Effects of mental practice on affected limb use and function in chronic stroke

Article Outline

• Abstract
• Methods
  • Participants
  • Instruments
    • Motor activity log
    • Action Research Arm Test
  • Design and pretesting
  • MP intervention
  • Control intervention
  • Postintervention test
• Results
• Discussion
• Conclusions
• References
• Copyright

Abstract 

Page SJ, Levine P, Leonard AC. Effects of mental practice on affected limb use and function in chronic stroke.

Objective

To determine the efficacy of a mental practice (MP) protocol in increasing the function and use of the more affected limb in stroke patients.

Design

Randomized, controlled, multiple baseline, pre-post, case series.

Setting

Outpatient rehabilitation hospital.

Participants

Eleven patients who had a stroke more than 1 year before study entry (9 men; mean age, 62.3±5.1y; range, 53–71y; mean time since stroke, 23.8mo; range, 15–48mo; 10 strokes exhibiting upper-limb hemiparesis on the dominant side) and who exhibited affected arm hemiparesis and nonuse.

Intervention

All patients received 30-minute therapy sessions 2 days a week for 6 weeks. The sessions emphasized activities of daily living (ADLs): 6 subjects randomly assigned to the MP condition concurrently received sessions requiring daily MP of the ADLs; 5 subjects (control group) received an intervention consisting of relaxation techniques.

Main outcome measures

The Motor Activity Log and Action Research Arm (ARA) test.

Results

Affected limb use as rated by MP patients and their caregivers increased (1.55, 1.66, respectively), as did patient and caregiver ratings of quality of movement (2.33, 2.15, respectively) and ARA scores (10.7). In contrast, the controls showed nominal increases in the amount they used their affected limb and in limb function. A Wilcoxon test on the ARA scores revealed significantly (P=.004) greater changes in the MP group’s scores.

Conclusions

Participation in an MP protocol may increase a stroke patient’s use of his/her more affected limb. Data further support that the protocol resulted in correlative, MP-induced, motor function improvements. The mechanisms whereby MP increases affected arm use are unknown. Perhaps using the more affected limb becomes more salient through MP, or perhaps motor schema are altered during MP to integrate limb use.

Key words:  Exercise therapy , Mental processes , Rehabilitation , Stroke

WHEN AN ANIMAL’S forelimb is rendered insensate by surgical deafferentation, 3-limbed movement patterns persist even after voluntary movement is possible with the fourth, deafferented limb.¹, ² However, this movement suppression can be overcome through forced, repeated use of the deafferented limb.³, ⁴ Similarly, hemiparetic stroke patients do not use their more affected limbs even when capable of doing so,⁵, ⁶ a response that has traditionally been termed hemiakinesia. Over time, this movement suppression becomes habitual: patients eventually use their less affected arm for most activities of daily living (ADLs). Stroke-induced affected arm nonuse often causes greater motor disability to be exhibited than that which actually exists, and this can produce affected limb bone and muscular atrophy.⁷, ⁸ However, as with animal findings, forced, repeated use of the more affected arm overcomes these nonuse patterns.⁹, ¹⁰ This finding has been translated into clinical protocols that increase use of the more affected limb and thus improve function in stroke patients.¹¹, ¹², ¹³, ¹⁴, ¹⁵ It is believed that such repeated, task-specific protocols induce brain reorganizations to bring about these functional improvements.¹⁶

Mental practice (MP) protocols, which require repeated, cognitive rehearsal of valued ADLs, appear to reduce impairment and improve motor function in the more affected arms of chronic¹⁷ and subacute¹⁸, ¹⁹, ²⁰ stroke patients. Because the same neuromuscular structures are activated during MP as during physical practice,²¹ some researchers²² have posited that repeated MP induces use-dependent brain reorganizations that are responsible for functional improvements. Recent findings have provided preliminary support for this hypothesis.²³ In our laboratory, we had informally observed that stroke patients participating in MP protocols exhibit increased use of their affected limb after intervention. It seems plausible that MP regimens may cause the increased use simply by making it more salient or palatable to patients. MP may also overcome limb nonuse by establishing new motor schema that incorporate the more affected limb, or it may alter preexisting motor schema that cause the more affected limb to be neglected.

