Exploring the Role of Cortical Reorganization in Postamputation Phantom Phenomena, Including Phantom Limb Pain in Lower Limb Amputees: A Cross-Sectional Study of the Patterns of Referral of Sensations into the Phantom

The missing link: How is the phantom limb influenced by prosthesis wearing in people with lower-limb amputation?

BACKGROUND

Recent therapeutic and technological solutions aim to improve the daily living of people with limb amputation by considering various aspects of the phantom limb, in particular painless phantom sensations (PS) and voluntary phantom movements (VPM).

OBJECTIVE

Although previous research has explored these phenomena mostly without considering the prosthesis, this study investigates the influence of prosthesis wearing on painless PS, painful PS, and VPM, in people with lower-limb amputation.

STUDY DESIGN

Cross-sectional study based on semi-directed interviews.

METHODS

Semi-directed interviews were conducted with 111 people with major lower-limb amputations. They described their phantom limb without and with the prosthesis, in a static seated position. The influence of the prosthesis wearing on the intensity of painless PS, painful PS, and on VPM ability was classified into 5 categories: disappearance, decrease, modification, increase, and appearance.

RESULTS

Prosthesis wearing leads mostly to an increase of painless PS intensity (44%), a decrease of painful PS intensity (44%), and an improvement of VPM ability (47%). The study also highlights the richness of prosthesis-related changes, including modifications in phantom limb position, shape, and size. The influence of prosthesis wearing on phantom phenomena was not related to the presence of referred sensations, the amputation etiology, the level of amputation, the time since amputation, or the use of medication, but might be related to the pressure applied by the socket on the residual limb.

CONCLUSIONS

This study provides valuable information on the influence of the prosthesis on PS and may allow for better consideration of this relationship in the context of research, engineering, and rehabilitation.

Pain in the Context of Sensory Deafferentation

Pain that accompanies deafferentation is one of the most mysterious and misunderstood medical conditions. Prevalence rates for the assorted conditions vary considerably but the most reliable estimates are greater than 50% for strokes involving the somatosensory system, brachial plexus avulsions, spinal cord injury, and limb amputation, with controversy surrounding the mechanistic contributions of deafferentation to ensuing neuropathic pain syndromes. Deafferentation pain has also been described for loss of other body parts (e.g., eyes and breasts) and may contribute to between 10% and upwards of 30% of neuropathic symptoms in peripheral neuropathies. There is no pathognomonic test or sign to identify deafferentation pain, and part of the controversy surrounding it stems from the prodigious challenges in differentiating cause and effect. For example, it is unknown whether cortical reorganization causes pain or is a byproduct of pathoanatomical changes accompanying injury, including pain. Similarly, ascertaining whether deafferentation contributes to neuropathic pain, or whether concomitant injury to nerve fibers transmitting pain and touch sensation leads to a deafferentation-like phenotype can be clinically difficult, although a detailed neurologic examination, functional imaging, and psychophysical tests may provide clues. Due in part to the concurrent morbidities, the physical, psychologic, and by extension socioeconomic costs of disorders associated with deafferentation are higher than for other chronic pain conditions. Treatment is symptom-based, with evidence supporting first-line antineuropathic medications such as gabapentinoids and antidepressants. Studies examining noninvasive neuromodulation and virtual reality have yielded mixed results.

Phantom Limb Pain and Sensations in Chinese Malignant Tumor Amputees: A Retrospective Epidemiological Study

OBJECTIVE

Phantom limb pain (PLP) was a common problem in malignant tumor amputees that can cause considerable suffering. The purposes of this study were to determine the incidence and factors associated with the occurrence of post-operation PLP, stump limb pain (SLP), and phantom limb sensations (PLS) in tumor amputees within the first month after surgery. Additionally, differences in phantom phenomena between upper and lower extremities were investigated.

METHODS

In total, 162 amputees participated in this retrospective study who underwent malignant limb amputation between 2012 and 2019. Clinical characteristics were collected from medical records and reconfirmed by telephone interviews. A numerical rating scale (NRS) was used to quantitate phantom phenomena. We used analysis of variance and non-parametric statistics for categorical variables and ordinal variables separately.

RESULTS

In the first month after malignant amputation, the incidence of PLP was 54.3%, that of PLS was 65.4%, and that of SLP was 32.7%. The duration of preoperative pain and amputation level was significantly different for the incidence of acute PLP. Further subgroup analysis of amputation level showed that patients whose amputation level was below the wrist and ankle joints had a significantly reduced incidence of PLP (p<0.0083 in Bonferroni test). Binary logistics regression analysis determined that amputation level was the primary risk factor for the incidence of PLP. Factors related to the severity of postoperative PLP also included amputation level, preoperative pain, and amputation times. By comparing the differences between upper and lower limbs after amputation, we found that the incidence of PLS was higher after lower limb amputation, but there was no significant difference in the incidence of PLP and SLP. Preoperative experience of chemotherapy was not a risk factor for PLP.

CONCLUSION

Proximal amputation and long-term preoperative pain seemed to count more for PLP incidence. Further research may be required to individually determine factors associated with the occurrence and chronicity of phantom phenomena.

