Reliability of Phantom Pain Relief in Neurorehabilitation using a Multimodal Virtual Reality System

The objective of this study is to demonstrate the reliability of relief from phantom limb pain in neurorehabilitation using a multimodal virtual reality system. We have developed a virtual reality rehabilitation system with multimodal sensory feedback and applied it to six patients with brachial plexus avulsion or arm amputation. In an experiment, patients executed a reaching task using a virtual phantom limb displayed in a three-dimensional computer graphic environment manipulated by their real intact limb. The intensity of the phantom limb pain was evaluated through a short-form McGill pain questionnaire. The experiments were conducted twice on different days at more than four-week intervals for each patient. The reliability of our task's ability to relieve pain was demonstrated by the test-retest method, which checks the degree of the relative similarity between the pain reduction rates in two experiments using Fisher's intraclass correlation coefficient (ICC). The ICC was 0.737, indicating sufficient reproducibility of our task. The average of the reduction rates across participants was 50.2%, and it was significantly different from 0 (p < 0.001). Overall, our findings indicate that neurorehabilitation using our multimodal virtual reality system reduces the phantom limb pain with sufficient reliability.