In patients with phantom limb pain, the reorganization was great enough to cause a change in cortical lip representation into the hand areas only during lip movements. It has also been found that there is a high correlation between the magnitude of phantom limb pain and the extent to which the shift of the cortical representation of the mouth into the hand area in motor and somatosensory cortical reorganization has occurred. Additionally, as phantom pains in upper extremity amputees increased, there was a higher degree of medial shift of the facial motor representation. There are multiple theories that try to explain how cortical remapping occurs in amputees, but none have been supported to a great extent. The neuromatrix
The neuromatrix theory proposes that there is an extensive network connecting the thalamus and the cortex, and the cortex and the limbic system. It is a theory that extends beyond body schema theory and incorporates the conscious awareness of oneself. This theory proposes that conscious awareness and the perception of self are generated in the brain via patterns of input that can be modified by different perceptual inputs. The network is genetically predetermined, and is modified throughout one’s lifetime by various sensory inputs to create a neurosignature. It is the neurosignature of a specific body part that determines how it is consciously perceived. The input systems contributing to the neurosignature are primarily the somatosensory, limbic, and thalamocortical systems. The neuromatrix theory aims to explain how certain activities associated with pain lead to the conscious perception of phantom pain.
"Little research was published on MT before 2009, and much of the research since then has been of low quality. Out of 115 publications between 2012 and 2017 about using mirror therapy to treat phantom limb pain, a 2018 review, found only 15 studies whose scientific results should be considered. From these 15 studies, the reviewers concluded that "MT seems to be effective in relieving PLP, reducing the intensity and duration of daily pain episodes. It is a valid, simple, and inexpensive treatment for PLP." Medication
Pharmacological techniques are often continued in conjunction with other treatment options. Doses of pain medications needed often drop substantially when combined with other techniques, but rarely are discontinued completely. Tricyclic antidepressants, such as amitriptyline, and sodium channel blockers, mainly carbamazepine, are often used to relieve chronic pain, and recently have been used in an attempt to reduce phantom pains. Pain relief may also be achieved through use of opioids, ketamine, calcitonin, and lidocaine. Deep-brain stimulation
Deep brain stimulation is a surgical technique used to alleviate patients from phantom limb pain. Prior to surgery, patients undergo functional brain imaging techniques such as PET scans and functional MRI to determine an appropriate trajectory of where pain is originating. Surgery is then carried out under local anesthetic, because patient feedback during the operation is needed. In the study conducted by Bittar et al., a radiofrequency electrode with four contact points was placed on the brain.