Phantom limbs as reported by S. Weir Mitchell

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.

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.

The various forms of sensorimotor plasticity following limb amputation and their link with rehabilitation strategies

Limb amputation is characterized by complex and intermingled brain reorganization processes combining sensorimotor deprivation induced by the loss of the limb per se, and compensatory behaviors, such as the over-use of the intact or remaining limb. While a large body of evidence documents sensorimotor representation plasticity following arm amputation, less investigations have been performed to fully understand the use-dependent plasticity phenomenon and the role of behavioral compensation in brain reorganization. In this article, I will review the findings on sensorimotor plasticity after limb amputation, focusing on these two aspects: sensorimotor deprivation and adaptive patterns of limb usage, and describe the models that attempt to link these reorganizational processes with phantom limb pain. Two main models have been proposed: the maladaptive plasticity model which states that the reorganization of the adjacent cortical territories into the representation of the missing limb is proportional to phantom pain intensity, and the persistent representation model, which rather suggests that the intensity of residual brain activity associated with phantom hand movements scales with phantom limb pain intensity. I will finally illustrate how this fundamental research helps designing new therapeutic strategies for phantom plain relief.

Neurophysiological models of phantom limb pain: what can be learnt

Phantom Limb Pain (PLP) is a dysesthesic painful sensations perceived in the lost limb, resulting from complex interactions between structural and functional nervous systems changes. We analyze its main pathogenetic models and speculate on candidate therapeutic targets. The neuroma model considers PLP to arise from spontaneous activity of residual limb injured axons. Other peripheral-origin models attribute PLP to damage of somatosensory receptors or vascular changes. According to the cortical remapping model, the loss of bidirectional nervous flow and the need to enhance alternative functions trigger reorganization and arm and face skin afferents "invade" the hand territory. On the contrary, the persistent representation model suggests that continued inputs preserve the lost limb representation and that, instead to a shrinkage, PLP is associated with larger representation and stronger cortical activity. In the neuromatrix model, the mismatch between body representation, which remains intact despite limb amputation, and real body appearance generates pain. Another hypothesis is that proprioceptive memories associate specific limb positions with pre-amputation pain and may be recalled by those positions. Finally, the stochastic entanglement model offers a direct relationship between sensorimotor neural reorganization and pain. Amputation disrupts motor and somatosensory circuits, allowing for maladaptive wiring with pain circuits and causing pain without nociception. Relief of PLP depends solely on motor and somatosensory circuitry engagement, making anthropomorphic visual feedback dispensable. Existing and apparently contradicting theories might not be mutually exclusive. All of them involve several intertwined potential mechanisms by which replacing the amputated limb by an artificial one could counteract PLP.

Supernumerary phantom limbs

Silas Weir Mitchell (1829-1914), justly regarded as one of the founding fathers of neurology, published accounts of phantom limbs in the 1860s and 1870s,1 around the time that neurology was emerging as an independent clinical discipline (although earlier accounts of phantom limbs are recognised2). Phantom limbs are most often observed in the context of amputation, but reports of extra limbs occurring without amputation have also appeared. Two brief cases are presented here to illustrate the clinical heterogeneity of the supernumerary limb, the possible pathophysiology of which is briefly considered.

A review of current theories and treatments for phantom limb pain

Following amputation, most amputees still report feeling the missing limb and often describe these feelings as excruciatingly painful. Phantom limb sensations (PLS) are useful while controlling a prosthesis; however, phantom limb pain (PLP) is a debilitating condition that drastically hinders quality of life. Although such experiences have been reported since the early 16th century, the etiology remains unknown. Debate continues regarding the roles of the central and peripheral nervous systems. Currently, the most posited mechanistic theories rely on neuronal network reorganization; however, greater consideration should be given to the role of the dorsal root ganglion within the peripheral nervous system. This Review provides an overview of the proposed mechanistic theories as well as an overview of various treatments for PLP.

Strategies for prevention of lower limb post-amputation pain: A clinical narrative review

Postamputation limb pain or phantom limb pain (PLP) develops due to the complex interplay of peripheral and central sensitization. The pain mechanisms are different during the initial phase following amputation as compared with the chronic PLP. The literature describes extensively about the management of established PLP, which may not be applicable as a preventive strategy for PLP. The novelty of the current narrative review is that it focuses on the preventive strategies of PLP. The institution of preoperative epidural catheter prior to amputation and its continuation in the immediate postoperative period reduced perioperative opioid consumption (Level II). Optimized preoperative epidural or intravenous patient-controlled analgesia starting 48 hours and continuing for 48 hours postoperatively decreased PLP at 6 months (Level II). Preventive role of epidural LA with ketamine (Level II) reduced persistent pain at 1 year and LA with calcitonin decreased PLP at 12 months (Level II). Peripheral nerve catheters have opioid sparing effect in the immediate postoperative period in postamputation patients (Level I), but evidence is low for the prevention of PLP (Level III). Gabapentin did not reduce the incidence or intensity of postamputation pain (Level II). The review in related context mentions evidence regarding therapeutic role of gabapentanoids, peripheral nerve catheters, and psychological therapy in established PLP. In future, randomized controlled trials with long-term follow-up of patients receiving epidural analgesia, perioperative peripheral nerve catheters, oral gabapentanoids, IV ketamine, or mechanism-based modality for prevention of PLP as primary outcome are required.

