Benchmarking Residual Limb Pain and Phantom Limb Pain in Amputees through a Patient-reported Outcomes Survey

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.

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.

Examining patient reported outcome measures for phantom limb pain: measurement use in a sample of Veterans with amputation

PURPOSE

Phantom limb pain (PLP) is treated with medications and non-drug treatments. Best clinical practices for measuring treatment outcomes have not been defined. The objective of this study was to evaluate the internal consistency of patient-reported outcomes measures (PROMs) in a sample of Veterans with lower limb amputation.

MATERIALS AND METHODS

The Veteran phone survey included administering PROMs [1) PLP numeric rating scale (NRS), 2) general pain NRS, 3) Pain, Enjoyment, and General Activity (PEG) scale, 4) Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference Short Form 6b Replacement, 5) PROMIS Short Form Depression 4a and 6) PROMIS Short Form Anxiety 4a].

RESULTS

Fifty Veterans (48 male, 2 female; average age: 66 years) completed PROMs. In our sample, 40 Veterans (80%) experienced PLP with an average PLP NRS of 5 (±3.4). Internal consistency of each measure was good to excellent based on Cronbach's alpha co-efficient of >0.80. Correlations were moderate between PLP NRS and all other measures (≤0.32). Although many Veterans expressed bothersome PLP, the scores reflecting pain interference and impact on function were lower than pain intensity. Consistent use of outcome measures is needed to determine the effect of interventions for amputation-related pain.

Phantom Limb Pain and Painful Neuroma After Dysvascular Lower-Extremity Amputation: A Systematic Review and Meta-Analysis

BACKGROUND

Phantom limb pain (PLP) and symptomatic neuroma can be debilitating and significantly impact the quality of life of amputees. However, the prevalence of PLP and symptomatic neuromas in patients following dysvascular lower limb amputation (LLA) has not been reliably established. This systematic review and meta-analysis evaluates the prevalence and incidence of phantom limb pain and symptomatic neuroma after dysvascular LLA.

METHODS

Four databases (Embase, MEDLINE, Cochrane Central, and Web of Science) were searched on October 5th, 2022. Prospective or retrospective observational cohort studies or cross-sectional studies reporting either the prevalence or incidence of phantom limb pain and/or symptomatic neuroma following dysvascular LLA were identified. Two reviewers independently conducted the screening, data extraction, and the risk of bias assessment according to the PRISMA guidelines. To estimate the prevalence of phantom limb pain, a meta-analysis using a random effects model was performed.

RESULTS

Twelve articles were included in the quantitative analysis, including 1924 amputees. A meta-analysis demonstrated that 69% of patients after dysvascular LLA experience phantom limb pain (95% CI 53-86%). The reported pain intensity on a scale from 0-10 in LLA patients ranged between 2.3 ± 1.4 and 5.5 ± .7. A single study reported an incidence of symptomatic neuroma following dysvascular LLA of 5%.

CONCLUSIONS

This meta-analysis demonstrates the high prevalence of phantom limb pain after dysvascular LLA. Given the often prolonged and disabling nature of neuropathic pain and the difficulties managing it, more consideration needs to be given to strategies to prevent it at the time of amputation.

Healthcare Utilization Following Hemipelvectomy or Hip Disarticulation in the Military Health System

INTRODUCTION

Amputations at the hip and pelvic level are often performed secondary to high-energy trauma or pelvic neoplasms and are frequently associated with a prolonged postoperative rehabilitation course that involves a multitude of health care providers. The purpose of this study was to examine the health care utilization of patients with hip- and pelvic-level amputations that received care in the U.S. Military Health System.

MATERIALS AND METHODS

We performed a retrospective review of all patients who underwent a hip- or pelvic-level amputation in the Military Health System between 2001 and 2017. We compiled and reviewed all inpatient and outpatient encounters during three time points: (1) 3 months pre-amputation to 1 day pre-amputation, (2) the day of amputation through 12 months post-amputation, and (3) 13-24 months post-amputation. Health care utilization was defined as the average number of encounter days/admissions for each patient. Concomitant diagnoses following amputation including post-traumatic stress disorder, traumatic brain injury, anxiety, depression, and chronic pain were also recorded.

