Task-Based Mirror Therapy Augmenting Motor Recovery in Poststroke Hemiparesis: A Randomized Controlled Trial Kamal Narayan Arya, MOT, PhD,* Shanta Pandian, MOT,* Dharmendra Kumar, MS, DNB,* and Vinod Puri, DM†
Background: To establish the effect of the task-based mirror therapy (TBMT) on the upper limb recovery in stroke. Methods: A pilot, randomized, controlled, assessorblinded trial was conducted in a rehabilitation institute. A convenience sample of 33 poststroke (mean duration, 12.5 months) hemiparetic subjects was randomized into 2 groups (experimental, 17; control, 16). The subjects were allocated to receive either TBMT or standard motor rehabilitation—40 sessions (5/week) for a period of 8 weeks. The TBMT group received movements using various goal-directed tasks and a mirror box. The movements were performed by the less-affected side superimposed on the affected side. The main outcome measures were Brunnstrom recovery stage (BRS) and Fugl-Meyer assessment (FMA)—FMA of upper extremity (FMA-UE), including upper arm (FMA-UA) and wrist–hand (FMA-WH). Results: The TBMT group exhibited highly significant improvement on mean scores of FMA-WH (P , .001) and FMA-UE (P , .001) at postassessment in comparison to the control group. Furthermore, there was a 12% increase in the number of subjects at BRS stage 5 (out of synergy movement) in the experimental group as compared to a 0% rise at the same stage in the control group. Conclusions: This pilot trial confirmed the role of TBMT in improving the wrist–hand motor recovery in poststroke hemiparesis. MT using tasks may be used as an adjunct in stroke rehabilitation. Key Words: Hemiparesis—mirror therapy—motor recovery— stroke rehabilitation—task-specific training—visual illusion. Ó 2015 by National Stroke Association
Mirror therapy (MT) is a favorable and cost-effective method in stroke rehabilitation.1,2 It is a form of motor imagery and action-observation technique which uses
From the *Department of Occupational Therapy, Pandit Deendayal Upadhyaya Institute for the Physically Handicapped, New Delhi; and †Department of Neurology, GB Pant Post Graduate Institute of Medical Education and Research, New Delhi, India. Received February 11, 2015; revision received March 6, 2015; accepted March 17, 2015. The present study was funded by Pandit Deendayal Upadhyaya Institute for the Physically Handicapped, New Delhi, India. The authors declare that they have no conflict of interest regarding this article. Address correspondence to Kamal Narayan Arya, MOT, PhD, Pandit Deendayal Upadhyaya Institute for the Physically Handicapped, 4 VD Marg, New Delhi 110002, India. E-mail: [email protected]
yahoo.com. 1052-3057/$ - see front matter Ó 2015 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2015.03.026
the concept of visual illusion.3 MT provides visual feedback through illusion. The therapy uses mirror to transmit visual information through observation of movements performed on the unaffected part.4,5 The movement is being perceived as the action of the affected side and creates an interaction between the visual, proprioceptive, and motor inputs. Neurophysiologically, MT mechanism facilitates motor learning and induces cortical reorganization associated with positive motor recovery.1,6,7 The training also promotes interhemispheric communication and induces a balance between the motor cortices.8 The specific neuronal system, known as mirror neurons, has also been considered responsible for the effect of MT.6 The neurons get activated by the performance of movement and by observing the resembling motor activity in the mirror. The firing of such neurons may induce positive cortical reorganization and associated motor control.9-11 MT is also being used as a component of graded motor
Journal of Stroke and Cerebrovascular Diseases, Vol. -, No. - (---), 2015: pp 1-11
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imagery to alleviate chronic pain by modulating cortical processing.12 In stroke, motor paresis does not provide a proprioceptive experience of usual motor action on the affected side. Through MT, the visual impression may be created by observing the image of the less-affected upper extremity as a projection over the affected limb.13 The technique allows acquaintance of normal movements on the subject’s own body. The role of MT has been explored for motor paresis in poststroke subjects.2,3,5,14-16 Both the upper limb and the lower limb have been investigated using MT. The technique has been suggested as an adjunct to the usual protocol for