Correlation of primary motor cortex changes with phantom limb pain after amputation
Phantom limb pain is the painful sensation that occurs soon after the surgery from the part of the limb which is not there anymore. After the hand amputation, the degree of phantom limb pain is regulated by the massive reorganization of primary sensory and motor cortices which was supplemented by a substantial body of evidence documents.
According to multiple therapies for phantom limb pain, the plastic changes after amputations are maladaptive and attempt to normalize representations of cortical areas vicinal to the hand area. The higher levels of phantom pain are associated with vigorous local activity and more structural integrity in the missing hand area rather than with reorganization of neighboring body parts as suggested by a recent data. The divergence between the models might be due to the fact that no single study has depicted the organization of lip, elbow, and hand movements in the same participants.
Although, these models appear to be mutually exclusive they could co-exist. Using the MRI techniques in this study, examination of 3D anatomy of the central sulcus and BOLD responses during movements of the hand, elbow and lips was done in 11 upper-limb amputees and 17 healthy control subjects. There were various reorganizational patterns for all three body parts as the former hand area presented few signs of reorganization, but the lip and elbow representations reorganized and shifted towards the hand area. In the lip and elbow topological changes, impecunious voluntary control and higher levels of pain in the phantom limb was also observed.
For the first time, we exhibited further support for the maladaptive plasticity model, motor capacities of the phantom limb correlate with post-amputation reorganization and that this reorganization is not restricted to the face and hand representations but also inculcates the proximal upper-limb.