Neurostimulation After Stroke.

Neural stimulation technology aids stroke survivors in regaining lost motor functions. This article explores its applications in upper and lower limb stroke rehabilitation. The authors review various methods to target the corticomotor system, including transcranial direct current stimulation, repetitive transcranial magnetic stimulation, and vagus nerve stimulation. In addition, the authors review the use of peripheral neuromuscular electrical stimulation for therapeutic and assistive purposes, including transcutaneous electrical nerve stimulation, neuromuscular electrical stimulation, and functional electrical stimulation. For each, the authors examine the potential benefits, limitations, safety considerations, and FDA status.

Adding Contralaterally Controlled Electrical Stimulation of the Triceps to Contralaterally Controlled Functional Electrical Stimulation of the Finger Extensors Reduces Upper Limb Impairment and Improves Reachable Workspace but not Dexterity: A Randomized Controlled Trial.

OBJECTIVE: Different methods of neuromuscular electrical stimulation may be used for poststroke upper limb rehabilitation. This study evaluated the effects of contralaterally controlled functional electrical stimulation of the triceps and finger extensors. DESIGN: This is a randomized controlled trial of 67 participants who were less than 2 yrs poststroke and assigned to the following: (a) arm + hand contralaterally controlled functional electrical stimulation, (b) hand contralaterally controlled functional electrical stimulation, or (c) arm + hand cyclic neuromuscular electrical stimulation. Participants were prescribed 10 sessions/week of assigned electrical stimulation at home plus 24 sessions of functional task practice in the laboratory for 12 wks. The primary outcome measure was the Box and Blocks Test. Secondary measures included reachable workspace, Upper Extremity Fugl-Meyer, Stroke Upper Limb Capacity Scale, Arm Motor Abilities Test, and Motor Activity Log. RESULTS: There were no significant between-group differences on the Box and Blocks Test. At 6 mos after treatment, arm + hand contralaterally controlled functional electrical stimulation improved reachable workspace more than hand contralaterally controlled functional electrical stimulation, between-group difference of 264 (95% confidence interval = 28-500) cm and more than arm + hand cyclic neuromuscular electrical stimulation, between-group difference of 281 (95% confidence interval = 22-540) cm. Arm + hand contralaterally controlled functional electrical stimulation improved Upper Extremity Fugl-Meyer score more than hand contralaterally controlled functional electrical stimulation, between-group difference of 6.7 (95% confidence interval = 0.6-12.7). The between-group differences on the Stroke Upper Limb Capacity Scale and Arm Motor Abilities Test were not significant. CONCLUSIONS: Adding contralaterally controlled elbow extension to hand contralaterally controlled functional electrical stimulation does not improve on gains in hand dexterity, but it further reduces upper limb impairment and improves reachable workspace measured in the laboratory. However, these additional benefits may not be large enough to be perceived by stroke survivors when they are performing activities of daily living at home.

Bilateral Contralaterally Controlled Functional Electrical Stimulation Reveals New Insights Into the Interhemispheric Competition Model in Chronic Stroke.

Background. Upper-limb chronic stroke hemiplegia was once thought to persist because of disproportionate amounts of inhibition imposed from the contralesional on the ipsilesional hemisphere. Thus, one rehabilitation strategy involves discouraging engagement of the contralesional hemisphere by only engaging the impaired upper limb with intensive unilateral activities. However, this premise has recently been debated and has been shown to be task specific and/or apply only to a subset of the stroke population. Bilateral rehabilitation, conversely, engages both hemispheres and has been shown to benefit motor recovery. To determine what neurophysiological strategies bilateral therapies may engage, we compared the effects of a bilateral and unilateral based therapy using transcranial magnetic stimulation. Methods. We adopted a peripheral electrical stimulation paradigm where participants received 1 session of bilateral contralaterally controlled functional electrical stimulation (CCFES) and 1 session of unilateral cyclic neuromuscular electrical stimulation (cNMES) in a repeated-measures design. In all, 15 chronic stroke participants with a wide range of motor impairments (upper extremity Fugl-Meyer score: 15 [severe] to 63 [mild]) underwent single 1-hour sessions of CCFES and cNMES. We measured whether CCFES and cNMES produced different effects on interhemispheric inhibition (IHI) to the ipsilesional hemisphere, ipsilesional corticospinal output, and ipsilateral corticospinal output originating from the contralesional hemisphere. Results. CCFES reduced IHI and maintained ipsilesional output when compared with cNMES. We found no effect on ipsilateral output for either condition. Finally, the less-impaired participants demonstrated a greater increase in ipsilesional output following CCFES. Conclusions. Our results suggest that bilateral therapies are capable of alleviating inhibition on the ipsilesional hemisphere and enhancing output to the paretic limb.