Does MP increase a person’s use of the affected limb? In the present study, we identified the effects of a 6-week MP intervention and compared them with a control intervention. Our subjects were 11 chronic stroke patients. We hypothesized that the 6 patients receiving MP would increase use of their affected limb and would have functional improvement. The 5 patients receiving identical motor therapy but with a control intervention would, we hypothesized, exhibit nominal changes in the use and function of their more affected limb.

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Methods 

Participants 

Subjects for this study were recruited as part of a larger MP study. We placed advertisements in therapy clinics and gave them to therapists in the midwestern United States. A research team member screened volunteers according to the following inclusion criteria: (1) 10° or more of active flexion in the more affected wrist, as well as in 2 digits of the more affected hand; (2) stroke experienced more than 1 year before study enrollment; (3) a score 70 or higher on the modified Mini-Mental Status Examination²⁴; (4) age greater than 18 but less than 95 years; (5) no excessive muscle spasticity in the more affected upper limb, defined as a score of 3 or lower on the Modified Ashworth Scale²⁵; (6) no excessive pain in the more affected upper limb, as measured by a score of 4 or lower on a 10-point visual analog scale; (7) only having experienced 1 stroke; (8) discharged from all forms of physical rehabilitation; and (9) not participating in any experimental rehabilitation or drug studies. An additional inclusion criterion for this substudy was that subjects had to exhibit nonuse of the more affected arm, defined as less than 2.5 on the Amount of Use (AOU) scale of the Motor Activity Log (MAL), which is described below.

Using these criteria, 11 subjects were included (9 men; mean age, 62.3±5.1y; range, 53–71y; mean time since stroke, 23.8mo; range, 15–48mo; 10 strokes exhibiting upper-limb hemiparesis on the dominant side).

Instruments 

The MAL is a semistructured interview measuring how patients use their affected limbs for ADLs. In separate MAL interviews, patients and their caregivers independently rated how much and how well the patient had used the affected arm for 30 ADLs during the past week. They used a 6-point AOU scale to rate how much the patient used his/her affected arm and a 6-point Quality of Movement (QOM) scale to rate how well he/she used it. The MAL has been successfully applied to measure more affected limb use in several stroke intervention studies.

The Action Research Arm (ARA) Test,²⁶ a 19-item test divided into 4 categories (grasp, grip, pinch, gross movement), with each item graded on a 4-point ordinal scale (0, can perform no part of the test; 1, performs test partially; 2, completes test but takes abnormally long time or has great difficulty; 3, performs test normally) for a total possible score of 57. The test is hierarchical; that is, if the patient is able to perform the most difficult skill in each category, he/she will be able to perform the other items within the category and, thus, need not be tested on those items. The ARA has high intrarater (r=.99) and retest (r=.98) reliability and validity.²⁶, ²⁷ The ARA has adequate sensitivity, shown in several previous MP studies and primarily measures fine motor function. Because our MP intervention primarily targeted distal function, the ARA was an ideal measure.

Design and pretesting 

A randomized, controlled, single-blinded, multiple baseline, pre- and posttest case series design was applied. After screening and signing consent forms approved by the local institutional review board, the ARA and MAL were administered on 2 occasions, 1 week apart. After the second pretesting session, patients were randomly assigned to 1 of 2 conditions described below, using a random numbers table.

All patients received therapy in the same environment in the same fashion and from the same therapists from whom they had received outpatient therapy. They had been discharged from this therapy due to a perceived performance “plateau” in which they were not responding to their therapy regimen. Thus, any improvements exhibited in the present study would be attributable to the MP regimen.

