Neurostimulation for control of phantom limb pain: Spinal cord, thalamus and cerebral cortex

Abstract

In patients with phantom limb, the primary somatosensory cortex may undergo reorganization of receptive field representation (invasion of the phantom limb area by the adjacent area). It has been reported that this reorganization is highly correlated with phantom limb pain and unrelated to the non-painful phantom sensation. These findings led to the hypothesis that restoration of the original cortical organization might diminish phantom limb pain. Similar reorganization of receptive field representation within the thalamic sensory relay nucleus has been shown by microrecordings and microstimulation during surgery for therapeutic electrode implantation. We review the published data and our own experience regarding the effects of neurostimulation therapies on phantom limb pain (spinal cord, thalamic sensory relay nucleus and motor cortex) from a view point that neurostimulation therapies produce their effects through restoration of the original receptive field organization by artificial input to the representation of the phantom limb area. Many phenomena observed during neurostimulation therapies are better explained by such a hypothesis rather than classic gate control theory.