Mirror therapy for patients with severe arm paresis after stroke a randomized controlled trial

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1 455651CRE / Clinical RehabilitationThieme et al Article CLINICAL REHABILITATION Mirror therapy for patients with severe arm paresis after stroke a randomized controlled trial Clinical Rehabilitation 27(4) The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalspermissions.nav DOI: / cre.sagepub.com Holm Thieme 1,2, Maria Bayn 3, Marco Wurg 3, Christian Zange 4, Marcus Pohl 5 and Johann Behrens 2 Abstract Objective: To evaluate the effects of individual or group mirror therapy on sensorimotor function, activities of daily living, quality of life and visuospatial neglect in patients with a severe arm paresis after stroke. Design: Randomized controlled trial. Setting: Inpatient rehabilitation centre. Subject: Sixty patients with a severe paresis of the arm within three months after stroke. Interventions: Three groups: (1) individual mirror therapy, (2) group mirror therapy and (3) control intervention with restricted view on the affected arm. Main measures: Motor function on impairment (Fugl-Meyer Test) and activity level (Action Research Arm Test), independence in activities of daily living (Barthel Index), quality of life (Stroke Impact Scale) and visuospatial neglect (Star Cancellation Test). Results: After five weeks, no significant group differences for motor function were found (P > 0.05). Pre post differences for the Action Research Arm Test and Fugl-Meyer Test: individual mirror therapy: 3.4 (7.1) and 3.2 (3.8), group mirror therapy: 1.1 (3.1) and 5.1 (10.0) and control therapy: 2.8 (6.7) and 5.2 (8.7). However, a significant effect on visuospatial neglect for patients in the individual mirror therapy compared to control group could be shown (P < 0.01). Furthermore, it was possible to integrate a mirror therapy group intervention for severely affected patients after stroke. Conclusion: This study showed no effect on sensorimotor function of the arm, activities of daily living and quality of life of mirror therapy compared to a control intervention after stroke. However, a positive effect on visuospatial neglect was indicated. Keywords Stroke, upper extremity, mirror therapy, motor function, visuospatial neglect Received: 3 February 2012; accepted: 30 June st European School for Physiotherapy, Occupational Therapy, and Speech and Language Therapy, Klinik Bavaria Kreischa, Kreischa, Germany 2 Martin Luther University Halle-Wittenberg, Faculty of Medicine, Institute for Health and Nursing Science, Halle (Saale), Germany 3 Department of Neurology and Neurooncology, Klinik Bavaria Kreischa, Kreischa, Germany 4 Zürcher Höhenklinik Wald, Department of Neurorehabilitation, Wald (ZH), Switzerland 5 Department of Neurology and Interdisciplinary Rehabilitation, Klinik Bavaria Kreischa, Kreischa, Germany Corresponding author: Holm Thieme, 1st European School for Physiotherapy, Occupational Therapy, and Speech and Language Therapy, Klinik Bavaria Kreischa, Dresdner Straße 12, Kreischa, Germany. holm.thieme@physiotherapie-schule-kreischa.de

2 Thieme et al. 315 Introduction Approximately 80% of stroke survivors have an upper and/or lower limb paresis. 1,2 Paresis of the arm explains up to 50% of the variance in functional limitation after stroke. 3 Six months after stroke between one-third and two-thirds of stroke patients will not regain functional arm use and only 5 20% will achieve full recovery of arm function. 4 An initial severe arm paresis was shown to be an important predictor for poor recovery. 4 A number of treatment strategies for the severe paretic arm are currently discussed. Systematic reviews demonstrated improved arm function after robotic training, functional electrical stimulation, electromyographic biofeedback, repetitive sensorimotor training techniques and motor imagery. 5 8 However, in most studies improved arm function but no gains in activities of daily living and quality of life were reported. Mirror therapy is a relatively new intervention initially developed for the treatment of phantom limb pain. 9 It was introduced to stroke rehabilitation in the late 1990s. 10 In contrast to most interventions working with sensorimotor training strategies, mirror therapy focuses on visual input. While moving the unimpaired arm an inverse reflection is created by a mirror which is positioned between the two arms. The reflection of the unimpaired arm creates a visual illusion of enhanced movement capability of the impaired arm. A Systematic Cochrane Review showed that mirror therapy after stroke is effective in improving short- and middle-term motor function, activities of daily living and in reducing pain, especially in patients with a complex regional pain syndrome. 11 One study showed positive effects of mirror therapy on visuospatial neglect after stroke. 12 However, no definitive conclusions could be drawn about the success of mirror therapy relative to severity of motor impairment or time since stroke onset. One study found mirror therapy to be effective only in patients who were paralysed in the early stages post stroke. 