Neuromodulation for Functional Electrical Stimulation.

This article describes the application of neuromodulation in different ways to motor recovery, to replace lost function, or to improve function of organ systems for those who have experienced spinal cord injury or stroke. Multiple devices have been developed and are currently available for use whereas others are still in the experimental stage. Multiple uses of neuromodulation are described.

Convergent Validity and Responsiveness of the SULCS.

OBJECTIVE: To evaluate the convergent validity and responsiveness of the Stroke Upper Limb Capacity Scale (SULCS) in comparison to the Arm Motor Ability Test (AMAT), the Box and Blocks Test (BBT), and the upper limb Fugl-Meyer Assessment (FMA). The SULCS is a relatively new measure that was designed to be easier to score and less time consuming than some existing measures. DESIGN: Prospective repeated-measures design. SETTING: Clinical research laboratory of a large public hospital. PARTICIPANTS: Patients (N=61) <2 years poststroke with moderate to severe upper limb hemiparesis. INTERVENTION: Participants received 12 weeks of therapy that included neuromuscular electrical stimulation of the paretic finger and thumb extensors. The SULCS, AMAT, BBT, and FMA were administered at weeks 0, 6, 12 (end of therapy), 20, 28, and 36 (6mo post-therapy). MAIN OUTCOME MEASURES: Convergent validity was evaluated with Spearman's correlation coefficients between pairs of measures at each time point. Responsiveness from 0 to 12 weeks and 0 to 36 weeks was evaluated with the standardized response mean (SRM). RESULTS: The SULCS demonstrated strong correlation with the AMAT (ρ=0.81-0.93), BBT (ρ=0.73-0.92), and FMA (ρ=0.78-0.92), at all 6 time points. All 4 measures had moderate to large SRMs (SULCS, 0.71-0.77; AMAT, 0.83-0.97; BBT, 0.73-0.82; FMA, 0.75-0.76). There was no significant difference in responsiveness among the 4 measures. CONCLUSIONS: The results support the use of the SULCS to measure upper limb capacity in patients who are less than 2 years poststroke with moderate to severe hemiplegia.

The Effect of Peripheral Nerve Stimulation on Shoulder Biomechanics: A Randomized Controlled Trial in Comparison to Physical Therapy.

OBJECTIVE: To establish the effects on shoulder biomechanics from a peripheral nerve stimulation (PNS) treatment compared to physical therapy (PT) in stroke survivors with chronic hemiplegic shoulder pain. DESIGN: Single-site, pilot, randomized controlled trial for adults with chronic shoulder pain after stroke. Participants were randomized to receive a 3-week treatment of single-lead PNS or physical therapy (PT). The outcomes included isometric shoulder abduction strength, pain-free shoulder external rotation range of motion (ROM), delay in initiation and termination of shoulder abduction electromyogram (EMG) activity, and the Fugl-Meyer Motor Assessment (upper extremity section). Outcomes were measured at baseline, and at weeks 1, 4, 12, and 16. RESULTS: Twenty-five participants were recruited, 13 to PNS and 12 to PT. There were significant improvements for both PNS and PT in maximum isometric shoulder abduction strength, pain-free external rotation ROM, and Fugl-Meyer Motor Assessment. There were no significant changes in delay of initiation or termination of deltoid EMG with either treatment. CONCLUSIONS: Both PNS and PT are capable of improving shoulder biomechanics in those with HSP, though changes in biomechanics alone do not account for the greater pain relief associated with PNS than PT.

Contralaterally Controlled Functional Electrical Stimulation Improves Hand Dexterity in Chronic Hemiparesis: A Randomized Trial.

