Phantom-limb pain: characteristics, causes, and treatment

[Digital technologies and strategies in amputation medicine]

Surgical techniques in amputation medicine did not change for a long time, while prosthesis technology underwent rapid development. The focus shifted to optimising the residual limb for prostheses use. At the same time, digital technologies such as gamification, virtual and mixed reality revolutionised rehabilitation. The use of gamification elements increases motivation and adherence to therapy, while immersive technologies enable realistic and interactive therapy experiences. This is particularly useful in the context of controlling modern prostheses and treating phantom pain. In addition, digital applications contribute to optimised documentation of symptoms and therapy successes. Overall, these technologies open up new, effective and personalised therapeutic approaches that can significantly improve the quality of life of amputation patients.

Identifying discriminant factors between phantom limb pain, residual limb pain, and both in people with lower limb amputations: a cross-sectional study

Postamputation pain is a common condition in patients with lower limb amputation (LLA), which compromises amputees' rehabilitation, use of the prosthesis, and quality of life. The aim of our study was to investigate the prevalence of phantom limb pain (PLP), residual limb pain (RLP), or both types of pain among individuals with LLA, and to identify the factors associated with the presence of one type of pain versus the other. Patients who underwent amputation for traumatic or vascular reasons and who reported on RLP or PLP were analyzed and divided into three groups: PLP, RLP, or a group of subjects that presented both pains. We searched for factors that affect the occurrence of limb pain using univariate analyses, followed by multinomial logistic regression. Among the 282 participants with transtibial and transfemoral amputations, 192 participants (150 male and 42 female) presented PLP, RLP, or both types of pain, while 90 participants declared to perceive no pain. The estimated prevalence of any type of pain after transfemoral and transtibial amputation was therefore 68% (27% PLP, 10% RLP, and 31% both). Among the studied characteristics, only amputation level was associated with the type of pain (P = 0.001). Multinomial logistic regression identified transfemoral amputation as the only statistically significant predictor for PLP (odds ratio = 2.8; P = 0.002). Hence, it was estimated that individuals with transfemoral amputation have nearly three times higher odds of experiencing PLP compared with those with transtibial amputation.

Development and pilot administration of the amputation-related pain and sensation assessment tool

PURPOSE

To develop and administer an assessment tool for facilitating patient-clinician discussions regarding amputation-related pain and sensation.

MATERIALS AND METHODS

An assessment tool was developed to measure the impact of different types of amputation-related pain and sensation on a patient's life. The tool first provides patients with written descriptions and images of three common types of amputation-related pain or sensations: residual limb pain, phantom limb sensation, and phantom limb pain. The tool then asks them to rate the frequency, intensity, and interference of each experience. Participants were also asked to provide qualitative descriptions of these experiences.

RESULTS

Fifty Veterans with lower limb amputation participated in the study. In the past month, 74% reported experiencing residual limb pain, 76% reported phantom limb sensation, and 84% reported phantom limb pain, with 52% reporting all three. Participants' descriptions of some experiences were distinct, while others (e.g., "tingling") were common between experiences. Phantom limb pain had the most varied descriptions.

CONCLUSIONS

The amputation-related pain and sensation assessment tool can be used to identify and measure the effects of different experiences on patients' lives, thereby improving the specificity of diagnosis and informing clinical treatment recommendations. Further development of this tool should include evaluating its psychometric properties.

[Fillet flap transfer as alternative to conventional lower limb amputation]

BACKGROUND

The fitting of a prosthesis after lower limb amputation is associated with several challenges. Skeletal stump-prosthesis interfaces and selective nerve transfer can partially overcome these but are also associated with new impairments that emphasize the necessity of innovative approaches. The concept of so-called spare part surgery with the use of fillet flaps could play an important role in this respect.

OBJECTIVE

An overview of the classical prosthesis-associated discomforts, advantages and disadvantages of treatment strategies and presentation of alternative surgical concepts.

MATERIAL AND METHODS

A selective literature search was carried out considering the experiences of the authors and perspectives with respect to the advantages and disadvantages of the surgical treatment options. Furthermore, a clinical case is presented.

RESULTS AND CONCLUSION

The transfer of the sole of the foot as a fillet flap to the weight-bearing region of the amputation stump offers a number of benefits, such as creating a fully weight-bearing stump, prevention of neuralgia, preserved sensation and conservation of the body image. As long as the calcaneal region is not impaired, this technique can be performed in amputations below as well as above the knee. The question of whether parts of the bone should be included in the transfer must be individually evaluated for each patient. This approach enables optimization of the residual limb stump for the subsequent fitting of a prosthesis for the patient.

Phantom limb syndrome: from pathogenesis to treatment. A narrative review

Phantom Limb Syndrome (PLS) can be defined as the disabling or painful sensation of the presence of a body part that is no longer present after its amputation. Anatomical changes involved in Phantom Limb Syndrome, occurring at peripheral, spinal and brain levels and include the formation of neuromas and scars, dorsal horn sensitization and plasticity, short-term and long-term modifications at molecular and topographical levels. The molecular reorganization processes of Phantom Limb Syndrome include NMDA receptors hyperactivation in the dorsal horn of the spinal column leading to inflammatory mechanisms both at a peripheral and central level. At the brain level, a central role has been recognized for sodium channels, BDNF and adenosine triphosphate receptors. In the paper we discuss current available pharmacological options with a final overview on non-pharmacological options in the pipeline.

Virtual and Augmented Reality in Management of Phantom Limb Pain: A Systematic Review

Upper and lower limb amputations are frequently associated with phantom limb pain (PLP). Recently, virtual reality (VR) and augmented reality (AR) have been reported as a potential therapy of PLP. We have conducted a systematic review of literature to evaluate the efficacy of VR and AR in managing PLP. Four databases were searched: PubMed, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and Web of Science. We utilized the Preferred Reporting Items for Systematic Reviews and Meta-Analysis for our organization. The initial search resulted in 164 results. After title, abstract, and full-text screening, 9 studies were included. One study was of good quality and 8 studies were of fair to poor quality. Seven studies utilized VR and 2 studies utilized AR. The number of treatment sessions ranged from 1 to 28 and the duration ranged from 10 minutes to 2 hours. Several pain scales were used to evaluate PLP pre- and postintervention including Numeric Rating Scale, Pain Rating Index, McGill Pain Questionnaire, and Visual Analog Scale. All the studies reported improvement of PLP on one or more of pain scales after one or more sessions of VR or AR. Despite the promising results reported by literature, we cannot recommend using VR or AR for PLP. Most of the studies are of poor design and have limited sample size with high bias levels. Therefore, no substantial evidence can be derived from them. However, we do believe further research with high-quality randomized controlled trials should take place to increase the knowledge of the potential advantages.

Case Report: Phantom limb pain relief after cognitive multisensory rehabilitation

Introduction

Relieving phantom limb pain (PLP) after amputation in patients resistant to conventional therapy remains a challenge. While the causes for PLP are unclear, one model suggests that maladaptive plasticity related to cortical remapping following amputation leads to altered mental body representations (MBR) and contributes to PLP. Cognitive Multisensory Rehabilitation (CMR) has led to reduced pain in other neurologic conditions by restoring MBR. This is the first study using CMR to relieve PLP.

Methods

A 26-year-old woman experienced excruciating PLP after amputation of the third proximal part of the leg, performed after several unsuccessful treatments (i.e., epidural stimulator, surgeries, analgesics) for debilitating neuropathic pain in the left foot for six years with foot deformities resulting from herniated discs. The PLP was resistant to pain medication and mirror therapy. PLP rendered donning a prosthesis impossible. The patient received 35 CMR sessions (2×/day during weekdays, October-December 2012). CMR provides multisensory discrimination exercises on the healthy side and multisensory motor imagery exercises of present and past actions in both limbs to restore MBR and reduce PLP.

