Mirror Therapy in Sensorimotor Recovery of Paretic Upper Extremity After Chronic Stroke

Stroke is characterized by poor brain perfusion resulting from an ischemic or hemorrhagic event, causing a sensorimotor disorder in the upper extremity (UE) contralateral to the lesion. Mirror Therapy (MT) has been used in rehabilitation and its effects are related to the activation of mirror neurons and cortical reorganization. However, few studies have investigated the isolated effect of MT on the rehabilitation of these individuals.

Objective: To investigate the isolated effect of MT on motor function, sensitivity, muscle strength, manual dexterity and spasticity of the paretic UE of individuals with chronic hemiparesis after stroke.

Design: Randomized simple-blind trial. Subject: Twenty-six patients post chronic, aged between 30 and 80 years, with mild or moderate sensorimotor impairment in UE will be evaluated.

Intervention: The subjects will be randomly distributed in: intervention group will perform 60 minutes of MT and the control group will perform 60 minutes of control therapy composed of the same exercises, but without the mirror. Both groups will hold two sessions per week for six weeks.

Main measure: Participants will be evaluated before and after the intervention. They will be evaluated through the Fugl-Meyer Scale to measure UL sensorimotor performance, Box-and-Block Test for manual dexterity, Dynamometry for palmar grip strength and Modified Ashworth Scale for spasticity. With this study, it was expected that the intervention group presented better results regarding the sensorimotor function when compared to the control group.

The data will be expressed as mean and 95% confidence interval (continuous variable) and absolute frequency (categorical variables). To compare the outcomes of the different experimental sessions and at the different moments (pre and post session), the Generalized Estimating Equations with post hoc LSD (Least Significant Difference) methods will be used. For all analysis the significance level was set at α = 0.05 and statistical software SPSS (Statistical Package for Social Sciences for Mac, version 22.0, IBM, USA) will be used.

Sample Size: The sampling was simple random and the calculation of the sample size needed to carry out this research was estimated using GPower software. The power and standard deviation were estimated from previous studies (Park et al., 2015) with a similar design. The sample size estimate for the present research project was 13 individuals per group (Mirror Therapy group and control group), totalizing 26 individuals, considering a level of significance (p) 5% and power of 80%.

Eligibility Criteria:
Inclusion Criteria:

1. Have suffered a single stroke, ischemic or hemorrhagic at least 6 months prior to the study and at most 5 years prior to the study, diagnosed by MRI and / or CT scan;
2. Age between 30 and 80 years;
3. Spasticity ≤ 3 in the flexor muscles of the elbow, wrist and fingers, shoulder horizontal adductor (Ashworth Modified Scale);
4. Mild or moderate sensorimotor impairment (Fugl-Meyer score scale - mild: 58-64 points, moderate: 39-57 points);
5. Present ability to understand the instructions of the study (Mini-Mental score ≥ 18 for schooled individuals and ≥ 13 for illiterate individuals);
6. Present muscular strength ≥ 3 in the flexor muscles of shoulder, and extensors of elbow and wrist.
7. Be able to stay in position for more than 30 minutes;

Exclusion Criteria:

1. Visual deficit that may limit participation in Mirror Therapy;
2. History of severe depression or severe psychiatric disorder;
3. Other neurological or musculoskeletal disorders in the upper limb not related to the stroke;
4. Severe visuospatial negligence.