BACKGROUND AND PURPOSE: It is unknown whether one method of neuromuscular electrical stimulation for poststroke upper limb rehabilitation is more effective than another. Our aim was to compare the effects of contralaterally controlled functional electrical stimulation (CCFES) with cyclic neuromuscular electrical stimulation (cNMES). METHODS: Stroke patients with chronic (>6 months) moderate to severe upper extremity hemiparesis (n=80) were randomized to receive 10 sessions/wk of CCFES- or cNMES-assisted hand opening exercise at home plus 20 sessions of functional task practice in the laboratory for 12 weeks. The task practice for the CCFES group was stimulation assisted. The primary outcome was change in Box and Block Test (BBT) score at 6 months post treatment. Upper extremity Fugl-Meyer and Arm Motor Abilities Test were also measured. RESULTS: At 6 months post treatment, the CCFES group had greater improvement on the BBT, 4.6 (95% confidence interval [CI], 2.2-7.0), than the cNMES group, 1.8 (95% CI, 0.6-3.0), between-group difference of 2.8 (95% CI, 0.1-5.5), P=0.045. No significant between-group difference was found for the upper extremity Fugl-Meyer (P=0.888) or Arm Motor Abilities Test (P=0.096). Participants who had the largest improvements on BBT were <2 years post stroke with moderate (ie, not severe) hand impairment at baseline. Among these, the 6-month post-treatment BBT gains of the CCFES group, 9.6 (95% CI, 5.6-13.6), were greater than those of the cNMES group, 4.1 (95% CI, 1.7-6.5), between-group difference of 5.5 (95% CI, 0.8-10.2), P=0.023. CONCLUSIONS: CCFES improved hand dexterity more than cNMES in chronic stroke survivors. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00891319.

Upper-Limb Recovery After Stroke: A Randomized Controlled Trial Comparing EMG-Triggered, Cyclic, and Sensory Electrical Stimulation.

BACKGROUND AND PURPOSE: This study compared the effect of cyclic neuromuscular electrical stimulation (NMES), electromyographically (EMG)-triggered NMES, and sensory stimulation on motor impairment and activity limitations in patients with upper-limb hemiplegia. METHODS: This was a multicenter, single-blind, multiarm parallel-group study of nonhospitalized hemiplegic stroke survivors within 6 months of stroke. A total of 122 individuals were randomized to receive either cyclic NMES, EMG-triggered NMES, or sensory stimulation twice every weekday in 40-minute sessions, over an 8 week-period. Patients were followed for 6 months after treatment concluded. RESULTS: There were significant increases in the Fugl-Meyer Assessment [F(1, 111) = 92.6, P < .001], FMA Wrist and Hand [F(1, 111) = 66.7, P < .001], and modified Arm Motor Ability Test [mAMAT; time effect: F(1, 111) = 91.0, P < .001] for all 3 groups. There was no significant difference in the improvement among groups in the FMA [F(2, 384) = 0.2, P = .83], FMA Wrist and Hand [F(2, 384) = 0.4, P = .70], or the mAMAT [F(2, 379) = 1.2, P = .31]. CONCLUSIONS: All groups exhibited significant improvement of impairment and functional limitation with electrical stimulation therapy applied within 6 months of stroke. Improvements were likely a result of spontaneous recovery. There was no difference based on the type of electrical stimulation that was administered.

Neuromuscular Electrical Stimulation for Motor Restoration in Hemiplegia.

This article reviews the most common therapeutic and neuroprosthetic applications of neuromuscular electrical stimulation (NMES) for upper and lower extremity stroke rehabilitation. Fundamental NMES principles and purposes in stroke rehabilitation are explained. NMES modalities used for upper and lower limb rehabilitation are described, and efficacy studies are summarized. The evidence for peripheral and central mechanisms of action is also summarized.

Tailoring Brain Stimulation to the Nature of Rehabilitative Therapies in Stroke: A Conceptual Framework Based on their Unique Mechanisms of Recovery.