Results

After CMR, PLP reduced from 6.5-9.5/10 to 0/10 for neuropathic pain with only 4-5.5/10 for muscular pain after exercising on the Numeric Pain Rating Scale. McGill Pain Questionnaire scores reduced from 39/78 to 5/78, and Identity (ID)-Pain scores reduced from 5/5 to 0/5. Her pain medication was reduced by at least 50% after discharge. At 10-month follow-up (9/2013), she no longer took Methadone or Fentanyl. After discharge, receiving CMR as outpatient, she learned to walk with a prosthesis, and gradually did not need crutches anymore to walk independently indoors and outdoors (9/2013). At present (3/2024), she no longer takes pain medication and walks independently with the prosthesis without assistive devices. PLP is under control. She addresses flare-ups with CMR exercises on her own, using multisensory motor imagery, bringing the pain down within 10-15 min.

Conclusion

The case study seems to support the hypothesis that CMR restores MBR which may lead to long-term (12-year) PLP reduction. MBR restoration may be linked to restoring accurate multisensory motor imagery of the remaining and amputated limb regarding present and past actions.

Towards efficient motor imagery interventions after lower-limb amputation

BACKGROUND

The therapeutic benefits of motor imagery (MI) are now well-established in different populations of persons suffering from central nervous system impairments. However, research on similar efficacy of MI interventions after amputation remains scarce, and experimental studies were primarily designed to explore the effects of MI after upper-limb amputations.

OBJECTIVES

The present comparative study therefore aimed to assess the effects of MI on locomotion recovery following unilateral lower-limb amputation.

METHODS

Nineteen participants were assigned either to a MI group (n = 9) or a control group (n = 10). In addition to the course of physical therapy, they respectively performed 10 min per day of locomotor MI training or neutral cognitive exercises, five days per week. Participants' locomotion functions were assessed through two functional tasks: 10 m walking and the Timed Up and Go Test. Force of the amputated limb and functional level score reflecting the required assistance for walking were also measured. Evaluations were scheduled at the arrival at the rehabilitation center (right after amputation), after prosthesis fitting (three weeks later), and at the end of the rehabilitation program. A retention test was also programed after 6 weeks.

RESULTS

While there was no additional effect of MI on pain management, data revealed an early positive impact of MI for the 10 m walking task during the pre-prosthetic phase, and greater performance during the Timed Up and Go Test during the prosthetic phase. Also, a lower proportion of participants still needed a walking aid after MI training. Finally, the force of the amputated limb was greater at the end of rehabilitation for the MI group.

CONCLUSION

Taken together, these data support the integration of MI within the course of physical therapy in persons suffering from lower-limb amputations.

Beyond traditional therapies: a network meta-analysis on the treatment efficacy for chronic phantom limb pain

BACKGROUND

Phantom limb pain (PLP) frequently affects individuals with limb amputations. When PLP evolves into its chronic phase, known as chronic PLP, traditional therapies often fall short in providing sufficient relief. The optimal intervention for chronic PLP remains unclear.

OBJECTIVE

The objectives of this network meta-analysis (NMA) were to examine the efficacy of different treatments on pain intensity for patients with chronic PLP.

EVIDENCE REVIEW

We searched Medline, EMBASE, Cochrane CENTRAL, Scopus, and CINAHL EBSCO, focusing on randomized controlled trials (RCTs) that evaluated interventions such as neuromodulation, neural block, pharmacological methods, and alternative treatments. An NMA was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome was pain score improvement, and the secondary outcomes were adverse events.

FINDINGS

The NMA, incorporating 12 RCTs, indicated that neuromodulation, specifically repetitive transcranial magnetic stimulation, provided the most substantial pain improvement when compared with placebo/sham groups (mean difference=-2.9 points, 95% CI=-4.62 to -1.18; quality of evidence (QoE): moderate). Pharmacological intervention using morphine was associated with a significant increase in adverse event rate (OR=6.04, 95% CI=2.26 to 16.12; QoE: low).

CONCLUSIONS

The NMA suggests that neuromodulation using repetitive transcranial magnetic stimulation may be associated with significantly larger pain improvement for chronic PLP. However, the paucity of studies, varying patient characteristics across each trial, and absence of long-term results underscore the necessity for more comprehensive, large-scale RCTs.

PROSPERO REGISTRATION NUMBER

CRD42023455949.

Distinct patterns of metabolic motor cortex activity for phantom and residual limb pain in people with amputations: A functional near-infrared spectroscopy study

BACKGROUND

Phantom pain limb (PLP) has gained more attention due to the large number of people with amputations around the world and growing knowledge of the pain process, although its mechanisms are not completely understood.

OBJECTIVES

The aim of this study was to understand, in patients with amputations, the association between PLP and residual limb pain (RLP), and the brain metabolic response in cortical motor circuits, using functional near-infrared spectroscopy (fNIRS).

METHODS

Sixty participants were recruited from the rehabilitation program in São Paulo, Brazil. Included patients were aged over 18 years, with traumatic unilateral lower-limb amputation, with PLP for at least 3 months after full recovery from amputation surgery. PLP and RLP levels were measured using visual analogue scales. fNIRS was performed during motor execution and motor mirror tasks for 20 s. In order to highlight possible variables related to variation in pain measures, univariate linear regression analyses were performed for both experimental conditions, resulting in four fNIRS variables (two hemispheres x two experimental conditions). Later, in order to test the topographic specificity of the models, eight multivariate regression analyses were performed (two pain scales x two experimental conditions x two hemispheres), including the primary motor cortex (PMC) related channel as an independent variable as well as five other channels related to the premotor area, supplementary area, and somatosensory cortex. All models were controlled for age, sex, ethnicity, and education.

RESULTS

We found that: i) there is an asymmetric metabolic activation during motor execution and mirror task between hemispheres (with a predominance that is ipsilateral to the amputated limb), ii) increased metabolic response in the PMC ipsilateral to the amputation is associated with increased PLP (during both experimental tasks), while increased metabolic response in the contralateral PMC is associated with increased RLP (during the mirror motor task only); ii) increased metabolic activity of the ipsilateral premotor region is associated with increased PLP during the motor mirror task; iii) RLP was only associated with higher metabolic activity in the contralateral PMC and lower metabolic activity in the ipsilateral inferior frontal region during motor mirror task, but PLP was associated with higher metabolic activity during both tasks.

CONCLUSION

These results suggest there is both task and region specificity for the association between the brain metabolic response and the two different types of post-amputation pain. The metabolic predominance that is ipsilateral to the amputated limb during both tasks was associated with higher levels of PLP, suggesting a cortical motor network activity imbalance due to potential interhemispheric compensatory mechanisms. The present work contributes to the understanding of the underlying topographical patterns in the motor-related circuits associated with pain after amputations.

Primary Motor Area Activity in Phantom Limb Imagery of Traumatic Unilateral Lower Limb Amputees With Phantom Limb Pain

Introduction

Estimates of the worldwide increase in amputees raises the awareness to solve long-standing problems. Understanding the functional brain modifications after a lower limb amputation (LLA) is one of the first steps towards proposing new rehabilitation approaches. Functional modifications in the central nervous system due the amputation could be involved in prosthesis use failures and Phantom Limb Pain (PLP), increasing costs and overwhelming the health services.

Objective

This study analyses orphan primary motor area (M1-Orphan) hemodynamic and metabolic behaviour, which previously controlled the limb that was amputated, in comparison with the M1-Preserved, responsible for the intact limb (IL) during phantom limb imagery moving during Mirror Therapy (MT), compared to Isolated Intact Limb Movement Task (I-ILMT).

Methodology

A case-control study with unilateral traumatic LLA with moderate PLP who measured [oxy-Hb] and [deoxy-Hb] in the M1 area by Functional Near InfraredSpectroscopy (fNIRS) during the real (I-ILMT) and MT task.

Results

Sixty-five patients, with 67.69% of men, young (40.32 ± 12.91), 65.63% amputated due motorcycle accidents, 4.71 ± 7.38 years ago, predominantly above the knee (57.14%). The M1 activation in the orphan cortex did not differ from the activation in the intact cortex during MT (P > .05).

