Biology and pathophysiology of symptomatic neuromas

Evaluation of MRI features of neuromas in oncological amputees, and the relation to pain

OBJECTIVE

The impact of time on neuroma growth and morphology on pain intensity is unknown. This study aims to assess magnetic resonance imaging (MRI) differences between symptomatic and non-symptomatic neuromas in oncological amputees, and whether time influences MRI-detected neuroma dimensions and their association with pain.

MATERIAL AND METHODS

Oncological patients who underwent traditional extremity amputation were included. Post-amputation MRIs were assessed before decision for neuroma surgery. Chart review was performed for residual limb pain (numeric rating scale, 0-10) and the presence of neuropathic symptoms. Neuromas were classified as symptomatic or non-symptomatic, with neuroma size expressed as radiological neuroma-to-nerve-ratio (NNR).

RESULTS

Among 78 neuromas in 60 patients, the median NNR was 2.0, and 56 neuromas (71.8%) were symptomatic with a median pain score of 3.5. NNR showed no association with symptomatology or pain intensity but correlated with a longer time-to-neuroma-excision interval and a smaller nerve caliber. Symptomatic neuromas were associated with lower extremity amputation, T2 heterogeneity, and the presence of heterotopic ossification. Lower extremity amputation, T2 heterogeneity, perineural edema, and presence of heterotopic ossification were associated with more painful neuromas.

CONCLUSION

MRI features associated with symptomatic neuromas and pain intensity were identified. Awareness of the potential clinical significance of these imaging features may help in the interpretation of MRI exams and may aid clinicians in patient selection for neuroma surgery in oncological amputees.

Perioperative Pain Management for Major Limb Amputation - A Systematic-Narrative Hybrid Review

INTRODUCTION

Post-amputation pain, including residual limb pain (RLP) and phantom limb pain (PLP), can affect the outcome of surgery and have an impact on quality of life. Effective management of acute post-amputation pain requires a multidisciplinary approach with collaboration among the surgical and anesthesia teams to optimize pain management. A systematic-narrative hybrid review was conducted to assess and report the effectiveness of various interventions in perioperative pain management for amputation surgery.

METHODS

MEDLINE, Embase, CENTRAL, and ClinicalTrials.gov databases were searched for studies evaluating interventional and/or pharmacological approaches to managing perioperative pain in major extremity amputation surgery. The data collected included treatment options, average dosage and/or duration of treatments, and reported pain outcomes.

RESULTS

Of the 27 studies evaluating interventions, 8 addressed neuraxial or perineural analgesia, 16 focused on peripheral nerve blocks (PNB), 2 examined peripheral nerve stimulators (PNS), and 1 investigated transcutaneous electrical nerve stimulation. Preoperative epidural analgesia was associated with a reduced incidence of postoperative pain. PNS, PNB, and catheter-based infusions were found to be effective in managing postoperative pain. The role of ketamine in treating post-amputation pain yielded mixed results, while other pharmacological agents, such as valproic acid and gabapentin, demonstrated limited efficacy.

CONCLUSIONS

While numerous pain interventions are available, no single approach has been shown to be superior. A multimodal strategy, incorporating PNBs, preoperative pain control, and potentially ketamine, appears to provide the most comprehensive pain management strategy. Further long-term prospective studies are required to refine and optimize pain management techniques for major extremity amputation surgery.

LEVEL OF EVIDENCE

III-Systematic reviews.

Evidence for regional anesthesia in preventing chronic postsurgical pain

Chronic postsurgical pain (CPSP) is a common adverse outcome following surgical procedures. Despite ongoing research, the risk factors and effective strategies for mitigating CPSP remain uncertain. Regional anesthesia is a potentially beneficial yet debated intervention for mitigating the risk of CPSP. This review will delve into the mechanistic aspects of regional anesthesia and critically assess the current literature to provide a thorough understanding of its role and effectiveness. The incidence and severity of CPSP are linked to nerve damage, neuroplastic changes and immunological responses. Although numerous mechanisms contributing to CPSP have been identified, translational research is sparse, and findings are often inconsistent. Evidence suggests that regional anesthetic techniques could have a role in reducing CPSP risk across various clinical scenarios. Techniques studied include wound infiltration, peripheral nerve blocks, fascial plane blocks, thoracic paravertebral blocks and epidural anesthesia. Current data indicate that epidural anesthesia might decrease CPSP risk following thoracotomy, wound infiltration may be effective after major breast surgery and cesarean delivery, and serratus anterior plane block or pectoralis/interpectoral plane blocks might be beneficial in breast surgery. However, the existing evidence is limited and marked by several constraints especially the multifactorial causes, underscoring the need for further research in this area.

