Mirror therapy for chronic complex regional pain syndrome type 1 and stroke

Mirror Therapy for Chronic Complex Regional Pain Syndrome Type 1 and Stroke To the Editor: Complex regional pain syndrome type 1 is characterized by pain, sensory disturbances (e.g., pain evoked by light brushing of the skin [allodynia]), motor impairment (e.g., weakness), and sympathetic dysfunction (e.g., edema). Pain in this syndrome may be induced by a mismatch between proprioceptive feedback and motor action.1 Visual feedback as a substitute for inappropriate proprioceptive feedback may reduce pain.1,2 Visual feedback may be achieved with mirror therapy, which was originally used to treat phan- tom pain.2 However, the use of mirror therapy3 and therapy involving imagery of movement4 in patients with chronic complex regional pain syndrome type 1 (lasting 6 months or more) remains controversial. We conducted a randomized, sham-controlled study involving 24 patients with stroke (11 men and 13 women). The median age was 62 years (range, 53 to 71), and the median time since stroke was 14 months (range, 7 to 21). Chronic complex regional pain syndrome type 1 of a paretic arm was diagnosed according to the criteria of Bruehl and colleagues.5 The investigators were unaware of the study-group assignments. Of the 24 patients, 15 (62%) had left hemiplegia and 19 (79%) had ischemic stroke. No cases of thalamic involvement or shoulder subluxation were recorded. None of the patients had signs of depression. We randomly assigned the 24 patients to one of three groups: one that viewed a reflected image of their unaffected arm in a mirror (the active- mirror group), one that viewed a covered mirror (the covered-mirror group), and one that received training in mental imagery (the mentalimagery group). All patients provided written informed consent. In both the active-mirror and covered-mirror groups, patients performed all of the cardinal (proximal to distal) movements of the affected arm for 30 minutes daily. Outcomes were measured in terms of pain on movement. The primary end point was the score for the severity of pain after 4 weeks of therapy, based on a visualanalogue scale from 0 to 100 mm, with higher scores indicating more severe pain. Secondary end points were motor function as assessed by the Wolf motor-function test, brush-induced allodynia, and edema after 4 weeks of therapy. The analysis-of-variance test was used. Baseline scores for pain on the visual-analogue scale were similar among the three groups (P = 0.71). After 4 weeks of active-mirror therapy, the pain intensity decreased (Fig. 1), and motor function, brush-induced allodynia, and edema improved (data not shown). In the active-mirror group, seven of eight patients (88%) reported reduced pain (median change in visual-analogue score, –51 mm; range, –70 to –18). In the covered-mirror group, only one of eight patients (12%) reported reduced pain, two patients (25%) reported no change in the pain level, and five patients (62%) reported increased pain. In the mental-imagery group, two of eight patients (25%) reported reduced pain and six patients (75%) reported increased pain. At 4 weeks, the scores for pain on the visual-analogue scale in the active-mirror group differed significantly from those in the covered-mirror group (P = 0.002) and mental-imagery group (P<0.001 for both comparisons). After the randomization period, 12 patients crossed over to active mirror therapy. After the crossover treatment period, 11 of the 12 patients (92%) who switched to active mirror therapy from either the covered-mirror group or the mentalimagery group had a significant reduction in pain (P = 0.002 and P = 0.004, respectively). Our results indicate that, unlike imagery therapy, mirror therapy effectively reduces pain and enhances motor function in the arm of patients with stroke and chronic complex regional pain syndrome type 1 in the arm. The traditional view that in patients with stroke, chronic complex regional pain syndrome type 1 in the arm is refractory to mirror therapy needs to be reconsidered.