Conclusion

The perception of the Phantom limb moving or intact limb moving is metabolically equivalent in M1, even in the absence of a limb. In other words, the amputation does not alter the brain metabolism in control of phantom movement.

Whole-Body Cryostimulation, a Complementary Treatment for Phantom Limb Syndrome: Preliminary Evidence from a Case Study

Phantom limb pain (PLP) is a challenging condition affecting a significant proportion of amputees. In this article, we describe the case of a 54-year-old Paralympic athlete with phantom limb syndrome following right leg amputation and widespread sports-related enthesitic pain who underwent a whole-body cryostimulation (WBC) cycle, an emerging treatment known for its rapid pain-relieving and anti-inflammatory effects. Assessments were conducted before and after a 10-session WBC cycle, including pain and quality of life assessment and use of medications. A substantial reduction in enthesitic pain, PLP intensity, paresthesia, and tingling related to atmospheric events and improved function and quality of life were reported after the WBC cycle and lasted for two weeks. One month after WBC, the enthesitic pain following sports activity and PLP gradually returned, but with lesser intensity. Similarly, the stump's sensitivity to atmospheric changes returned, but with lower frequency. Pain at night remained lower than before WBC, with significantly improved quality of sleep. This case study suggests that WBC could be a valuable adjuvant treatment for alleviating PLP. Controlled studies are warranted to validate the findings of this case report and elucidate the mechanisms underlying the positive effects of WBC in this condition.

Effect of multidimensional physiotherapy on non-specific chronic low back pain: a randomized controlled trial

BACKGROUND

Many people with non-specific chronic low back pain (NSCLBP) do not recover with current conventional management. Systematic reviews show multidimensional treatment improves pain better than usual active interventions. It is unclear whether multidimensional physiotherapy improves pain better than usual physiotherapy. This study determines the effectiveness of this treatment to reduce pain and disability and improve quality of life, pain cognitions, and electroencephalographic pattern in individuals with NSCLBP.

METHODS

70 eligible participants aged 18 to 50 years with NSCLBP were randomized into either the experimental group (multidimensional physiotherapy) or the active control group (usual physiotherapy). Pain intensity was measured as the primary outcome. Disability, quality of life, pain Catastrophizing, kinesiophobia, fear Avoidance Beliefs, active lumbar range of motion, and brain function were measured as secondary outcomes. The outcomes were measured at pre-treatment, post-treatment, 10, and 22 weeks. Data were analyzed using intention-to-treat approaches.

RESULTS

There were 17 men and 18 women in the experimental group (mean [SD] age, 34.57 [6.98] years) and 18 men and 17 women in the active control group (mean [SD] age, 35.94 [7.51] years). Multidimensional physiotherapy was not more effective than usual physiotherapy at reducing pain intensity at the end of treatment. At the 10 weeks and 22 weeks follow-up, there were statistically significant differences between multidimensional physiotherapy and usual physiotherapy (mean difference at 10 weeks, -1.54; 95% CI, -2.59 to -0.49 and mean difference at 22 weeks, -2.20; 95% CI, - 3.25 to - 1.15). The standardized mean difference and their 95% confidence intervals (Cohen's d) revealed a large effect of pain at 22 weeks: (Cohen's d, -0.89; 95% CI (-1.38 to-0.39)). There were no statistically significant differences in secondary outcomes.

CONCLUSIONS

In this randomized controlled trial, multidimensional physiotherapy resulted in statistically and clinically significant improvements in pain compared to usual physiotherapy in individuals with NSCLBP at 10 and 22 weeks.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04270422; IRCT IRCT20140810018754N11.

Risk Factors Analysis of Phantom Limb Pain in Amputees with Malignant Tumors

Purpose

Postamputation neuropathic pain is a common disease in patients with malignant tumor amputation, seriously affecting amputees' quality of life and mental health. The objective of this study was to identify independent risk factors for phantom limb pain in patients with tumor amputation and to construct a risk prediction model.

Methods

Patients who underwent amputation due to malignant tumors from 2013 to 2023 were retrospectively analyzed and divided into phantom limb pain group and non-phantom limb pain group. To determine which preoperative factors would affect the occurrence of phantom limb pain, we searched for candidate factors by univariate analysis and used multivariate logistic regression analysis to identify independent factors and construct a predictive model. The receiver operating characteristic curve (ROC) was drawn to further evaluate the accuracy of the prediction model in evaluating the phantom limb pain after amputation of bone and soft tissue tumors.

Results

Multivariate analysis showed that age (OR, 1.054; 95% CI, 1.027 to 1.080), preoperative pain (OR, 5.773; 95% CI, 2.362 to 14.104), number of surgeries (OR, 3.425; 95% CI, 1.505 to 7.795), amputation site (OR, 5.848; 95% CI, 1.837 to 18.620), amputation level (OR, 8.031; 95% CI, 2.491 to 25.888) were independent risk factors for phantom limb pain for bone and soft tissue tumors. The the area under the curve (AUC) of this model was 0.834.

Conclusion

Risk factors for postoperative phantom limb pain were the site of amputation, proximal amputation, preoperative pain, multiple amputations, and older age. These factors will help surgeons to individualize and stratify phantom limb pain and help patients with risk counseling. In particular, an informed clinical decision targeting those modifiable factors can be considered when needed.

Efficacy of Mirror Therapy in Patients with Phantom Pain after Amputation of a Lower Limb: A Systematic Literature Review

Up to 80% of patients after amputation are affected by phantom limb pain. This may be due to various mechanisms of cortical reorganisation. Non-surgical treatment of the neuropathic phantom limb pain involves mirror therapy. Thereby, the use of a mirror should induce the illusion that the extremity has been preserved. This illusion should initiate processes to restore the original organisation of the somatosensory and motor cortex and thus to reduce pain. Evidence of mirror therapy to treat lower extremity phantom limb pain is rare. Therefore, the aim of this systematic review is to qualitatively analyse the efficacy of mirror therapy for treatment of phantom limb pain in adult patients after unilateral amputations of the lower extremity.The databases Medline (PubMed), Physiotherapy Evidence Database (PEDro), Cochrane Library (Central), and OPENGREY were systematically searched until 26th November 2020, followed by continued searches in these databases to provide a review of updated literature. Study selection, data extraction, and risk of bias evaluation (Risk of Bias Tool [RoB]) of included studies were conducted by two reviewers independently. The primary outcome was pain intensity, and secondary outcomes were pain frequency, pain duration, activities of daily life (ADL), and quality of life. The methodology of this review follows the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and the Cochrane Handbook for Systematic Reviews of Interventions.The search revealed 234 articles. Four articles were included in the analysis. A reduction in pain intensity due to mirror therapy was reported in all studies, however, in only 2 studies there were significant differences between mirror therapy and the comparison after 4 weeks of treatment (p < 0.001; p < 0.05). This significant difference was maintained after 3 and 6 months follow-up in one of those studies (p < 0.001). The outcomes pain frequency, pain duration, and ADL were decreased after 4 and 10 weeks of mirror therapy compared to comparison, but with no statistical significance (p > 0.05). After 6 months, there was a significant improvement in the duration of pain and in ADL after mirror therapy compared with the control group (p < 0.05). Differences in the results quality of life between the intervention group and comparison were observed in 2 studies.Mirror therapy of high frequency and duration is an effective intervention to reduce phantom limb pain in patients after unilateral lower extremity amputation. The superiority of mirror therapy to other interventions cannot be concluded, as the evidence was of low quality.

Bibliometric Analysis of Research Articles on Virtual Reality in the Field of Pain Medicine Published from 1993 to 2022

Purpose

This study aims to analyze global and regional (China, Japan, and South Korea) research on virtual reality (VR) in the field of pain medicine over the past 30 years. Specifically, we quantify VR-related publications, examine the distribution of research topics on chronic and acute pain, and identify trends and future directions.

Methods

The Web of Science Core Collection (WoSCC) database was used for bibliometric analysis. This study included articles written in English between 1993 and 2022. The search strategy used predefined terms related to VR and pain. Based on the articles' titles and abstracts, two pain physicians independently reviewed and classified them as acute or chronic pain. Quantitative data on countries, institutions, journals, and research categories were analyzed. VOSviewer software was used for keyword mapping and clustering.

