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NeuroRehabilitation 34 (2014) 267–276 DOI:10.3233/NRE-131035 IOS Press

Motor imagery group practice for gait rehabilitation in individuals with post-stroke hemiparesis: A pilot study1 Ruth Dicksteina,∗ , Sandra Levyb , Sara Shefia , Sarit Holtzmana , Sara Pelegc and Jean-Jacques Vatined a Department

of Physical Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel Alliance for Europe (SAFE) c Department of Physical Therapy, Reuth Medical Center, Tel Aviv, Israel d Outpatient and Research Division, Reuth Medical Center, Sackler Faculty of Medicine, Tel Aviv, Israel b Stroke

Abstract. BACKGROUND: Stroke is the leading cause of adult disability, with walking impairment being a devastating indicator of chronic post-stroke hemiparesis. Limited resources exist for individual treatments; therefore, the delivery of safe group exercise therapy is highly desired. OBJECTIVE: To examine whether the application of group-based motor imagery practice to community-dwelling individuals with chronic hemiparesis improves gait. METHODS: Sixteen individuals with chronic hemiparesis from two community centers participated in the study, with eight from each center. Four participants in each center received five weeks of the experimental intervention, consisting of group-based motor imagery exercises of gait tasks, followed by five weeks of control treatment of motor imagery exercises for the affected upper extremity. Four other subjects in each center received the same treatments in reverse order. Pre- and post intervention measurements included clinical and biomechanical gait parameters. RESULTS: Comparisons within (pre- vs. post) and between treatments (experimental vs. control) indicated no significant change in any gait variable. Nevertheless, the verbal reports of most participants alluded to satisfaction with the experimental intervention and to an increase in self-confidence. CONCLUSIONS: Despite the lack of evidence for the effectiveness of group-based motor imagery practice in improving gait among individuals with chronic hemiparesis, the contrast between the measured outcomes and the positive verbal reports merits further inquiry. Keywords: Stroke, gait, CVA, rehabilitation

1. Introduction

1 This study was supported by grant no 3-3710 from the chief scientist of the Ministry of Health, Israel. ∗ Address for correspondence: Ruth Dickstein, DSc, Department of Physical Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Mt Carmel, Haifa 31905, Israel. Fax: +972 4 8288140; E-mail: [email protected].

Community-dwelling individuals with chronic hemiparesis following stroke are often not eligible for receiving routine physical therapy treatments by public services (Putman et al., 2009), despite their gait limitations. Many of these individuals maintain a constrained lifestyle, are at high risk of falling, and suffer from low fall-related self-efficacy (Algure, Fridlund, Cieza,

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Sunnerhagen, & Christensson, 2012; Dean et al., 2012; Wade, Collen, Robb, & Warlow, 1992; Weerdesteyn, de Niet, van Duijnhoven, & Geurts, 2008). Motor imagery practice offers a useful alternative option for the rehabilitation of gait in post-stroke patients (Dunsky Dickstein, Marcovitz, Levy, & Deutsch, 2008; Malouin & Richards, 2010), given its risk-free application, the ease of use at home, and its acknowledged effectiveness.(Cha, Yoo, Jung, & Park, 2012). However, one apparent shortcoming of such motor imagery practice is the relatively high cost of home visits required for individual application. Although group therapy may substantially lower the costs associated with individual exercise programs (Harrington et al., 2010; van de Port et al., 2009), reports on the application of motor imagery group therapy to post-stroke patients are rare and limited to the practice of upper limb activities. For example, Page and colleagues demonstrated that physical upper extremity ADL practice combined with audiotape group therapy for mental practice resulted in greater therapeutic benefits to the experimental group than those achieved by physical practice alone (Page, Levine, & Leonard, 2007). Similar results in a randomized controlled trial were reported by Riccio and colleagues, who demonstrated the advantage of adding group mental practice to physical practice in treatment of the affected upper extremity in post-stroke patients (Riccio, Iolascon, Barillari, Gimigliano, & Gimigliano, 2010). Studies addressing group-based motor imagery practice for gait limitations were not found in the literature. Support groups for individuals with post-stroke hemiparesis in community centers often provide maintenance programs for preventing deterioration in their physical status. This preliminary study was aimed at applying group-based motor imagery practice of gait to these subjects and examining the effects. We hypothesized that participation in a structured group therapy program focusing on the motor imagery practice of gait tasks would improve walking performance.

