EMG Biofeedback
Biofeedback is a non-invasive rehabilitative therapy that measures biological information and provides feedback to the patient (or therapist) to increase awareness and control over biological processes (Sturma et al. 2018). EMG measures the myoelectric activity of muscles and converts this data into visual and or auditory information (Sturma et al. 2018). Several studies have addressed the use of augmented feedback, such as biofeedback, with spinal cord injured populations. Van Dijik et al. (2005) conducted a systematic review of RCTs analyzing the effect of augmented feedback on motor function of the upper extremity in SCI patients. Much of the information about augmented feedback comes from motor learning literature where it has been noted that feedback combined with task practice enhances motor skill learning (Newell 1991; Schmidt & Lee 1999). There are two types of performance-related information or feedback. The first type of feedback is task intrinsic (inherent feedback). It involves sensory-perceptual information and is a natural part of performing a skill. The second type of feedback is augmented feedback (information-based extrinsic or artificial feedback). Augmented feedback refers to enhancing task intrinsic feedback with an external source (Magill 2001; Schmidt & Lee 1999), such as a therapist or device (biofeedback or timer) (van Dijik et al. 2005). It has been suggested that augmented feedback may have practical implications for rehabilitation therapy since re-acquisition of motor skills is an important part of functional motor recovery (Jarus 1994; Jarus & Ratzon 2005; Kilduski & Rice 2003; Winstein 1991).
The ability to use intrinsic feedback to guide performance is impaired in patients with cognitive and perceptual deficits (Flnn & Radomski 2002). In persons who are compromised by sensory impairments, augmented feedback is important (Sabari 2001).
The methodological details and results of three studies evaluating EMG biofeedback for upper extremity motor rehabilitation in SCI patients are presented in Table 9.
| Author Year
Country Research Design Score Total Sample Size |
Methods | Outcome | |
| Kohlmeyer et al., 1996
USA RCT PEDro=10 NInitial=60; NFinal=45 |
Population: Mean age: 39 yr; Gender: males=40, females=5; Level of injury: C4-C6; Severity of injury: complete, incomplete. Intervention: Extremities were randomly assigned to one of four treatment groups: 1. conventional strengthening; 2. electrical stimulation; 3. biofeedback and electrical stimulation; 4. biofeedback. Participation ranged from five to six weeks post SCI. Outcome Measures: Manual muscle test, Activities of Daily Living (ADL) performance. |
1. Comparison of Groups (Increment or Decrement or No Change): no relationship between treatment group and observed change; no treatment produced a significantly higher proportion of individuals that improved relative to the proportion showing no change or a decrement; no change between treatment groups. 2. Influence of Initial Muscle Grade: a correlation between the initial muscle grade and increment in muscle grade was seen at the end of treatment; poorer initial muscle grades, more likely to see a larger increment in muscle grade as a result of treatment. |
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| Klose et al., 1993
USA RCT PEDro=5 NInitial=31; NFinal=28 |
Population: Age: 18-35 yr; Gender: males=24, females=4; Level of injury: C5-C7; Time since injury: ≥1 yr. Intervention: Both groups received 45 min of aggressive exercise therapy three times per week for 12 weeks along with 30 min of neuromuscular stimulation (NMS) to assist with upper extremity muscle strength. Experimental group also received 12 wk of 30 min EMG biofeedback 3x/wk. Outcome Measures: Manual muscle test, Functional activities score. |
1. Scores after training indicated no significant differences for the muscle test score and functional activities score between groups. 2. Analysis of the repeated measures factor showed a significant change for the manual muscle test and functional activities score (p<0.05). |
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| Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.
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| Brucker & Bulaeva 1996 USA
Pre-post N=100 |
Population: Age: 17-63 yr; Gender: males=81, females=19; Level of injury: C2-C6; Time since injury: 1-29.7 yr. Intervention: Electromyography (EMG) biofeedback treatment sessions. Outcome Measures: EMG scores. |
1. T-test analysis of the differences before and after initial biofeedback treatment was done. An increase of 19.21% of normal EMG scores for right triceps and increase of 19.59% of normal EMG scores from the left triceps from one biofeedback treatment session were found, significant (p<0.001). 2. T-test analysis of the difference from before initial biofeedback treatments to after additional treatments, increase in percentage of normal EMG scores of 41.55% right triceps and 38.31% left triceps, significant (p<0.001). Increases in percentage of normal EMG scores after initial biofeedback treatment to after additional biofeedback treatment 22.3% right triceps and 18.72% for left triceps, significant (p<0.001). 3. Correlation coefficient for manual muscle test score and EMG pretest before initial treatment was r=0.569 for right triceps and r=0.437 for left triceps, significant (p<0.001). 4. Increases in percentage of normal EMG before, after, and after additional treatments was significant in right and left triceps regardless of initial manual muscle test. |
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Discussion
Two of the three studies concluded that there was no evidence for the effectiveness of augmented feedback to improve arm function in rehabilitation. These three studies are the only RCTs to date that have test augmented feedback for arm rehabilitation post SCI.
One study by Brucker et al. (1996) tested biofeedback treatment among 100 participants and found an increase in normal EMG scores in the right and left triceps, however, this study did not include a control group.
In a systematic review, van Dijik et al. (2005) recommended the following be considered in future research in this area: (1) content, form, and timing of augmented feedback to clarify its importance in rehabilitation, (2) difference between performance and learning effects concerning reacquisition of motor skills by re-examining the study population after a follow up period.
Conclusion
There is level 1a evidence (from one randomized controlled trials: Kohlmeyer et al. 1996) that augmented feedback is not effective in improving upper limb function in tetraplegia.
There is level 2 evidence (from one randomized control trial: Klose et al. 1993) that the addition of biofeedback does not improve patient scores in rehabilitation more than physical exercise alone.
There is level 4 evidence (from one pre-post test: Bruker & Bulaeva 1996) that EMG biofeedback sessions can significantly improve normal EMG muscle test scores of both triceps.