Results

We analyzed 808 VR-related articles on pain medicine. Over the past three decades, the number of publications in this field has increased steadily. The United States of America (n = 259) had the highest number of publications. Moreover, China (n = 42), Japan (n = 18), and South Korea (n = 24) also contributed continuously. Acute and chronic pain research accounted for 44.2% and 37.9% of the articles, respectively. The most common acute pain topic was procedure-related (n = 129, 16.0%), whereas the most common chronic pain topic was neuropathic (n = 104, 12.9%). Keywords clustered around neuroscience, pediatric pain management, and chronic pain management.

Conclusion

Our study revealed academic achievements and growing interest in VR-related research in pain medicine. Researchers worldwide have shown balanced interest in applying VR technology to acute and chronic pain, with specific contributions from China, Japan, and South Korea. Harnessing VR technology is promising for improving pain management and enhancing patients' quality of life in the field of pain medicine.

Vibrotactile Feedback for a Person with Transradial Amputation and Visual Loss: A Case Report

Background and Objectives: After major upper-limb amputation, people face challenges due to losing tactile information and gripping function in their hands. While vision can confirm the success of an action, relying on it diverts attention from other sensations and tasks. This case report presents a 30-year-old man with traumatic, complete vision loss and transradial left forearm amputation. It emphasizes the importance of restoring tactile abilities when visual compensation is impossible. Materials and Methods: A prototype tactile feedback add-on system was developed, consisting of a sensor glove and upper arm cuff with related vibration actuators. Results: We found a 66% improvement in the Box and Blocks test and an overall functional score increase from 30% to 43% in the Southampton Hand Assessment Procedure with feedback. Qualitative improvements in bimanual activities, ergonomics, and reduced reliance on the unaffected hand were observed. Incorporating the tactile feedback system improved the precision of grasping and the utility of the myoelectric hand prosthesis, freeing the unaffected hand for other tasks. Conclusions: This case demonstrated improvements in prosthetic hand utility achieved by restoring peripheral sensitivity while excluding the possibility of visual compensation. Restoring tactile information from the hand and fingers could benefit individuals with impaired vision and somatosensation, improving acceptance, embodiment, social integration, and pain management.

Regenerative Peripheral Nerve Interface Surgery: Anatomic and Technical Guide

Regenerative peripheral nerve interface (RPNI) surgery has been demonstrated to be an effective tool as an interface for neuroprosthetics. Additionally, it has been shown to be a reproducible and reliable strategy for the active treatment and for prevention of neuromas. The purpose of this article is to provide a comprehensive review of RPNI surgery to demonstrate its simplicity and empower reconstructive surgeons to add this to their armamentarium. This article discusses the basic science of neuroma formation and prevention, as well as the theory of RPNI. An anatomic review and discussion of surgical technique for each level of amputation and considerations for other etiologies of traumatic neuromas are included. Lastly, the authors discuss the future of RPNI surgery and compare this with other active techniques for the treatment of neuromas.

A novel mixed reality system to manage phantom pain in-home: results of a pilot clinical trial

Introduction

Mirror therapy for phantom limb pain (PLP) is a well-accepted treatment method that allows participants to use a mirror to visually perceive the missing limb. Mixed reality options are now becoming increasingly available, but an in-home virtual mirror therapy option has yet to be adequately investigated.

Methods

We had previously developed a mixed reality system for Managing Phantom Pain (Mr. MAPP) that registers the intact limb and mirrors it onto the amputated limb with the system's visual field, allowing the user to engage with interactive games targeting different large lower limb movements. Feasibility and pilot outcomes of treating patients with lower extremity PLP by using Mr. MAPP at home for 1 month were evaluated in this study. Pain intensity and interference were assessed using the McGill Pain Questionnaire, Brief Pain Inventory, and a daily exercise diary. Function was assessed using the Patient Specific Functional Scale (PSFS). The clinical trial registry number for this study is NCT04529083.

Results

This pilot study showed that it was feasible for patients with PLP to use Mr. MAPP at home. Among pilot clinical outcomes, statistically significant differences were noted in mean current pain intensity [1.75 (SD = 0.46) to 1.125 (SD = 0.35) out of 5, P = .011] and PSFS goal scores [4.28 (SD = 2.27) to 6.22 (SD = 2.58) out of 10, P = .006], with other outcome measures showing non-significant trends towards improvement.

Discussion

This pilot study revealed that in-home use of Mr. MAPP has potential to provide pain relief and improve function in patients with lower extremity PLP and is feasible. Each scale used provided unique perspective on the functional impact of PLP. Further expanded studies and investigation, including a fully powered clinical trial, with these scales are warranted.

Clinical Trial Registration

https://www.clinicaltrials.gov/ct2/show/NCT04529083, Identifier: NCT04529083.

Calcitonin in the Treatment of Phantom Limb Pain: A Systematic Review

INTRODUCTION

Phantom limb pain (PLP) refers to pain perceived in a part of the body removed by amputation or trauma. Despite the high prevalence of PLP following amputation and the significant morbidity associated with it, robust therapeutic approaches are currently lacking. Calcitonin, a polypeptide hormone, has recently emerged as a novel analgesic with documented benefits in the treatment of several pain-related conditions.

METHODS

We present a systematic review that comprehensively evaluates the analgesic effects of calcitonin for patients with PLP. We searched MEDLINE, OLDMEDLINE, and PubMed Central databases with the key words "calcitonin" "phantom limb pain" and "phantom pain" to identify clinical studies evaluating the efficacy or effectiveness of calcitonin administration, in any form and dose, for the treatment of PLP. Additionally, Google Scholar was searched manually with the search term "calcitonin phantom limb pain". All four databases were searched from inception until 1 December 2022. The methodological quality of each included study was assessed using the Downs and Black checklist and the GRADE criteria were used to assess effect certainty and risk of bias.

RESULTS

Our search identified 4108 citations, of which six ultimately met the criteria for inclusion in the synthesis. The included articles described a mix of open-label (n = 2), prospective observational cohort (n = 1), and randomized clinical trials (n = 3). The most common treatment regimen in the current literature is a single intravenous infusion of 200 IU salmon-derived calcitonin.

CONCLUSION

The available evidence supported the use of calcitonin as either monotherapy or adjuvant therapy in the treatment of PLP during the acute phase, while the evidence surrounding calcitonin treatment in chronic PLP is heterogeneous. Given the limited treatment options for the management of PLP and calcitonin's relatively wide therapeutic index, further research is warranted to determine the role that calcitonin may play in the treatment of PLP and other pain disorders.

Somatosensory and motor representations following bilateral transplants of the hands: A 6-year longitudinal case report on the first pediatric bilateral hand transplant patient

A vascularized composite tissue allotransplantation (VCA) was performed at the Children's Hospital of Philadelphia (CHOP), on an 8-year-old patient in 2015, six years after bilateral hand and foot amputation. Hand VCA resulted in reafferentation of the medial, ulnar, and radial nerves serving hand somatosensation and motor function. We used magnetoencephalography (MEG) to assess somatosensory cortical plasticity following the post-transplantation recovery of the peripheral sensory nerves of the hands. Our 2-year postoperative MEG showed that somatosensory lip representations, initially observed at "hand areas", reverted to canonical, orthotopic lip locations with recovery of post-transplant hand function. Here, we continue the assessment of motor and somatosensory responses up to 6-years post-transplant. Magnetoencephalographic somatosensory responses were recorded eight times over a six-year period following hand transplantation, using a 275-channel MEG system. Somatosensory tactile stimuli were presented to the right lower lip (all 8 visits) as well as right and left index fingers (visits 3-8) and fifth digits (visits 4-8). In addition, left and right-hand motor responses were also recorded for left index finger and right thumb (visit 8 only).During the acute recovery phase (visits 3 and 4), somatosensory responses of the digits were observed to be significantly larger and more phasic (i.e., smoother) than controls. Subsequent measures showed that digit responses maintain this atypical response profile (evoked-response magnitudes typically exceed 1 picoTesla). Orthotopic somatosensory localization of the lip, D2, and D5 was preserved. Motor beta-band desynchrony was age-typical in localization and response magnitude; however, the motor gamma-band response was significantly larger than that observed in a reference population.These novel findings show that the restoration of somatosensory input of the hands resulted in persistent and atypically large cortical responses to digit stimulation, which remain atypically large at 6 years post-transplant; there is no known perceptual correlate, and no reports of phantom pain. Normal somatosensory organization of the lip, D2, and D5 representation remain stable following post-recovery reorganization of the lip's somatosensory response.

