Correlation between kinesthetic motor imagery of an amputated limb and phantom limb pain

Neural correlates of phantom motor execution: A functional neuroimaging systematic review and meta-analysis

Phantom motor execution (PME) shows promise as a new treatment for phantom limb pain (PLP) by inducing motor-related analgesia and retraining the pain network activation. However, the current understanding of the neural correlates underlying PME is limited. Databases were systematically searched for multimodal neuroimaging studies to explore the neural correlates of PME. A narrative synthesis (17 studies, n = 328) and coordinate-based meta-analysis were performed to identify activation commonalities. Contrasting PME-vs-REST revealed differential activation of the supplementary motor area (SMA), post-central gyrus, and dorsolateral superior frontal gyrus; while PME-vs-ME revealed differential activation of the right anterior insula, anterior cingulate, left amygdala, and right striatum. Further narrative synthesis revealed a positive correlation between PME-induced brain activity and PLP intensity, and a specific connectivity pattern during PME on the SMA-M1 network compared to ME and motor imagery. Our results suggest that the PME represents a distinct type of motor network activation, partially overlapping with ME and motor imagery activations but with special activation of interoceptive regulation and mood-related regions. Thus, confirming its potential as a therapeutic approach for PLP.

Case Report: Virtual reality training for phantom limb pain after amputation

Several reports have demonstrated the effectiveness of neurorehabilitation, such as mirror therapy or virtual reality, in treating phantom limb pain (PLP). This case study describes the effect of virtual reality training (VRT) on severe, long-term PLP and upper limb activity on the amputated side in a patient who underwent digit amputation 9 years prior. A woman in her 40 s underwent amputation of 2-5 fingers 9 years prior due to a workplace accident. She experienced persistent pain in the palms of her hand near the amputation sites. A single case design (ABA'B') was applied. Periods A and A' were set as periods without VRT intervention, and Periods B and B' were set as periods with VRT intervention. Periods A, B, A', and B' lasted 4, 10, 8, and 10 weeks, respectively. VRT was a task during which visual stimulation and upper limb movements were linked. The task consisted of catching a rolling ball in the display with a virtual hand, operated with both hands using a controller. VRT was performed once every 2-4 weeks for 30 min. Pain intensity was assessed using the short-form McGill Pain Questionnaire-2. Bilateral upper limb activity was measured continuously for 24 h using a triaxial accelerometer attached to the right and left wrist joints. The pain intensity was 147/220 points during Period A, 128 points during Period B, 93 points during Period A', and 100 points during Period B', showing a gradual decrease. Upper limb activity occurred mainly on the intact side during Periods A and B, whereas the activity on the amputated side increased 2-fold after Period A', and both upper extremities were used equally. Virtual reality training resulted in reduced pain intensity and increased activity in the upper limb. VRT may have induced reintegration of the sensory-motor loop, leading to a decrease in the PLP intensity. The upper limb activity on the amputated side may have also increased with the pain reduction. These results suggest that VRT may be valuable in reducing severe, long-term PLP.

Motor Imagery and Pain Processing in Patients With Entrapment Neuropathies: A Cross-sectional Study

OBJECTIVES

(1) To assess the ability to generate both kinesthetic and visual motor imagery in participants with carpal tunnel syndrome (CTS), compared with asymptomatic participants. (2) To assess the influence of psychophysiological and functional variables in the motor imagery process.

METHODS

Twenty patients with unilateral CTS and 18 pain-free individuals were recruited. An observational case-control study with a nonprobability sample was conducted to assess visual and kinesthetic movement imagery ability and psychophysiological variables in patients with CTS compared with asymptomatic participants in a control group. The trial was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology statement.

RESULTS

CTS patients have more difficulties in generating visual motor images compared with asymptomatic individuals ( t =-2.099; P <0.05; d=0.70). They need more time to complete the mental tasks (visual t =-2.424; P <0.05 and kinesthetic t =-2.200; P <0.05). A negative correlation was found between the ability to imagine and functional deficits ( r =-0.569; P =0.021) for the kinesthetic subscale and temporal summation ( r =-0.515; P <0.5). A positive correlation was found between pain pressure threshold homolateral (homolateral) and time to generate the visual mental images ( r =0.537; P <0.05).

DISCUSSION

CTS patients have greater difficulty generating motor images than asymptomatic individuals. Patients also spend more time during mental tasks. CTS patients present a relationship between temporal summation and the capacity to generate kinesthetic images. In addition, the CST patients presented a correlation between chronometry mental tasking and mechanical hyperalgesia.