MP intervention 

To test the hypothesis that the combination of physical practice and MP of ADLs would be more effective than physical practice alone, subjects were assigned to 1 of 2 conditions. Subjects randomly assigned to the MP group (n=6) practiced the same set of ADLs, both through physical practice (ie, affected arm therapy) and through MP. Specifically, all subjects received therapy for the more affected arm 2 times a week in 30-minute segments for 6 weeks. During therapy sessions, emphasis was placed on performing selected ADLs (table 1) bimanually through the entire range of motion. This ADL practice dominated the sessions, while stretching and compensatory exercises were provided as needed to assist patients with ability to perform the ADLs.

Table 1. Audiotape Sequences and Where and When Tape Was Used

After therapy, MP subjects received the appropriate, recorded, 30-minute MP intervention corresponding to the week of therapy in which they were currently engaged. For example, during weeks 1 and 2, patients practiced reaching for and grasping a cup in their therapy session and they also mentally practiced the same ADL(s) at home and in our laboratory. The MP interventions were provided on audiotape, recorded by a psychologist with 10 years’ experience in the application of MP to improve motor skills. The tape consisted of relaxation in the opening 5 minutes, asking patients to imagine themselves in a warm, relaxing place (eg, a beach) and asking them to contract and relax their muscles (ie, progressive relaxation). This portion of the tapes was followed by suggestions for internal, cognitive polysensory images²⁸ related to using the affected arm in the functional tasks listed in table 1. The final 3 to 5 minutes allowed patients to refocus into the room.

Control intervention 

Patients in the control group (n=5) received the same motor therapy regimen as those in the MP group. Their therapists and contact parameters were identical to those of the MP patients. Control patients also listened to a 30-minute tape after motor therapy. Their taped relaxation sequence featured only progressive relaxation protocol, in which they were told to flex the toes and then to release them, to flex the leg muscles and then to release them, and so on. We formulated this control condition (as opposed to providing only therapy or providing a no-treatment condition) to keep contact time consistent across groups; we used relaxation as a sham condition (as opposed to having patients listen to instructions or information) because our pilot work suggested that it keeps participants interested, compliant, and blinded (ie, they feel that they are receiving a perceived benefit from participating in the relaxation and do not realize that it is the control condition).

Postintervention test 

After 6 weeks, all patients returned to the laboratory, where they were again administered the ARA and MAL by the same examiner who pretested them. The examiner was blinded to each patient’s experimental condition.

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Results 

Before the intervention, none of the subjects used their more affected upper limb for ADLs, as indicated by self-rated pretest mean AOU scores of 1.1 and 0.9 for the MP and control groups, respectively. The caregivers’ mean AOU ratings for the preintervention MAL closely corroborated patient estimates, with scores of 1.05 and 1.15 for MP and control groups, respectively. After the intervention, AOU ratings by MP patients and their caregivers were 2.60 and 2.71, respectively. Mean change scores computed by the formula at the bottom of table 2 were 1.55 and 1.66, respectively, for patient and caregiver AOU rating. In contrast, postintervention control AOU ratings were 1.4 and 1.5 for patients and caregivers, respectively, with mean change scores of 0.49 and 0.30, respectively.

Table 2. MAL Scores Before and After Intervention

NOTE. Pre 1 and Pre 2 are the 2 preintervention tests conducted 1 week apart; values are mean scores. Post denotes mean score obtained during the postintervention test. Formula used to compute mean change scores:

Before the intervention, the MP group’s QOM ratings averaged .53 and .59 for preintervention tests 1 and 2, respectively. Mean QOM levels for controls were .43 and .50 for preintervention test sessions 1 and 2, respectively. After the intervention, the MP group’s average QOM was 2.8 (mean change score, 2.24), whereas the control group’s mean QOM rating was .67 (mean postintervention change score, .21).

