Phantom limbs

Perception, action, and the body model

In 1992, Goodale and Milner proposed to study the visual system based on function, thus dissociating vision for perception (ventral stream) and vision for action (dorsal stream). This became known as the Perception and Action model (PAM). Following the PAM in the visual system, a somatosensory PAM was proposed including a body representation for perception and a separate for action. This review explores the body model of the hand and how it relates to the PAM. The body model refers to the internal representation of the body that is responsible for position sense. Previous research has shown that the representation of the hand features systematic distortions: an overestimation of hand width and an underestimation of finger length. These distortions have been reported using different paradigms, different body parts, and in various settings. Thus, body model distortions appear to be a characteristic of human body representation. If the body model of the hand is distorted, how can actions like reaching and grasping be accurate? We review evidence that body model distortions may in fact provide a functional benefit to our actions, that cortical maps in the somatosensory and motor cortices reflect these distortions, and that actions rely on a distorted body model. We argue that the body model is a product of both the ventral and dorsal somatosensory streams. Further, we suggest that the body model is an example of the inextricable link between the two streams.

The Role of Early Rehabilitation and Functional Electrical Stimulation in Rehabilitation for Cats with Partial Traumatic Brachial Plexus Injury: A Pilot Study on Domestic Cats in Portugal

This prospective observational cohort pilot study included 22 cats diagnosed with partial traumatic brachial plexus injury (PTBPI), aiming to explore responses to an early intensive neurorehabilitation protocol in a clinical setting. This protocol included functional electrical stimulation (FES), locomotor treadmill training and kinesiotherapy exercises, starting at the time with highest probability of nerve repair. The synergetic benefits of this multimodal approach were based on the potential structural and protective role of proteins and the release of neurotrophic factors. Furthermore, FES was parametrized according to the presence or absence of deep pain. Following treatment, 72.6% of the cats achieved ambulation: 9 cats within 15 days, 2 cats within 30 days and 5 cats within 60 days. During the four-year follow-up, there was evidence of improvement in both muscle mass and muscle weakness, in addition to the disappearance of neuropathic pain. Notably, after the 60 days of neurorehabilitation, 3 cats showed improved ambulation after arthrodesis of the carpus. Thus, early rehabilitation, with FES applied in the first weeks after injury and accurate parametrization according to the presence or absence of deep pain, may help in functional recovery and ambulation, reducing the probability of amputation.

Giving Up on Consciousness as the Ghost in the Machine

Consciousness as used here, refers to the private, subjective experience of being aware of our perceptions, thoughts, feelings, actions, memories (psychological contents) including the intimate experience of a unified self with the capacity to generate and control actions and psychological contents. This compelling, intuitive consciousness-centric account has, and continues to shape folk and scientific accounts of psychology and human behavior. Over the last 30 years, research from the cognitive neurosciences has challenged this intuitive social construct account when providing a neurocognitive architecture for a human psychology. Growing evidence suggests that the executive functions typically attributed to the experience of consciousness are carried out competently, backstage and outside subjective awareness by a myriad of fast, efficient non-conscious brain systems. While it remains unclear how and where the experience of consciousness is generated in the brain, we suggested that the traditional intuitive explanation that consciousness is causally efficacious is wrong-headed when providing a cognitive neuroscientific account of human psychology. Notwithstanding the compelling 1st-person experience (inside view) that convinces us that subjective awareness is the mental curator of our actions and thoughts, we argue that the best framework for building a scientific account is to be consistent with the biophysical causal dependency of prior neural processes. From a 3rd person perspective, (outside view), we propose that subjective awareness lacking causal influence, is (no more) than our experience of being aware, our awareness of our psychological content, knowing that we are aware, and the belief that that such experiences are evidence of an agentive capacity shared by others. While the human mind can be described as comprising both conscious and nonconscious aspects, both ultimately depend on neural process in the brain. In arguing for the counter-intuitive epiphenomenal perspective, we suggest that a scientific approach considers all mental aspects of mind including consciousness in terms of their underlying, preceding (causal) biological changes, in the realization that most brain processes are not accompanied by any discernible change in subjective awareness.

Comparison of Relative Benefits of Mirror Therapy and Mental Imagery in Phantom Limb Pain in Amputee Patients at a Tertiary Care Center

OBJECTIVE

To determine the relative benefit of mirror therapy and mental imagery in phantom limb pain.

DESIGN

Prospective randomized controlled trial.

SETTING

Physical Medicine and Rehabilitation Department, All India Institute of Medical Sciences, Patna.

PARTICIPANTS

Amputees (N=92) with no significant difference in baseline characteristics. There was a male predominance in both groups (mirror therapy: 36 men, 10 women; mental imagery: 37 men, 9 women).

INTERVENTION

Patients of both groups underwent a conventional amputee rehabilitation program and daily treatment of either mirror therapy or mental imagery on a regular basis, first in a rehabilitation care unit and later at home.

MAIN OUTCOME MEASURES

Phantom limb pain (PLP) was measured by visual analog scale (VAS) score at baseline (0) and at 4, 8, and 12 months.

RESULTS

This study included 92 patients ranging in age from 12 to 75 years (average, 34.79y). There was no significant difference in VAS score between the groups at baseline, but we found a significant reduction of pain in both groups at follow-up. However, upon comparing the improvement in both groups, we determined that the mirror therapy group had better improvement (from 7.07±1.74 to 2.74±0.77) compared with the mental imagery group (from 7.85±0.76 to 5.87±1.41).