improving the upper limb motor and daily function.17 In addition to motor control, MT also induces sensory recovery in chronic stroke.2 Although the use of object may induce greater motor recovery, none of the studies has used motor-functional tasks to impart the intervention.18 Among various motor therapies, task-specific training has strong evidence for stroke rehabilitation.19 The training comprises goal-oriented repetitive practice of tasks to facilitate motor recovery in stroke.20 Goaloriented task has been defined as a meaningful activity in which the movements appear out of an interaction between multiple brain areas to manipulate a real-world object.21,22 Such movements increase the cortical activity and may induce greater motor recovery than the movements without task.18 The response of mirror neuron (responsible for the effect of MT) is better for the object-directed actions as compared to nonobject actions.23 Hence, MT in the form of tasks may use twoway neural reorganization and enhance substantial motor recovery. In the preliminary study, MT using tasks such as picking up an object was provided to a group of poststroke hemiparetic subjects.13 The findings of task-based MT (TBMT) in the single-group design have been found to be feasible and beneficial in improving wrist and hand motor recovery in chronic stroke. However, a randomized controlled trial investigating the potential benefit of the program has not been performed yet. The aim of this trial was to determine the effect of the TBMT on upper limb recovery in poststroke hemiparetic subjects. TBMT trial represents a pilot, randomized, single-blind study to investigate the effect of MT through tasks in chronic poststroke hemiparetic subjects.
Method Participants After the screening of 67 poststroke hemiparetic subjects, 33 participants were finally enrolled from the Department of Occupational Therapy, Pandit Deendayal Upadhyaya Institute for the Physically Handicapped (PDUIPH). Stroke diagnosis was confirmed by the neurologist using clinical presentation supported by computed
tomography or magnetic resonance imaging findings.24 All the subjects were briefed about the study before they signed the informed consent form. Only those subjects who met the following inclusion criteria were recruited: aged less than 60 years, single unilateral stroke with hemiparesis, more than 24 weeks poststroke, able to understand instructions, and Brunnstrom recovery stage of arm (BRS-A) 2 or above.25 The subjects were excluded from the study if they exhibited the following: associated neurological complications, severe perceptual and visual deficits (as evaluated by the National Institutes of Health Stroke Subscales26 and clinical tests: copying and drawing, line-bisection, cancellation tasks, and functional performance), shoulder subluxation, and uncontrolled medical illness. The present study was approved by the Ethics Committee of PDUIPH.
Design The study was a prospective, pretest–posttest, assessorblinded, pilot, randomized, controlled, single-center trial (Fig 1). The subject-blinding was not possible as the rationale of moving the less-affected limb (considered as sound side) during the experimental protocol is usually inquired by the participants.
Sample Size Calculation The power calculation was performed using the values for Fugl-Meyer assessment of wrist and hand (FMA-WH) from the preliminary study.13 Considering b 5 .2 and a 5 .05, the calculation inferred that 12 subjects in each group would be sufficient to detect the desired change. However, to increase the power, 15 subjects in each group were planned. In view of possible dropouts (10%), 33 subjects were enrolled.
Recruitment and Randomization The subjects were conveniently selected as per the inclusion criteria and randomly allocated into the experimental and control groups. The randomization was performed by using computer-generated random numbers. After the blocks were numbered, a randomnumber generator program was used to select numbers that found the series in which the subjects were assigned to either one or the other group. The allocated interventions were enclosed in sealed envelopes, which were opaque and serially numbered. A therapist, not part of the study, conducted the random-number program. The assessments were performed by the one of the investigators who was blinded to the objective of the study and the group to which the participants were assigned. Two sessions, one each for preintervention and postintervention, were devoted to carry out the assessment process.