Despite showing early promise, several recent clinical trials of noninvasive brain stimulation (NIBS) failed to augment rehabilitative outcomes of the paretic upper limb. This article addresses why pairing NIBS with unilateral approaches is weakly generalizable to patients in all ranges of impairments. The article also addresses whether alternate therapies are better suited for the more impaired patients, where they may be more feasible and offer neurophysiologic advantages not offered with unilateral therapies. The article concludes by providing insight on how to create NIBS paradigms that are tailored to distinctly augment the effects of therapies across patients with varying degrees of impairment.

Control of robotic assistance using poststroke residual voluntary effort.

Poststroke hemiparesis limits the ability to reach, in part due to involuntary muscle co-activation (synergies). Robotic approaches are being developed for both therapeutic benefit and continuous assistance during activities of daily living. Robotic assistance may enable participants to exert less effort, thereby reducing expression of the abnormal co-activation patterns, which could allow participants to reach further. This study evaluated how well participants could perform a reaching task with robotic assistance that was either provided independent of effort in the vertical direction or in the sagittal plane in proportion to voluntary effort estimated from electromyograms (EMG) on the affected side. Participants who could not reach targets without assistance were enabled to reach further with assistance. Constant anti-gravity force assistance that was independent of voluntary effort did not reduce the quality of reach and enabled participants to exert less effort while maintaining different target locations. Force assistance that was proportional to voluntary effort on the affected side enabled participants to exert less effort and could be controlled to successfully reach targets, but participants had increased difficulty maintaining a stable position. These results suggest that residual effort on the affected side can produce an effective command signal for poststroke assistive devices.

Contralaterally controlled functional electrical stimulation for recovery of elbow extension and hand opening after stroke: a pilot case series study.

OBJECTIVE: The aims of this study were to determine whether patients with moderate-to-severe upper limb hemiplegia could use contralaterally controlled functional electrical stimulation at the arm and hand (Arm+Hand CCFES) at home and to evaluate the feasibility of Arm+Hand CCFES to reduce arm and hand motor impairment. DESIGN: With Arm+Hand CCFES, the paretic elbow and hand extensors were stimulated with intensities proportional to the degree of elbow extension and hand opening, respectively, of the contralateral unimpaired side. For 12 wks, four participants with chronic (≥6 mos) upper limb hemiplegia received ∼7 hrs per week of self-administered home-based stimulation-mediated elbow extension and hand opening exercise plus ∼2.5 hrs per week of therapist-supervised laboratory-based stimulation-assisted functional task practice. Assessments of upper limb impairment were made at pretreatment, posttreatment, and 1 mo after treatment. RESULTS: All four participants were able to use the Arm+Hand CCFES system at home either independently or with very minimal assistance from a caregiver. All four participants had increases in the Fugl-Meyer score (1-9 points) and the Wolf Motor Function Test (0.2-0.8 points) and varying degrees of improvement in maximum hand opening, maximum elbow extension, and simultaneous elbow extension and hand opening. CONCLUSIONS: Arm+Hand CCFES can be successfully administered in stroke patients with moderate-to-severe impairment and can reduce various aspects of upper limb impairment. A larger efficacy study is warranted.

Functional electrical stimulation to augment poststroke reach and hand opening in the presence of voluntary effort: a pilot study.

BACKGROUND: Hemiparesis after stroke can severely limit an individual's ability to perform activities of daily living. Functional electrical stimulation (FES) has the potential to generate functional arm and hand movements. We have observed that FES can produce functional hand opening when a stroke patient is relaxed, but the FES-produced hand opening is often overpowered by finger flexor coactivation in response to patient attempts to reach and open the hand. OBJECTIVE: To determine if stimulating both reaching muscles and hand opening muscles makes it possible to achieve useful amounts of simultaneous reach and hand opening even in the presence of submaximal reaching effort. METHODS: We measured reach and hand opening during a reach-then-open the hand task under different combinations of voluntary effort and FES for both reach and hand opening. RESULTS: As effort was reduced and stimulation generated more movement, a greater amount of reach and hand opening was achieved. For the first time, this study quantified the effect of voluntary effort for reach and hand opening on stimulated hand opening. It also showed variability in the interaction of voluntary effort and stimulation between participants. Additionally, when participants were instructed to reach with partial effort during simultaneous FES, they achieved greater reach and hand opening. CONCLUSIONS: Simultaneous reaching and FES hand opening is improved by including FES for reach and reducing voluntary effort. In the future, an upper extremity neuroprosthesis that uses a combination of voluntary effort and FES assistance may enable users to perform activities of daily living.