CONCLUSIONS

Mirror therapy and mental imagery are both good and cost-effective rehabilitation aids for amputee patients to reduce PLP, but mirror therapy appears to be more effective than mental imagery.

Neuropathic Itch

Neurologic insults as varied as inflammation, stroke, and fibromyalgia elicit neuropathic pain and itch. Noxious sensation results when aberrantly increased afferent signaling reaches percept-forming cortical neurons and can occur due to increased sensory signaling, decreased inhibitory signaling, or a combination of both processes. To treat these symptoms, detailed knowledge of sensory transmission, from innervated end organ to cortex, is required. Molecular, genetic, and behavioral dissection of itch in animals and patients has improved understanding of the receptors, cells, and circuits involved. In this review, we will discuss neuropathic itch with a focus on the itch-specific circuit.

[Amputations around the knee]

An amputation around, through or below the knee joint constitutes a "huge" change in a patient's life. In Orthopaedics, amputations are most frequently performed in cases with musculoskeletal tumours or failed total knee arthroplasty. A multidisciplinary team approach (surgeon, anaesthetist, pain specialists, orthotist, psychologist etc.) and patient-specific treatment regime from the outset as well as a meticulous surgical technique are of the outmost importance. Nowadays, prosthetic legs can be fitted for nearly any amputation level. The functional outcome of amputations below the knee is usually superior to amputations above or through the knee joint. Postoperative stump conditioning is paramount and the final prosthetic leg should not be fitted earlier than 4-6 months postoperatively. Problems with wound healing, muscle contractures and phantom limb pain represent common complications which might adversely affect patient outcomes.

Alterations in Brain Structural Connectivity After Unilateral Upper-Limb Amputation

Previous studies have indicated that amputation induces reorganization of functional brain network. However, the influence of amputation on structural brain network remains unclear. In this study, using diffusion tensor imaging (DTI), we aimed to investigate the alterations in fractional anisotropy (FA) network after unilateral upper-limb amputation. We acquired DTI from twenty-two upper-limb amputees (15 dominant-side and 7 nondominant-side amputees) as well as fifteen healthy controls. Using DTI tractography and graph theoretical approaches, we examined the topological changes in FA network of amputees. Compared with healthy controls, dominant-side amputees showed reduced global mean strength, increased characteristic path length, and decreased nodal strength in the contralateral sensorimotor system and visual areas. In particular, the nodal strength of the contralateral postcentral gyrus was negatively correlated with residual limb usage, representing a use-dependent reorganization. In addition, the nodal strength of the contralateral middle temporal gyrus was positively correlated with the magnitude of phantom limb sensation. Our results suggested a degeneration of FA network after dominant-side upper-limb amputation.

Weight-Discrimination Sensitivity in Congenitally Blind and Sighted Adults

This study compared the weight-discrimination sensitivity of 41 congenitally blind and 41 normally sighted adults. The superior weight-discrimination sensitivity of the congenitally blind subjects suggests that blindness from birth can cause compensatory adaptations within the cutaneous modality.

The burden of amputation in patients with peripheral arterial disease in the Netherlands

INTRODUCTION

Peripheral arterial disease (PAD) can lead to severe cases of critical limb ischemia (CLI), which in turn might lead to amputation. Amputation can have substantial consequences for patients. This publication aims to give a better understanding of the amputation-related burden in patients with PAD in the Netherlands.

EVIDENCE ACQUISITION

A systematic review and grey literature searches were conducted followed by qualitative interviews with a multidisciplinary team of clinical experts in amputation. Subsequently, IQVIA's Dutch hospital claims data were analyzed.

EVIDENCE SYNTHESIS

Twenty-seven publications were identified. Dutch claims data identified claims for 2328 patients after amputation for PAD. Data for the following topics were found: incidence, mortality, complications, mobility, daily functioning, quality of life, utilities, length of stay (LoS), costs, and resource use. Annually, 90% of the 3300 amputations carried out in the Netherlands were due to vascular disease. One-year mortality in patients with an amputation ranged from 49.6% (above-the-knee amputation) to 9% (specialized care). Patients' quality of life was substantially affected and utility of post-major amputation for PAD was 0.54. LoS after amputation varied from 11.4 (general rehabilitation) to 53.4 days (amputation of the leg). Total budget incurred based on frequently claimed DBC's from Dutch claims data in patients with PAD undergoing an amputation over 2012 to 2016 was € 136,651,374. Mean cost per patient was € 17,821.

CONCLUSIONS

Amputation leads to substantial burden in patients with PAD in the Netherlands. Identified results give a better understanding of the specific Dutch burden of amputation.

Can phantom limb pain be reduced/eliminated solely by techniques applied to peripheral nerves?

About 0.5% of the US population (1.7 million) is living with a lost limb and this number is expected to double by 2050. This number is much higher in other parts of the world. Within days to weeks of an extremity amputation, up to 80% of these individuals develop neuropathic pain presenting as phantom limb pain (PLP). The level of PLP increases significantly by one year and remains chronic and severe for about 10% of individuals. PLP has a serious negative impact on individuals’ lives. Current pain treatment therapies, such pharmacological approaches provide limited to no pain relief, some other techniques applied to the central nervous system (CNS) and peripheral nervous system (PNS) reduce or block PLP, but none produces long-term pain suppression. Therefore, new drugs or novel analgesic methods must be developed that prevent PLP from developing, or if it develops, to reduce the level of pain. This paper examines the potential causes of PLP, and present techniques used to prevent the development of PLP, or if it develops, to reduce the level of pain. Finally it presents a novel technique being developed that eliminates/reduces chronic neuropathic pain and which may induce the long-term reduction/elimination of PLP.