TASK-BASED MIRROR THERAPY IN HEMIPARESIS
Assessed for eligibility (n=67)
Excluded (n=34) Did not meet inclusion criteria (n=15) Refuse to participate (n=03) Other reasons (n=16)
Allocated to experimental intervention (n=17) Received allocated intervention (n=17) Did not receive allocated intervention
Allocated to control intervention (n=16) Received allocated intervention (n=16) Did not receive allocated intervention
Centers (n =01) performing the intervention Care provider (n=01)
Centers (n =01) performing the intervention Care provider (n=01)
Loss to follow-up (n=0) Discontinued intervention (n=0)
Loss to follow-up (n=01) Discontinued intervention (n=01)
Analyzed (n=17; Last observation carried forward 0) Excluded from analysis (n=0)
Analyzed (n=16; including 02 last observation carried forward) Excluded from analysis (n=0)
Flow chart of the study.
Interventions All the subjects were given 40 sessions, 90 minutes each—for 8 weeks (5 sessions per week). The control group received conventional occupational therapy program for the entire 90-minute session. The experimental group had undergone the conventional therapy and TBMT for 45 minutes each. The rationale for providing the conventional therapy to the experimental group was to avoid deprivation of the affected upper limb from the motor training. In conventional management, movement therapy was provided using the principles of Brunnstrom and Bobath approaches.27,28 The management specifically comprised movements using associated reactions (resisting movement on the sound side), weight bearing on the elbow and wrist, self-assisted bilateral movements, lengthening contraction of paretic muscles, and active assistive movements. All the techniques were applied
on the affected upper limb only, considering the hierarchical order of motor recovery. The control intervention was carried out in a usual setup of the occupational therapy department. TBMT protocol was formulated based on the intervention used in the preliminary study.13 On similar guidelines, a wooden mirror box was made. However, the size was modified (24 3 18 3 14 inches) to allow adequate vision with correct posture for taller subjects. The box was painted black both outside and inside to create favorable surroundings for illusion. The objects used to provide TBMT were a duster, a glass, wooden blocks of different sizes and shapes, a spongy ball, paper clips, beads, coins, clay, and so forth. The subject was made to sit close to a table on which the mirror box was placed vertically at the midsternum level. The less-affected upper limb was placed in front of the mirror to visualize the image
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10 per session. Gross activities were mainly provided for the subjects at BRS-A 2 to 3, whereas fine activities for BRS-A 4 and above.
Outcome Measures Brunnstrom Recovery Stage
Figure 2. A right-sided hemiparetic subject is reaching for a glass by the left less-affected upper extremity (the affected limb hidden in the mirror box). The left side is reflected as a projection over the right side, creating an illusion.
whereas the affected limb was placed inside the mirror box. Subject could perceive the image of the lessaffected limb as the affected limb. By observing the image of the less-affected upper extremity as a projection over the affected limb, an illusion was created (Fig 2). The subject was instructed to remove any rings/bangles/wristwatch from the less-affected upper limb. The session comprised practice of the less-affected elbow, forearm, wrist, and finger movements using various tasks (Table 1). Because it was not feasible to manipulate the object inside the box by the