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Functional Electrical Stimulation

Functional electrical stimulation (FES) is a form of neuromuscular electrical stimulation (NMES) (see NMES section). Similar to NMES, FES involves the application of peripheral electrical stimulation to the nerves to activate muscles and induce movement of an impaired limb (Hodkin et al., 2018). However, FES simultaneously stimulates a number of muscle groups to coordinate movement of a functional activity such as cycling, standing or walking, unlike NMES (Bekhet et al., 2019). In a recent meta analysis, FES interventions improved activity in stroke patients when compared to no intervention and training alone (Howlett et al., 2015). The beneficial effects of FES are thought to arise from neuroplastic changes in motor circuits (Hodkin et al., 2018). These changes may be induced through the pairing of cortical and peripheral activity, whereby “cells that fire together, wire together” (Hebb’s principle) (Hodkin et al., 2018).

A total of seven studies investigating FES to enhance upper extremity rehabilitation were found. The methodological details and results of these studies are presented in Table 14.

Table 14 Functional Electrical Stimulation Interventions

Author Year

Country

Research Design

Score

Total Sample Size

MethodsOutcome
Harvey et al., 2017

Australia

RCT

PEDro=7

N=70

Population: Intervention (n=37): Mean age=29 yr; Gender: males=33, females=4; Time since injury: 81 d; Level of injury: Not reported; Severity of injury: AISA A=14, B=7, C=3, D=13.

Control (n=33): Mean age=28 yr; Gender: males=28, females=5; Time since injury: 62 d; Severity of injury: AISA A=10, B=5, C=9, D=9.

Intervention: Participants in the intervention group (n=37) received intensive training for one hand (training with an exercise workstation plus FES) for one h per d, five days per wk for eight wk. The control group (n=33) received conventional therapy and 15 min of one-to-one hand therapy three times per wk without FES. Outcome measures were assessed at 11 and 26 wk after randomization.

Outcome Measures: Hand and arm function (Modified Action Research Arm Test).

1.     No difference in hand and arm function was observed with intensive task-specific hand-training involving FES, standard care and three, 15 min sessions per wk of one-to-one hand therapy compared to controls (p>0.05).
Popovic et al., 2006

Canada

RCT

PEDro=6

N=21

Population: Age: 25-70 yr; Level of injury: tetraplegia; Severity of injury: AIS A-D, incomplete; Time Since Injury: 15-243 day; Chronicity: acute/subacute.

Intervention: The control group received conventional Occupational Therapy; Intervention group received Functional Electrical Therapy and conventional Occupational Therapy.

Outcome Measures: Functional Independence Measure (FIM), Spinal Cord Independence Measure (SCIM), Rehabilitation Engineering Laboratory Hand Function Test (REL Test), Consumer Perceptions.

1.     A great deal of variance between participants in most measures due to low numbers of subjects, no significant differences was found between the Control and Intervention groups.
Iwahashi et al., 2017
JapanRCTPEDro=5N=29
Population: Therapeutic electrical stimulation (n=15): Mean age=57.7±16.9 yr; Gender: males=15; Time since injury: 1 wk; Level of injury: Not reported; Severity of injury: Frankel grade B=6; Frankel grade C=9.

Control (n=14): Mean age=59.4±18.5 yr; Gender: males=13, females=1

Intervention: Participants were randomized to either a therapeutic electrical stimulation (n=15) or control group (n=14). The therapeutic electrical stimulation group received electrical stimulation through a neuroprosthesis for 5 to 20 min daily for four wk. Both groups received conventional therapy as well. Outcomes were assessed at baseline, one wk, one and three mo.

Outcome Measures: Total passive motion of the fingers; Edema; Upper Extremity Motor Score of the International Standards for the Neurological Classification of Spinal Cord Injury (UEMS).

1.     There were no significant differences between any of the groups at three mo for all outcome measures (p>0.05).

 

Zoghi & Galea 2017

Australia

RCT

PEDro=3

N=7

Population: Intervention (n=3): Gender: males=3; Level of injury: C3 – C8; Severity of injury: AISA A=1, B=0, C=0, D=2.

Control (n=4): Gender: males=3, females=1; Level of injury: C3 – C8; Severity of injury: AISA A=0, B=1, C=1, D=2.

Intervention: Participants were randomized to a control group receiving the standard of care or an experimental group receiving the standard of care plus an intensive task-specific hand training program with FES for eight weeks. Outcome measures were assessed at baseline and every three mo for a yr.

Outcome Measures: Upper limb brain motor control assessment (BMCA); Modified action research arm test (ARAT); GRASSP.

1.     Some participants showed significant improvement after 8 wk of rehabilitation based on ARAT and GRASSP scores (p<0.05). This improvement was not reflected in the pattern of muscle activation that was captured by BMCA.
 

 

 

 

 

Hoffman & Field-Fote 2013

USA

RCT

PEDro=4

N=24

Population: Experimental Group (n=11): Mean Age: N/R; Gender: males=7, females=4; Level of Injury: C3=2, C4=3, C5=1, C6=3, C7=2; Severity of Injury: AIS B=1, AIS C=4, AIS D=6.

Control Group (n=13): Mean Age: N/R; Gender: males=10, females=3; Level of Injury: C4=2, C5=2, C6=5, C7=4; Severity of Injury: AIS A=2, AIS B=3, AIS C=5, AIS D=3.