Acupuncture Treatment of Phantom Limb Pain and Phantom Limb Sensation in Amputees

Three case histories are presented in which amputees with acute or chronic phantom limb pain and phantom limb sensation were treated with Western medical acupuncture, needling the asymptomatic intact limb. Two out of the three cases reported complete relief of their phantom limb pain and phantom limb sensation. Acupuncture was successful in treating phantom phenomena in two of these cases, but a larger cohort study would be needed to provide more evidence for the success rate of this treatment technique for this indication.

Relief from intractable phantom pain by combining psilocybin and mirror visual-feedback (MVF)

AL's leg was amputated resulting in phantom-limb pain (PLP). (1) When a volunteer placed her foot on or near the phantom - touching it evoked organized sensations in corresponding locations on AL's phantom. (2) Mirror-visual-feedback (MVF) relieved PLP, as did, "phantom massage". (3) Psilocybin-MVF pairing produced synergistic effects, complete elimination of PLP, and reduction in paroxysmal episodes. (4) Touching the volunteer's leg where AL previously had external fixators, evoked sensation of nails boring through the leg. Using a "telescoping" nail, we created the illusion of a nail being removed with corresponding pain relief. (5) Artificial flames produced warmth in the phantom.

Efficacy of eye movement desensitization and reprocessing on the phantom limb pain of patients with amputations within a 24-month follow-up

The aim of this study was to evaluate the efficacy of eye movement desensitization and reprocessing (EMDR) on the phantom limb pain (PLP) of patients with amputations within a 24-month follow-up. This study was a randomized-controlled trial. A total of 60 patients with amputations were selected by a purposive sampling and patients were divided randomly into two experimental and control groups. Samples were assigned through randomized allocation. EMDR therapy was administered individually to the experimental group participants in 12 one-hour sessions over a 1-month period In each session, the patient completed the Subjective Units of Distress Scale and a pain-rating scale before and after the intervention. Follow-up measures were obtained 24 months later for the experimental group. The participants in the control group were measured on the two scales at an initial session and again after 1- and 24-month follow-up. The mean PLP decreased in the experimental group between the first and last sessions and remained so at a 24-month follow-up. No decrease occurred for the control group over the 1- and 24-month period. The differences were statistically significant (P<0.001) according to a repeated-measures analysis of variance. EMDR therapy proved to be a successful treatment for PLP. Because of its efficacy and the fact that the positive effects were maintained at the 24-month follow-up, this therapy is recommended for the treatment of PLP.

Switching to the Rubber Hand

Inducing the rubber hand illusion (RHI) requires that participants look at an imitation hand while it is stroked in synchrony with their occluded biological hand. Previous explanations of the RHI have emphasized multisensory integration, and excluded higher cognitive functions. We investigated the relationship between the RHI and higher cognitive functions by experimentally testing task switch (as measured by switch cost) and mind wandering (as measured by SART score); we also included a questionnaire for attentional control that comprises two subscales, attention-shift and attention-focus. To assess experience of RHI, the Botvinick and Cohen (1998) questionnaire was used and illusion onset time was recorded. Our results indicate that rapidity of onset reliably indicates illusion strength. Regression analysis revealed that participants evincing less switch cost and higher attention-shift scores had faster RHI onset times, and that those with higher attention-shift scores experienced the RHI more vividly. These results suggest that the multi-sensory hypothesis is not sufficient to explain the illusion: higher cognitive functions should be taken into account when explaining variation in the experience of ownership for the rubber hand.

Chasing the Rainbow: The Non-conscious Nature of Being

Despite the compelling subjective experience of executive self-control, we argue that “consciousness” contains no top-down control processes and that “consciousness” involves no executive, causal, or controlling relationship with any of the familiar psychological processes conventionally attributed to it. In our view, psychological processing and psychological products are not under the control of consciousness. In particular, we argue that all “contents of consciousness” are generated by and within non-conscious brain systems in the form of a continuous self-referential personal narrative that is not directed or influenced in any way by the “experience of consciousness.” This continuously updated personal narrative arises from selective “internal broadcasting” of outputs from non-conscious executive systems that have access to all forms of cognitive processing, sensory information, and motor control. The personal narrative provides information for storage in autobiographical memory and is underpinned by constructs of self and agency, also created in non-conscious systems. The experience of consciousness is a passive accompaniment to the non-conscious processes of internal broadcasting and the creation of the personal narrative. In this sense, personal awareness is analogous to the rainbow which accompanies physical processes in the atmosphere but exerts no influence over them. Though it is an end-product created by non-conscious executive systems, the personal narrative serves the powerful evolutionary function of enabling individuals to communicate (externally broadcast) the contents of internal broadcasting. This in turn allows recipients to generate potentially adaptive strategies, such as predicting the behavior of others and underlies the development of social and cultural structures, that promote species survival. Consequently, it is the capacity to communicate to others the contents of the personal narrative that confers an evolutionary advantage—not the experience of consciousness (personal awareness) itself.