paretic upper limb, no voluntary movements were allowed on the paretic side. The arrangement reduced probable interruption in creating illusion. The tasks were selected considering the typical impairment of motor control among the poststroke hemiparetic subjects such as finger dexterity, mass grasp/ finger flexion, release/finger extension, wrist dorsiflexion, and forearm supination.27,28 Furthermore, the objective of selection was to improve the individual movement control. In addition to the preliminary study,13 few tasks were either modified or added to increase the repetitiveness of the desired movements. TBMT session was provided in a distraction-free and moderately lightened room. Task practice was demonstrated by a model before prescribing to a subject. Each task was practiced 20 to 100 times in an increment of 5-
BRS29 measures stereotypical sequence of motor recovery of the upper limbs: arm (BRS-A) and hand (BRS-H) in the form of 7 ordinal stages (stage 1, flaccidity; stage 2, appearance of basic limb synergies; stage 3, complete synergistic movements appear; stage 4, some movement components out of synergy; stage 5, advanced movement out of synergy; stage 6, synergy disappears; stage 7, nearto-normal motor control). The subject will be assigned a stage only when all the prescribed criteria are fulfilled. If an individual has few components of the lower level and partial items of the higher stage, a transitional stage would be awarded. For instance, if a subject is able to perform 2 motor components of BRS-A stage 4 and achieved only 1 movement of stage 5, the level of recovery will be considered as stage 4-5. Each higher stage indicates positive recovery. It is a performance-based measure. BRS has been found to be a valid and responsive measure to categorize motor recovery level in hemiparetic subjects.30,31 It demonstrated acceptable concurrent and predictive validity.30-32 Fugl-Meyer Assessment Based on the natural progression in poststroke hemiparesis, FMA33 assesses subjects as per the sequential recovery stages. FMA is an objective measure of motor recovery after stroke. The items are hierarchically organized from reflexive to synergistic and out-of-synergy to voluntary movements. Each item is scored on 0 (no performance) to 2 (faultless performance) with the total score of 100. The maximum score for the upper extremity subsection of FMA (FMA-UE) is 66, with a subscore of 36 for the upper arm (FMA-UA) and 30 for the wrist and hand (FMA-WH). FMA-UA items mainly comprise reflex activity, volitional movements within-, mixing-, and no
Table 1. Goal-directed activities for task-based mirror therapy Activities Drinking water Turning a wooden block Grasping and lifting a rectangular block using the wrist Cleaning table using a duster by wrist Grasping/releasing a soft ball Picking up paper clips, beads, coins, and cereals Clay activities (ball making, rolling, pressing, pinching, and breaking)
Target movement Mass grasp, mid-prone position, elbow flexion-extension, shoulder flexed position Forearm pronation-supination, elbow flexed position Wrist dorsiflexion, radial-ulnar deviation, forearm pronated position Wrist radial-ulnar deviation Spherical grasp, finger flexion, thumb opposition Dexterity, in-hand manipulation, tip prehension Finger flexion, extension and abduction, in-hand manipulation, tip prehension, and grasp and release
S. no. 1. 2. 3. 4. 5. 6. 7. 8. 9.
10. 11. 12. 13. 14. 15. 16.
17. 18. 19.