2. Method

members of each group explaining the project, volunteers were recruited to participate in the study. Inclusion criteria were an age range of 30–70 years; a time gap of at least three months between the stroke and admission to the study; appropriate cognitive ability (Mini-mental state exam score not lower than 24 points); the ability to walk a minimal distance of 10 meters without stopping; the absence of any medical condition that would prohibit participation; and the absence of any communication problem that would interfere with participation. The study was approved by the Helsinki committee of Center R, which applied to both the community centers. Prior to participation, all of the subjects signed an informed consent with their rights clearly outlined. 2.2. Design The study was conducted in two community centers, applying a full crossover design. During the first five weeks, five subjects in each center were assigned to the experimental intervention, which consisted of the motor imagery practice of walking activities for the purpose of improving gait. Five other subjects were assigned to the control intervention, comprising the motor imagery practice of movements for the affected upper extremity. The control treatment was applied in order to maintain the subjects’ motivation and thereby prevent dropouts. A post-intervention assessment of subjects in both treatments was performed at the end of the five-week period, followed by a two-week break (which also served as a wash-out period). A follow-up assessment was conducted after the break and was also considered to be a pre-intervention assessment for the second fiveweek period of the study, in which the crossover design was implemented. Subjects who had initially received the control treatment “crossed over” to the experimental treatment, while those who had initially received the experimental treatment were assigned to the control treatment. Thus, by the end of the study, each subject had received both interventions. The order of assignment to the experimental and the control treatments during the first period was determined by the order of admission to the study.

2.1. Participants 2.3. Interventions Participants were 20 community-dwelling individuals with post-stroke hemiparesis who belonged to two support groups in their local community centers (Centers H and R). Group members met regularly twice a week at each center. Following a presentation to the

Two physical therapists served as group instructors in each center, with one instructing the experimental treatment and the other the control treatment. General plans for the exercise regimens in the two centers were

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established during a workshop that preceded the study. The instructions for each intervention session were prepared and recorded prior to the meetings. Subjects in both the experimental and the control treatments met twice a week in each community center during the morning hours. The structure of each group meeting consisted of the following five steps: 1) Short conversation between the subjects and the instructor, with the instructor providing feedback for the subjects’ comments on home exercises and feelings; 2) Explanation and demonstration of the assignment for the week; 3) Relaxation phase (2–3 minutes); 4) Motor imagery practice (10 minutes, see details in Tables 1 and 2 below); 5) Refocusing on the environment (2 minutes). During the weekly sessions, both visual and kinesthetic imagery practice of the same motor tasks was applied to both treatments. The tasks were changed once a week, with the instructions provided for each session uniformly presented. During the visual imagery practice, the subjects were encouraged to “see” themselves performing the requested tasks. Imagery of zooming

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through a camera was frequently described to assist them in focusing on movement of the target body parts. During the kinesthetic imagery practice, the subjects were asked to feel their body parts, focusing on movement of the joint(s) of the affected extremity during the practiced task. Repetitions were introduced, along with reinforcement for the sensations that were associated with the imagery performance. Subjects receiving the experimental intervention participated in the imagery training of gait activities. The protocol was similar to that which has previously been applied in an individualized format (Dunsky, Dickstein, Ariav, & Markovitz, 2006; Dunsky, Dickstein, Marcovitz, Levy, & Deutsch, 2008), with the focus of the intervention on enhancing the force of push-off and on lengthening the support time on the involved extremity. These intervention targets were chosen because of the known deficits in performance of these gait phases in post-stroke patients (Lehmann, 1993; Olney, Griffin, & McBride, 1998). All subjects were asked to practice the “activity of the week” at home for five minutes twice a day and were asked to mark each practice session in a log. A descriptive summary of the imagery exercises that were applied weekly is presented in Tables 1 and 2 for the experimental and the control interventions, respectively.

