Neuroelectric source imaging of steady-state movement-related cortical potentials in human upper extremity amputees with and without phantom limb pain

Abstract

Whereas several studies reported a close relationship between changes in the somatotopic organization of primary somatosensory cortex and phantom limb pain, the relationship between alterations in the motor cortex and amputation-related phenomena has not yet been explored in detail. This study used steady-state movement-related cortical potentials (MRCPs) combined with neuroelectric source imaging to assess the relationship of changes in motor cortex and amputation-related phenomena such as painful and non-painful phantom and residual limb sensations, telescoping, and prosthesis use. Eight upper limb amputees were investigated. A significant positive relationship between reorganization of the motor cortex (distance of the MRCP source location from the mirrored source for hand movement) and phantom limb pain was found. Non-painful phantom sensations as well as painful and non-painful residual limb sensations were unrelated to motor cortical reorganization. A higher amount of motor reorganization was associated with less daily prosthesis use, which also tended to be related to more severe phantom limb pain. These results extend previous findings of a positive relationship between somatosensory reorganization and phantom limb pain to the motor domain and suggest a potential positive effect of prosthesis use on phantom limb pain and cortical reorganization.

Role of distorted body image in pain

“…Perhaps this increased excitability enhances cortical reorganization processes in S1 and M1, as it is observed in experimentally induced increased excitability [57]. Data from animal studies suggest underlying reorganization processes are likely due to cortical rather than subcortical mechanisms [58], which suggests that the increased cortical excitability found in pain patients [59,60] may help drive cortical reorganization. This finding might explain the rapid normalization of S1 organization when pain is eliminated [61].…”

Botulinum Toxin Type B in the Treatment of Residual Limb Hyperhidrosis for Lower Limb Amputees

“…Reduced usability of the prosthetic device is very common and has a substantial impact on the quality-of-life of the affected patient and incurs costs owing to absenteeism from work. 7 In addition, it is known that phantom limb pain occurs significantly less with intensive use of the artificial leg 42 ; therefore, treatment leading to reduced sweating may have a beneficial effect on phantom limb pain, and this, in turn, may contribute to a subjective feeling of ''being one with the artificial limb.'' 6 Thus, from our point of view, a few BTX-B treatments administered throughout the year are not only going to reduce hyperhidrosis but also going to contribute to keeping costs due to sick leave down, not to mention the long-term abatement of phantom limb pain.…”

Amygdala hyperactivity and tonotopic shift after salicylate exposure

“…Tonotopic map expansion in the AC has been considered as a neural correlate of tinnitus, much like somatotopic map expansion is for individuals with phantom limb pain (Karl et al, 2004; Montoya et al, 1998; Muhlnickel et al, 1998). Moreover, the AC is often hyperactive in participants with tinnitus and impaired loudness despite the fact the hearing loss reduces neural activity in the cochlea (Gu et al, 2010; Lockwood et al, 1998; Qiu et al, 2000).…”