Characteristics Age (y) mean 6 SD Time since stroke (mo) mean 6 SD Male/female (%) Educational qualification (5th/10th/12th standard and above) (%) Marital status (married/unmarried/widow) Socioeconomic status (below poverty line/ lower/middle/higher) (%) Ischemic/hemorrhagic (%) Area of involvement (frontoparietal/basal ganglia/thalamus/others/multiple) Risk factors Hereditary Hypertensive Chronic smokers Alcoholic Diabetes mellitus Obesity Side of involvement (right/left) (%) Dominant side (right/left) (%) HMSE FMA-UE Upper-limb spasticity (modified Ashworth scale grade 1/11/2) (%) Pain (shoulder/wrist) (%)* Sensory impairment (tight touch/deep touch/touch localization/two-point discrimination) (%)* Perceptual deficit (hemispatial neglect/ apraxia/right-left discrimination) (%)* Poststroke depression (%)* Language impairment (aphasia/dysarthria) (%)*
Experimental group (n 5 17)
Control group (n 5 16)
48.76 6 13.58 12.88 6 8.05 15 (88%)/02 (12%) 03 (18%)/06 (35%)/01 (06%)/07 (41%)
42.12 6 12.52 12.25 6 5.74 10 (62.5%)/06 (37.5%) 06 (37.5%)/02 (12.5%)/04 (25%)/04 (25%)
t:P 5 .155 t:P 5 .798 f:P 5 .118 —
15 (88%)/2 (12%)/0 (0%) 00 (00%)/07 (41%)/10 (59%)/00 (00%)
14 (87.5%)/1 (6%)/1 (6%) 01 (06%)/06 (37.5%)/08 (50%)/01 (06%)
07 (41%)/10 (59%) 06 (35%)/02 (12%)/01 (06%)/02 (12%)/06 (35%)
10 (62.5%)/06 (37.5%) 05 (31%)/01 (6%)/03 (19%)/03 (19%)/04 (25%)
c2:P 5 .221 —
05 (29%) 10 (59%) 09 (53%) 09 (53%) 06 (35%) 05 (29%) 13 (76.5%)/4 (23.5%) 17 (100%)/0 (0%) 25.09 6 2.80 19.71 6 7.22 05 (29%)/10 (59%)/02 (12%)
01 (06%) 12 (75%) 03 (19%) 05 (31%) 03 (19%) 03 (19%) 13 (81%)/3 (19%) 15 (94%)/1 (6%) 26.01 6 2.17 18.25 6 5.43 03 (19%)/11 (69%)/02 (12.5%)
f:P 5 .175 f:P 5 .465 f:P 5 .071 c2:P 5 .208 f:P 5 .438 f:P 5 .688 f:P 5 1 — t:P 5 .301 t:P 5 .105 —
05 (29%)/02 (12%) 02 (12%)/02 (12%)/01 (06%)/04 (23.5%)
06 (37.5%)/03 (19%) 00 (00%)/00 (00%)/01 (06%)/03 (19%)
01 (06%)/02 (12%)/02 (12%)
01 (06%)/00/01 (06%)
02 (12%) 03 (18%)/04 (23.5%)
01 (06%) 02 (12.5%)/03 (19%)
TASK-BASED MIRROR THERAPY IN HEMIPARESIS
Table 2. Demographic and clinical characteristics of the participants
Abbreviations: FMA-UE, Fugl-Meyer assessment (upper extremity); f, Fisher exact test; HMSE, Hindi mental state examination58; SD, standard deviation; t, independent t test; c2, chi square test. *Mild-to-moderate.
Table 3. Preintervention and postintervention outcome measures of the experimental and control groups Preintervention
Outcome measure FMA-UA Mean 6 SD Maximum score, 36 FMA-WH Mean 6 SD Maximum score, 30 FMA-UE Mean 6 SD Maximum score, 66 BRS-A (n/%) Stage 2 Stage 2-3 Stage 3 Stage 3-4 Stage 4 Stage 4-5 Stage 5 BRS-H (n/%) Stage 2 Stage 2-3 Stage 3 Stage 3-4 Stage 4 Stage 4-5 Stage 5
Experimental group (n 5 17)
Control group (n 5 16)
Experimental group (n 5 17)
Control group (n 5 16)
Difference between the means (95% CI)
16.94 6 5.01
15.31 6 3.75
21.41 6 6.24
18.87 6 3.77
2.76 6 2.84
2.94 6 2.89
9.00 6 3.58
4.12 6 2.77
19.71 6 7.22
18.25 6 5.43
30.41 6 9.07
23.00 6 5.58
01 (06%) 01 (06%) 08 (47%) 05 (29%) 01 (06%) 01 (06%) 00 (00%)
00 (00%) 01 (06%) 05 (31%) 06 (37.5%) 02 (12.5%) 02 (12.5%) 00 (00%)
00 (00%) 00 (00%) 05 (29%) 06 (35%) 03 (18%) 01 (06%) 02 (12%)
00 (00%) 00 (00%) 06 (37.5%) 05 (31%) 02 (12.5%) 03 (19%) 00 (00%)
01 (06%) 01 (06%) 06 (35%) 01 (06%) 03 (18%) 03 (18%) 02 (12%)
00 (00%) 02 (12.5%) 04 (25%) 02 (12.5%) 04 (25%) 04 (25%) 00 (00%)
00 (00%) 01 (06%) 03 (18%) 04 (23.5%) 01 (06%) 04 (23.5%) 04 (23.5%)
00 (00%) 01 (06%) 02 (12.5%) 03 (19%) 05 (31%) 05 (31%) 00 (00%)
P value .334
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Abbreviations: BRS-A, Brunnstrom recovery stage of arm; BRS-H, Brunnstrom recovery stage of hand; CI, confidence interval; F, test value for repeated-measures 2-way analysis of variance; FMA, Fugl-Meyer assessment; SD, standard deviation; UA, upper arm; UE, upper extremity; WH, wrist and hand. *Statistically significant.