An illusion of disownership over one's own limb is associated with pain perception

Viewing one's body and even a fake/virtual body experienced as one's own has been suggested to modulate pain perception. However, what happens to pain perception when one's own body part is felt as not belonging to one? We designed a paradigm to induce an illusory feeling of disownership regarding one's limb, investigating whether the feeling affects pain threshold. Participants observed right-side images of their bodies from a third-person perspective via a head-mounted display in real-time. Following instructions, they moved their left hand while keeping their left elbow behind the upper body, so that the connection of their arm to the torso was not visible (test condition), or in front of it, so they could see the arm being part of them (control condition). Then, pain threshold was tested with a thermal stimulator. We found a significantly higher strength of disownership in the test condition than in the control condition. While there was no pain modulation within and between conditions, disownership ratings negatively correlated with pain-threshold changes, where the participants reporting explicit disownership showed lower pain-threshold changes than the others. The finding suggests that while multisensory disintegration had no modulatory effect, the individual sense of disownership was associated with pain perception.

Prevalence of Phantom Phenomena in Congenital and Early-Life Amputees

Phantom limb pain (PLP) is a common consequence of the amputation of a limb. Persons with congenital limb absence (congenital amputees) or an acquired limb amputation at an early age seem to rarely experience PLP. However, the number of available studies and their sample sizes are low. In the present cross-sectional study, we assessed the presence of several phantom phenomena in a sample of 99 adult unilateral congenital amputees (con) of whom 34 had a limb correction later in life (limbc) and 153 adult participants with a unilateral amputation before the age of 6 years (subgroups: amputation between birth and 2 years (0-2y; n = 48), 3-4 years (3-4y; n = 46), and 5 to 6 years (5-6y; n = 59)). We found a higher prevalence and intensity of PLP in the 5-6y group compared to the other groups. Residual limb pain (RLP) intensity was higher in the 3 to 4 y and 5 to 6 y groups compared to the con group. Non-painful phantom limb sensation (PLS) intensity and telescoping intensity were higher in the 5 to 6 y group compared to the con and 0 to 2 y groups. Our results indicate that PLP prevalence as well as intensity is low when the limb loss happened before the age of 5 years. PERSPECTIVE: The prevalence of phantom limb pain, residual limb pain, and non-painful phantom limb sensation in congenital amputees and participants with an amputation early in life is low. This might be due to the missing or reduced nociceptive input from the residual limb to the brain and higher development-associated adaptability of the somatosensory system.

Effect of a continuous perineural levobupivacaine infusion on pain after major lower limb amputation: a randomised double-blind placebo-controlled trial

OBJECTIVES

Randomised controlled trial of the effect of a perineural infusion of levobupivacaine on moderate/severe phantom limb pain 6 months after major lower limb amputation.

SETTING

Single-centre, UK university hospital.

PARTICIPANTS

Ninety patients undergoing above-knee and below-knee amputation for chronic limb threatening ischaemia under general anaesthesia. Exclusion criteria were patients having surgery under neuraxial anaesthesia; inability to operate a patient-controlled analgesia device or complete a Visual Analogue Scale; amputation for trauma or malignancy; or contraindication to levobupivacaine.

INTERVENTIONS

Either levobupivacaine 0.125% or saline 0.9% (10 mL bolus, infusion of 8 mL/hour for 96 hours) via a sciatic or posterior tibial nerve sheath catheter placed under direct vision during surgery.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the presence of phantom limb pain, residual limb pain and phantom limb sensations up to 6 months after amputation. Secondary outcome measures included early postoperative pain and morphine requirements after surgery.

RESULTS

Data from 81 participants were analysed; 6-month follow-up data were available for 62 patients. Pain and morphine requirements varied widely before and after amputation in both groups. The incidences of moderate/severe phantom limb pain, residual limb pain and phantom limb sensations were low from 6 weeks with no significant differences between groups in phantom limb pain at rest (OR 0.56, 95% CI 0.14 to 2.14, p=0.394) or movement (OR 0.58, 95% CI 0.15 to 2.21, p=0.425) at 6 months. Early postoperative pain scores were low in both groups with no between-group differences in residual limb pain or phantom limb sensations (rest or movement) at any time point. High postoperative morphine consumption was associated with worsening phantom limb pain both at rest (-17.51, 95% CI -24.29 to -10.74; p<0.001) and on movement (-18.54, 95% CI -25.58 to -11.49; p<0.001). The incidence of adverse effects related to the study was low in both groups: postoperative nausea, vomiting and sedation scores were similar, and there were no features of local anaesthetic toxicity.

CONCLUSIONS

Long-term phantom limb pain, residual limb pain and phantom limb sensations were not reduced significantly by perineural infusion of levobupivacaine, although the study was underpowered to show significant differences in the primary outcome. The incidence of phantom limb pain was lower than previously reported, possibly attributable to frequent assessment and early intervention to identify and treat postoperative pain when it occurred. There were large variations in postoperative pain scores, high requirements for analgesics before and after surgery and some problems maintaining recruitment and long -term follow-up. Knowledge of these potential problems should inform future research in this group of patients. Further work should investigate the association between perioperative morphine requirements and late phantom limb pain.

TRIAL REGISTRATION NUMBERS

EudraCT 2007-000619-27; ISRCTN68691928.

Comparative Effects of Interventions on Phantom Limb Pain: A Network Meta-Analysis

BACKGROUND

Phantom limb pain (PLP) is a common type of chronic pain that occurs after limb amputation. Many treatment approaches are available; however, the treatment of PLP is still a challenge. This study aimed to quantify and rank the efficacy of interventions for phantom limb pain.

METHODS

A comprehensive literature search was performed using the databases of PubMed, MEDLINE, Embase, Web of Science, and Cochrane. A network meta-analysis was applied to formulate direct and indirect comparisons among interventions for PLP.

RESULTS

Twenty-two studies comprising 662 patients and 13 different interventions were included in this study. The mirror therapy (MT) (-1.00; 95% confidence interval, -1.94 to -0.07) and MT + phantom exercise (PE) (-6.05; 95% confidence interval, -8.29 to -3.81) group presented significantly lower pain intensity compared with placebo. In SUCRA (surface under the cumulative ranking curve) analysis, the MT+PE and neuromodulation techniques groups had the highest SUCRA value (81.2).

CONCLUSIONS

Our results suggest that MT is the most optimal treatment for PLP, and a combination of therapies would enhance the therapeutic effect.

The applications of cryoneurolysis for acute and chronic pain management

BACKGROUND

Cryoneurolysis is a term used to describe the application of extreme cold to targeted nerve tissue. The primary goal of the application of a thermal neurolytic technique is to disrupt the conduction of pain signals from the periphery to the central nervous system and eliminate or diminish the experience of pain. Recent advancements in ultrasound technology coupled with the development and approval of handheld devices specifically designed to deliver cryoneurolysis has expanded the use of this modality in the perioperative setting.

APPLICATION

Surgical procedures including total knee arthroplasties, shoulder arthroplasties, thoracotomies, and mastectomies have all demonstrated long-term pain relief benefits when cryoneurolysis has been administered days to weeks prior to the planned procedure. In addition, the newly designed handheld device allows for office-based clinical use and has been utilized for various chronic pain conditions including neuropathic and phantom limb pain.