Contralaterally controlled neuromuscular electrical stimulation for recovery of ankle dorsiflexion: a pilot randomized controlled trial in patients with chronic post-stroke hemiplegia.

OBJECTIVE: The aim of this study was to compare the effects of contralaterally controlled neuromuscular electrical stimulation (CCNMES) vs. cyclic neuromuscular electrical stimulation (NMES) on lower extremity impairment, functional ambulation, and gait characteristics. DESIGN: Twenty-six survivors of stroke with chronic (≥6 mos) foot drop during ambulation were randomly assigned to 6 wks of CCNMES or cyclic NMES. Both groups had ten sessions per week of self-administered home application of either CCNMES or cyclic NMES plus two sessions per week of gait training with a physical therapist. Primary outcomes included lower extremity Fugl-Meyer score, modified Emory Functional Ambulation Profile, and gait velocity. Assessments were made at pretreatment and posttreatment and at 1 and 3 mos after treatment. RESULTS: There were no significant differences between the groups in the outcome trajectories for any of the measures. With data from both groups pooled, there were significant but modest and sustained improvements in the Fugl-Meyer score and the modified Emory Functional Ambulation Profile but not in gait velocity. CONCLUSIONS: The results support the hypothesis that gait training combined with either CCNMES or cyclic NMES reduces lower extremity impairment and functional ambulation but do not support the hypothesis that CCNMES is more effective than cyclic NMES in patients with chronic post-stroke hemiplegia.

Implanted neuroprosthesis for assisting arm and hand function after stroke: a case study.

Loss of arm and hand function is common after stroke. An implantable, 12-channel, electromyogram (EMG)-controlled functional electrical stimulation neuroprosthesis (NP) may be a viable assistive device for upper-limb hemiplegia. In this study, a research participant 4.8 yr poststroke underwent presurgical screening, surgical installation of the NP, training, and assessment of upper-limb impairment, activity limitation, and satisfaction over a 2.3 yr period. The NP increased active range of finger extension from 3 to 96 degrees, increased lateral pinch force from 16 to 29 N, increased the number of objects from 1 to 4 out of 6 that the participant could grasp and place in a Grasp-Release Test, and increased the Arm Motor Abilities Test score by 0.3 points. The upper-limb Fugl-Meyer score increased from 27 at baseline to 36 by the end of the study. The participant reported using the NP at home 3-4 d/wk, up to 3 h/d for exercise and household tasks. The effectiveness of the NP to assist with activities of daily living was dependent on the degree of flexor tone, which varied with task and level of fatigue. The EMG-based control strategy was not successfully implemented; button presses were used instead. Further advancements in technology may improve ease of use and address limitations caused by muscle spasticity.

Contralaterally controlled functional electrical stimulation for stroke rehabilitation.

Contralaterally controlled functional electrical stimulation (CCFES) is an innovative method of delivering neuromuscular electrical stimulation for rehabilitation of paretic limbs after stroke. It is being studied to evaluate its efficacy in improving recovery of arm and hand function and ankle dorsiflexion in chronic and subacute stroke patients. The initial studies provide preliminary evidence supporting the efficacy of CCFES.

Variations in neuromuscular electrical stimulation's ability to increase reach and hand opening during voluntary effort after stroke.

Functional Electrical Stimulation (FES) has shown potential as a mechanism to augment functional arm and hand movement after stroke. However, neuroprostheses that combine voluntary effort and FES must account for co-activation patterns (synergies) that limit movement. The goal of this study is to explore the conditions under which voluntary effort and FES can be combined to achieve useful reach and hand opening in different subjects. Subjects performed a reach and hand opening task where different levels of voluntary effort and FES were applied to produce reach and hand opening while measuring the resulting hand opening and distance from a target. Initial results indicate that there are significant variations between participants and how much effort can be exerted while still eliciting effective reach and hand opening.

Contralaterally controlled functional electrical stimulation for upper extremity hemiplegia: an early-phase randomized clinical trial in subacute stroke patients.