12 However, other studies included patients with moderate motor impairment and also found significant effects for these patients. Furthermore, studies in a subacute stage after stroke are rare and inconclusive. 11 The objectives of this study are to determine (1) whether mirror therapy as group and/or individual therapy is more effective in improving upper limb sensorimotor function, activities of daily living, quality of life and visuospatial neglect than a control intervention in patients with severe arm paresis in subacute stroke patients and (2) if the effects of a group training protocol of mirror therapy are different from those of an individual treatment. Methods A randomized controlled study was conducted in an inpatient rehabilitation centre. The study received ethical approval from the local ethics committee (Sächsische Landesärztekammer EK-BR-03/09-1) and was registered in the German Register for Clinical Studies (DRKS ). Participants and allocation Stroke patients were referred to the study by their physicians or physical therapists. Patients were screened and invited to participate in the study on the basis of the following inclusion criteria: (a) they had to have had a first supratentorial stroke within the previous three months, ensured through the diagnosis of the primary care hospital, (b) be aged between 18 and 80 years and (c) be clinically diagnosed with a severe distal hemiparesis of the arm (Medical Research Council 13 grading of 0 or 1 for wrist and finger extensors). Patients were excluded if they had (a) visual impairments which may limit the participation in mirror therapy, (b) severe cognitive and/or language deficits that could prevent them from following instructions, (c) other neurological or musculoskeletal impairments of the upper extremity unrelated to stroke and (d) a severe visuospatial neglect (clinically evaluation: the patients did not turn their face to an examiner on their contralesional side if they were asked to do so). Before being included in the study, patients were informed about the aims and course of the study, after which they gave their informed written consent to participate. Patients were then randomly

3 316 Clinical Rehabilitation 27(4) allocated to one of three intervention groups. Randomization was carried out using a computergenerated random number sequence. A person who was otherwise not involved in the trial was contacted by telephone and allocated patients to their groups. Interventions All participants underwent regular therapy during their stay at the rehabilitation facility. This included single and group physical therapy, occupational therapy, training of basic daily activities and, according to individual impairments, sports therapy, speech and language therapy and/or neuropsychological therapy. In addition, patients were treated in one of three intervention groups: 1) Individual mirror therapy: Mirror therapy for the upper limb using an individual therapy protocol (i.e. one therapist treated one patient). In the first treatment session, patients were informed about mirror therapy and the principles of therapy in a single setting. Mirror therapy was minimally standardized as follows: both arms of the patient were placed on a table. A mirror (50 cm 50 cm) was positioned between the two arms. The reflecting side of the mirror was adjusted to the non-affected arm. Patients were instructed to move both arms while looking in the mirror. The affected arm should be moved as well as possible. In the first week isolated movements of fingers, wrist, lower arm, elbow and shoulder joints were performed in all degrees of freedom. In each direction up to 50 repetitions per series and up to four series were possible. In the second and third week additional movements were used. Therapists were instructed to include objectrelated movements, such as putting a ball or bigger squares in different directions, moving sticks or wipe-like movements with a cloth. Type of movements, repetitions and series were adapted by therapists according to patients abilities. 2) Mirror therapy group: Patients in this group underwent mirror therapy within a group therapy protocol (i.e. one therapist treated between 2 and 6 patients at the same time). Mirror therapy in this group followed the same protocol as described for individual therapy. 