The Effect of Prosthesis Use on Hand Mental Rotation After Unilateral Upper-Limb Amputation

Amputation of a limb induces changes in the so-called body schema, which might be influenced by the use of prosthetic devices. Changes in the body representation associated with prosthesis use could be investigated using a hand mental rotation task. However, direct neurophysiologic evidence for the effect of prosthesis use on hand mental rotation is still lacking. In this paper, we recruited two groups of unilateral upper-limb amputees, i.e., amputees using a prosthesis or with a history of prosthesis use (Pro group) and amputees without a prosthesis (non-Pro group), as well as a sample of matched healthy controls. Using concurrent behavioral and electrophysiological assessments, we found that Pro amputees were comparable to healthy controls in either behavior or event-related potentials (ERPs), while non-Pro amputees showed prolonged response time as well as divergent ERP patterns. The P200 amplitude of non-Pro amputees was significantly larger for the non-dominant hand pictures than that for the dominant hand pictures, while such a hand difference in P200 was not found in either healthy controls or Pro amputees. Furthermore, the typical angular modulation of the N200 amplitude in healthy controls and Pro amputees was not presented in non-Pro amputees. Our results suggest that prosthesis use could preserve mental rotation ability by maintaining the performance of motor imagery and visual perception of hands, which represents a preservation of the body schema.

The meaning and consequences of amputation and mastectomy from the perspective of pain and suffering

BACKGROUND

The concepts 'pain' and 'suffering' are frequently treated as synonymous. However, they are clearly distinct phenomena. Phantom phenomena including pain and sensory disturbances are still recognized as long-lasting problems after limb amputation and after mastectomy. The complex nature of phantom phenomena makes the interpretation of its results ambiguous, regarding the prevalence of pain, sensory disturbances and the accompanying suffering. There is clinical experience that suffering is a great burden for the individual but there is a lack of systematic studies of patients' own evaluations of the suffering caused by their phantom phenomena.

OBJECTIVES

The overall aim of this study was to identify and describe patients' suffering related to, and as a part, of their post-amputation situation.

METHODS

The present study constitutes a part of a prospective, two-year follow up project investigating interviews of 28 men and women in different ages and who have undergone a limb amputation or mastectomy. The reason for amputation or mastectomy varied among the patients and included vascular diseases, cancer (sarcoma and breast-cancer) and trauma. Our ambition was to extract as much variations as possible in different, individualized aspects of the actual pain and suffering producing situation. The participants were, here, invited to open-ended, narrative-oriented interviews one month after the surgery. The interviews were transcribed verbatim and analyzed within qualitative methodology: thematic content analysis.

RESULTS

Twenty-two of 28 interviewees experienced phantom pain and phantom sensations. The two surgical processes amputation and mastectomy meant for a majority of the interviewees a critical event with threatening consequences for everyday life such as loss of function and personal integrity. Nine interviewees felt even stigmatized as a result of their lost body part. Numerous inter-related factors following the amputation/mastectomy, which can inflict severe suffering on the amputee, were uncovered. The context in which the interviewees were informed about the decision to amputate proved to be one such critical and important factor.

CONCLUSION

To understand potential suffering in relation to phantom phenomena, it will never be enough merely to have knowledge of the underlying physiological or neurological mechanisms and/or the intensity of phantom pain and phantom sensations. Rather, it is necessary to find out how the loss of the body part and its everyday consequences are experienced by patients.

IMPLICATIONS

It is important to create time for real dialogue with the patients both during pre-operative preparation and post-operative rehabilitation in order to clarify and verbalize elements that constitute the patients individual suffering. Hopefully this strategy can alleviate future chronic pain problems, severe psycho-social distress and suffering. Such an approach ought to have impact also for perceived suffering after other types of surgery or different invasive treatments.

Psychophysical Evaluation of the Capability for Phantom Limb Movement in Forearm Amputees

A phantom limb is the sensation that an amputated limb is still attached to the body and is moving together with other body parts. Phantom limb phenomenon is often described on the basis of the patient’s subjective sense, for example as represented using a visual analog scale (VAS). The aim of this study was to propose a novel quantification method for behavioral aspect of phantom limb by psychophysics. Twelve unilateral forearm amputees were asked to perform phantom wrist motion with various motion frequencies (60, 80, 100, 120, 140, 160, 180, 200, 220, 240% of preferred speed). The attainment of phantom limb motion in each session was rated by the VAS ranging from 0 (hard) to 10 (easy). The relationship between the VAS and motion frequency was mathematically fitted by quadric function, and the value of shift and the degree of steepness were obtained as evaluation variables for the phantom limb movement. In order to test whether the proposed method can reasonably quantify the characteristics of phantom limb motion, we compared the variables among three different phantom limb movement conditions: (1) unilateral (phantom only), (2) bimanual, and (3) bimanual wrist movement with mirror reflection-induced visual feedback (MVF). While VAS rating showed a larger extent of inter- and intra-subject variability, the relationship of the VAS in response to motion frequency could be fitted by quadric curve, and the obtained parameters based on quadric function well characterize task-dependent changes in phantom limb movement. The present results suggest the potential usefulness of psychophysical evaluation as a validate assessment tool of phantom limb condition.

Distorted body representations in healthy cognition

Delusions and misperceptions about the body are a conspicuous feature of numerous neurological and psychiatric conditions. In stark contrast to such pathological cases, the immediacy and familiarity of our ordinary experience of our body can make it seem as if our representation of our body is highly accurate, even infallible. Recent research has begun to demonstrate, however, that large and systematic distortions of body representation are a normal part of healthy cognition. Here, I describe this research, focusing on distortions of body representations underlying tactile distance perception and position sense. I also discuss evidence for distortions of higher-order body representations, such as the conscious body image. Finally, I will end with a discussion of the potential relations among different body representations and their distortions.