Intervention: Patients were randomly assigned to either an experimental group or a control group then further divided into four conditions, Unimanual Somatosensory Stimulation (Uni-SS), Bimanual SS (Bi-SS), Unimanual Functional Electrical Stimulation (Uni-FES) and Bimanual FES (Bi-FES). For patients who received SS, electrodes were placed over median nerve in the wrist. FES electrodes were also placed on the median nerve in the wrist but FES was only triggered when muscle activation exceeded the threshold value. During each session, patients completed a set of activities (either unimanually or bimanually) including grasping, grasping and rotation, pinching, pinch with rotation, and finger isolation. Control patients received the interventions after an initial delayed control period. The interventions were provided 2hr/day, 5day/wk for a total of 3 wk. Assessments were conducted at baseline and at post treatment.

Outcome Measures: Jebsen Taylor

Hand Function Test (JTHF), Corticomotor activity, Chedoke Arm and Hand Activity Inventory (CAHAI).

1.     A significant Time x Group interaction was reported for JTHF scores with the experimental group improving significantly from baseline to post treatment on the JTHF compared to the control group (p=0.03).

2.     A significant improvement in JTHF scores were found after the control group received the interventions (p=0.01) when comparing baseline to post treatment. However, the correlation between initial scores and the amount of change was not significant (p=0.19) indicating the improvement may have been due to chance.

3.     After analysing all four conditions, only a significant effect of Time was found (p=0.0006) indicating that regardless of intervention, patients all demonstrated improvement on JTHF scores from baseline to post treatment.

4.     No significant difference in JTHF scores were found between FES and SS from baseline to post treatment (p=0.46).

5.     No significant difference in JTHF scores were found between bimanual and unimanual activities from baseline to post treatment (p=0.57).

6.     A significant Time x Group interaction was reported for Corticomotor activity with the experimental group demonstrating an increase in Corticomotor map area whilst the control group did not demonstrate any changes (p=0.03).

7.     A significantly greater amount of change from baseline to post treatment was found for patients in both bimanual conditions on the CAHAI compared to patients in the unimanual conditions (p=0.03).

Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.

Hodkin et al., 2018

U.K.

PCT

N=6

Population: Mean age=37±6 yr; Gender: males=6, Time since injury: 8±2 yr; Level of injury: C2 – C7; Severity of injury: AISA A=2, C=5

Intervention: Participants attended five FES sessions (one hour each, with a target of 200 repetitions per session) and aimed to complete blocks of 20 to 25 repetitions followed by one minute rests. Current values ranged from 20 to 35mA, stimulation pulse widths of 130 to 350µs, and stimulation frequency was fixed at 40Hz. The hand/side best suited to completing FES assistance, was trained during the intervention, while the untrained side acted as a control. Outcome measures were assessed before and after the intervention period.

Outcome Measures: Action Research Arm Test (ARAT); Qualitative feedback.

1.     ARAT scores significantly increased on the trained side (3.4±1.1) when compared to the untrained side (0.1±0.8) (p=0.03).

 

2.     Six out of seven SCI participants reported benefit from using the device, three out of seven reported improvements in ADL, cost and availability to devices was reported as a barrier to use.

Table 14.1 Functional Electrical Stimulation Systematic Reviews

 

 

 

 

 

 

Patil et al.,

2015

UK

Review of published articles between September 2009-September 2014

N= 5

 

Method: Comprehensive literature search of full-length, peer reviewed studies of patients with complete or incomplete cervical SCI, investigating functional electrical stimulation (FES) (possibly comparing to other conventional therapies) in adult and human studies.

Databases: EMBASE, PsycInfo, PubMed and Food, Science and Technology abstracts.

Level of evidence:  Jovell and Navarro-Rubio classification: Good (I-II): Meta-analysis of randomized controlled trials (RCTs), Large-sample RCTs; Good-to-fair (III-V): Small-sample RCTS, non-randomized controlled prospective trials, non-randomized controlled retrospective trials; Fair (VI-VII): cohort studies, case-control studies; Poor (VIII-IX): non-controlled clinical series; descriptive studies, anecdotes or case reports.

Questions/measures/hypothesis:

Examine the evidence for FES on motor control and functional ability of the upper limb in spinal cord injured people.

1.     Two studies were scored a III, one study scored a VI, and two studies scored VIII.

2.     In total, there were 10 different outcome measures between the five included studies assessing functional outcomes and motor control.

3.     All 5 studies reported improvement, both immediate and follow-up, in motor control and functional ability of upper extremity as result of FES or FES with conventional therapy.

Discussion

Upon review of the literature, there is conflicting evidence on the efficacy of FES. Four randomized controlled trials found that FES has no added benefit over conventional therapy on upper extremity motor function. On the other hand, two randomized controlled trials, one prospective controlled trial and a systematic review found that FES improves motor control and function of the upper extremity. These discrepancies are likely due to differences in methodologies. An ongoing challenge in the FES field is determining what electrical stimulation patterns and duration of treatment are necessary. Future research should focus on determing effective electrical stimulation patterns. In addition, subject variability may also be a contributing factor to differences in outcomes and should be examined in further research. In summary, there is conflicting evidence to support the use of FES therapy.

Conclusion

There is level 1b evidence (from two randomized controlled trials; Harvey et al., 2017; Popovic et al., 2006) that FES has no added benefit over conventional therapy.

There is level 2 evidence (from one randomized controlled trial; Iwahashi et al., 2017) that therapeutic electrical stimulation has no effect on upper extremity motor function.

There is level 2 evidence (from two randomized controlled trials; Zoghi and Galea, 2017; Hoffman & Field-Fote 2013) that FES in combination with intensive hand task training improves upper extremity motor function.

There is level 2 evidence (from one prospective controlled trial; Hodkin et al., 2018) that multiple FES sessions improves upper extremity motor function.

  • The evidence is conflicting as to whether FES is effective alone or in combination with massed practice training.