Table 1 Experimental intervention: Summary of weekly exercises of motor imagery gait practice Week

Kinesthetic imagery

Visual imagery

1

Description of room and of self walking in the room, “feeling” the foot on the solid floor, of the force of push off and of the subsequent swing Checking participation: Instructor counts 5 steps, asks subjects to continue silent counting during gait and to raise hand when done. Reinforcement: Instructor stresses feelings of confidence and comfort. Description of own room, of a ring at the door; “sensing” standing up and walking toward the door, focusing on pushing the floor with either leg; opening the door is rewarded by the guest Exercise is repeated at faster pace, with stronger push offs and feelings of making “large” steps. Description of the kitchen and of walking to the refrigerator; the rest of the exercise, as in week 2. Description of outdoor neighborhood environment. Feeling of own presence walking on a familiar trail. Focus on sensing push off from the ground, and on forward alternate advancement of the paretic and non-paretic leg. Checking participation: Set cadence by a metronome to 45 steps/min, then turn metronome off and ask subjects to proceed at the same tempo and rais hand after 5 additional steps. Reinforcement: by stressing the feelings of safety and self confidence in walking. Description of beach environment; feelings of own beach walking; focus on pushing off the hard beach soil; sensing single support without collapsing on the affected leg; further practice of symmetrical imagery walking. Repeat at an increased rate.

Description of room and of self walking in the room “zoom” on legs, on push off, and on symmetrical gait. Increasing rate, Increasing speed, Checking participation: Instructor counts 5 steps, asks subjects to continue silent counting during gait and to raise hand when done. Reinforcement: Instructor stresses feelings of confidence and comfort. Description of own room, of a ring at the door; “seeing oneself” standing up and walking toward the door, focusing on push off with “zooming” on either leg; opening the door is rewarded by the guest Exercise is repeated in at a faster pace, with stronger push-offs and larger steps. Description of the kitchen, walking to the refrigerator; the rest of the exercise, as in week 2. Description of outdoor neighborhood environment. “Seeing” oneself walking on a familiar trail. Focus on push-off as seen by a zooming camera and on forward alternate advancement of the paretic and non-paretic leg. Checking participation: Set cadence by a metronome to 45 steps/min, then turn metronome off and ask the subjects to proceed at the same tempo and raise hand after 5 additional steps Reinforcement: by stressing the feelings of safety and self confidence in walking. Description of beach environment; “seeing” oneself walking on the beach; “zooming” on pushing off the hard beach soil; “seeing” single support on the affected leg through the zooming camera; further practice of symmetrical imagery walking. Repeat at an increased rate

2

3 4

5

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R. Dickstein et al. / Motor imagery group practice post-stroke Table 2 Control intervention: Summary of weekly exercises for imagery practice of movements of the affected upper extremity

Week

Kinesthetic Imagery

Visual Imagery

1

Description of home environment while sitting in front of a table, hands on the arm rests and a glass with favorite drink positioned on the table. The subject is instructed to try to “feel” the hands positioned on the armrests, the lifting and extending the affected upper extremity towards the glass, to feel the fingers stretched (open) and closed around the glass, to feel the glass in the hand while raising it to the mouth and drinking, then placing it on the table. Reinforcement: by feeling of satisfaction while drinking one’s favorite drink

2

Description of the setting and exercise, as in week 1, but, reaching toward a bottle. In addition to the requirements in week 1, the subject is asked to pay attention to the feeling of the temperature, the texture and the contour of the bottle. Description of the subject sitting in the living room, with the TV remote on the table and the TV across the room. Imagery practice of kinesthetic senses associated with reaching towards the remote with the affected extremity and turning on the TV. Reinforcement is fostered by success Description of the subject standing in the kitchen facing the refrigerator, reaching to the door handle to open, feeling the inside of the refrigerator (temperature, contours, textures), the reaching for the desired piece of food, taking it, pulling the hand back, and closing the door. Several repeats are performed without instructions with subjects asked to raise hand after each performance of the task. Description of the subject sitting on the couch, feeling the elbow extending and the hand reaching toward the ringing phone, picking up the phone and lifting to the ear, talking to a loved family member, then putting the phone back.. Several repeats are performed without instructions with subjects asked to raise their hand after each time performance of the task.