TASK-BASED MIRROR THERAPY IN HEMIPARESIS
Figure 3. This shows changes in Fugl-Meyer assessment: wrist–hand (FMA-WH) (A) and Fugl-Meyer assessment: upper extremity (FMA-UE) (B) scores (mean and confidence interval) between the experimental group (dotted bar) and control group (grey bar) at preassessment and postassessment following TBMT.
synergies. FMA-WH consists of wrist ability, hand functions, and coordination.33 FMA showed high reliability and validity for assessing the motor recovery in poststroke hemiparetic patients.34-38
Statistical Analysis Data were collected using clinical methods and outcome measures; the same was entered in MS excel spreadsheet. The data were analyzed by SPSS version 21.0 (IBM Corp., NY, USA). The last observation was carried forward for the 2 missing data (control group) to conduct an intention-to-treat analysis. The Mann–Whitney U, independent t, Fisher exact, and chi-square tests were used to examine the demographic and baseline characteristics of the 2 groups. Analysis of covariance was used to study the difference in the postintervention scores between the groups.39 The preintervention score was considered as the covariate with group as the independent variable and posttest score as the dependent variable. The significance level was set at P less than .05. Kolmogorov–Smirnov test was used to check the normal distribution of the variables.
The study participants were recruited from February 2013 to January 2014. Sixty-seven subjects were screened for the enrollment, and 34 did not meet the eligibility criteria (Fig 1). All the participants were provided the allocated intervention. However, 1 subject from the control group discontinued the intervention after few sessions and another did not report for the postassessment. All other subjects were adhered to the respective intervention and completed the prescribed sessions. The mean age of the subjects was 45 years. Among all the participants, 25 (76%) were men and 26 (79%) were right-side paretic. The average poststroke duration was 12.5 months. Before intervention, the participants were at the median stage 3-4 of BRS-A and exhibited a score of 19/66 for FMA-UE. The demographic details for both the study groups are given in Table 2. The groups did not significantly differ in any of the characteristics. All the participants reported to receive typical medical and rehabilitation management before enrollment in the study. The experimental group exhibited highly significant (P , .001) improvement than the control group for FMA-WH and FMA-UE at postassessment (Table 3, Fig 3). In the experimental group, FMA-WH improved by 21% compared with only 4% among the control group subjects. Similarly, FMA-UE improved by 16% in the experimental group compared with 7% in the control group. However, no significant difference was found between the groups for FMA-UA (12% in the experimental group versus 8% in the control group) at posttest. After intervention, the experimental group exhibited a 12% increase in the number of subjects at stage 5 both for BRS-A and BRS-H compared with 0% for the same in the control group (Table 3). There were 5 subjects who exhibited a change of at least 2 stages either on BRS-A or BRS-H after the experimental intervention. These participants were men and aged between 30 and 34 years, with a poststroke duration of 6 to 8 months. Furthermore, 3 subjects had left-side paresis and 3 had a hemorrhagic type of stroke. None of the subjects from both the groups could achieve stage 6 or above. In addition to the above-mentioned findings, most of the experimental subjects reported certain perception in the affected limb during the course of the protocol. Most of the perceptions were observed till the end of first week. The perceptions are summarized in Table 4 for each participant.
