system was used to track the kinematic patterns of the pelvis and legs of 10 chronic hemiparetic stroke subjects and 5 age matched controls as they walked in the Lokomat. The subject's legs were attached to the Lokomat using instrumented shank and thigh cuffs while instrumented footlifters were applied to the impaired foot of stroke subjects to aid with foot clearance during swing. With minimal body-weight support, subjects walked at 2.5 km/hr on an instrumented treadmill capable of measuring ground reaction forces. Through a custom inverse dynamics model, the ankle, knee, and hip joint torques were calculated in both the frontal and sagittal planes. A single factor ANOVA was used to investigate differences in joint torques between control, unimpaired, and impaired legs at various points in the gait cycle.

Results

While the kinematic patterns of the stroke subjects were quite similar to those of the control subjects, the kinetic patterns were very different. During stance phase, the unimpaired limb of stroke subjects produced greater hip extension and knee flexion torques than the control group. At pre-swing, stroke subjects inappropriately extended their impaired knee, while during swing they tended to abduct their impaired leg, both being typical abnormal torque synergy patterns common to stroke gait.

Conclusion

Despite the Lokomat guiding stroke subjects through physiologically symmetric kinematic gait patterns, abnormal asymmetric joint torque patterns are still generated. These differences from the control group are characteristic of the hip hike and circumduction strategy employed by stroke subjects.

Quantification of functional weakness and abnormal synergy patterns in the lower limb of individuals with chronic stroke

Background

The presence of abnormal muscle activation patterns is a well documented factor limiting the motor rehabilitation of patients following stroke. These abnormal muscle activation patterns, or synergies, have previously been quantified in the upper limbs. Presented here are the lower limb joint torque patterns measured in a standing position of sixteen chronic hemiparetic stroke subjects and sixteen age matched controls used to examine differences in strength and coordination between the two groups.

Methods

With the trunk stabilized, stroke subjects stood on their unaffected leg while their affected foot was attached to a 6-degree of freedom load cell (JR3, Woodland CA) which recorded forces and torques. The subjects were asked to generate a maximum torque about a given joint (hip abduction/adduction; hip, knee, and ankle flexion/extension) and provided feedback of the torque they generated for that primary joint axis. In parallel, EMG data from eight muscle groups were recorded, and secondary torques generated about the adjacent joints were calculated. Differences in mean primary torque, secondary torque, and EMG data were compared using a single factor ANOVA.

Results

The stroke group was significantly weaker in six of the eight directions tested. Analysis of the secondary torques showed that the control and stroke subjects used similar strategies to generate maximum torques during seven of the eight joint movements tested. The only time a different strategy was used was during maximal hip abduction exertions where stroke subjects tended to flex instead of extend their hip, which was consistent with the classically defined "flexion synergy." The EMG data of the stroke group was different than the control group in that there was a strong presence of co-contraction of antagonistic muscle groups, especially during ankle flexion and ankle and knee extension.

Conclusion

The results of this study indicate that in a standing position stroke subjects are significantly weaker in their affected leg when compared to age-matched controls, yet showed little evidence of the classic lower-limb abnormal synergy patterns previously reported. The findings here suggest that the primary contributor to isometric lower limb motor deficits in chronic stroke subjects is weakness.

The Therapeutic Effect of Functional and Transcutaneous Electric Stimulation on Improving Gait Speed in Stroke Patients: A Meta-Analysis

OBJECTIVE

To determine the effect of previous treatments of functional electric stimulation (FES) and transcutaneous electric stimulation (TENS) on improving gait speed in subjects poststroke.

DATA SOURCES

Relevant articles were obtained through a search of English-language articles cited in Medline, EMBASE, CINHAL, and PubMed databases from January 1966 to May 2005.

STUDY SELECTION

Prospective clinical studies were included if electric stimulation was used to treat subjects poststroke and gait speed was used as an outcome measure. Excluded studies examined subjects with a variety of neurologic conditions, used implantable electrodes, or combined electric stimulation with treadmill training. A paired consensus between authors produced 8 articles.

DATA EXTRACTION

Two investigators extracted data independently. The methodologic quality of the studies was assessed with the Downs and Black checklist.

DATA SYNTHESIS

A fixed-effects model produced a mean difference (.18; 95% confidence interval, .08-.28) that was significant (z=3.65, P<.01), indicating the effectiveness of FES treatment at increasing gait speed in subjects poststroke. The effect sizes of the studies ranged from -.11 to 1.43 for FES and .19 to .42 for TENS. The type of FES and TENS devices, location of electrodes, amount of exposure, and subjects' stages of recovery varied between the studies.

CONCLUSIONS

FES is effective at improving gait speed in subjects poststroke. Future research should examine the effectiveness of practical and readily available FES units to improve function in subjects in the subacute stages of recovery from a stroke. These studies should attempt to use a randomized controlled design with blinding and standardized outcome measures.