BACKGROUND: Contralaterally controlled functional electrical stimulation (CCFES) is an experimental treatment intended to improve hand function after stroke. OBJECTIVE: To compare the effects of 6 weeks of CCFES versus cyclic neuromuscular electrical stimulation (NMES) on upper extremity impairment and activity limitation in patients ≤6 months poststroke. METHODS: Twenty-one participants were randomized to CCFES or cyclic NMES. Treatment for both groups consisted of daily stimulation-assisted repetitive hand-opening exercise at home plus twice-weekly lab sessions of functional task practice. Assessments were made at pretreatment and posttreatment and at 1 month and 3 months posttreatment. They included maximum voluntary finger extension angle, finger movement tracking error, upper extremity Fugl-Meyer score, Box and Blocks test, and Arm Motor Abilities test. Treatment effects were estimated using a 2-factor repeated measures analysis of variance with the value of the baseline measure as a covariate. RESULTS: Seventeen patients completed the treatment phase (9 CCFES, 8 cyclic NMES). At all posttreatment time points, CCFES produced larger improvements than cyclic NMES on every outcome measure. Maximum voluntary finger extension showed the largest treatment effect, with a mean group difference across the posttreatment time points of 28° more finger extension for CCFES. CONCLUSIONS: The results favor CCFES over cyclic NMES though the small sample size limits the statistical power of the study. The effect size estimates from this study will be used to power a larger trial.

A novel neuromuscular electrical stimulation treatment for recovery of ankle dorsiflexion in chronic hemiplegia: a case series pilot study.

OBJECTIVE: To evaluate the feasibility of improving active ankle dorsiflexion with contralaterally controlled neuromuscular electrical stimulation (CCNMES). DESIGN: CCNMES dorsiflexes the paretic ankle with a stimulation intensity that is directly proportional to the degree of voluntary dorsiflexion of the unimpaired contralateral ankle, which is detected by an instrumented sock. Three subjects with chronic (>6-mo poststroke) dorsiflexor paresis participated in a 6-wk CCNMES treatment, which consisted of self-administering CCNMES-assisted ankle dorsiflexion exercises at home daily and practicing an ankle motor control task in the research laboratory twice a week. RESULTS: For subjects 1 and 2, respectively, maximum voluntary ankle dorsiflexion increased by 13 and 17 degrees, ankle movement tracking error decreased by approximately 57% and 57%, and lower limb Fugl-Meyer score (maximum score is 34) increased by 4 and 5 points. Subject 3 had no appreciable improvement in these measures. Both subjects 1 and 2 maintained their performance in ankle movement tracking through the 3-mo follow-up; subject 2 also maintained the gains in maximum ankle dorsiflexion and Fugl-Meyer score. CONCLUSIONS: These results suggest that CCNMES may have a positive effect on ankle motor impairment in some stroke survivors. Further investigation of the effect of CCNMES on gait is warranted.

Neuroprosthetic effect of peroneal nerve stimulation in multiple sclerosis: a preliminary study.

OBJECTIVE: To determine the neuroprosthetic effect of a peroneal nerve stimulator on tasks of functional ambulation in multiple sclerosis (MS). DESIGN: A single point-in-time assessment of functional ambulation tasks under the conditions of no device and peroneal nerve stimulator. SETTING: Outpatient academic medical center. PARTICIPANTS: Participants (N=11) with diagnosis of MS (>6mo), dorsiflexion weakness, and prior usage of an ankle-foot orthosis. INTERVENTION: Surface peroneal nerve stimulator for ambulation. MAIN OUTCOME MEASURES: Timed 25-foot Walk portion of the MS Functional Composite; Floor, Carpet, Up and Go, Obstacle, and Stair components of the Modified Emory Functional Ambulation Profile. RESULTS: Peroneal nerve stimulator-Stair performance was significantly enhanced (P=.05) versus no device, and statistical significance was approached for peroneal nerve stimulator-Obstacles (P=.09) versus no device. There were no significant differences between peroneal nerve stimulator and no device conditions in the remaining outcome measures. CONCLUSIONS: The neuroprosthetic effect of the peroneal nerve stimulator is modest relative to no device in the performance of specific functional tasks of ambulation in MS gait. A longitudinal, controlled trial is needed to show effectiveness.