Discussion Upper limb paresis is one of the challenging manifestations in poststroke patients. TBMT may be useful in alleviating such impairment. The present pilot trial demonstrated the positive effect of TBMT in terms of
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Table 4. Participant’s perception in the affected upper limb during task-based mirror therapy
Participant Participant 1
Participant 3 Participant 4 Participant 5 Participant 6 Participant 7 Participant 8
Participant 9 Participant 10 Participant 11 Participant 12 Participants 13 to 17
Time of perception during the protocol
Minimal involuntary movement in the hand Tingling sensation with mild pain in dorsal aspect of hand and mid-forearm Later (till fourth week) Mild pain at the interphalageal joints of hand and shoulder Tingling sensation disappeared after few minutes of the session Initially (within a week) Minimal involuntary movement in the hand and forearm Later (till sixth week) Tingling sensation and mild pain while doing the finger flexion-extension Initially (within a week) Minimal involuntary movement in the hand Associated movement in the hand while squeezing the ball Initially (within a week) Heaviness in the fingers while doing fine activities Heaviness in arm while doing gross activities Initially (within a week) Minimal involuntary movement in the fingers and palm Mild pain over the arm Initially (within a week) Minimal involuntary movement in the fingers Initially (within a week) Minimal involuntary movement while squeezing the ball Initially (within a week) Minimal involuntary movement in the hand Movement in the affected elbow and wrist while doing drinking activity Initially Pin-pricking sensation in the hand and elbow during gross activities Later (within 3 weeks) Tingling sensation in the hand Initially Tingling sensation in the arm and forearm while performing wrist flexion and extension Initially Minimal involuntary movement in the fingers, wrist, and forearm Initially Minimal involuntary movement in the wrist and fingers Did not report any perception in the affected upper limb Initially (within a week)
improving the voluntary control of the paretic upper extremity, particularly wrist and hand. The trial supports and expands the findings of the previous single-group study.13 After MT, significant motor recovery of hand was also observed in a study conducted by Yavuzer et al40 in subacute stroke. Overall improvement in FMA-UE was also observed in MT group by a score of 4; however, the average poststroke duration was 4 years.15 In addition to the changes in wrist–hand, the present study exhibited significant motor recovery of the entire upper extremity. However, it is understandable that the positive change in FMA-UE could be attributed to FMA-WH. The TBMT protocol comprised wrist and hand activities more than the upper arm. The design of the mirror box does not allow the upper arm movements such as shoulder overhead movement and rotations. This could be the reason for the less significant improvement in the FMA-UA as compared to FMA-WH among the experimental group subjects. Furthermore, the reason could also be attributed to the bilateral neural representation for the proximal upper limb in contrast to unilateral fibers exclusively responsible for the wrist and hand.41,42 MT demonstrated excitation of primary motor area ipsilateral to the moving hand in healthy and stroke
individuals.43,44 The neural differentiation between the proximal and distal movements in MT has not been established yet. The neuromechanism of MT (visual illusion, activation of mirror neuron in the lesioned brain, activation of the motor area on the lesioned side, and enhancement of motor control on the contralateral side) may be confounding for the bilaterally represented movements. This has implication to design and explore TBMT comprising bilateral movements. In the present study, the experimental participants exhibited a change of 6 points on FMA-WH after the TBMT protocol as compared to 1 point among the control group subjects. Similarly, the participants demonstrated a change of 11 points on FMA-UE in the experimental group in comparison to 5 points among the control group subjects. Poststroke subjects who attain a score of 2 to 3 on FMA-WH and 9 to 10 on FMA-UE are more likely to experience a clinically important improvement than those who score less.45 Furthermore, similar magnitude of motor improvement for FMA-UE (10.5 points in 8 weeks) was observed after MT in chronic stroke (8.5 months poststroke).3 As the left-paretic subjects carried out the TBMT activities by right-dominant side, their performance was more synchronized than that of the right-paretic individuals.