RESULTS

A total of 106 individuals with hip- and pelvic-level amputations were analyzed (69 unilateral hip disarticulation, 6 bilateral hip disarticulations, 27 unilateral hemipelvectomy, 2 bilateral hemipelvectomies, and 2 patients with a hemipelvectomy and contralateral hip disarticulation). Combat trauma contributed to 61.3% (n = 65) of all amputations. During the time period of 3 months pre-amputation, patients had an average of 3.8 encounter days. Following amputation, health care utilization increased in both the year following amputation and the time period of 13-24 months post-amputation, averaging 170.8 and 77.4 encounter days, respectively. Patients with trauma-related amputations averaged more total encounter days compared to patients with disease-related amputations in the time period of 12 months following amputation (203.8 vs.106.7, P < .001) and the time period of 13-24 months post-amputation (92.0 vs. 49.0, P = .005). PTSD (P = .02) and traumatic brain injuries (P < .001) were more common following combat-related amputations.

CONCLUSIONS

This study highlights the increased health care resource demand following hip- and pelvic-level amputations in a military population, particularly for those patients who sustained combat-related trauma. Additionally, patients with combat-related amputations had significantly higher rates of concomitant PTSD and traumatic brain injury. Understanding the extensive needs of this unique patient population helps inform providers and policymakers on the requirements for providing high-quality care to combat casualties.

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.

Targeted muscle reinnervation and regenerative peripheral nerve interfaces for pain prophylaxis and treatment: A systematic review

OBJECTIVE

Nerve pain frequently develops following amputations and peripheral nerve injuries. Two innovative surgical techniques, targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNI), are rapidly gaining popularity as alternatives to traditional nerve management, but their effectiveness is unclear.

LITERATURE SURVEY

A review of literature pertaining to TMR and RPNI pain results was conducted. PubMed and MEDLINE electronic databases were queried.

METHODOLOGY

Studies were included if pain outcomes were assessed after TMR or RPNI in the upper or lower extremity, both for prophylaxis performed at the time of amputation and for treatment of postamputation pain. Data were extracted for evaluation.

SYNTHESIS

Seventeen studies were included, with 14 evaluating TMR (366 patients) and three evaluating RPNI (75 patients). Of these, one study was a randomized controlled trial. Nine studies had a mean follow-up time of at least 1 year (range 4-27.6 months). For pain treatment, TMR and RPNI improved neuroma pain in 75%-100% of patients and phantom limb pain in 45%-80% of patients, averaging a 2.4-6.2-point reduction in pain scores on the numeric rating scale postoperatively. When TMR or RPNI was performed prophylactically, many patients reported no neuroma pain (48%-100%) or phantom limb pain (45%-87%) at time of follow-up. Six TMR studies reported Patient-Reported Outcomes Measurement Information System (PROMIS) scores assessing pain intensity, behavior, and interference, which consistently showed a benefit for all measures. Complication rates ranged from 13% to 31%, most frequently delayed wound healing.

CONCLUSIONS

Both TMR and RPNI may be beneficial for preventing and treating pain originating from peripheral nerve dysfunction compared to traditional techniques. Randomized trials with longer term follow-up are needed to directly compare the effectiveness of TMR and RPNI with traditional nerve management techniques.

Outcomes of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces for Chronic Pain Control in the Oncologic Amputee Population

BACKGROUND

Outcomes of targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) in the oncologic population are limited. We sought to examine the safety and effectiveness of TMR and RPNI in controlling postamputation pain in the oncologic population.

STUDY DESIGN

A retrospective cohort study of consecutive patients who underwent oncologic amputation followed by immediate TMR or RPNI was conducted from November 2018 to May 2022. The primary study outcome was postamputation pain, assessed using the Numeric Pain Scale and Patient-Reported Outcomes Measurement Information System (PROMIS) for residual limb pain (RLP) and phantom limb pain (PLP). Secondary outcomes included postoperative complications, tumor recurrence, and opioid use.

RESULTS

Sixty-three patients were evaluated for a mean follow-up period of 11.3 months. The majority of patients (65.1%) had a history of previous limb salvage. At final follow-up, patients had an average Numeric Pain Scale score for RLP of 1.3 ± 2.2 and for PLP, 1.9 ± 2.6. The final average raw PROMIS measures were pain intensity 6.2 ± 2.9 (T-score 43.5), pain interference 14.6 ± 8.3 (T-score 55.0), and pain behavior 39.0 ± 22.1 (T-score 53.4). Patient opioid use decreased from 85.7% preoperatively to 37.7% postoperatively and morphine milligram equivalents decreased from a mean of 52.4 ± 53.0 preoperatively to 20.2 ± 38.4 postoperatively.

