Physiotherapy - The Journal of Indian Association of Physiotherapists

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 15  |  Issue : 1  |  Page : 17--21

A study of motor imagery training on motor strategies of sit-to-stand task and functional mobility in individuals with chronic stroke


Devanshi Manesh Doshi, R Ravindran 
 Department of Physiotherapy, All India Institute of Physical Medicine and Rehabilitation, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Devanshi Manesh Doshi
31, Jyoti, Shivram Society, Devidayal Road, Mulund (West), Mumbai - 400 080, Maharashtra
India

Abstract

AIM: To evaluate the effects of motor imagery (MI) intervention on parameters used to assess motor strategies in sit-to-stand (STS) task and functional mobility in individuals with chronic stroke. STUDY DESIGN: Experimental, simple, randomized control trial. SUBJECT AND METHODS: Forty individuals with chronic stroke, who fulfilled the inclusion and exclusion criteria, were included in the study and randomly allocated to control (Group A) and experimental (Group B) groups through the sealed envelope method. INTERVENTION: Group A received conventional therapy for STS, whereas Group B received MI training. Both the groups were intervened for 3 sessions per week for 4 weeks along with other rehabilitation services. Weight symmetry, sway velocity, rising index, and weight transfer time (WTT) were assessed to evaluate the motor strategies of STS and Timed Up and Go test to assess the functional mobility. They were assessed before starting the intervention and post 4 weeks of training. RESULTS: Intra-group analysis showed that there was significant improvement found in weight symmetry (Group A, P = 0.01 and Group B, P = 0.04) and functional mobility (P = 0.001 for Group A and B) while significant improvement in rising index was found only in the control group. There was no significant improvement of sway velocity and WTT in both the groups. Inter-group analysis showed that there is no significant difference in all outcome measures between the groups. CONCLUSION: There was no overt effect of MI over conventional treatment for STS task.



How to cite this article:
Doshi DM, Ravindran R. A study of motor imagery training on motor strategies of sit-to-stand task and functional mobility in individuals with chronic stroke.Physiother - J Indian Assoc Physiother 2021;15:17-21


How to cite this URL:
Doshi DM, Ravindran R. A study of motor imagery training on motor strategies of sit-to-stand task and functional mobility in individuals with chronic stroke. Physiother - J Indian Assoc Physiother [serial online] 2021 [cited 2022 Nov 30 ];15:17-21
Available from: https://www.pjiap.org/text.asp?2021/15/1/17/324127


Full Text



 Introduction



Stroke, a noncommunicable disease, involves an episode of acute neurological dysfunction presumed to be caused by ischemia or hemorrhage, persisting ≥24 h or until death.[1] It is often attributed to some vascular cause which includes transient ischemic attack, cerebral infarction, intra-cerebral hemorrhage, and sub-arachnoid hemorrhage, predisposing an individual to disability.[2]

Stroke affects 80.1 million people globally in 2016[1] with crude prevalence ranging from 44.2–559/100,000 people in India.[3] It produces various impairments which have consequent effect on functional activities such dexterity, gait, and sit-to-stand (STS).[4],[5],[6],[7]

In healthy individuals, STS is assumed to be symmetrical activity of both lower extremity in sagittal plane[8] which is divided into four phases: Phase I (Flexion-Momentum Phase), Phase II (Momentum Transfer Phase), Phase III (Extension Phase), and Phase IV (Stabilization Phase).[9]

For increasing the effectiveness of a motor task, an individual chooses motor strategy which is often dependent upon musculoskeletal functions combined with timing, weight distribution, and balance.[10] Individuals with stroke take longer time to recover STS due to impaired postural control, muscle strength deficits, sensorimotor, and perceptual impairments.[9] There exists incoordination between the trunk and lower extremity movements, increased trunk flexion and trunk lean over nonparetic side, insufficient muscle activation of paretic side, and incomplete hip and knee joint extension leading to instability.[5],[11],[12],[13],[14] This predisposes an individual to falls.

