Non-invasive interventions to alter maladaptive neuroplasticity in the Complex Regional Pain Syndrome: A systematic review and a pilot study
Dool, J. van den
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Systematic review: Objective: Phantom Limb Pain (PLP) and Complex Regional Pain Syndrome (CRPS) are associated with partial or complete loss of sensorimotor input from the affected limb and changes in somatosensory cortices. Several interventions are aimed at reversing these neuroplastic maladaptations. The aim of this review was to investigate the effects of these interventions on pain and motor function. Methods: Electronic databases were systematically searched. Relevant articles were assessed for methodological quality by the Downs & Black checklist (D&B). A Best Evidence Synthesis (BES) was conducted to determine the level of evidence for the effects of an intervention. Results: 31 studies were included from the literature search. Methodological quality ranged from 7 to 25 points on the D&B checklist. The BES demonstrated limited evidence for reducing pain and improving motor function in PLP by Graded Motor Imagery (GMI) and indicative findings by Mirror Visual Feedback. Sensory Training showed only indicative findings for pain reduction. In CRPS, strong evidence was found for pain reduction and limited evidence for the reduction of motor function by GMI. Limited evidence was found for short term pain reduction by rTMS and indicative findings for the reduction of pain by Sensorimotor Training. Conclusion: Most evidence is found for the effects on decreasing pain. Evidence for the effects on motor func-tion is still very limited. However, GMI showed promising results for decreasing pain and improving motor function. Because of the limited evidence, more high quality studies are needed to demonstrate the real effec-tiveness of these interventions. Pilot study: Background: Complex Regional Pain Syndrome (CRPS) related dystonia is associated with changes in the somatosensory cortices and incongruence between afferent input from the af-fected limbs and motor commands, causing pain and motor disturbances. One strategy to alter the incongruence between motor commands and sensory feedback is Mirror Visual Feedback (MVF). The primary aim of this pilot study was to investigate the influences of Graded Motor Imagery (GMI) and MVF on motor function and pain in CRPS related dystonia. Secondary aims were to investigate the feasibility of a MVF intervention in these patients and the suita-bility of several outcome measures. Methods: Five patients underwent a six week training protocol consisting of two weeks GMI training, four weeks MVF training and daily home exercises. Measurements were performed after each training phase and at follow-up, six weeks after finishing the MVF training. Results: The outcomes indicated a general decrease in motor function after two weeks of GMI, an improvement after four weeks of MVF training compared to baseline, and a wash out at follow-up. Changes were mostly seen in AROM and finger tap movements, especially in the three patients who had some function in their affected limb at baseline. Pain did not decrease in any of the patients. Conclusion: The GMI and MVF protocol was feasible to treat patients with CRPS related dystonia. Patients who are less affected by dystonia are probably more susceptible for MVF treatment. Effectiveness might be improved by lengthening the intervention period, specifica-tion of the training to more functional, daily life tasks and combining it with medical treat-ment to reduce dystonic postures like botulinum toxin. The possible effects were best meas-ured with AROM, velocity of finger tap movements. However, these results should be inter-preted with caution because it was a small, unblinded study with only five cases that had a great variation in severity of CRPS and dystonia.