CONCLUSION

The evidence clearly demonstrates that cryoneurolysis has a low risk profile and when administered appropriately, provides prolonged analgesia without promoting motor blockade. This narrative review article describes the unique mechanism of action of cryoneurolysis for prolonged pain relief and provides emerging evidence to support its applications in both acute and chronic pain management.

Effect of mirror therapy in the treatment of phantom limb pain in amputees: A systematic review of randomized placebo-controlled trials does not find any evidence of efficacy

BACKGROUND AND OBJECTIVE

Phantom limb pain (PLP) concerns >50% of amputees and has a negative impact on their rehabilitation, mental health and quality of life. Mirror therapy (MT) is a promising strategy, but its effectiveness remains controversial. We performed a systematic review to: (i) evaluate the effectiveness of MT versus placebo in reducing PLP, and (ii) determine MT effect on disability and quality of life.

DATABASES AND DATA TREATMENT

We selected randomized-controlled trials in five databases (Medline, Cochrane Library, CINAHL, PEDro and Embase) that included patients with unilateral lower or upper limb amputation and PLP and that compared the effects on PLP of MT versus a placebo technique. The primary outcome was PLP intensity changes and the secondary outcomes were PLP duration, frequency, patients' disability and quality of life.

RESULTS

Among the five studies included, only one reported a significant difference between the MT group and control group, with a positive MT effect at week 4. Only one study assessed MT effect on disability and found a significant improvement in the MT group at week 10 and month 6.

CONCLUSIONS

Our systematic review did not allow concluding that MT reduces PLP and disability in amputees. This lack of strong evidence is probably due to (i) the low methodological quality of the included studies, and (ii) the lack of statistical power. Future trials should include a higher number of patients, increase the number and frequency of MT sessions, have a long-term follow-up and improve the methodological quality.

SIGNIFICANCE

Recent meta-analyses concluded that MT is effective for reducing phantom limb pain. Conversely, the present systematic review that included only studies with the best level of evidence did not find any evidence about its effectiveness for this condition. We identified many ways to improve future randomized-controlled trials on this topic: increasing the number of participants, reducing the intra-group heterogeneity, using a suitable placebo and intensifying the MT sessions and frequency.

Electrically-evoked referred sensations induce embodiment of rubber limb

Introduction

Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, the quality of referred sensations evoked using surface electrical stimulation was evaluated using the rubber hand and foot illusions.

Methods

The rubber hand and foot illusions were attempted under 4 conditions: (1) multi-location tapping; (2) one-location tapping; (3) electrical stimulation of sensation referred to the hand or foot; (4) asynchronous control. The strength of each illusion was quantified using a questionnaire and proprioceptive drift, where a stronger response suggested embodiment of the rubber limb.

Results

45 able-bodied individuals and two individuals with amputations participated in this study. Overall, the illusion evoked by nerve stimulation was not as strong as illusions evoked by physically tapping but stronger than the control illusion.

Conclusion

This study has found that the rubber hand and foot illusion can be performed without touching the distal limb of the participant. Electrical stimulation that produced referred sensation in the distal extremity was realistic enough to partially incorporate the rubber limb into a person's body image.

Experience of adults with upper-limb difference and their views on sensory feedback for prostheses: a mixed methods study

Background

Upper-limb prostheses are regularly abandoned, in part due to the mismatch between user needs and prostheses performance. Sensory feedback is among several technological advances that have been proposed to reduce device abandonment rates. While it has already been introduced in some high-end commercial prostheses, limited data is available about user expectations in relation to sensory feedback. The aim of this study is thus to use a mixed methods approach to provide a detailed insight of users’ perceptions and expectations of sensory feedback technology, to ensure the addition of sensory feedback is as acceptable, engaging and ultimately as useful as possible for users and, in turn, reduce the reliance on compensatory movements that lead to overuse syndrome.

Methods

The study involved an online survey (N = 37) and video call interviews (N = 15) where adults with upper-limb differences were asked about their experience with limb difference and prosthesis use (if applicable) and their expectations about sensory feedback to prostheses. The survey data were analysed quantitatively and descriptively to establish the range of sensory feedback needs and their variations across the different demographics. Reflexive thematic analysis was performed on the interview data, and data triangulation was used to understand key behavioural issues to generate actionable guiding principles for the development of sensory feedback systems.

Results

The survey provided a list of practical examples and suggestions that did not vary with the different causes of limb difference or prosthesis use. The interviews showed that although sensory feedback is a desired feature, it must prove to have more benefits than drawbacks. The key benefit mentioned by participants was increasing trust, which requires a highly reliable system that provides input from several areas of the hand rather than just the fingertips. The feedback system should also complement existing implicit feedback sources without causing confusion or discomfort. Further, the effect sensory feedback has on the users’ psychological wellbeing was highlighted as an important consideration that varies between individuals and should therefore be discussed. The results obtained were used to develop guiding principles for the design and implementation of sensory feedback systems.

Conclusions

This study provides a mixed-methods research on the sensory feedback needs of adults with upper-limb differences, enabling a deeper understanding of their expectations and worries. Guiding principles were developed based on the results of a survey and interviews to inform the development and assessment of sensory feedback for upper-limb prostheses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-022-01054-y.

Neurofeedback Training without Explicit Phantom Hand Movements and Hand-Like Visual Feedback to Modulate Pain: A Randomized Crossover Feasibility Trial

Phantom limb pain is attributed to abnormal sensorimotor cortical representations, although the causal relationship between phantom limb pain and sensorimotor cortical representations suffers from the potentially confounding effects of phantom hand movements. We developed neurofeedback training to change sensorimotor cortical representations without explicit phantom hand movements or hand-like visual feedback. We tested the feasibility of neurofeedback training in fourteen patients with phantom limb pain. Neurofeedback training was performed in a single-blind, randomized, crossover trial using two decoders constructed using motor cortical currents measured during phantom hand movements; the motor cortical currents contralateral or ipsilateral to the phantom hand (contralateral and ipsilateral training) were estimated from magnetoencephalograms. Patients were instructed to control the size of a disk, which was proportional to the decoding results, but to not move their phantom hands or other body parts. The pain assessed by the visual analogue scale was significantly greater after contralateral training than after ipsilateral training. Classification accuracy of phantom hand movements significantly increased only after contralateral training. These results suggested that the proposed neurofeedback training changed phantom hand representation and modulated pain without explicit phantom hand movements or hand-like visual feedback, thus showing the relation between the phantom hand representations and pain. PERSPECTIVE: Our work demonstrates the feasibility of using neurofeedback training to change phantom hand representation and modulate pain perception without explicit phantom hand movements and hand-like visual feedback. The results enhance the mechanistic understanding of certain treatments, such as mirror therapy, that change the sensorimotor cortical representation.

Altered bodily perceptions in chronic neuropathic pain conditions and implications for treatment using immersive virtual reality

Chronic neuropathic pain is highly disabling and difficult to treat and manage. Patients with such conditions often report altered bodily perceptions that are thought to be associated with maladaptive structural and functional alterations in the somatosensory cortex. Manipulating these altered perceptions using body illusions in virtual reality is being investigated and may have positive clinical implications for the treatment of these conditions. Here, we have conducted a narrative review of the evidence for the types of bodily distortions associated with a variety of peripheral and central neuropathic pain conditions. In addition, we summarize the experimental and clinical studies that have explored embodiment and body transformation illusions in immersive virtual reality for neuropathic pain relief, which are thought to target these maladaptive changes, as well as suggesting directions for future research.

An Algorithm Approach to Phantom Limb Pain

Phantom limb pain (PLP) is a common condition that occurs following both upper and lower limb amputation. First recognized and described in 1551 by Ambroise Pare, research into its underlying pathology and effective treatments remains a very active and growing field. To date, however, there is little consensus regarding the optimal management of phantom limb pain. With few large well-designed clinical trials of which to make treatment recommendations, as well as significant heterogeneity in clinical response to available treatments, the management of PLP remains challenging. Below we summarize the current state of knowledge in the field, as well as propose an algorithm for the approach to the treatment of PLP.