Motor imagery (MI) is one of the emerging concepts which is often considered as “backdoor to motor system after stroke.”[15] It can be given in all recovery stages of stroke. It activates same areas of the brain which generally occur in physical execution (PE) of the task.[16] There is paucity over its efficacy in STS. Thus, the primary objective was to examine the effect of MI training over conventional physiotherapy intervention for STS on motor strategies of STS task and functional mobility in chronic stroke population.

 Subject and Methods



It was an experimental control trial with concealed allocation which was carried out in physiotherapy department of a tertiary care health care center over duration of 1 year. Convenient sampling was used.

Participants aged between 18 and 65 years, suffering from stroke >6 months and were independent in performing STS were included in the study. Patients having Montreal Cognitive Assessment score <26, suffered stroke twice, presence of other neurological conditions, suffering from any orthopedic conditions, and pain or who wish to withdraw from participation were excluded from the study.

The study was approved by the Institutional Ethics Committee of the place of study prior to recruitment of the participants. All the participants were explained about the nature of the study, their role in the study, and their rights as per the informed consent document in the language best known to them. Individuals fulfilling inclusion and exclusion criteria and gave a written informed consent were included in this study. Forty individuals (33 men and 7 women), ranging in age from 35 to 61 years, participated in the study. Of 40 participants, 21 had right and 19 had left hemiparesis [Table 1].{Table 1}

Randomization and allocation

Forty participants were allocated to one of the two groups by the sealed envelope method to ensure concealed allocation process. Sealed envelopes contained 20 denominations for each group, respectively. The envelopes were opaque, sequentially numbered, and stapled. The envelopes were shuffled and given to participants by an independent faculty of the department who was not involved in this research study. Researcher was kept blinded during the allocation procedure. It was an unblinded randomized controlled trial as the interventions delivered demanded active participation from participants.

The outcome measures such as weight symmetry, rising index, sway velocity, and weight transfer time (WTT) were assessed using NeuroCom Balance Master 9.2. It is 60” computerized static long force platform having sensors. It is connected to the Windows supported desktop computer containing NeuroCom software. Functional Mobility was assessed using Timed Up and Go Test(TUG).[15] It was performed by researcher immediately before and after the intervention trial of 4 weeks. A slow motion video of participants performing STS was taken in the anterior and lateral views on mobile phone camera after the assessment of outcome measures, prior to the commencement of the trial. The view was shot at the vertical distance of 3ft from the subject and was kept uniform for all the subjects.

Intervention

The control group (Group A) received conventional treatment for STS involving 10 repetitions of STS by placing paretic foot posterior to the normal leg at half the distance from the normal leg. If they could perform this easily, STS was performed with paretic leg posterior to non-paretic leg along with reducing the chair height by 1 inch and removing the arm support of the chair. They were shown health related documentary video after performing STS.

The experimental group (Group B) received MI training for STS. All subjects were shown a video of normal person doing STS task followed by their video of STS task. They were explained about phases of STS as mentioned above. Subjects were asked to identify their deviations from the normal video phase-wise.

Training phase involved providing relaxation for 5 min. The patient was shown a normal adult's correct STS slow motion video. They had to concentrate on the movement occurring at each phase of normal adult's STS video several times till they registered it. The patient was asked how he/she would correct the problem with reinforcements added by the therapist. Participants closed their eyes and were given auditory instruction of how to do the correct movement in their mind by the therapist. Once the pattern was corrected as reported by the patient, it was rehearsed five times in the mind followed by one PE of that phase. In every therapy session, the participants performed five sets (5 repetitions of MI followed by 1 PE of the phase). After each set, the patient was given feedback by the therapist on his/her performance while execution. This helped to provide feedback of correct movement for the next set, correcting each movement pattern phase-wise. Once subjects had achieved correction of the entire phase, progression was achieved by imagining the whole STS with corrected movement sequence.

Hence, MI was performed by doing five times of mental practice (MP) and 1 PE of the task. 5MP: 1PE was repeated 10 times. Both the groups received respective intervention for three sessions per week for 4 weeks. All outcome measures were assessed immediately after the 4th week. All participants continued receiving same set of conventional physiotherapy program and other rehabilitation services during the entire study.

