Objective: To determine whether training with a brain–computer interface (BCI) to control an image of a phantom hand, which moves based on cortical currents estimated from magnetoencephalographic signals, reduces phantom limb pain.

Methods: Twelve patients with chronic phantom limb pain of the upper limb due to amputation or brachial plexus root avulsion participated in a randomized single-blinded crossover trial. Patients were trained to move the virtual hand image controlled by the BCI with a real decoder, which was constructed to classify intact hand movements from motor cortical currents, by moving their phantom hands for 3 days (“real training”). Pain was evaluated using a visual analogue scale (VAS) before and after training, and at follow-up for an additional 16 days. As a control, patients engaged in the training with the same hand image controlled by randomly changing values (“random training”). The two trainings were randomly assigned to the patients. This trial is registered at UMIN-CTR (UMIN000013608).

Results: VAS at day 4 was significantly reduced from the baseline after real training (45.3 [24.2] to 30.9 [20.6], 1/100mm, mean [SDs]; P=0.009<0.025), but not after random training (P=0.047>0.025). Compared to VAS at day 1, VAS at days 4 and 8 was significantly reduced by 32% and 36%, respectively, after real training and was significantly lower than VAS after random training (P<0.01).

Conclusion: Three-day training to move the hand images controlled by BCI significantly reduced pain for one week.
Classification of evidence: This study provides Class &#8546; evidence that BCI reduces phantom limb pain.

These are the supplementary information for the manuscript entitled "BCI training to move a virtual hand reduces phantom limb pain: A randomized crossover trial" published in Neurology.