Mean ARA scores before the intervention for the MP patients were 34.00±2.19 and 32.20±5.35 at preintervention test sessions 1 and 2, respectively. After intervention, the MP group’s mean ARA score was 43.80±3.09 (change score, 10.70). Mean ARA scores for control patients before the intervention were 33.60±1.67 and 34.60±1.82 for sessions 1 and 2, respectively; the post-ARA score was 38.70±1.20 (change score, 4.60). A Wilcoxon rank-sum test was performed on the change scores of members of each group. Of the 11 subjects, the 6 with the highest change scores were the 6 experimental subjects, resulting in an exact 2-sided P value of .004.

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Discussion 

Stroke patients often do not use their more affected arms for ADLs, even when they are capable of doing so. In addition to causing a greater handicap level, this nonuse can undermine motor return, because limb use appears to be related to cortical reorganization and, ultimately, to reacquisition of motor function. This case series examined MP as a strategy to increase use and function of the more affected limb after stroke.

The MAL AOU scores showed that all subjects not only met the criterion of an AOU score of 2.5 or lower, but also that they barely used their affected limbs for ADLs. Most subjects and/or their caregivers confirmed during pretesting that they did not use their more affected limbs and had not made attempts to use it for ADLs in months. In contrast, after intervention, MP subjects uniformly showed appreciable increases in use of the more affected arm for ADLs, as reflected by a mean self-reported AOU change score of 1.55. Caregivers corroborated this increase, rating patients’ AOU at 2.71 after intervention, for a 1.66 increase. Although postintervention AOU levels were not as high as postintervention levels reported with other interventions that used the MAL to measure limb use, the changes we found were still clinically meaningful. Indeed, after the intervention, patients reported performing ADLs with their more affected hands that they had not performed in months, such as eating and writing with utensils and performing various grooming activities (eg, using a toothbrush) using the more affected limb. With these changes noted, the study would have been strengthened had we used additional measures of more affected limb activity, such as activity monitors. Activity monitors provide objective, quantified measurement of limb activity and have been used for that purpose in previous stroke interventions.²⁹ To our knowledge, the prevalence of more affected limb nonuse has not been documented in a stroke population, but data described herein suggest that more affected limb nonuse may be common. Future efforts will thus incorporate activity monitor use.

The ARA and QOM data trends were similar to AOU data trends for MP patients. Specifically, before the intervention, all patients’ motor deficits were relatively stable and patients’ scores did not change substantially between the 2 preintervention tests (see table 2). The MP subjects self-rated their QOM to be .47, while their caregivers rated it as about .65. The ARA scores before the intervention were also relatively stable. Conversations with all patients, their therapists, and their physicians confirmed that motor status scores had changed negligibly since discharge. After the intervention, QOM and ARA data showed marked increases only in the MP group. The ARA data trends were consistent with those observed in previous MP studies with stroke patients. Specific ARA items on which patients showed improvement included particular grip and grasp items, such as pincer grasp and picking up small items. As noted previously, all patients received therapy in the same environment, in the same fashion, and from the same therapists from whom they had received outpatient therapy. They had been discharged from this therapy due to a perceived performance “plateau,” in which they were no longer responding to this therapy regimen. Because the therapy for the study was nearly identical to that received previously and was, in fact, less intense, any improvements exhibited in the study are probably attributable to the MP regimen.

The increased use and motor function changes exhibited only by the MP patients confirmed our hypothesis that MP would increase more affected limb use. After stroke, it is believed that patients express greater motor disability on their more affected sides than actually exists. Over time, this movement suppression becomes habitual: patients eventually use the less affected side for most ADLs. Data obtained in this study suggest that nonuse of the more affected limb can be overcome by participation in MP. The ARA and QOM data further support the finding that participation in MP can elicit functional changes. Neuroimaging studies that are underway by our group will indicate whether the increased limb use patterns observed in the present study are enough to induce cortical reorganizations, which, in turn, may be responsible for the functional changes we found.

It is believed that most motor recovery occurs during the first 6 to 12 months after stroke.³⁰, ³¹ It is worth noting that chronic stroke patients in this study responded favorably to this novel intervention, and other researchers also report positive responses to other novel interventions, bringing into question this precept.