Prevalence and incidence of phantom limb pain, phantom limb sensations and telescoping in amputees: A systematic rapid review

BACKGROUND AND OBJECTIVE

This systematic, rapid review aimed to critically appraise and synthesize the recent literature (2014-2019) evaluating the incidence and prevalence of post-amputation phantom limb pain (PLP) and sensation (PLS).

DATABASES AND DATA TREATMENT

Five databases (Medline, Embase, Emcare, PsychInfo, Web of Science) and Google Scholar were searched, with two independent reviewers completing eligibility screening, risk of bias assessment and data extraction.

RESULTS

The search identified 1,350 studies with 12 cross-sectional and 3 prospective studies included. Studies evaluated traumatic (n = 5), atraumatic (n = 4), and combined traumatic/atraumatic (n = 6) amputee populations, ranging from 1 month to 33 years post-amputation. Study heterogeneity prevented data pooling. The majority of studies had a high risk of bias, primarily due to limited generalizability. Three studies evaluated PLP incidence, ranging from 2.2% (atraumatic; 1 month) to 41% (combined; 3 months) and 82% (combined; 12 months). Only one study evaluated PLS/telescoping incidence. Across contrasting populations, PLP point prevalence was between 6.7%-88.1%, 1 to 3-month period prevalence was between 49%-93.5%, and lifetime prevalence was high at 76%-87%. Point prevalence of PLS was 32.4%-90%, period prevalence was 65% (1 month) and 56.9% (3 months), and lifetime prevalence was 87%. Telescoping was less prevalent, highest among traumatic amputees (24.6%) within a 1-month prevalence period. Variations in population type (e.g. amputation characteristics) and incidence and prevalence measures likely influence the large variability seen here.

CONCLUSIONS

This review found that lifetime prevalence was the highest, with most individuals experiencing some type of phantom phenomena at some point post-amputation.

SIGNIFICANCE

This systematic rapid review provides a reference for clinicians to make informed prognosis estimates of phantom phenomena for patients undergoing amputation. Results show that most amputees will experience phantom limb pain (PLP) and phantom limb sensations (PLS): high PLP incidence 1-year post-amputation (82%); high lifetime prevalence for PLP (76%-87%) and PLS (87%). Approximately 25% of amputees will experience telescoping. Consideration of individual patient characteristics (cause, amputation site, pre-amputation pain) is pertinent given their likely contribution to incidence/prevalence of phantom phenomena.

Neural Correlates of Esophageal Speech: An fMRI Pilot Study

OBJECTIVES

The esophageal speech is one of the possible alaryngeal voices resulting after total laryngectomy. Its production is made by the regurgitation of the air coming from the esophagus, sonorized through the passage from the walls of the upper esophageal sphincter. The neural correlates of this voice have never been investigated, while the neural control of laryngeal voice has been already documented by different studies.

METHODS

Four patients using esophageal speech after total laryngectomy and four healthy controls underwent functional magnetic resonance imaging. The fMRI experiment was carried out using a "Block Design Paradigm."

RESULTS

Comparison of the phonation task in the two groups revealed higher brain activities in the cingulate gyrus, the cerebellum and the medulla as well as lower brain activities in the precentral gyrus, the inferior and middle frontal gyrus and the superior temporal gyrus in the laryngectomized group.

CONCLUSIONS

The findings in this pilot study provide insight into neural phonation control in laryngectomized patients with esophageal speech. The imaging results demonstrated that in patients with esophageal speech, altered brain activities can be observed. The adaptive changes in the brain following laryngectomy reflect the changes in the body and in the voice modality. In addition, this pilot study establishes that a blocked design fMRI is sensitive enough to define a neural network associated with esophageal voice and lays the foundation for further studies in this field.

An investigation into the effects of a virtual reality system on phantom limb pain: a pilot study

Background

There is no first-line treatment available for phantom limb pain (PLP). For some years, there has been interest in the use of mirrors and other techniques based on visual feedback. Unfortunately, up until now, all published studies have had methodological weaknesses with two recent systematic reviews concluding that therapies of this kind need more evidence to support their use.

Aim

To evaluate the effects of a virtual reality (VR) activity on PLP.

Methods

This was a prospective pilot study of upper limb amputees using questionnaires to evaluate a VR system. Eleven participants were recruited, with nine completing all three sessions of VR. Participants undertook three sessions of VR, one a month for 3 months. Outcome measures were PLP pain intensity using an 11-point numerical rating scale (NRS), number of PLP episodes and duration of the PLP episodes. All participants were also asked for their judgement of change. Open-ended questions captured the qualitative experience of all aspects of the VR experience.

Results

The mean PLP pain score following three VR sessions reduced (6.11 v 3.56) but this was not a statistical difference (t = 2.1, df = 8, p = 0.07). No statistical difference was found for the number of PLP episodes (Pearson chi-square = 3.43, df = 2, p = 0.18) or the duration of each PLP episode (Pearson chi-square = 22.50, df = 16, p = 0.13). Three groups emerged: those whose pain reduced (the majority), those whose pain remained the same (small number) and one those whose pain increased slightly.

Discussion

There is insufficient evidence from these results to identify an effect of VR on PLP; however, this is a small group and qualitatively most were content with the treatment and wanted a longer trial.