CONCLUSIONS

In the oncologic population TMR and RPNI are safe surgical techniques associated with significant reductions in RLP, PLP, and improvements in patient-reported outcomes. This study provides evidence for the routine incorporation of TMR and RPNI in the multidisciplinary care of oncologic amputees.

Free Fillet Flap of Lower Extremity: 38 Amputations with Seven Examples of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces

BACKGROUND

Extremely high-level lower extremity amputations are rare procedures that require significant soft-tissue and bony reconstruction. This study describes the use of fillet flaps for oncologic reconstruction and the incorporation of targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNIs) for chronic pain prevention.

METHODS

The authors performed a retrospective review of patients who underwent lower extremity fillet flaps at MD Anderson Cancer Center from January of 2004 through April of 2021. Surgical outcomes were summarized and compared. Numeric rating scale and patient-reported outcomes measures were collected.

RESULTS

Thirty-eight fillet flaps were performed for lower extremity reconstruction. Extirpative surgery included external hemipelvectomy (42%), external hemipelvectomy with sacrectomy (32%), and supratrochanteric above-knee amputation (26%). Median defect size was 600 cm 2 , and 50% included a bony component. Twenty-one patients (55%) experienced postoperative complications, with 16 requiring operative intervention. There was an increased trend toward complications in patients with preoperative radiotherapy, although this was not significant (44% versus 65%; P = 0.203). Seven patients underwent TMR or RPNI. In these patients, the mean numeric rating scale residual limb pain score was 2.8 ± 3.4 ( n = 5; range, 0 to 4/10) and phantom limb pain was 4 ± 3.2 ( n = 6; range, 0 to 7/10). The mean Patient-Reported Outcomes Measures Information Systems T scores were as follows: pain intensity, 50.8 ± 10.6 ( n = 6; range, 30.7 to 60.5); pain interference, 59.2 ± 12.1 ( n = 5; range, 40.7 to 70.1); and pain behavior, 62.3 ± 6.7 ( n = 3; range, 54.6 to 67.2).

CONCLUSIONS

Lower limb fillet flaps are reliable sources of bone, soft tissue, and nerve for reconstruction of oncologic amputation. TMR or RPNI are important new treatment adjuncts that should be considered during every amputation.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Clinical Assessment of Pain and Sensory Function in Peripheral Nerve Injury and Recovery: A Systematic Review of Literature

Peripheral nerve injuries (PNIs) often present with variable symptoms, making them difficult to diagnose, treat, and monitor. When neurologic compromise is inadequately assessed, suboptimal treatment decisions can result in lasting functional deficits. There are many available tools for evaluating pain and functional status of peripheral nerves. However, the literature lacks a detailed, comprehensive view of the data comparing the clinical utility of these modalities, and there is no consensus on the optimal algorithm for sensory and pain assessment in PNIs. We performed a systematic review of the literature focused on clinical data, evaluating pain and sensory assessment methods in peripheral nerves. We searched through multiple databases, including PubMed/Medline, Embase, and Google Scholar, to identify studies that assessed assessment tools and explored their advantages and disadvantages. A total of 66 studies were selected that assessed various tools used to assess patient's pain and sensory recovery after a PNI. This review may serve as a guide to select the most appropriate assessment tools for monitoring nerve pain and/or sensory function both pre- and postoperatively. As the surgeons work to improve treatments for PNI and dysfunction, identifying the most appropriate existing measures of success and future directions for improved algorithms could lead to improved patient outcomes.

Making sense of phantom limb pain

Phantom limb pain (PLP) impacts the majority of individuals who undergo limb amputation. The PLP experience is highly heterogenous in its quality, intensity, frequency and severity. This heterogeneity, combined with the low prevalence of amputation in the general population, has made it difficult to accumulate reliable data on PLP. Consequently, we lack consensus on PLP mechanisms, as well as effective treatment options. However, the wealth of new PLP research, over the past decade, provides a unique opportunity to re-evaluate some of the core assumptions underlying what we know about PLP and the rationale behind PLP treatments. The goal of this review is to help generate consensus in the field on how best to research PLP, from phenomenology to treatment. We highlight conceptual and methodological challenges in studying PLP, which have hindered progress on the topic and spawned disagreement in the field, and offer potential solutions to overcome these challenges. Our hope is that a constructive evaluation of the foundational knowledge underlying PLP research practices will enable more informed decisions when testing the efficacy of existing interventions and will guide the development of the next generation of PLP treatments.