Phantom limb perception interferes with motor imagery after unilateral upper-limb amputation

A potential contributor to impaired motor imagery in amputees is an alteration of the body schema as a result of the presence of a phantom limb. However, the nature of the relationship between motor imagery and phantom experiences remains unknown. In this study, the influence of phantom limb perception on motor imagery was investigated using a hand mental rotation task by means of behavioral and electrophysiological measures. Compared with healthy controls, significantly prolonged response time for both the intact and missing hand were observed specifically in amputees who perceived a phantom limb during the task but not in amputees without phantom limb perception. Event-related desynchronization of EEG in the beta band (beta-ERD) in central and parietal areas showed an angular disparity specifically in amputees with phantom limb perception, with its source localized in the right inferior parietal lobule. The response time as well as the beta-ERD values were significantly positively correlated with phantom vividness. Our results suggest that phantom limb perception during the task is an important interferential factor for motor imagery after amputation and the interference might be related to a change of the body representation resulting from an unnatural posture of the phantom limb.

Perceptual and Conceptual Distortions of Implicit Hand Maps

Recent studies have revealed that human position sense relies on a massively distorted representation of hand size and shape. By comparing the judged location of landmarks on an occluded hand, Longo and Haggard (2010) constructed implicit perceptual maps of represented hand structure, showing large underestimation of finger length and overestimation of hand width. Here, we investigated the contribution of two potential sources of distortions to such effects: perceptual distortions reflecting spatial warping of the representation of bodily tissue itself, perhaps reflecting distortions of somatotopic cortical maps, and conceptual distortions reflecting mistaken beliefs about the locations of different landmarks within the body. In Experiment 1 we compared distorted hand maps to a task in which participants explicitly judged the location of their knuckles in a hand silhouette. The results revealed the conceptual distortions are responsible for at least part of the underestimation of finger length, but cannot explain overestimation of hand width. Experiment 2 compared distortions of the participant’s own hand based on position sense with a prosthetic hand based on visual memory. Underestimation of finger length was found for both hands, providing further evidence that it reflects a conceptual distortion. In contrast, overestimation of hand width was specific to representation of the participant’s own hand, confirming it reflects a perceptual distortion. Together, these results suggest that distorted body representations do not reflect a single underlying cause. Rather, both perceptual and conceptual distortions contribute to the overall configuration of the hand representation.

Crossmodal illusions in neurorehabilitation

In everyday life, many diverse bits of information, simultaneously derived from the different sensory channels, converge into discrete brain areas, and are ultimately synthetized into unified percepts. Such multisensory integration can dramatically alter the phenomenal experience of both environmental events and our own body. Crossmodal illusions are one intriguing product of multisensory integration. This review describes and discusses the main clinical applications of the most known crossmodal illusions in rehabilitation settings. We consider evidence highlighting the contribution of crossmodal illusions to restore, at least in part, defective mechanisms underlying a number of disorders of body representation related to pain, sensory, and motor impairments in neuropsychological and neurological diseases, and their use for improving neuroprosthetics. This line of research is enriching our understanding of the relationships between multisensory functions and the pathophysiological mechanisms at the basis of a number of brain disorders. The review illustrates the potential of crossmodal illusions for restoring disarranged spatial and body representations, and, in turn, different pathological symptoms.

Perceptions of phantom limb pain in lower limb amputees and its effect on quality of life: a qualitative study

BACKGROUND

Phantom limb pain (PLP) is a prevalent complication post-amputation. Currently, qualitative literature exploring the experience of PLP in amputees is sparse, and little is known about whether the educational needs of amputees are being met.

OBJECTIVES

To explore lower limb amputees' descriptive lived experiences of PLP, to understand how PLP affects quality of life and to determine whether amputees feel they are provided with adequate information about PLP.

METHODS

A qualitative descriptive approach, situated under the constructivist paradigm was taken, consisting of cross-sectional semi-structured interviews. A purposive sample of 15 lower limb amputees, 1-3 months post-surgery with past or current experience of PLP were interviewed once about their experience of PLP. Interviews were audio-recorded, transcribed verbatim and analysed using Framework Analysis. Interviews were conducted while participants were inpatients at an amputee rehabilitation unit in London.

RESULTS

Six key themes were identified during analysis, of which three were related to PLP and are reported on in this article (real and physical phantoms, living with a phantom and being informed). PLP had numerous painful qualities. The phantom felt real, with kinetic and kinaesthetic properties. PLP had multiple meanings to amputees, was considered a reminder of circumstances and could affect quality of life. Information provided about PLP was inadequate.

CONCLUSION

PLP can be a severe and annoying experience acting as a reminder of amputees' circumstances. Information provided about PLP is inadequate, with some amputees still perceiving PLP as mental and imaginary. Education about PLP and awareness and accessibility to non-pharmacological interventions needs to be improved.

Etiology of phantom limb syndrome: Insights from a 3D default space consciousness model

In this article, we examine phantom limb syndrome to gain insights into how the brain functions as the mind and how consciousness arises. We further explore our previously proposed consciousness model in which consciousness and body schema arise when information from throughout the body is processed by corticothalamic feedback loops and integrated by the thalamus. The parietal lobe spatially maps visual and non-visual information and the thalamus integrates and recreates this processed sensory information within a three-dimensional space termed the "3D default space." We propose that phantom limb syndrome and phantom limb pain arise when the afferent signaling from the amputated limb is lost but the neural circuits remain intact. In addition, integration of conflicting sensory information within the default 3D space and the loss of inhibitory afferent feedback to efferent motor activity from the amputated limb may underlie phantom limb pain.

Developing An Acupuncture Protocol for Treating Phantom Limb Pain: A Delphi Consensus Study

Background

Little is known about how a Traditional Chinese Medicine (TCM) approach could be used to treat phantom limb pain (PLP). There is currently no standard acupuncture protocol in the literature to treat this syndrome.

