People with transhumeral amputations continue to have muscle activity patterns in their residual arms and experience phantom hand movements. However, according to a new study, the behavior has not been directly investigated, leaving the neurophysiological origin poorly understood. To that end, the researchers examined muscle activity patterns related to phantom hand movements.
They found that similar to the forearm and hand muscles during intact hand movements, each signal recorded from the residual upper arm during phantom hand movements displayed phases that were synchronized with the onset and offset of each movement repetition.
The researchers found that the patterns of phasic muscle activity related to phantom hand movements were specific not only to the type of movement but also to the electrode site, even within the same upper-arm muscle, while the muscles exhibited homogeneous activities in the intact arms.
The results suggested the existence of peripheral reorganization, the study concluded, which potentially occurs through the sprouting of severed axons and the recapture of muscle fibers in the residual limb. The authors suggested further research to understand the mechanism and its relationship with phantom hand movements, which would have significant implications for the rehabilitation process and myoelectric prosthesis control.
The open-access study, “New insights into muscle activity associated with phantom hand movements in transhumeral amputees,” was published in Frontiers in Human Neuroscience.