Description of home environment while sitting in front of a table, hands on the arm rests and a glass with favorite drink positioned on the table. The subject is instructed to watch himself as if seen through a video camera, to see the glass on the table, to “see” himself reaching with the affected limb towards the glass, zooming on the arm as it lifts up and the elbow extends, then the fingers open and close around the glass; zooming out, “seeing” oneself holding the glass and moving it towards the mouth and drinking, then placing the glass on the table. Reinforcement by feeling of satisfaction while drinking one’s favorite drink Description of the setting and exercise, as in week 1, but, reaching toward a bottle. The subject is asked to “see” oneself reaching and grasping the bottle with the affected hand, while the opening of the bottle is done with the unaffected hand. Description of the subject sitting in the living room, the TV remote on the table and the TV across the room. Imagery practice of “seeing” oneself reaching towards the remote with the affected extremity and turning on the TV. Reinforcement is fostered by success Description of the subject standing in the kitchen facing the refrigerator, reaching to the door handle to open, zooming through the camera on the inside of the refrigerator, the reaching for to the desired piece of food, taking it, pulling the hand back, and closing the door. Several repeats are performed without instructions with subjects asked to raise their hand after each performance of the task. Description of the subject sitting on the couch, with the camera zooming on the hand reaching toward the ringing phone, picking up the phone and lifting to the ear, talking to a loved family member, then putting the phone back. Several repeats are performed without instructions with subjects asked to raise their after each performance of the task.

3

4

5

2.4. Tests and measurements Pre-intervention, post-intervention, and follow-up measurements were performed in each center by one evaluator, who was a senior physical therapist that did not participate in the application of the treatments and was blind to the subjects’ treatment assignment. The measurements were always performed during the morning hours in a designated hall and consisted of: 1) The 10 m walk test, a widely used, valid and reliable test (r > 0.9), (Bohannon, 1997) with the mean of three repetitions used for analysis. 2) The monitoring of vertical forces loaded on the affected lower extremity and of temporal gait data while walking along the 10 m path. Both the vertical forces and the temporal gait data were collected by a dedicated system called the “Smart Step” system (Dickstein, Yoeli, Holtzman, Faust, & Markoviz, 2010; Isakov, 2007). Validity of the system (tested against force plate data) and reli-

ability were shown to exceed 0.9 (Isakov, 2007). The data were transferred onto a computer at a rate of 40 Hz and analyzed off line. 3) The Tinetti gait test, a traditional well-established test, was applied in order to establish functional gait ability (Huang, & Wang, 2009; Tinetti, 1986). 4) Subjects’ fall-related self-efficacy was assessed using the Activities-specific Balance Confidence (ABC) scale. The psychometric properties of the ABC scale have been extensively reported, with validity and reliability values ranging from 0.65 to 0.9(Myers et al., 1996; Salbach, Mayo, Hanley, Richards, & Wood-Dauphinee, 2006). 5) The Box and Blocks test (with validity and reliability values ranging from 0.89 to 0.97) was applied in order to determine the dexterity score for each hand and to assess eventual changes in the function of the involved upper extremity (Desrosiers, Bravo, Hebert, Dutil, & Mercier, 1994). The data gathered through this test were considered secondary because the focus of the

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study was on gait enhancement, while the upper limb imagery practice was used for control purposes only. In addition to the above measurements, the subjects were asked to rate their gait performance between 0 and 10 on a visual analog scale (VAS) (Celenza, & Rogers, 2011), and to answer open questions about their feelings and impressions regarding the effect of the intervention program on their functional walking. The purpose of these questions was to get a better sense of the subjects’ response to the motor imagery intervention. Prior to the intervention, the motor imagery capacity of each subject was determined via the short Kinesthetic and Visual Imagery (KVIQ) questionnaire (Malouin et al., 2007; Malouin, Richards, Durand, & Doyon, 2008). 2.5. Data handling and analysis Demographic information and the data from the pre-intervention, post-intervention, and follow-up evaluations for both treatments in the two centers were entered into one data sheet. Regarding the data gathered from the “Smart Step” system, the vertical forces that were transmitted onto the hind-foot and forefoot were normalized to the percentage of body weight. In addition, the duration of the stance period of the monitored affected lower extremity was expressed in the percentage of the gait cycle of the affected lower extremity. The effect size of the experimental intervention was calculated for the 10 m walk test and for the vertical forces measured via the “Smart Step” system. Descriptive and non-parametric inferential statistics were applied. Possible differences in the subjects’ gait performance between the two centers were pre-tested by comparing the respective pre-intervention values of the 10 m walk tests, as well as the vertical ground reaction forces. In addition, in order to validate the absence of carry-over effects from the first to the second intervention period, the effect of order was tested by comparing between the pre-intervention values of the same variables in the first study period and the corresponding values in the second period. Due to the small sample size and the subjects’ heterogeneity, the Wilcoxon rank-sum test was used to study the differences between the experimental and the control interventions and a possible effect of the center, while the Wilcoxon signed-rank test was applied to test a possible order effect of treatment assignment on the results.