Objectives

To achieve consensus among a group of acupuncture practitioners on the pathology and recommended treatment of PLP and devise an acupuncture protocol for the treatment of this condition.

Methods

A classical Delphi approach was used using two parallel online Delphi studies. One study focused on participants with past experience of treating PLP (TPLP, n=7) and the other on practitioners with no past experience (NTPLP, n=16). Two hypothetical case studies were provided and participants were asked for responses on how they would treat these patients. Three rounds were included. Participants were also invited to rate and comment on the finalised protocol. Round 1 data were analysed using content analysis. In subsequent rounds an a priori criterion for defining consensus was set at ≤1.75 IQR. A group median of 5–6 was considered to mean ‘agree’.

Results

19 participants completed all Delphi rounds (12 NTPLP, 7 TPLP). 108 NTPLP and 76 TPLP statements were generated and circulated in round 2; 53% of the NTPLP statements and 62% of the TPLP statements met consensus in round 2 and 45% of the NTPLP statements and 44% of the TPLP statements met consensus in round 3. Participants all agreed with the final protocol developed.

Conclusions

The protocol developed does not claim to be best practice but provides a preliminary consensus from practitioners practising acupuncture for the treatment of PLP.

"Imprisoned" in pain: analyzing personal experiences of phantom pain

This article explores the phenomenon of "phantom pain." The analysis is based on personal experiences elicited from individuals who have lost a limb or live with a paralyzed body part. Our study reveals that the ways in which these individuals express their pain experience is an integral aspect of that experience. The material consists of interviews undertaken with men who are living with phantom pain resulting from a traumatic injury. The phenomenological analysis is inspired by Zahavi (J Conscious Stud 8(5-7):151-167, 2001) and Merleau-Ponty (Phenomenology of perception. Routledge and Kegan Paul, London, 1962/2000). On a descriptive level the metaphors these patients invoke to describe their condition reveal immense suffering, such as a feeling of being invaded by insects or of their skin being scorched and stripped from their body. Such metaphors express a dimension of experience concerning the self that is in pain and others whom the sufferer relates to through this pain, as well as the agony that this pain inflicts in the world of lived experience. This pain has had a profound impact on their lives and altered their relationship with self (body), others and the world. Their phantom pain has become a reminder of their formerly intact and functioning body; they describe the contrast between their past and present body as an ambiguous and disturbing experience. We conclude that these sensitive and personalized experiences of phantom pain illuminates how acts of expression--spoken pain--constitute a fundamental dimension of a first-person perspective which contribute to the field of knowledge about "phantom pain".

Inter-individual difference in the effect of mirror reflection-induced visual feedback on phantom limb awareness in forearm amputees

Objective

To test whether the phantom limb awareness could be altered by observing mirror reflection-induced visual feedback (MVF) in unilateral forearm amputees.

Methods

Ten unilateral forearm amputees were asked to perform bilateral (intact and phantom) synchronous wrist motions with and without MVF. During wrist motion, electromyographic activities in the extensor digitorum longus (EDL) and flexor carpi radialis muscles (FCR) were recorded with bipolar electrodes. Degree of wrist range of motion (ROM) was also recorded by electrogoniometry attached to the wrist joint of intact side. Subjects were asked to answer the degree of attainment of phantom limb motion using a visual analog scale (VAS: ranging from 0 (hard) to 10 (easy)).

Results

VAS and ROM were significantly increased by utilizing MVF, and the extent of an enhancement of the VAS and wrist ROM was positively correlated (r = 0.72, p<0.05). Although FCR EMG activity also showed significant enhancement by MVF, this was not correlated with the changes of VAS and ROM. Interestingly, while we found negative correlation between EDL EMG activity and wrist ROM, MVF generally affected to be increasing both EDL EMG and ROM.

Conclusions

Although there was larger extent of variability in the effect of MVF on phantom limb awareness, MVF has a potential to enhance phantom limb awareness, in case those who has a difficulty for the phantom limb motion. The present result suggests that the motor command to the missing limb can be re-activated by an appropriate therapeutic strategy such as mirror therapy.

Phantom phenomena – Their perceived qualities and consequences from the patient’s perspective

Background and aim

The curious phenomenon phantom limbs early became the object of research, and its underlying mechanisms have been discussed over the years. The complex nature of phantom phenomena makes interpretation of the results ambiguous, regarding both prevalence and the accompanying suffering. There is a lack of knowledge about how amputees experience the meaning and consequences of phantom phenomena. The present aim, therefore, was to investigate how individuals, in an interview situation, described the qualities of possible perceived phantom phenomena, and how their experience affected their lives one month after the amputation/mastectomy.

Methods

Twenty-eight women and men who had undergone a limb amputation or mastectomy were interviewed. The focused, narrative-oriented interviews were transcribed verbatim and the scripts were analysed with content analysis.

Results

One month after the amputation the informants described and related their phantom pain and phantom sensations in sensory-discriminative, motivational-affective and cognitive-evaluative dimensions. The phantom sensations were experienced mainly as more agonizing than the phantom pain.

Despite both the high intensity of and the high annoyance at the phantom pain and phantom sensations, a majority felt that the phantom phenomena were not a hindrance in their attempts to recapture ordinary life. But when the hindrance was evaluated as high, the annoyance was evaluated as the highest possible for both phenomena or for the phantom sensations alone, never for phantom pain alone. The interviewees’ reported attitudes of hindrance were also described and estimated in the light of their sociocultural circumstances. Thus, other preceding and/or co-existent pain conditions as well as factors such as pre-operative information, the respondents’ views on pain treatment, and their knowledge and understanding of phantom phenomena were mentioned and related to the pain-producing situation.