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Conclusions 

MP appears to be a promising protocol for improving more affected upper-limb motor function in stroke patients. Our data also suggest that MP participation increases more affected limb use. These use patterns may be altered by demonstrating to patients that they are capable of performing more with the affected limb than they believed. It is also plausible that more affected limb use becomes more salient through MP use because new motor schema are developed, or preexisting motor schema are augmented with MP use. Current studies in our laboratory are investigating these questions using functional magnetic resonance imaging at 4T.

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References 

1. Taub E , Ellman SJ , Berman AJ . Deafferentation in monkeys (effect on conditioned grasp response) . Science . 1966;151: 594–4
   • View In Article
2. Taub E . Motor behavior following deafferentation in the developing and motorically mature monkey . In:  Herman R ,  Grillner S ,  Ralston HJ ,  Stein PS ,  Stuart D editor. Neural control of locomotion . New York: Plenum; 1976;p. 675–705
   • View In Article
3. Taub E . Movement in nonhuman primates deprived of somatosensory feedback . In: Exercise and sports science reviews . Santa Barbara: Journal Publishing Affiliates; 1977;p. 335–374
   • View In Article
4. Taub E . Somatosensory deafferentation research with monkeys (implications for rehabilitation medicine) . In:  Ince LP editors. Behavioral psychology in rehabilitation medicine (clinical applications) . New York: Williams & Wilkins; 1980;p. 371–401
   • View In Article
5. Tower SS . Pyramidal lesions in the monkey . Brain . 1940;63:36–90
   • View In Article
6. Lashley KS . Studies of cerebral function in learning: V. The retention of motor areas in primates . Arch Neurol Psychiatry . 1924;12:249–276
   • View In Article
7. Ryan AS , Dobrovolny CL , Smith GV , Silver KH , Macko RF . Hemiparetic muscle atrophy and increased intramuscular fat in stroke patients . Arch Phys Med Rehabil . 2002;83:1703–1707
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (98 KB)
   • CrossRef
8. Yavuzer G , Ataman S , Suldur N , Atay M . Bone mineral density in patients with stroke . Int J Rehabil Res . 2002;25:235–239
   • View In Article
   • MEDLINE
   • CrossRef
9. Wolf S , LeCraw DE , Barton LA , Jann BB . Forced use of hemiplegic upper extremities to reverse the effect of learned nonuse among chronic stroke and head-injured patients . Exp Neurol . 1989;104:125–132
   • View In Article
   • MEDLINE
   • CrossRef
10. Miltner W , Bauder H , Sommer M , Dettmers C , Taub E . Effects of constraint-induced movement therapy on patients with chronic motor deficits after stroke (a replication) . Stroke . 1999;30:586–592
    • View In Article
    • MEDLINE
    • CrossRef
11. Page SJ , Sisto SA , Johnston MV , Levine P , Hughes M . Modified constraint induced therapy (a randomized, feasibility and efficacy study) . J Rehabil Res Dev . 2001;38:583–590
    • View In Article
    • MEDLINE
12. Page SJ , Sisto S , Johnston MV , Levine P . Modified constraint-induced therapy after subacute stroke (a preliminary study) . Neurorehabil Neural Repair . 2002;16:290–295
    • View In Article
    • MEDLINE
13. Page SJ , Sisto S , Levine P , McGrath R . A promising, clinically-practical intervention for hemiparesis after chronic stroke . Arch Phys Med Rehabil . 2004;85:14–18
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (65 KB)
    • CrossRef
14. Ferraro M , Palazzolo JJ , Krol J , Krebs HI , Hogan N , Volpe BT . Robot-aided sensorimotor arm training improves outcome in patients with chronic stroke . Neurology . 2003;61:1604–1607