3) Control therapy: Patients underwent a control therapy using a group intervention protocol. In this group the mirror was turned, so a wooden board restricted the view on the impaired arm. Patients in this group were instructed to move both arms while looking at the non-affected arm and imaging the analogous movements of the affected arm but then followed the same protocol as in the mirror therapy groups. In all three groups, patients received a maximum of 30 minutes of mirror therapy or control therapy daily with a total of 20 sessions during five weeks. The intervention time included transferring, treatment preparation and therapist-selected rests during the intervention. Ten hours of additional intervention were chosen because we expected that this would be the minimum dose for a difference between groups and because it seems realistic to additionally include this time in routine rehabilitation of stroke patients. Study interventions were integrated into daily routine. Therefore the frequency of interventions per week varied between three and five sessions. Monitoring of dose and frequency was ensured through documentation of treating therapists. All interventions were simultaneously conducted on the ward. Therapy was carried out by trained physiotherapists or physiotherapy students in their last year of professional training. The training for therapists included information about the principles of mirror therapy, an introduction to training guidelines and a therapy manual. In the first therapy session, an experienced therapist accompanied physiotherapy students and gave relevant instructions where needed. Data collection Measurements were taken at baseline and after the intervention. The investigation of primary outcome measures were videotaped and rated by one out of two observers (MW, CZ) both blinded to group allocation. Video rating of the chosen primary outcome measures was shown to have very high inter-rater

4 Thieme et al. 317 and test retest reliability. 14 Secondary outcome measures were assessed by a person not blinded to group allocation (HT). Because of organizational restrictions, the blinded assessment of secondary outcomes could not be realized. Measures Demographic and medical variables included age, sex, side of lesion, type of stroke and level of distal upper limb paresis (Medical Research Council grading 13 ). Primary outcome measures. The primary measures were carried out with regard to arm function (a) on an impairment level assessed with the motor score of the Fugl-Meyer Test arm section 15,17 and (b) on a functional level with the Action Research Arm Test. 16,17 The total motor score of the Fugl-Meyer Test arm section ranged from 0 to 66 points with more points indicating better motor function. The Action Research Arm Test contains four subscales: grasp, grip, pinch and gross movement. Sum score ranges from 0 to 57 points, with higher scores indicating better functioning. Secondary outcome measures. Secondary outcome measures included the Barthel Index for evaluating basic activities of daily living, 18 the Stroke Impact Scale to detect self-reported influence of strokerelated functioning on quality of life, 19 the somatosensory, pain and range of motion sections of the Fugl-Meyer Test arm section, 15 the modified Ashworth Scale to detect changes in resistance to passive movement of finger and wrist flexors 20 and the Star Cancellation Test for assessing visuospatial neglect. 21 Patients below a baseline cut-off point of 43 in the Star Cancellation Test were integrated in the analysis on visuospatial neglect. Sample size calculation For sample size calculation we expected an effect size d of 0.4 as indicated by a study with mirror therapy on plegic patients. 12 A significance level of α = 0.05 and a power of 0.80 were chosen. For three groups a total sample size of 66 was calculated. Therefore we planned to include 22 patients per group. Statistics Differences between baseline characteristics were tested using an analysis of variance (ANOVA) for continuous variables, the Kruskal Wallis test for ordinal scaled variables and the chi-square test for dichotomous variables. For testing group differences between baseline and post-intervention data we used an ANOVA to compare change scores between pre- and post-intervention data for continuous variables and the Kruskal Wallis test for ordinal scaled variables. If significant results were found we underwent a post-hoc comparison. All tests were conducted on a 5% significance level. An intention-to-treat analysis was performed using the last observation carried forward method. For statistical analysis, PASW 19 software (SPSS Inc., Chicago, IL, USA) was used. Changes to protocol In the initial protocol of our study we planned to grant participants 30 minutes of interventional therapy five times a week over four weeks. Because of organizational issues, we extended the intervention time to five weeks with a total of 20 study treatments. An intended follow-up measurement at six months after the intervention could not be realized because of organizational and staff restrictions. Results Between April 2009 and July 2011 we screened 205 patients for eligibility. Of these, 60 fulfilled our eligible criteria and gave their informed written consent to participate. Participants were then randomized to treatment groups. During the intervention phase a total of 11 participants (18.3%) were lost during follow-up for different reasons (Figure 1). Therefore, after the intervention 49 participants could be assessed. One patient who was allocated to control group was wrongly receiving mirror therapy because of a mistake in therapy planning.