Two-thirds of the interviewees had received post-surgical information and for some, the phenomena were well-known from earlier experience. A majority applied some version of the medical explanation model, irrespective of age or level of education. However neither information nor medical explanation, or both, sufficed for them to understand their own phantom phenomena. Thus, differences between the concepts explanation and understanding seemed significant for the annoyance related to the phantom phenomena.

Regarding background data

(i) the majority of the interviewees had had pre-amputation pain problems; (ii) the breast-cancer phantoms differed in several ways; (iii) there were some age and gender differences in the descriptions of hindrance.

Conclusions and implications

These findings highlight the importance of observing the individual approach to the phenomena as a process of evaluation and selection. In addition, experience and understanding of the phantoms also have sociocultural aspects. There follows the need for individualized communication and information from the clinician, and for incorporating a socioscientific and meaning-centred approach in future studies. The present insights could also be of value in other iatrogenic pain conditions.

Disentangling motor execution from motor imagery with the phantom limb

Amputees can move their phantom limb at will. These 'movements without movements' have generally been considered as motor imagery rather than motor execution, but amputees can in fact perform both executed and imagined movements with their phantom and they report distinct perceptions during each task. Behavioural evidence for this dual ability comes from the fact that executed movements are associated with stump muscle contractions whereas imagined movements are not, and that phantom executed movements are slower than intact hand executed movements whereas the speed of imagined movements is identical for both hands. Since neither execution nor imagination produces any visible movement, we hypothesized that the perceptual difference between these two motor tasks relies on the activation of distinct cerebral networks. Using functional magnetic resonance imaging and changes in functional connectivity (dynamic causal modelling), we examined the activity associated with imagined and executed movements of the intact and phantom hands of 14 upper-limb amputees. Distinct but partially overlapping cerebral networks were active during both executed and imagined phantom limb movements (both performed at the same speed). A region of interest analysis revealed a 'switch' between execution and imagination; during execution there was more activity in the primary somatosensory cortex, the primary motor cortex and the anterior lobe of the cerebellum, while during imagination there was more activity in the parietal and occipital lobes, and the posterior lobe of the cerebellum. In overlapping areas, task-related differences were detected in the location of activation peaks. The dynamic causal modelling analysis further confirmed the presence of a clear neurophysiological distinction between imagination and execution, as motor imagery and motor execution had opposite effects on the supplementary motor area-primary motor cortex network. This is the first imaging evidence that the neurophysiological network activated during phantom limb movements is similar to that of executed movements of intact limbs and differs from the phantom limb imagination network. The dual ability of amputees to execute and imagine movements of their phantom limb and the fact that these two tasks activate distinct cortical networks are important factors to consider when designing rehabilitation programmes for the treatment of phantom limb pain.

Phantom pain reduction by low-frequency and low-intensity electromagnetic fields

Although various treatments have been presented for phantom pain, there is little proof supporting the benefits of pharmacological treatments, surgery or interventional techniques, electroconvulsive therapy, electrical nerve stimulation, far infrared ray therapy, psychological therapies, etc. Here, we report the preliminary results for phantom pain reduction by low-frequency and intensity electromagnetic fields under clinical circumstances. Our method is called as Electromagnetic-Own-Signal-Treatment (EMOST). Fifteen people with phantom limb pain participated. The patients were treated using a pre-programmed, six sessions. Pain intensity was quantified upon admission using a 0-10 verbal numerical rating scale. Most of the patients (n = 10) reported a marked reduction in the intensity of phantom limb pain. Several patients also reported about improvement in their sleep and mood quality, or a reduction in the frequency of phantom pain after the treatments. No improvements in the reduction of phantom limb pain or sleep and mood improvement were reported in the control group (n = 5). Our nonlinear electromagnetic EMOST method may be a possible therapeutic application in the reduction of phantom limb pain. Here, we also suggest that some of the possible effects of the EMOST may be achieved via the redox balance of the body and redox-related neural plasticity.

The moving phantom: motor execution or motor imagery?

Amputees who have a phantom limb often report the ability to move this phantom voluntarily. In the literature, phantom limb movements are generally considered to reflect motor imagery rather than motor execution. The aim of this study was to investigate whether amputees distinguish between executing a movement of the phantom limb and imagining moving the missing limb. We examined the capacity of 19 upper-limb amputees to execute and imagine movements of both their phantom and intact limbs. Their behaviour was compared with that of 18 age-matched normal controls. A global questionnaire-based assessment of imagery ability and timed tests showed that amputees can indeed distinguish between motor execution and motor imagery with the phantom limb, and that the former is associated with activity in stump muscles while the latter is not. Amputation reduced the speed of voluntary movements with the phantom limb but did not change the speed of imagined movements, suggesting that the absence of the limb specifically affects the ability to voluntarily move the phantom but does not change the ability to imagine moving the missing limb. These results suggest that under some conditions, for example amputation, the predicted sensory consequences of a motor command are sufficient to evoke the sensation of voluntary movement. They also suggest that the distinction between imagined and executed movements should be taken into consideration when designing research protocols to investigate the analgesic effects of sensorimotor feedback.

The menacing phantom: what pulls the trigger?