    • View In Article
    • CrossRef
15. Aisen ML , Krebs HI , Hogan N , McDowell F , Volpe BT . The effect of robot-assisted therapy and rehabilitative training on motor recovery following stroke . Arch Neurol . 1997;54:443–446
    • View In Article
    • MEDLINE
16. Taub E , Uswatte G , Pidikiti R . Constraint-Induced Movement Therapy (a new family of techniques with broad application to physical rehabilitation—a clinical review) . J Rehabil Res Dev . 1999;36:237–251
    • View In Article
    • MEDLINE
17. Page SJ . Imagery improves motor function in chronic stroke patients with hemiplegia (a pilot study) . Occup Ther J Res . 2000;20:200–215
    • View In Article
18. Crosbie JH , McDonough SM , Gilmore DH , Wiggam MI . The adjunctive role of mental practice in the rehabilitation of the upper limb after hemiplegic stroke (a pilot study) . Clin Rehabil . 2004;18:60–68
    • View In Article
    • MEDLINE
    • CrossRef
19. Page SJ , Levine P , Sisto S , Johnston M . Imagery combined with physical practice for upper limb motor deficit in sub-acute stroke (a case report) . Phys Ther . 2001;8:1455–1462
    • View In Article
20. Page SJ , Levine P , Sisto S , Johnston M . A randomized, efficacy and feasibility study of imagery in acute stroke . Clin Rehabil . 2001;15:233–240
    • View In Article
    • MEDLINE
    • CrossRef
21. Ito M . Movement and thought (identical control mechanisms by the cerebellum) . Trends Neurosci . 1993;16:453–454
    • View In Article
    • CrossRef
22. Page SJ . Mental practice (a promising restorative technique in stroke rehabilitation) . Top Stroke Rehabil . 2001;8(3):54–63
    • View In Article
    • MEDLINE
    • CrossRef
23. Jackson PL , Lafleur MF , Malouin F , Richards CL , Doyon J . Functional cerebral reorganization following motor sequence learning through mental practice with motor imagery . Neuroimage . 2003;20:1171–1180
    • View In Article
    • MEDLINE
    • CrossRef
24. Teng EL , Chui HC . The Modified Mini-Mental State (3MS) exam . J Clin Psychiatry . 1987;48:314–318
    • View In Article
    • MEDLINE
25. Bohannon RW , Smith MB . Interrater reliability of a modified Ashworth scale of muscle spasticity . Phys Ther . 1987;67:206–207
    • View In Article
    • MEDLINE
26. Lyle RC . A performance test for assessment of upper limb function in physical rehabilitation treatment and research . Int J Rehabil Res . 1981;4:483–492
    • View In Article
    • MEDLINE
    • CrossRef
27. Van der Lee JH , De Groot V , Beckerman H , Wagenaar RC , Lankhorst GJ , Bouter LM . The intra- and interrater reliability of the action research arm test (a practical test of upper extremity function in patients with stroke) . Arch Phys Med Rehabil . 2001;82:14–19
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (59 KB)
    • CrossRef
28. Paivio A . Cognitive and motivational functions of imagery in human performance . J Appl Sport Sci . 1985;10(4):22–28
    • View In Article
29. Page SJ , Sisto SA , Levine P . Modified constraint-induced therapy in chronic stroke . Am J Phys Med Rehabil . 2002;81:870–875
    • View In Article
    • MEDLINE
    • CrossRef
30. Parker VM , Wade DT , Langton-Hewer R . Loss of arm function after stroke (measurement, frequency, and recovery) . Int Rehabil Med . 1986;8:69–73
    • View In Article
    • MEDLINE
31. Jorgenson HS , Nakayama H , Raaschou H , Vive-Larsen J , Stoier M , Olsen T . Outcome and time course of recovery in stroke: Part II. Time course of recovery. The Copenhagen Stroke Study . Arch Phys Med Rehabil . 1995;76:406–412
    • View In Article
    • Abstract
    • Full-Text PDF (666 KB)
    • CrossRef