5 318 Clinical Rehabilitation 27(4) 205 assessed for eligibility 60 randomized 145 excluded -110 did not met selection criteria -6 declined to participate -29 rehabilitation stay too short 18 allocated to individual mirror therapy 21 allocated to group mirror therapy 21 allocated to control therapy 15 received allocated intervention 3 lost to follow-up -discharged prior to completion (N=3) 16 received allocated intervention 5 lost to follow-up -discharged prior to completion (N=2) - withdrawal consent (N=2) -died (N=1) 17 received allocated intervention 1 received mirror therapy (group) 3 lost to follow-up -discharged prior to completion (N=2) -withdrawal consent (N=1) 15 assessed after treatment 16 assessed after treatment 18 assessed after treatment 18 followed for intention to treat 21 followed for intention to treat 21 followed for intention to treat Figure 1. Flowchart: subjects assessed for eligibility, included and randomized subject, number and reasons for drop-outs in groups, subjects followed for intention-to-treat. This patient was followed as receiving control therapy on an intention-to-treat basis. Participants had a mean age of 67.2 (10.5) years. Thirty-five males and 15 females were included; 45 patients had an ischaemic and 15 a haemorrhagic stroke. Thirty-seven patients had a right-sided and 23 a left-sided lesion. Time since stroke was 45.0 (23.6) days. The median Medical Research Council grading was 0, ranging between 0 and 1 for hand and finger extensors. The baseline Fugl-Meyer Test arm score score for all participants was 7.7 (6.0) points and for the Action Research Arm Test 0.7 (2.6) points. Baseline characteristics and motor scores for each group are listed in Table 1. There were no significant group differences for baseline characteristics. Primary outcome Results for primary outcome measures are listed in Table 2. After the intervention, the Action Research Arm Test score of all participants increased significantly over time (F = 10.2, P = 0.002). There were no significant group differences (F = 0.8, P = 0.44). Fugl-Meyer Test motor scores for the upper limb for all participants increased over time (F = 18.0,

6 Thieme et al. 319 Table 1. Sociodemographic and clinical baseline characteristics of participants. Individual mirror therapy (N = 18) Mirror therapy group (N = 21) Control therapy (N = 21) P-value Age in years, mean (SD) 63.8 (12.1) 69.1 (10.2) 68.3 (8.9) NS Gender, male/female 11/7 10/11 14/7 NS Stroke aetiology, ischaemic/haemorrhagic 13/5 16/4 15/6 NS Lesion side, right/left 14/4 11/8 11/10 NS Time post stroke (days), mean (SD) 47.6 (25.8) 36.2 (21.1) 51.4 (22.5) NS MRC wrist extension, median (range) 0 (0 1) 0 (0 1) 0 (0 1) NS MRC finger extension, median (range) 0 (0 1) 0 (0 1) 0 (0 1) NS Received study interventions, mean (SD) 19.1 (2.0) 19.1 (1.1) 19.0 (1.7) NS NS, not significant; MRC, Medical Research Council. P < 0.001) with no differences between groups (F = 0.4, P = 0.71). Regarding the Fugl-Meyer Test subscores for the arm, hand and fingers, no significant interactions between groups were detected. Secondary outcome Results for secondary outcome measures are listed in Table 2. The Barthel Index increased in all patients over time (F = 68.5, P < 0.001). However, no significant group differences were found (F = 0.4, P = 0.7). The Stroke Impact Scale total score for all participants was significantly higher at the end of treatment (F = 45.9, P < 0.001) but no significant group differences were detected (F = 0.3, P = 0.78). Even the somatosensory subscore of the Fugl-Meyer Test for all patients significantly changed over time (F = 6.2, P = 0.02) with no significant group interaction (F = 0.4, P = 0.68). The passive range of motion and pain scores for all participants decreased over time (F = 26.4, P < 0.001; F = 15.0, P < 0.001). However, no group interactions were found (F = 1.5, P = 0.23; F = 0.4, P = 0.69) (Table 2). Resistance against passive movement measured with the Modified Ashworth Scale changed significantly over time for the finger flexors (F = 16.3, P < 0.001) but not for wrist flexors (F = 3.3, P = 0.08). We detected a significant group difference between individual mirror therapy and the mirror therapy group intervention, indicating higher scores for individual mirror therapy after the intervention (P < 0.05). No significant group interaction was found for wrist flexors (P = 0.82) (Table 2). Fourteen patients were found to have a visuospatial neglect using the Star Cancellation Test. Three patients receiving individual mirror therapy, five in the mirror therapy group intervention and six in the control group were included in the analysis. Patients receiving individual mirror therapy had an increase of the total score of 20.0 (14.5); those receiving group mirror therapy had an increase of 4.4 (6.7). In contrast, the score decreased by about 2.3 (5.2) for the six participants in the control group. We found a significant group interaction for the Star Cancellation Test score over time (F = 7.5, P = 0.009). Post-hoc analysis revealed a significant group difference between individual mirror therapy and the control group (P < 0.01) (Figure 2). No other group comparisons were significant. Compliance and drop-out rate During the mirror therapy group intervention, between two and six patients participated in each session. Five participants dropped out during this intervention. This was slightly more than in the other groups (three drop-outs each). Reason for dropping out in mirror therapy group intervention were discharge prior to study end (n = 2), withdrawal of consent (n = 2) and one study-unrelated death. Patients in each group participated on a mean of 19 therapy sessions of the intended 20 sessions. Therefore, a mirror therapy group intervention for

7 320 Clinical Rehabilitation 27(4) Table 2. Primary and secondary outcome measures. Group Individual mirror therapy Mirror therapy group Control therapy Group difference Baseline Mean (SD) Follow-up Mean (SD) Mean difference (SD) Baseline Mean (SD) Follow-up Mean (SD) Mean difference (SD) Baseline Mean (SD) Follow-up Mean (SD) Mean difference (SD) P-value ARAT 1.7 (4.5) 5.1 (11.4) 3.4 (7.1) 0.2 (0.7) 1.3 (3.1) 1.1 (3.1) 0.3 (0.9) 3.1 (7.1) 2.8 (6.7) NS FM motor 5.3 (8.6) 8.5 (11.4) 3.2 (3.8) 3.2 (4.1) 8.2 (11.5) 5.1 (10.0) 4.1 (4.6) 9.2 (10.6) 5.2 (8.7) NS BI 45.3 (17.9) 57.2 (20.2) 11.9 (12.1) 44.3 (10.2) 56.8 (13.3) 12.5 (11.9) 47.5 (15.0) 62.5 (22.8) 15.0 (12.3) NS SIS 47.8 (14.2) 56.3 (11.6) 9.5 (11.3) 47.1 (9.1) 55.3 (11.1) 8.2 (8.1) 49.9 (11.4) 57.2 (17.0) 7.3 (8.6) NS FM sensory 8.3 (3.6) 9.1 (3.2) 0.7 (2.1) 8.2 (4.0) 9.1 (3.8) 0.9 (2.1) 8.2 (3.6) 8.5 (3.9) 0.3 (1.8) NS FM range of 21.0 (3.6) 20.1 (3.5) 0.9 (2.2) 21.7 (2.0) 20.1 (2.6) 1.6 (1.9) 20.6 (2.8) 18.4 (2.4) 2.2 (2.5) NS motion FM pain 19.7 (4.1) 18.3 (4.5) 1.3 (3.8) 21.4 (3.5) 19.6 (3.7) 1.8 (3.5) 20.4 (3.6) 18.1 (4.5) 2.3 (3.6) NS MAS finger, 1 (0 4) 3 (0 4) 1 (0 3) 0 (2 4) 1 (2 4) 0 ( 3 4) 0 (0 4) 1 (0 4) 0 ( 2 3) < 0.05 median (range) MAS wrist, median (range) 2 (0 4) 2 (0 4) 0 ( 1 1) 1 (0 4) 2 (0 4) 0( 1 1) 1 (0 4) 1 (0 4) 0 ( 2 3) NS SCT 26.0 (5.0) 46.0 (13.1) 20.0 (14.5) 39.0 (9.9) 43.4 (7.7) 4.4 (6.7) 42.0 (5.1) 39.7 (8.8) 2.3 (5.2) < 0.01 NS, not significant; ARAT, Action Research Arm Test; FM, Fugl-Meyer Test; BI, Barthel Index; SIS, Stroke Impact Scale; MAS, modified Ashworth Scale; SCT, Star Cancellation Test. Significant difference between individual mirror therapy and group mirror therapy P < Significant difference between individual mirror therapy and control therapy P < 0.01.