Statistical analysis

It was performed using GraphPad Prism 8.0.2 by GetPCSofts, Windows installer package located in San Diego, California. The results were considered to be significant at P < 0.05 and confidence interval at 95%.The data passed normality test by the Shapiro–Wilk test. Hence, Paired t-test was used for intra group and unpaired t-test for used for intergroup analysis.

 Results



Forty chronic stroke patients were recruited in the study in which 1 from each group did not follow up for therapy sessions and were hence dropped out of the study. Therefore, data analysis was performed for 38 patients (19 patients in each group, respectively). Intragroup Analysis showed that both the groups were significant in improving weight symmetry [Group A(P = 0.01) and Group B (P = 0.04)] and TUG (Group A,P = 0.001 and Group B,P = 0.001) [Table 2] and [Table 3] and TUG (Group A, P = 0.001; Group B, P = 0.001) [Table 2] and [Table 3]. There was no significant improvement in sway velocity (Group A [P = 0.75]; Group B [P = 0.2]) and WTT (Group A [P = 0.27]; Group B [P = 0.3]). Rising index improved significantly in Group A [P = 0.02] but not in Group B [P = 0.95] [Table 2] and [Table 3].{Table 2}{Table 3}

Inter-group analysis was done using the unpaired t-test. It showed that there was no significant difference among all outcome measures between both the groups [Table 4].{Table 4}

 Discussion



Improvement in weight symmetry in the experimental group can be attributed to augmentation of working memory and internal representation of the task involved. Working memory involves three domains: Verbal, visuospatial, and kinesthetic. During MP, the internal representation of the task will be modified helping to unlearn the learned nonuse of the paretic limb and stimulating brain circuits to activate the pathways to load the paretic limb.[16],[17] PE of the task along with verbal cue will further benefit MI by providing a feedback to the brain through closed loop, thereby correcting errors and refining the representation of the task,[18],[19] i.e., improving working memory. A study done by Malouin et al., paretic limb loading had significantly improved in MP group.[20] However, contradictory findings were found in a study by Guttman et al. who concluded that there was no effect of MI on weight symmetry.[21]

Individuals with stroke have more medio-lateral sway compared to anteroposterior sway found normally in healthy individuals. This attributes to falls in hemiplegic patients while performing dynamic tasks such as STS.[12],[21],[22] WTT involves the activation of lower extremity muscles at appropriate time to generate force to counteract ground reaction force. It is closely related to sway velocity and rising index.[9],[10],[23] We had hypothesized that with MI, imagined movement of trunk flexion activity initiated with whole trunk along with loading of paretic side can help to increase anterior projection of CoM during seat off and recruitment of muscles at appropriate time. However, the results of this study did not find any significant improvement. Furthermore, there is a paucity of literature to support or contradict our findings. Hence, it is inconclusive to comment whether MI will have any effect on sway velocity and WTT for the clinical application.

It was presumed that while performing MI, activation of premotor cortex may irradiate its effect in getting recruitment of muscles. However, we are unable to confirm whether the imagery training can cause changes in cortico-spinal tract excitability to recruit the muscles in the peripheral extremities. Furthermore, due to the lack of electromyography (EMG) data, it is inappropriate to comment on whether before intervention, recruitment of muscles improved and whether after post intervention, were it sufficient enough to generate the torque required. This study did not find significant improvement in rising index in the experimental group.

Improvement in weight symmetry and reduction in CoP displacements would have led to improvement in functional mobility. A study done by Lee et al. found significant improvement in Berg Balance scores and TUG post 6 week of MI intervention for STS task.[24]

 Conclusion



MI for STS task had no overt benefit when compared to conventional treatment for STS task. Both the interventions were effective in bringing improvement in some parameters of motor strategies of STS and functional mobility in individuals with chronic stroke.

Scope for future study

The scope of the study can be extended to using MI along with conventional therapy to explore whether it has any added effect in improving STS.

The use of MI alone for can be further strengthen by using instruments sensitive to pick up changes in the quality of movement such EMG analysis and 3D motion analysis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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