Intervention for phantom limb pain: A randomized single crossover study of mirror therapy

INTRODUCTION

Mirror therapy suggested to help relieve phantom limb pain (PLP) by resolving the visual- proprioceptive dissociation in the brain, but studies so far either had shorter follow-up or smaller sample size.

MATERIALS AND METHODS

In this randomized single crossover trial, 64 amputees with PLP in the age group of 15-75 years of age were distributed into test and control groups by simple randomization method. Of these 28 in control and 32 in test groups, respectively, completed the 4 weeks of mirror therapy and 12 weeks of follow-up assessments. A standardized set of exercises for 15 min/day for 4 and 8 weeks in test and control groups (in the first 4 weeks, the mirror was covered), respectively, was administered under supervision of one of the authors. All were assessed using the visual analog scale and Short-Form McGill Pain Questionnaire on day 0 and at 4, 8, and 12 weeks after therapy. In control group for the initial 4 weeks, the mirror was covered. The assessing author was blinded to the group to which the participants belonged.

RESULTS

Significant reduction in PLP was noted in the test group at 4 weeks compared to the control group (P < 0.0001). Significant reduction was seen in control group also after the switchover and sustained for 12 weeks in both. No harm was reported.

CONCLUSION

Mirror therapy is effective in relieving the intensity, duration, frequency, and overall PLP, and improvement is maintained up to 12 weeks' posttherapy.

Incidence and Management of Phantom Limb Pain According to World Health Organization Analgesic Ladder in Amputees of Malignant Origin

Antidepressants and anticonvulsants are currently considered to be the drug treatment of choice for neuropathic pain. Opioids are effective in relieving neuropathic pain, including phantom pain in the early postoperative course. The present study of 42 cancer patients with limb amputation was conducted to determine the incidence of phantom limb pain and phantom sensation and to test the utility of the World Health Organization 3-step analgesic ladder in phantom limb pain management. Patients were monitored monthly for the first 2 months postoperatively and every 2 months thereafter for 2 years. The World Health Organization analgesic ladder was followed for pain management. The patients complaining of phantom sensation, phantom pain, and stump pain decreased from 69%, 60%, and 31%, respectively, at 1 month to 32%, 32%, and 5%, at the end of 2 years with the addition of opioids. The World Health Organization analgesic ladder played significant role in phantom limb pain management.

Five early accounts of phantom limb in context: Paré, Descartes, Lemos, Bell, and Mitchell

PHANTOM LIMB WAS described long before American physician and surgeon Silas Weir Mitchell coined the term and drew attention to the disorder in the 1860s. The early descriptions of Ambroise Paré, René Descartes, Aaron Lemos, Charles Bell, and then Mitchell of this strange consequence of amputation are presented in historical and cultural context. These five men described phantom limbs for various reasons. They also differed when it came to explaining and dealing with these illusory sensations. The rich history of phantom limbs can begin to be appreciated by viewing the contributions of these individuals in perspective and by realizing that their writings represent only a fraction of what was published about phantom limbs more than 130 years ago.

Phantom finger phenomena and the effects of toe-to-finger transplantation

Phantom finger phenomena and the effects of toe-to-finger transplantation were studied in 76 patients who had had traumatic finger amputation. Phantom finger phenomena were observed in 48 (63%) patients with the presence of phantom finger only in 30, phantom finger with sensation in nine, and phantom finger with motion also in nine. After toe transplantation, phantom finger phenomena disappeared immediately in about half of the transplanted fingers that had phantom phenomena before toe transplantation, and also in about half of the amputated fingers without the surgery. Conversely, phantom toe phenomena occurred in 13 (17%) patients. Although some patients had mild-to-moderate unpleasant phantom sensations, none had severe or distressing phantom finger pain or phantom toe pain. It is concluded that phantom phenomena occurred in both finger and toe amputations, and that toe-to-finger transplantation appeared to facilitate the disappearance of phantom phenomena not only in the transplanted fingers but also in the amputated but untransplanted fingers. Possible mechanisms for these observations are discussed.

Pathophysiology and management of phantom limb pain

Phantom pain phenomenon is a poorly understood but relatively common sequela of limb amputation that may result in significant psychological and physical morbidity. In this review, proposed pathoneurophysiological mechanisms for the development of phantom pain are reviewed as well as psychological mechanisms that may be involved. The authors recommend an integrated approach to management of chronic phantom pain that takes into consideration the multiple factors that may contribute to its etiology.

The mystery of phantom pain: growing evidence for psychophysiological mechanisms

The direct, and much of the indirect, evidence supporting the existence psychophysiological mechanisms for phantom limb pain is reviewed. Phantom pain is shown to be a symptom class composed of different, but similarly described problems, each having its own underlying mechanisms. At least some descriptive types of phantom pain probably have mainly peripheral, as opposed to only central, origins. Although much of the direct data are preliminary, burning phantom pain is probably related to decreased blood flow in the residual limb, while cramping phantom pain is mainly related to spikelike muscle spasms in the major muscles of the residual limb. Little support is provided for psychological causes for phantom pain, but the expression of phantom pain does appear to be influenced by psychological mechanisms similarly to the ways other chronic pain conditions are influenced. The importance of a careful psychophysiological assessment of patients to treatment success is discussed. Because several different mechanisms are involved, no one treatment is likely to be effective for all of the different types of phantom pain. Appropriate combinations of self-regulation strategies aimed at controlling the underlying physiological problems are likely to be effective in reducing the incidence and severity of burning and cramping types of phantom pain.