Clinical feasibility and preliminary outcomes of a novel mixed reality system to manage phantom pain: a pilot study

Background

To assess the clinical feasibility of a virtual mirror therapy system in a pilot sample of patients with phantom pain.

Methods

Our Mixed reality system for Managing Phantom Pain (Mr. MAPP) mirrors the preserved limb to visualize the amputated limb virtually and perform exercises. Seven patients with limb loss and phantom pain agreed to participate and received the system for 1-month home use. Outcome measures were collected at baseline and 1 month.

Results

Four (of seven recruited) participants completed the study, which was temporarily suspended due to COVID-19 restrictions. At 1 month, in-game data showed a positive trend, but pain scores showed no clear trends. Functioning scores improved for 1 participant.

Conclusions

Mr. MAPP is feasible and has the potential to improve pain and function in patients with phantom pain.

Trial registration

Clinical Trials Registration, NCT04529083

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-01187-w.

Effectiveness of mirror therapy in phantom limb pain: A literature review

INTRODUCTION

Phantom limb pain (PLP) is a type of neuropathic pain that affects the territory of an amputated limb or other surgically removed body parts. Between 60% and 90% of amputees suffer from PLP during follow-up. There are a range of therapeutic options for PLP, both pharmacological (gabapentin, amitriptyline, tricyclic antidepressants, etc) and non-pharmacological (transcutaneous electrical nerve stimulation, hypnosis, acupuncture, etc). A widely accepted hypothesis considers PLP to be the consequence of postamputation cortical reorganisation. New treatment approaches, such as mirror therapy (MT), have been developed as a result of Ramachandran's groundbreaking research in the 1990s. This review analyses the current evidence on the efficacy of MT for treating PLP.

DEVELOPMENT

We performed a literature review of publications registered from 2012 to 2017 on the CINAHL, Cochrane, Scopus, and PubMed (including Medline) databases Using the descriptors "phantom limb‿ and "mirror therapy.‿ We identified 115 publications addressing MT in PLP. Of these, 17 (15%) contributed useful information for pooled analysis.

CONCLUSIONS

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. The methodological quality of most publications in this field is very limited, highlighting the need for additional, high-quality studies to develop clinical protocols that could maximise the benefits of MT for patients with PLP.

Treating phantom limb pain: cryoablation of the posterior tibial nerve

Phantom limb pain (PLP) is a complex pathophysiologic process involving both the central and peripheral nervous system for which there is no definitive treatment. The number of individuals living with amputated limbs is predicted to increase to 3.5 million by 2050, and up to 80% of these patients will have PLP. In this case report, we will demonstrate successful reduction of PLP in a patient with bilateral phantom toe pain utilizing nerve blockade and subsequent cryoablation of the posterior tibial nerves.

On the use of virtual reality for individuals with upper limb loss: a systematic scoping review

INTRODUCTION

Virtual reality has recently become a popular application for rehabilitation and motor control research. This technology has emerged as a valid addition to conventional therapy and promises a successful rehabilitation. This study describes recent research related to the use of virtual reality applications in the rehabilitation of individuals with upper limb loss and to see whether this technology has enough proof of its applicability.

EVIDENCE ACQUISITION

Searches were conducted with the Web of Science, Google Scholar, IEEE Xplore, and PubMed databases from inception up to September 2020. Articles that employed virtual reality in the rehabilitation of individual with upper limb loss were included in the research if it is written in English, the keyword exists in the title and abstract; it uses visual feedback in nonimmersive, semi-immersive, or fully immersive virtual environments. Data extraction was carried out by two independent researchers. The study was drafted using the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols (PRISMA).

EVIDENCE SYNTHESIS

A total of 38 articles met the inclusion criteria. Most studies were published between 2010 and 2020. Thirty-nine percent of the studies (N.=15), originates from North America; 55% of the studies (N.=21), were publicly funded; 61% of the studies (N.=24), was without disclosure of conflict of interest; 82% of the studies (N.=31), were cited in other studies. All the studies were published in journals and conference proceedings. Sixty-six percent of the studies (N.=25) has come out with positive outcome. The design studies were mostly case reports, case series, and poorly designed cohort studies that made up 55% (N.=21) of all the studies cited here.

CONCLUSIONS

The research conducted on the use of virtual reality in individual with upper limb loss rehabilitation is of very low quality. The improvements to the research protocol are much needed. It is not necessary to develop new devices, but rather to assess existing devices with well-conducted randomized controlled trials.

An Algorithm for Elective Amputation Combined with Targeted Muscle Reinnervation in Complex Regional Pain Syndrome—A Perspective

Complex regional pain syndrome (CRPS) can result in a devastating condition. For a small number of patients, there is a non-response to any existing multimodal therapies and they ultimately request amputation. Such a drastic and final decision is not easy to take for both the patient and the surgeon and requires careful and interdisciplinary assessments and considerations. Furthermore, new surgical procedures, such as targeted muscle reinnervation (TMR) and hybrid prosthetic fitting, and multidisciplinary board advice should be included when considering amputation. In order to help other therapeutic teams in decision making for such rare but more than demanding cases, we aimed to propose an advanced algorithm for amputation indications in CRPS patients combining all these new factors. This algorithm consists of extensive pre-operative psychiatric assessment, diagnostic hybrid prosthetic fitting including fMRI analyses, multidisciplinary board advice as well as targeted muscle reinnervation and amputation procedures with final prosthetic fitting and rehabilitation. By involving multiple disciplines, this algorithm should provide optimized and individualized patient treatment on the one hand and a reliable base for decision making for therapists on the other.

Mechanosensitive Ion Channel TMEM63A Gangs Up with Local Macrophages to Modulate Chronic Post-amputation Pain

Post-amputation pain causes great suffering to amputees, but still no effective drugs are available due to its elusive mechanisms. Our previous clinical studies found that surgical removal or radiofrequency treatment of the neuroma at the axotomized nerve stump effectively relieves the phantom pain afflicting patients after amputation. This indicated an essential role of the residual nerve stump in the formation of chronic post-amputation pain (CPAP). However, the molecular mechanism by which the residual nerve stump or neuroma is involved and regulates CPAP is still a mystery. In this study, we found that nociceptors expressed the mechanosensitive ion channel TMEM63A and macrophages infiltrated into the dorsal root ganglion (DRG) neurons worked synergistically to promote CPAP. Histology and qRT-PCR showed that TMEM63A was mainly expressed in mechanical pain-producing non-peptidergic nociceptors in the DRG, and the expression of TMEM63A increased significantly both in the neuroma from amputated patients and the DRG in a mouse model of tibial nerve transfer (TNT). Behavioral tests showed that the mechanical, heat, and cold sensitivity were not affected in the Tmem63a^-/- mice in the naïve state, suggesting the basal pain was not affected. In the inflammatory and post-amputation state, the mechanical allodynia but not the heat hyperalgesia or cold allodynia was significantly decreased in Tmem63a^-/- mice. Further study showed that there was severe neuronal injury and macrophage infiltration in the DRG, tibial nerve, residual stump, and the neuroma-like structure of the TNT mouse model, Consistent with this, expression of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β all increased dramatically in the DRG. Interestingly, the deletion of Tmem63a significantly reduced the macrophage infiltration in the DRG but not in the tibial nerve stump. Furthermore, the ablation of macrophages significantly reduced both the expression of Tmem63a and the mechanical allodynia in the TNT mouse model, indicating an interaction between nociceptors and macrophages, and that these two factors gang up together to regulate the formation of CPAP. This provides a new insight into the mechanisms underlying CPAP and potential drug targets its treatment.