The influence of nerve surgical techniques at time of amputation on the prevalence of heterotopic ossification in transtibial amputees

BACKGROUND

Heterotopic ossification (HO) can form after amputation and may cause pain and functional impairment. We aimed to describe the prevalence of HO in a civilian population of transtibial amputees. We hypothesized that the decreased rate of symptomatic neuroma following active nerve surgery (Targeted Muscle Reinnervation (TMR) or Regenerative Peripheral Nerve Interface (RPNI)) may subsequently lead to a lower prevalence of HO compared to passive nerve surgery (i.e. traction neurectomy) performed at the time of amputation.

METHODS

Adult patients undergoing transtibial amputation at a tertiary care center between 2000 and 2023 were included. Patient data were collected through chart review. The most recent post-amputation X-ray of the residual limb was assessed for HO presence, according to the Walter Reed classification. A random subset of X-rays (10.0 %) was independently assessed by five clinicians and two radiologists, and inter-rater reliability (IRR) was calculated using Cohen's kappa (κ). Multivariable logistic regression was conducted to identify factors associated with HO presence.

RESULTS

In total, 665 limbs of 632 patients were included. The median time between amputation and X-ray was 1.7 years (IQR: 0.3-6.2). HO was identified in 326 X-rays (49.0 %) and was commonly present on the distal residual tibia (68.1 %) and fibula (69.0 %). Traditional amputations (i.e. those without TMR or RPNI (OR: 2.0, p = 0.014)), and the presence of a symptomatic neuroma (OR: 2.3, p < 0.001), were independently associated with a higher prevalence of HO. The IRR of the two radiologists was κ = 0.99, the overall IRR of all evaluators was κ = 0.92.

CONCLUSIONS

HO is a common finding in transtibial amputees. Peripheral nerve surgerical techniques that actively address amputated nerve endings to reduce symptomatic neuroma formation may decrease the prevalence of HO.

Neuroma morphology: A macroscopic classification system

INTRODUCTION/AIMS

Neuromas come in different shapes and sizes; yet the correlation between neuroma morphology and symptomatology is unknown. Therefore, we aim to investigate macroscopic traits of excised human neuromas and assess the validity of a morphological classification system and its potential clinical implications.

METHODS

End-neuroma specimens were collected from prospectively enrolled patients undergoing symptomatic neuroma surgery. Protocolized images of the specimens were obtained intraoperatively. Pain data (Numeric rating scale, 0-10) were prospectively collected during preoperative interview, patient demographic and comorbidity factors were collected from chart review. A morphological classification is proposed, and the inter-rater reliability (IRR) was assessed. Distribution of neuroma morphology with patient factors, was described.

RESULTS

Forty-five terminal neuroma specimens from 27 patients were included. Residual limb patients comprised 93% of the population, of which 2 were upper (8.0%) and 23 (92.0%) were lower extremity residual limb patients. The proposed morphological classification, consisting of three groups (bulbous, fusiform, atypical), demonstrated a strong IRR (Cohen's kappa = 0.8). Atypical neuromas demonstrated higher preoperative pain, compared with bulbous and fusiform. Atypical morphology was more prevalent in patients with diabetes and peripheral vascular disease.

DISCUSSION

A validated morphological classification of neuroma is introduced. These findings may assist surgeons and researchers with better understanding of symptomatic neuroma development and their clinical implications. The potential relationship of neuroma morphology with the vascular and metabolic microenvironment requires further investigation.

The neuroma map: A systematic review of the anatomic distribution, etiologies, and surgical treatment of painful traumatic neuromas

BACKGROUND

This study analyzed all reported cases of painful traumatic neuromas to better understand their anatomic distribution, etiologies, and surgical treatment.

METHODS

PubMed, Embase, Cochrane, and Web of Science were searched in October 2023 for articles describing painful traumatic neuromas.

RESULTS

In total, 414 articles reporting 5,562 neuromas were included and categorized into head/neck, trunk, upper extremity, lower extremity, and autonomic nerves. Distribution was as follows: Head/neck: 83 articles reported on 393 neuromas (93.2% iatrogenic) most frequently involving the lingual (44.4%), cervical plexus (15.0%), great auricular (8.6%), inferior/superior alveolar (8.3%), and occipital (7.2%) nerves. Trunk: 47 articles reported on 552 neuromas (92.9% iatrogenic) most commonly involving the intercostal (40.0%), ilioinguinal (18.2%) and genitofemoral (16.2%) nerves. Upper extremity: 160 articles reported on 2082 neuromas (42.2% after amputation) most frequently involving the digital (47.0%), superficial radial (18.3%), and median (7.0%) nerves. Lower extremity: 128 articles reported on 2,531 neuromas (53.0% after amputation) most commonly involving the sural (17.9%), superficial peroneal (17.3%), and saphenous (16.0%) nerves. Autonomic nerves: 17 articles reported on 53 neuromas (100% iatrogenic) most frequently involving the biliary tract (64.2%) and vagus nerve (18.9%). Compared with the extremities, neuromas in the head/neck and trunk had significantly longer symptom duration before surgical treatment and the nerve end was significantly less frequently reconstructed after neuroma excision.