8 Thieme et al. 321 Figure 2. Box plot: group differences in change scores for the Star Cancellation Test (SCT). MT, mirror therapy; CT, control therapy. patients with a severe arm paresis after stroke seems to have comparable compliance and drop-out rates compared to individual mirror therapy. Discussion When comparing mirror therapy carried out as an individual or a group intervention with a control intervention we found no different effects on sensorimotor function, activities of daily living, quality of life, range of motion and pain in this study. However, we detected a positive effect of individual mirror therapy on visuospatial neglect compared to control therapy and we found that patients receiving individual mirror therapy developed more resistance to passive motion than patients in the mirror therapy group intervention. Furthermore, we found that it was possible to structure mirror therapy as a group intervention even for stroke patients with severe motor impairment with no relevant differences in drop-out rate and compliance compared to the other groups. These findings are in contrast to a Cochrane Review which showed significant effects of mirror therapy for improving motor function, activities of daily and pain after stroke. 11 Interestingly, a comparable study in patients with a severe arm paresis within a subacute phase after stroke found significant effects of mirror therapy on distal motor function for patients with an initial plegic arm. In addition, they found better sensory function regarding touch for all included patients after mirror therapy. Furthermore, the authors also found a significant effect on visuospatial neglect. 12 When attempting to explain these results, one point to mention with regard to the effectiveness of mirror therapy is the dose of treatment. In the mentioned study a six-week period of mirror therapy was performed and patients trained five times a week

9 322 Clinical Rehabilitation 27(4) over 30 minutes. In total, patients performed 15 hours of additional mirror therapy in this study. 12 In the present study, patients underwent 19 sessions of 30 minutes during a period of five weeks, therefore additional mirror therapy duration was 9.5 hours. This lower intensity and frequency may be an explanation for the different effects between these two studies since there is some evidence for better effects with higher therapy intensity. 22 It could be argued, especially in patients with severe arm paresis, that the intensity and frequency of augmented therapy should be higher to produce a clinically and statistically significant effect. In contrast, one study found significant improvements in hand function after only 5 7 hours of mirror therapy. However, patients in this study had a better baseline arm motor function early after stroke. 23 A further explanation for missing group differences in primary outcomes and maybe the most limiting factor of this study is the relatively small sample size. We calculated a sample size of 66 participants to detect a medium effect size indicated by the study of Dohle et al. 12 However, it is possible that this was an overestimated effect for severely affected patients and therefore the study may be underpowered. Estimating a small effect size of 0.25, 159 patients should be included for a wellpowered study. In our planned timeframe of the study it was only possible to include 60 patients. Furthermore, hand function was shown to be a very important prognostic factor for functional recovery after stroke. 4,24 Kwakkel et al. found a Fugl-Meyer Test score of 19 points or more four weeks after stroke as an independent predictor for reaching some dexterity in the arm within six months. 4 In the present study the mean Fugl-Meyer Test score at baseline was 7.7 points after a mean of six weeks, therefore patients had a poor prognosis for recovery. This correlates with evidence that patients with a more severe impairment are less likely to improve, even with additional therapy. 25 In contrast to sensorimotor function we found a significant effect on spatial neglect after mirror therapy but not after control intervention. Dohle et al. demonstrated different neural substrates of body mirroring and mirroring of spatial coordinates. 26 During mirror therapy, an activation of the superior temporal gyrus was shown. 27 This area may play an important role in the presence and possibly in the recovery of a neglect and thus mirror therapy may influence visuospatial neglect in this way. 28 The group difference was significant for patients receiving individual mirror therapy but not in the group mirror therapy. This may indicate that patients in the group intervention had more problems with holding attention during mirror therapy than patients in the individual treatment. However, the results regarding visuospatial neglect should be interpreted with caution since only a small group of patients was analysed. Another point to mention is related to the time post stroke. Patients in the present study were recruited in a subacute phase after stroke (within three months post stroke). There is evidence that brain activation involves different areas and pathways during motor recovery, depending on the time after stroke. 29 Consequently, different treatment regimens may be effective relative to time post stroke. 30 However, the effects of mirror therapy were shown in the subacute phase and in the chronic phase after stroke. 