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Data were analyzed with SPSS version 15. Significance level was set at 0.05.

3. Results 3.1. Drop-outs and sample characteristics During the first week of the study, there were four dropouts (two in each center), three of which were due to technical difficulties hindering compliance with the timing of the prescheduled intervention plan. One participant ceased to visit the community center due to unrelated health problems. The described findings are thus based on the data from 16 subjects, including 12 men and four women, with eight subjects in each center and four subjects receiving either the experimental or the control treatment in each of the two periods of the study. A flowchart of the study design that includes the actual number of participants is presented in Fig. 1. The demographic and major clinical details of the participants are outlined in Table 3. All subjects were independent walkers. Six of them used no assistive walking devices, while five used a single-point cane and five others a four-point cane. Five subjects used an Ankle–Foot Orthosis (AFO). The mean scores of the subjects on the visual and kinesthetic subscales of the short KVIQ test were 20.4 and 18.5, respectively, indicating good imagery ability (Malouin et al., 2007; Malouin, Richards, Durand, & Doyon, 2008). In accordance with the study design, all 16 subjects were treated by both the motor imagery practice of gait activities (experimental treatment) and the motor imagery practice of upper extremity functional movements (control treatment). No adverse effects were observed for either the experimental or the control interventions. Twelve subjects reported practicing at home once a day, but only a few reported practicing twice each day. Analysis of the data indicated neither center nor order effects. This means that there were no differences found in the pre-intervention values of the dependent variables in subjects allocated to the experimental versus the control treatment in either center, nor were such differences found between the two centers. Furthermore, no carryover effects from the first to the second intervention period were detected. Therefore, the findings for each intervention type were collapsed, disregarding both the center and the order of treatment application. Values of the 10 m walk test and the scores on the Tinetti test and the ABC scale are presented in Table 4.

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Fig. 1. A flowchart of the study design. Table 3 Major demographic characteristics Age (years)

Sex (n)

63 ± 7

M:12 F:4

Months from Insult

Stroke Aetiology (n)

Stroke territory (n)

Affected Body side (n)

50.2 ± 28.5

Thromboembolic:14 Hemorrhagic: 2

Ant. Circulation:14 Vertebrobasilar: 2

Left: 10 Right: 6

Table 4 Mean (and SD) values of clinical gait and self efficacy test scores at pre- and post- measurements of the experimental and control intervention Ten Meters Walk (sec) Experimental Control Tinetti Gait Score Experimental Control ABC score Experimental Control

Pre – Intervention

Post – Intervention

24.5 (13.6) 20.1 (12.1)

20.9 (12.3) 21.2 (12.9)

7.8 (2.1) 8.4 (2.1)

8.9 (1.9) 8.7 (2.2)

62.3 (20.1) 65.5 (18.8)

65.5 (18.7) 57.9 (14.9)