Deep brain stimulation for phantom limb pain

Phantom limb pain is a rare cause of chronic pain in children but it is associated with extremely refractory pain and disability. The reason for limb amputation is often due to treatment for cancer or trauma and it has a lower incidence compared to adults. The mechanism of why phantom pain exists remains uncertain and may be a result of cortical reorganisation as well as ectopic peripheral input. Treatment is aimed at reducing both symptoms as well as managing pain related disability and functional restoration. Neuromodulatory approaches using deep brain stimulation for phantom limb pain is reserved for only the most refractory cases. The targets for brain stimulation include the thalamic nuclei and motor cortex. Novel targets such as the anterior cingulate cortex remain experimental as cases of serious adverse effects such as seziures have limited their widespread uptake. A multidisciplinary approach is crucial to successful rehabilitation using a biopsychosocial pain management approach.

The influence of a manipulation of threat on experimentally-induced secondary hyperalgesia

Pain is thought to be influenced by the threat value of the particular context in which it occurs. However, the mechanisms by which a threat achieves this influence on pain are unclear. Here, we explore how threat influences experimentally-induced secondary hyperalgesia, which is thought to be a manifestation of central sensitization. We developed an experimental study to investigate the effect of a manipulation of threat on experimentally-induced secondary hyperalgesia in 26 healthy human adults (16 identifying as female; 10 as male). We induced secondary hyperalgesia at both forearms using high-frequency electrical stimulation. Prior to the induction, we used a previously successful method to manipulate threat of tissue damage at one forearm (threat site). The effect of the threat manipulation was determined by comparing participant-rated anxiety, perceived threat, and pain during the experimental induction of secondary hyperalgesia, between the threat and control sites. We hypothesized that the threat site would show greater secondary hyperalgesia (primary outcome) and greater surface area (secondary outcome) of induced secondary hyperalgesia than the control site. Despite a thorough piloting procedure to test the threat manipulation, our data showed no main effect of site on pain, anxiety, or threat ratings during high-frequency electrical stimulation. In the light of no difference in threat between sites, the primary and secondary hypotheses cannot be tested. We discuss reasons why we were unable to replicate the efficacy of this established threat manipulation in our sample, including: (1) competition between threats, (2) generalization of learned threat value, (3) safety cues, (4) trust, and requirements for participant safety, (5) sampling bias, (6) sample-specific habituation to threat, and (7) implausibility of (sham) skin examination and report. Better strategies to manipulate threat are required for further research on the mechanisms by which threat influences pain.

Multicenter, Double-Blinded, Randomized, Active-Sham Controlled Clinical Study Design to Assess the Safety and Effectiveness of a Novel High Frequency Electric Nerve Block System in the Treatment of Post-Amputation Pain (The QUEST Study)

Background

Chronic pain that follows amputation of a limb is reported as “one of the most severe pains in the human experience,” due to the magnitude of tissue injury and the multiple potential of pain generators at the local peripheral, spinal, and cortical levels. The Altius® System was developed to deliver high-frequency nerve block (HFNB) therapy via a cuff electrode applied to the peripheral nerve(s) and an implantable pulse generator. We report a novel clinical trial design for the first study of an active-implantable medical device in subjects with lower-limb post-amputation pain utilizing a multicenter, double-blinded, randomized, active-sham controlled clinical study protocol called QUEST, which is an ongoing investigational device exemption study to support United States Food and Drug Administration approval.

Methods

The study enrollment of 180 subjects was completed in September 2021. Subjects were randomized 1:1 to the treatment group or the active-sham control group for the 3-month primary effectiveness and safety endpoints. After month 3, the active-sham control program group crossed over to the treatment program group and all subjects continued to the 12-month study endpoint. Study effectiveness success is determined by a superiority test between responder rates in the treatment and control groups at 3 months. A responder is defined as someone who experiences a 50% or greater reduction in pain scores – after a 30-minute treatment session – for more than 50% of all pain episodes in which the treatment was used.

Discussion

The QUEST study design employs an active-sham control group to objectively assess the effectiveness of HFNB therapy. Additionally, the electronic diary repeated measures data collection in QUEST is expected to reduce the intra-subject variation typically observed in pain treatment studies. Finally, the longitudinal measurement of health-related quality of life and use of pain medication may, for example, show effectiveness in reducing opioid use over time.

Failed Targeted Muscle Reinnervation: Findings at Revision Surgery and Concepts for Success

Although it was initially described for improved myoelectric control, targeted muscle reinnervation (TMR) has quickly gained popularity as a technique for neuroma control. With this rapid increase in utilization has come broadening indications and variability in the described technique. As a result, it becomes difficult to interpret published outcomes. Furthermore, there is no literature discussing the management of failed cases which are undoubtedly occurring.

Focusing on cognitive potential as the bright side of mental atypicality

Standard accounts of mental health are based on a "deficit view" solely focusing on cognitive impairments associated with psychiatric conditions. Based on the principle of neural competition, we suggest an alternative. Rather than focusing on deficits, we should focus on the cognitive potential that selective dysfunctions might bring with them. Our approach is based on two steps: the identification of the potential (i.e., of neural systems that might have benefited from reduced competition) and the development of corresponding training methods, using the testing-the-limits approach. Counterintuitively, we suggest to train not only the impaired function but on the function that might have benefitted or that may benefit from the lesser neural competition of the dysfunctional system.

Visualizing the Unseen: Illustrating and Documenting Phantom Limb Sensations and Phantom Limb Pain With C.A.L.A

Currently, there is neither a standardized mode for the documentation of phantom sensations and phantom limb pain, nor for their visualization as perceived by patients. We have therefore created a tool that allows for both, as well as for the quantification of the patient's visible and invisible body image. A first version provides the principal functions: (1) Adapting a 3D avatar for self-identification of the patient; (2) modeling the shape of the phantom limb; (3) adjusting the position of the phantom limb; (4) drawing pain and cramps directly onto the avatar; and (5) quantifying their respective intensities. Our tool (C.A.L.A.) was evaluated with 33 occupational therapists, physiotherapists, and other medical staff. Participants were presented with two cases in which the appearance and the position of the phantom had to be modeled and pain and cramps had to be drawn. The usability of the software was evaluated using the System Usability Scale and its functional range was evaluated using a self-developed questionnaire and semi-structured interview. In addition, our tool was evaluated on 22 patients with limb amputations. For each patient, body image as well as phantom sensation and pain were modeled to evaluate the software's functional scope. The accuracy of the created body image was evaluated using a self-developed questionnaire and semi-structured interview. Additionally, pain sensation was assessed using the SF-McGill Pain Questionnaire. The System Usability Scale reached a level of 81%, indicating high usability. Observing the participants, though, identified several operational difficulties. While the provided functions were considered useful by most participants, the semi-structured interviews revealed the need for an improved pain documentation component. In conclusion, our tool allows for an accurate visualization of phantom limbs and phantom limb sensations. It can be used as both a descriptive and quantitative documentation tool for analyzing and monitoring phantom limbs. Thus, it can help to bridge the gap between the therapist's conception and the patient's perception. Based on the collected requirements, an improved version with extended functionality will be developed.

Rotationplasty Salvage Procedure as an Effective Alternative to Femoral Amputation in an Adult With a History of Osteosarcoma: A Case Report and Review

Rotationplasty or Borggreve-Van Ness surgery is lower limb salvage surgery, indicated mainly in the management of femoral bone sarcoma and congenital femur malformations in children. It can also be an interesting surgery option for managing chronic osteoarticular infections, or in cases of non union when curative therapy is no longer an option, as an alternative to femoral amputation. The principle of this surgery is to remove the affected knee and to apply a rotation of 180° to the distal part of the lower limb in order to give the ankle the function of a neo-knee. With the help of an adapted prosthesis, the aim is to allow patients to resume their social and professional activities by keeping most of their lower limb, thus avoiding the known complications of amputation (ghost limb pain, proprioceptive deficit, psychological disorders). Nevertheless, this surgery is complex and exceptional, with vascular, infectious, and psychological risks - the chimeric aspect of the lower limb may cause significant ill-being for the patient. This article reports the case of a 38-year-old patient consulting for management of a complex septic distal femoral non-union following osteosarcoma considered as being in remission. The patient underwent rotationplasty surgery on his left lower limb, with very good functional results and no surgical revision to date. In light of this particular case, we propose a didactic overview of the literature data concerning this surgery, especially in adulthood.