TASK-BASED MIRROR THERAPY IN HEMIPARESIS
This could explain the reason for most of the lefthemiparetic subjects exhibiting favorable recovery on BRS-A and BRS-H. In a study conducted by Dohle et al MT was provided to severely hemiparetic subjects in acute stage. However, in the experimental protocol, subjects were asked to move their paretic limb during the performance by the affected side. In TBMT protocol which comprises the movement using the objects, it is unfeasible to move the affected limb. However, the performance of functional task by the unaffected side during MT may induce greater neural organization than that without the meaningful task.20 Furthermore, as recommended, MT can also be imparted to acute stroke subjects with no motor ability on the affected side.46 Contrary to other combinations of MT, TBMT allows integration of 2 therapeutic methods (mirror therapy and task-based training) in an undifferentiated way. Although various studies have proved the effectiveness of taskspecific training and MT separately, no study used the underlying mechanism of each in a single protocol.17,47 The present study was the first randomized controlled trial which investigated the dual key concepts of motor rehabilitation in stroke. It is assumed that such a method leads to a greater neural plasticity for the desired motor outcome. MT using tasks might have created illusion of bimanual task performance and functionally connected the 2 upper limbs to the ipsilateral brain.48 In the present study, some of the subjects perceived sensorimotor effects in the affected upper limbs (hidden inside the box) during the TBMT. The assessment of perception was not planned; it was inadvertently observed during the course of intervention. Although the participants were not instructed to move the paretic limb, minimal involuntary movements in the hand and fingers were either perceived or observed. This undesired motor finding was the commonest among all the sensorimotor perceptions. Such mirror movements exhibit disrupted interhemispheric inhibition because of unilateral brain damage.49 Mild pain, heaviness, and pin-pricking sensations were among the sensory effects, and 35% of subjects reported such perception. Some patients also experienced tingling sensation and mild tolerable pain for few minutes mostly during the initial sessions. The intensity and duration of pain disappeared usually after few therapy sessions. It is assumed that TBMT might have increased the activation of pain-related mirror neurons (fired while observing somebody else being hurt) initially. However, as the TBMT sessions progressed, the neurons might have got regulated. The modulation of mirror neurons by MT is also evident in conditions like phantom pain and complex regional pain syndrome. The findings of the present study may have implications for the sequence of MT in graded motor imagery for pain management. The episode of involuntary movements in response to MT is evident among healthy indi-
viduals also, indicating reduced motor awareness. In the present study, most of the participants experienced the motor perceptions initially that stop after a week. Movement-related mirror neurons are found in the frontal and parietal lobes along with motor neurons. They are bimodal visuomotor neurons that are active during action observation, mental stimulation (imagery), and action execution.51,52 These neurons help in the learning of new skills by visual inspection of the skill. Mirror neuron system may be responsible for the effect of MT.6 The system integrates visuoperceptual motor inputs inducing cortical reorganization and associated motor recovery. After MT, positive cortical reorganization has been observed in chronic stroke subjects.15 Bilateral primary sensorimotor cortex gets activated in response to MT. Furthermore, mirror illusion increases activity in the precuneus and the posterior cingulate cortex.51,52 The mirror neurons, present in the premotor cortex, get activated during observation of the goal-directed tasks such as reaching and picking up the food material. The activation is similar when the task is being performed.53,54 Furthermore, the mirror neuron activates separately for observation of object- and nonobject-related movements. The presence of object induces greater stimulation of the concerned cortical area.23 Thus, task performance along with MT has potential benefit for improving motor impairment in stroke. Although TBMT used goal-directed activities, they were not client-centered (subject-chosen). TBMT activities were predecided and identical for all the subjects. Clientcentered activities may further enhance motor recovery and client’s occupational performance.55,56 In the present study, the change in such performance was not measured; however, few participants reported attaining independency in daily tasks. Clinically, quality of movement was found to be improved for many participants after TBMT; however, in the present study, no measure was used to assess such changes. Long-term intervention57 till the achievement of maximum independency in functional performance and subsequent follow-up were some of the other limitations of the study. In the present pilot trial, the sample size was estimated statistically. In view of heterogenity in the clinical presentation among stroke subjects, the size appeared to be small. This could also be considered as a limitation of the present study. Further studies in the form of trials are needed to investigate the effect of TBMT in comparison to MT alone. It is also recommended to investigate the effect of TBMT using hand function tests, kinematic analysis, pain rating scale, and neuroradiological measures. TBMT protocol may also be refined considering the control of specific movement component and tasks comprising dexterity and coordination. Furthermore, overhead arm movements may be incorporated using a large size mirror. Studies to explore TBMT at various stroke stages are also warranted.
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Conclusion The present study validates the effects of TBMT in poststroke hemiparetic subjects. TBMT along with the conventional intervention augments the wrist–hand recovery better than that induced by the standard method alone. Acknowledgments: We acknowledge Mr. Ashutosh Verma and Ms. C.R. Abhilasha, research assistants at the study site, for extending their support in data collection.
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