Another wasted mirror therapy research, NO PROTOCOL created.
Effects of a Mirror-Induced Visual Illusion on a Reaching Task in Stroke Patients: Implications for Mirror Therapy Training
Abstract
Background.
Although most mirror therapy studies have shown improved motor
performance in stroke patients, the optimal mirror training protocol
still remains unclear. (So no protocols yet, start guessing about what you need to do.)
Objective.
To study the relative contribution of a mirror in training a reaching task and of unilateral and bimanual training with a mirror.
Methods.
0A total of 93 stroke patients at least 6 months poststroke were instructed to perform a reaching task as fast and as fluently as possible. They performed 70 practice trials after being randomly allocated to 1 of 5 experimental groups: training with (1) the paretic arm with direct view (Paretic-No Mirror), (2) the nonparetic arm with direct view (Nonparetic-No Mirror), (3) the nonparetic arm with mirror reflection (Nonparetic Mirror), (4) both sides and with a nontransparent screen preventing visual control of paretic side (Bilateral-Screen), and (5) both sides with mirror reflection of the nonparetic arm (Bilateral-Mirror). As baseline and follow-up, patients performed 6 trials using only their paretic side. Primary outcome measure was the movement time.
Results.
We found the largest intervention effect in the Paretic-No Mirror condition. However, the Nonparetic-Mirror condition was not significantly different from the Paretic-No Mirror condition, while the Unaffected-No Mirror condition had significantly less improvement than the Paretic-No Mirror condition. In addition, movement time improved significantly less in the bimanual conditions and there was no difference between both bimanual conditions or between both mirror conditions.
Conclusion.
The present study confirms that using a mirror reflection can facilitate(not will facilitate) motor learning. In this task, bimanual movement using mirror training was less effective than unilateral training.
Introduction
It has been reported that 55% to 75% of stroke survivors suffer from a paretic arm.1 Intensive, task-specific training programs have been shown to improve motor function, even in patients in the chronic phase of stroke,2 but are generally time consuming and expensive. Mirror therapy, originally designed by Ramachandran et al3 to alleviate phantom limb pain, is a cheap and promising intervention that has been shown to improve upper limb function in acute,4 subacute5 and chronic stroke patients.6
Although most studies on mirror therapy have shown improved motor performance in their participants, the quantum of improvements has been relatively small, not always reaching clinical significance.4,6 In addition, there are differences between studies in how mirror therapy is performed. Among others, differences exist in whether the paretic hand behind the mirror is instructed to move as much as possible bimanually with the uninvolved hand in front of the mirror. In most mirror therapy studies in stroke patients, participants are instructed to practice bimanually, moving affected and unaffected limbs together. This provides a direct motor training paradigm, related to the known effects of bimanual training programs.7 The added value of mirror therapy in this form of training is that the mirror replaces feedback on movement of the affected side by a form of “virtual feedback” that creates the illusion that the paretic side moves with a normal movement pattern. However, from the relatively small number of trials and the lack of a direct comparison of different types of mirror training, the most optimal training is presently unclear.
While from a motor learning perspective it may be most effective to instruct patients to move the paretic side behind the mirror as much as possible, it could be argued that the strength of the mirror illusion decreases as a result of paretic side movement, as it causes an incongruence between task performance and visual feedback. In addition, movement of the paretic arm behind the mirror may increase proprioceptive feedback of the arm behind the mirror, which then may partly disrupt the visual illusion. This would suggest that movement of the arm behind the mirror is not beneficial or even detrimental. In addition, if movement of the hand behind the mirror is not necessary to obtain a motor learning effect, it would indicate the added value of using mirror therapy in severely affected patients without any residual paretic arm function, for whom there are very few therapeutic options currently available.
The aim of the present study was to gain insight in the relative contribution of a mirror in exercising a reaching task and in the differences in unilateral and bimanual exercises when training such a reaching task with and without a mirror. To realize this, we used a short-term motor learning task, which allowed us to compare several conditions in an effective, controlled manner. The aim was not to create a clinically meaningfully change in hand function, but to show differences in learning due to the different learning conditions. In all conditions, the task was to perform a reaching movement to a target from a standardized position as quickly as possible. We had stroke patients train this task under the following experimental conditions: (1) task performance with affected hand and direct view of affected side (Affected-Only condition), (2) task performance with the unaffected side and direct view of the unaffected side (Unaffected-No Mirror), (3) task performance with the unaffected side and mirror reflection of unaffected side as if the affected side is also moving (Unaffected-Mirror), (4) task performance with both sides and a screen between arms preventing view of affected side (Bimanual-No Mirror), and (5) task performance with both sides and mirror reflection of the unaffected side as if the affected side is moving similarly (Bimanual-Mirror).
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