Phantom phenomena are frequent following amputation, but how this often painful experience is modified or triggered by spontaneous events or sensations often puzzles amputees and clinicians alike. We explored triggers of phantom phenomena in a heterogeneous sample of 264 upper and lower limb adult amputees with phantom sensations. Participants completed a structured questionnaire to determine the prevalence and nature of the triggers of phantom phenomena. The four categories of triggers identified include: (a) a quarter of participants experiencing psychological, emotional or autonomic triggers; (b) half experiencing behavioral triggers, "forgetting" the limb's absence and attempting to use the phantom; (c) one-fifth experiencing weather-induced triggers; and (d) one-third experiencing sensations referred from parts of the body. Upper limb amputees; and were more likely to experience weather-induced phantom phenomena than lower limb amputees; and upper and lower limb amputees were equally likely to experience referred sensations from the genitals, contradicting the homuncular remapping hypothesis. Traumatic amputees were more likely to report emotional triggers. Further, while those with emotional triggers exhibited poorer acceptance of the limitations of amputation, they were more likely to employ adaptive coping mechanisms. Finally, habitual "forgetting" behaviors were most common soon after amputation, whereas other more adaptive schemata (e.g., self-defense) were equally likely to be performed at any time following amputation. Various likely inter-related mechanisms are discussed in relation to phantom triggers. Ultimately, optimizing stump and neuroma management, as well as restoring function of central networks for pain, limb movement, and amputation-related memories, should help manage spontaneously triggered phantom phenomena.

A multisensory investigation of the functional significance of the "pain matrix"

Functional neuroimaging studies in humans have shown that nociceptive stimuli elicit activity in a wide network of cortical areas commonly labeled as the "pain matrix" and thought to be preferentially involved in the perception of pain. Despite the fact that this "pain matrix" has been used extensively to build models of where and how nociception is processed in the human brain, convincing experimental evidence demonstrating that this network is specifically related to nociception is lacking. The aim of the present study was to determine whether there is at least a subset of the "pain matrix" that responds uniquely to nociceptive somatosensory stimulation. In a first experiment, we compared the fMRI brain responses elicited by a random sequence of brief nociceptive somatosensory, non-nociceptive somatosensory, auditory and visual stimuli, all presented within a similar attentional context. We found that the fMRI responses triggered by nociceptive stimuli can be largely explained by a combination of (1) multimodal neural activities (i.e., activities elicited by all stimuli regardless of sensory modality) and (2) somatosensory-specific but not nociceptive-specific neural activities (i.e., activities elicited by both nociceptive and non-nociceptive somatosensory stimuli). The magnitude of multimodal activities correlated significantly with the perceived saliency of the stimulus. In a second experiment, we compared these multimodal activities to the fMRI responses elicited by auditory stimuli presented using an oddball paradigm. We found that the spatial distribution of the responses elicited by novel non-target and novel target auditory stimuli resembled closely that of the multimodal responses identified in the first experiment. Taken together, these findings suggest that the largest part of the fMRI responses elicited by phasic nociceptive stimuli reflects non nociceptive-specific cognitive processes.

Factors associated with phantom limb pain: a 3½-year prospective study

Objective: To analyse the prevalence of phantom (limb) pain over time and to analyse factors associated with phantom (limb) pain in a prospective cohort of amputees.

Design: A multicentre longitudinal study.

Patients: One hundred and thirty-four patients scheduled for amputation were included.

Methods: Patients filled in questionnaires before amputation, and postal questionnaires six months, 1½ years and 2½ years to a maximum of 3½ years after amputation. Preoperative assessment included patients’ characteristics, date, side and level of, and reason for amputation. The follow-up questionnaires assessed the frequencies of the experienced phantom pain, prosthetic use and walking distance. The occurrence of phantom pain was defined as phantom pain a few times a day or more frequently.

Results: Pre- and postoperative questionnaires were available filled in by 85 amputees (33 females and 52 males). The percentage of lower limb amputees with phantom pain was the highest at six months after amputation, and of upper limb amputees at 1½ years. In general, more women than men experienced phantom pain. One and a half years and 2½ years after amputation the highest percentages of the lower limb amputees used their prosthesis more than 4 hours a day (66%), after that time this percentage decreased to 60%. The results of the two-level logistic regression analysis to predict phantom pain show that phantom pain was less frequently present in men (odds ratio (OR) = 0.12), in lower limb amputees (OR = 0.14) and that it decreased in due course (OR = 0.53 for 1 year).

Conclusion: Protective factors for phantom pain are: being male, having a lower limb amputation and the time elapsed since amputation.

A perspective for viewing the history of psychophysics

Fechner's conception of psychophysics included both “outer psychophysics” the relation between stimulus intensity and the response reflecting sensation strength, and “inner psychophysics” the relation between neurelectric responses and sensation strength. In his own time outer psychophysics focussed on the form of the psychophysical law, with Fechner espousing a logarithmic law, Delboeuf a variant of the logarithmic law incorporating a resting level of neural activity, and Plateau a power law. One of the issues on which the dispute was focussed concerned the appearance of contrasts if the overall illumination was increased or decreased; another issue was the question of whether a sensation of a “just noticeable difference” established for one value of a sensory dimension appeared the same for a value elsewhere on the dimension. The development of “inner psychophysics” led through the works of Delboeuf, Solomons, Jastrow, and Thurstone to modern signal detection theory. A third line of research, devoted to the question of what was meant by the “measurement” of sensation strength, stemmed from the criticism of Fechner's work by von Kries (1882) and others. Although a valid body of science could be built up without the intervening variable called “sensation strength,” such a science might be a cumbersome representation of reality. When an optical contrast is set up, and its overall illumination is increased or decreased, subjective contrasts involving medium levels of lightness vary little as illumination varies (as a power law based on sensation ratios or a logarithmic law based on sensation differences predict), but subjective contrasts involving extreme levels of lightness might be subject to the effects of other variables.