Motor Imagery

Motor imagery is defined as a cognitive process, in which a person imagines rehearsing a task without performing the physical movement (Scandola et al. 2017). Neuroimaging studies have demonstrated that motor imagery produces similar patterns of neural activation to those of motor execution, particularly in pre-motor areas such as the left intraparietal sulcus, basal ganglia and cerebellum (Scandola et al. 2017; Athanasiou et al. 2018). Neuroimaging aside, motor imagery has shown the potential to assist in motor skill learning and rehabilitation for upper limb paralysis. In particular, motor imagery stimulated cerebral reorganization and improved motor functioning in patients with stroke and Parkinson’s disease (Page et al. 2009; Sun et al. 2013). Despite increasing interest in motor imagery for rehabilitative therapy, very few studies have investigated motor imagery for SCI rehabilitation.

The methodological details and results of these studies are presented in Table 4.

Author Year

Country
Research Design

Score
Total Sample Size

Methods Outcome
Di Rienzo et al., 2015

France

Pre-Post

N=8

PopulationSCI participants (n=4): Mean age: 27.5 yr; Gender: males=2, females=2; Severity of Injury: AIS C6=4; Mean time since injury: 14.5 mo.

Intervention: SCI participants had motor imagery (MI) training imbedded within traditional physiotherapy for 5 additional wk (3x/wk) to investigate effect of MI training on Tenodesis prehension (TP), compared to healthy control group (HC) performing physical practice (PP)-based training.

Outcome Measures: Magnetoencephalography (MEG) measurements, Motor performance data, Kinesthetic and Visual Imagery Questionnaire (KVIQ), Movement Time (MT), Movement Variability (MV), Synthetic aperture magnetometry (SAM).

1.      No statistically significant differences between groups on KVIQ scores or sub-scores (all p>0.05).

2.      MT were greater in SCI participants during the first pretest compared to the third pretests of the design (p<0.01) but not in HC (p>0.05).

3.      In SCI participants, post-test MV was superior to the median pretest value (p<0.05), but not in HC (p>0.05).

4.      The total number of SAM sources elicited during MI was similar in HC and SCI groups across experimental sessions (p=0.89).

5.      Post-test values showing cortical recruitment (SAM sources) were significantly higher than those recorded during the pretests in the SCI group (p<0.01) but not in HC (p>0.05).

6.      MV was statistically predicted by the number of SAM rouces activated during MI in the SCI group (p<0.001) but not in HC (p=0.32).

Di Rienzo et al., 2014

France

Pre-Post

N=12

Population: SCI participants (n=6); Age: 18-55 yr; Level of injury: C6/C7=6.

Intervention: SCI participants received motor imagery (MI) training imbedded within traditional physiotherapy for 5 wk (3x/wk) to investigate effect of MI training on Tenodesis prehension (TP). This was compared to a healthy control group (HP) performing physical practice (PP)-based training.

Outcome Measures: Magnetoencephalography (MEG) measurements, Kinesthetic and Visual Imagery Questionnaire (KVIQ), Movement Time (MT), Movement Variability (MV).

1.     Mean KVIQ visual and kinesthetic subscores, as well as KVIQ total scores were comparable in both groups (p=0.52).

2.     Data from the mental chronometry task showed significant correlation between MI and PP durations at the whole-group level (p<0.001).

3.     No significant difference between MI and PP durations (p=0.66).

4.     A higher MV during the pre-test 3 as compared to the pre-test 2 in HP (p<0.05); in the SCI group, MV during the post-test 1 was significantly lower than during each of the pre-tests (all p<0.01).

5.     Lower MT and MV in HP compared to SCI subjects, for each experimental session (all p<0.01).

6.     There was no MV difference between post-test 1 and 2 in SCI participants (p>0.05).

Discussion

Two studies authored by one group of researchers tested the use of MI in improving motor learning post SCI.

Di Rienzo et al. (2014, 2015) conducted two small studies and applied the same methodology involving SCI participants receiving MI and traditional physiotherapy compared to healthy controls performing physical practice. These studies resulted in mixed findings, however, SCI participants’ movement time and variability generally improved after MI.

Future studies should investigate the effect of completeness of the lesion on different types of MI in SCI. In addition, the effect of duration of injury, degree of autonomy, and presence of pain should be examined in relation to MI outcomes.

Conclusion

There is level 4 evidence (from two pre-post studies: Di Rienzo et al. 2014b, 2015) that MI treatment incorporated into physiotherapy for individuals with SCI may help to improve movement time and variability performance.