The differences found between these values at the preand post-interventions were not significant for either treatment modality. Likewise, no differences between the effects of the experimental and the control treatments were discerned for any of these tested variables (for all comparisons, p > 01). The percentage of body weight loaded on the hindfoot and on the forefoot of the affected lower extremity was also not affected by either the experimental or the control intervention, with no significant differences found between the effects of these interventions. The same findings also pertain to stance time (% of the gait cycle) and to cadence. Values of these variables are pre-

sented in Figs. 2 and 3 for the experimental and control interventions, respectively. Analysis of the effect size of the experimental and the control interventions for the 10 m walk test and for the variables derived from measurements of the vertical ground reaction forces resulted in negligible effect sizes, with no differences found between the treatments. The results for the follow-up tests were similar and are therefore not presented. Box and Blocks test scores of the paretic and nonparetic upper extremity following the experimental and the control interventions are presented in Table 5. There were no significant differences found between the pre- and post-intervention measurements for either treatment. 3.2. Verbal responses The VAS scores, as determined by the subjects’ selfratings of their walking performance, were not significantly affected by the experimental intervention. Nevertheless, the verbal feedback given by the participants was by and large positive. Six of the eight participants from Center R stated that the group and the additional home practice of gait activities via motor imagery had had a positive effect on their gait. Five

R. Dickstein et al. / Motor imagery group practice post-stroke

Fig. 2. Gait variables (means and SEM) at the pre- and post-experimental intervention (motor imagery practice of gait performance), as measured by the Smart Step system. The Y axis for the two left pairs of bars denotes the percentage of body weight for the hind-foot and forefoot (HF and FF, respectively); for the third pair the y axis denotes stance (ST) as percentage of gait cycle; and for the far right pair – cadence (Cad) – in steps/min. HF PRE: Percentage loaded on the hind-foot at the pre-intervention measurement. HF POST: Percentage loaded on the hind-foot at the post-intervention measurement. FF PRE: Percentage loaded on the forefoot at the pre-intervention measurement. FF POST: Percentage loaded on the forefoot at the post-intervention measurement. ST PRE: Percentage of stance time (from gait cycle) at the pre-intervention measurement. ST POST: Percentage of stance time (from gait cycle) at the post-intervention measurement. CAD PRE: Cadence at the pre-intervention measurement. CAD POST: Cadence at the post-intervention measurement.

of these six subjects reported a substantial improvement in their self-confidence, with a corresponding impact on their gait performance. One additional participant reported gait improvement, yet speculated that the improvement was not associated with the program. Only one participant expressed skepticism about the merits of the motor imagery practice of gait. Gait improvement was described in terms of “taking larger steps,” “walking at higher speed,” “walking without a cane,” “walking outdoors without supervision,” “walking long distances in the city,” and “walking on the beach.” Four subjects stated using imagery for activities other than those practiced during group training, such as walking in the street. As for the function of the affected upper extremity, five out of the eight subjects expressed satisfaction with the control program and described improvements in function associated with their motor imagery practice. Phrases used to describe improvements in their upper extremity function were: “increase in range of motion of the elbow and fingers,” “ability to drink soup while holding the bowl with both hands,” “improvement in dressing and grooming ability,” “ability to do some house cleaning and cooking,” and “improvement in use of the affected

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Fig. 3. Gait variables (means and SEM), at the pre- and post-control intervention (motor imagery practice of the affected upper extremity), as measured by the Smart Step system. The Y axis for the two left pairs of bars denotes the percentage of body weight for the hind-foot and forefoot (HF and FF, respectively); for the third pair – stance (ST) – as the percentage of gait cycle; and for the far right pair – cadence (Cad) – in steps/min. For abbreviations, see Footnotes for Fig. 2. Table 5 Box and Blocks test scores of the paretic and non paretic upper extremity following the experimental and the control intervention Box and Blocks score, non paretic limb Experimental Control Box and Blocks score, paretic limb Experimental Control

Pre-Intervention

Post-Intervention

45.5 (12.5) 46.8 (15.9)

46.6 (8.9) 43.3 (15.9)

15.5 (16.9) 20.7 (21.6)

17.9 (18.2) 18.5 (18.7)

hand for eating.” Satisfaction was also expressed by participants from center H with four of them commenting on improvements in their ability to apply motor imagery practice of gait; one additional subject reported applying motor imagery to real-life situations, such as practicing climbing steep steps to a restaurant before actually visiting the place. An ancillary interesting finding was that two subjects who suffered from impaired somatosensory sensations complained about limb pain associated with practice (more during the upper extremity control practice than during the experimental gait practice). These two patients were reluctant to utilize motor imagery practice as a means to improve their gait or upper extremity function. 4. Discussion The findings of this study failed to indicate that motor imagery group practice in subjects with chronic post-