11 It remains unclear whether time post stroke influences the effects of mirror therapy. The study has some limitations. As mentioned above, a total number of 60 participants may be too small to detect a small effect as indicated by sample size calculation. Especially the results for visuospatial neglect must be interpreted with caution. Only a very small group of included patients were analysed for this outcome. Furthermore, a drop-out rate of nearly 20% could be regarded as high. However, we tried to minimize the effects on outcome using an intention-to-treat analysis. The secondary outcome parameters activities of daily living, quality of life, sensory function, range of motion, pain and visuospatial neglect were not blindly assessed. This could have biased the results. Finally, our results are limited to a very disabled stroke population in a subacute phase post stroke. Therefore, the results cannot be generalized to other stroke populations. One aim of our study was to prove if drop-out rate and compliance in a group therapy protocol of mirror therapy is comparable to an individual therapy protocol. We could show this even in stroke

10 Thieme et al. 323 patients with a severe hemiparesis of the arm, a group of patients which could be rarely included in group settings. We could show that it was possible to conduct and apply such a group intervention. However, the smaller effect on visuospatial neglect in this group may indicate problems with holding the attention in a group setting. Therefore, patients with neglect or with attentional deficits should not be included in such a group setting. However, dropout rate and received number of interventions were comparable to those in the individual mirror therapy session. Therefore, it can be concluded that a group intervention, even for severely disabled stroke patients, using mirror therapy seems to be possible. Clinical messages Mirror therapy was not more effective in improving sensorimotor function, independence in activities of daily living, quality of life, range of motion and pain compared to a control therapy for patients with a severe arm paresis in the subacute phase after stroke. Mirror therapy may have a positive effect on visuospatial neglect. It was possible to implement mirror therapy as a group intervention for a severely disabled stroke population, with some limitations for patients with visuospatial neglect and attentional deficits. Acknowledgments We would like to thank all physical therapists and physical therapy students from the Klinik Bavaria Kreischa for being part of the therapeutic team that applied mirror therapy during our study. Special thanks go to Stefan Koch, Simone Mückel and Anja Müller. We further thank Dr Christian Dohle and Friderike Schmidt von Wühlisch for their helpful comments on the manuscript. Conflict of interest Holm Thieme received and will receive honorarium for presentations and seminars on mirror therapy. All other authors declare that there is no conflict of interest. Funding This work was supported by the Klinik Bavaria Kreischa. References 1. Barker WH and Mullooly JP. Stroke in a defined elderly population, A less lethal and disabling but no less common disease. Stroke 1997; 28: Nakayama H, Jørgensen HS, Raaschou HO, et al. Recovery of upper extremity function in stroke patients: the Copenhagen Stroke Study. Arch Phys Med Rehabil 1994; 75: Mercier L, Audet T, Hebert R, et al. Impact of motor, cognitive, and perceptual disorders on ability to perform activities of daily living after stroke. Stroke 2001; 32: Kwakkel G, Kollen BJ, van der Grond J, et al. Probability of regaining dexterity in the flaccid upper limb: impact of severity of paresis and time since onset in acute stroke. Stroke 2003; 34: French B, Thomas LH, Leathley MJ, et al. Repetitive task training for improving functional ability after stroke. Cochrane Database Syst Rev 2007; (4): CD Mehrholz J, Platz T, Kugler J, et al. Electromechanical and robot-assisted arm training for improving arm function and activities of daily living after stroke. Cochrane Database Syst Rev 2008; (4): CD Zimmermann-Schlatter A, Schuster C, Puhan M, et al. Efficacy of motor imagery in post-stroke rehabilitation: a systematic review. J Neuroeng Rehabil 2008; 5: Urton ML, Kohia M, Davis J, et al. Systematic literature review of treatment interventions for upper extremity hemiparesis following stroke. Occup Ther Int 2007; 14: Ramachandran VS. Phantom limbs, neglect syndromes, repressed memories, and Freudian psychology. Int Rev Neurobiol 1994; 37: Altschuler EL, Wisdom SB, Stone L, et al. Rehabilitation of hemiparesis after stroke with a mirror. Lancet 1999; 353: Thieme H, Mehrholz J, Pohl M, et al. Mirror therapy for improving motor function after stroke. Cochrane Database Syst Rev 2012; 3: CD Dohle C, Püllen J, Nakaten A, et al. Mirror therapy promotes recovery from severe hemiparesis: a randomized controlled trial. Neurorehabil Neural Repair 2009; 23: Medical Research Council. Aids to the examination of the peripheral nervous system, Memorandum no. 45. London: HMSO, Platz T, Pinkowski C, van Wijck F, Kim IH, di Bella P and Johnson G. Reliability and validity of arm function assessment with standardized guidelines for the Fugl-Meyer Test, Action Research Arm Test and Box and Block Test: a multicentre study. Clin Rehabil 2005; 19:

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