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stroke hemiparesis is associated with improvement in the values of temporal gait variables or in the vertical forces generated by the affected limb during walking. Fall-related self-efficacy, as evaluated by the ABC questionnaire, was also not improved. Notably, in contrast to these findings, previous studies have shown that group-based real physical exercises for similar subjects suffering from lasting gait dysfunction (Dean et al., 2012; Donovan, Lord, McNaughton, & Weatherall, 2008) had a positive effect on walking capacity, with improvements reported in balance, knee strength, cardio-respiratory fitness, ADL parameters (Macko et al., 2008; Marigold et al., 2005), and quality of life (Macko et al., 2008). However, the effects of group exercise on biomechanical gait variables, such as the forces generated during gait, are not well established. Considering the positive effect of real physical group exercises, as well as the positive effect of individually applied motor imagery practice on post-stroke gait performance (Dunsky Dickstein, Marcovitz, Levy, & Deutsch, 2008; Malouin & Richards, 2010), (albeit less effective than real practice), the failure of group-based motor imagery practice is intriguing. The advantage of physical over mental practice is well known, and thus the greater effectiveness of group-based real practice relative to group-based imagery practice is self-explanatory. Regarding the comparison between individual and group-based motor imagery practice, a major advantage of individual treatment is the ability to customize the content to each individual. For example, the environment in which walking takes place is familiar to the subject and the imagined tasks are chosen by relevance, thereby enhancing motivation and performance. These features may be lost in group practice, especially in a heterogeneous group of individuals with great variability in terms of personal, social, and cultural variables. This was the case in the current study, and the imagery group exercises could not be equally tailored to the aims, needs, and abilities of each individual in the group. Furthermore, the instructions to practice at home twice a day were not followed by most of the participants, though they practiced one time each day. Additionally, the fact that the study was conducted in two centers with four treating and two assessing therapists may have further increased the variability of the outcomes. It is possible that group exercises combining real and imagery practice would have yielded more positive results. The merits of such a combination have frequently been reported (Malouin, Richards, Durand, & Doyon, 2009; Page, Levine, & Leonard, 2007; Riccio, Iolascon, Barillari, Gimigliano, & Gimigliano, 2010).

Especially noteworthy is the study conducted by Hwang and colleagues, in which physical therapy plus locomotor imagery training brought about larger improvements in gait parameters as compared to a control group that received only physical therapy (Hwang et al., 2010). Despite the failure in demonstrating quantitative improvement, the personal feedback of a great number of the participants pointed to a positive contribution of the program. Although a placebo effect cannot be ruled out, the established positive effect of motor imagery practice on motivation and self-confidence (e.g Garza, & Feltz, 1998) raises the possibility of a similar effect in the current subjects. Accordingly, the positive reinforcement induced by motor imagery gait practice may explain subjects’ motivation and courage to practice gait activities in their daily lives. The need to reduce the cost of ongoing treatment to patients with chronic post-stroke hemiparesis may be met via group practice, especially if provided in community centers. Furthermore, the merits of motor imagery practice indicate the advantage of their application. Given that the current results are based on a pilot study composed of only 16 post-stroke subjects, the notion that the study was under-powered is certainly conceivable. Larger-scale studies, applying not only an RCT but also a Practice Based Evidence (PBE) (Horn & Gassaway, 2007, 2010) design, may be useful in overcoming the inherent heterogeneity in patients with chronic post-stroke hemiparesis and may underscore the characteristics of subjects that would benefit from group-based motor imagery practice (Gassaway et al., 2005). 5. Conclusions Based on objective measurements, the findings of this study do not indicate a measurable contribution of group-based motor imagery practice to the gait performance of community-dwelling subjects with chronic post-stroke hemiparesis. Yet, taking into account both the limitations stemming from the pilot nature of the study with a small sample size, as well as the thoughtprovoking positive feedback of the respondents, further inquiry is warranted. Declaration of interest No conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.

R. Dickstein et al. / Motor imagery group practice post-stroke

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Motor imagery group practice for gait rehabilitation in individuals with post-stroke hemiparesis: a pilot study.

Stroke is the leading cause of adult disability, with walking impairment being a devastating indicator of chronic post-stroke hemiparesis. Limited res...
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