CONCLUSION

Painful neuromas are predominantly reported in the extremities yet may occur throughout the body primarily after iatrogenic injury. Knowledge of their anatomic distribution from head to toe will encourage awareness to avoid injury and expedite diagnosis to prevent treatment delay.

Mesenchymal Stem Cell Engagement Modulates Neuroma Microenviroment in Rats and Humans and Prevents Postamputation Pain

Postamputation pain is currently managed unsatisfactorily with neuron-targeted pharmacological and interventional therapies. Non-neuronal pain mechanisms have emerged as crucial factors in the development and persistence of postamputation pain. Consequently, these mechanisms offer exciting prospects as innovative therapeutic targets. We examined the hypothesis that engaging mesenchymal stem cells (MSCs) would foster local neuroimmune interactions, leading to a potential reduction in postamputation pain. We utilized an ex vivo neuroma model from a phantom limb pain patient to uncover that the oligodeoxynucleotide IMT504 engaged human primary MSCs to promote an anti-inflammatory microenvironment. Reverse translation experiments recapitulated these effects. Thus, in an in vivo rat model, IMT504 exhibited strong efficacy in preventing autotomy (self-mutilation) behaviors. This effect was linked to a substantial accumulation of MSCs in the neuroma and associated dorsal root ganglia and the establishment of an anti-inflammatory phenotype in these compartments. Centrally, this intervention reduced glial reactivity in the dorsal horn spinal cord, demonstrating diminished nociceptive activity. Accordingly, the exogenous systemic administration of MSCs phenocopied the behavioral effects of IMT504. Our findings underscore the mechanistic relevance of MSCs and the translational therapeutic potential of IMT504 to engage non-neuronal cells for the prevention of postamputation pain. PERSPECTIVE: The present study suggests that IMT504-dependent recruitment of endogenous MSCs within severely injured nerves may prevent post-amputation pain by modifying the inflammatory scenario at relevant sites in the pain pathway. Reinforcing data in rat and human tissues supports the potential therapeutic value of IMT504 in patients suffering postamputation pain.

Social Deprivation is Associated with Increased Pain in Patients Presenting with Neuropathic Pain

Background

Neuropathic pain following nerve injury can be debilitating and negatively impact quality of life. Targeted muscle reinnervation (TMR) is an efficacious technique for the management of neuropathic pain. However, this technique may be unequally available for many geographical locations. Therefore, the aim of this study was to evaluate the association between Area Deprivation Index (ADI) and preoperative pain in patients undergoing TMR for treatment of neuropathic pain.

Methods

Patients who underwent TMR for neuropathic pain in the lower and upper extremities were prospectively enrolled at our tertiary care clinic. A chart review was conducted to obtain socioeconomic, surgery, and comorbidity parameters. Preoperative pain scores (0-10 pain score index), and the ADI, reflecting deprivation status on a 0-100 scale, were collected.

Results

A total of 162 patients from 13 different states were included, of which 119 were amputees (74%). The median ADI was 25 (IQR: 16-41) and the median preoperative pain score was 6 (IQR: 5-8). A higher ADI was independently associated with higher preoperative pain. The time interval from nerve injury to TMR was not associated with ADI.

Conclusions

Patients undergoing surgical treatment of neuropathic pain from more socially deprived settings have increased pain experience upon initial evaluation, despite having similar time from nerve injury or amputation to TMR. These findings highlight the importance of identifying patients presenting from socially deprived settings, as this may impact their physical and mental health along with their coping mechanisms, resulting in increased pain.

Neuroma Analysis in Humans: Standardizing Sample Collection and Documentation

INTRODUCTION

The biology of symptomatic neuromas is poorly understood, particularly the factors causing pain in human neuromas. Pain presence varies among and within individuals, with some having painful and nonpainful neuromas. To bridge these knowledge gaps, our group developed a protocol for assessing neuroma pain and collecting tissue for molecular analysis. This manuscript outlines our workflow and challenges and aims to inspire other centers to share their experiences with these tissues.

METHODS

For every included patient and collected nerve or bone tissue specimens, we perform a detailed chart review and a multifaceted analysis of pain and pain perception immediately before surgery. We collect patient-reported outcome measures (PROMs) on pain, function, and mental well-being outcomes at preoperative assessment and at the 6-month follow-up postoperatively. Before surgery, the patient is assessed once again to obtain an immediate preoperative pain status and identify potential differences in pain intensity of different neuromas. Intraoperatively, specimens are obtained and their gross anatomical features are recorded, after which they are stored in paraformaldehyde or frozen for later sample analyses. Postoperatively, patients are contacted to obtain additional postoperative PROMs.

RESULTS

A total of 220 specimens of nerve tissue have been successfully obtained from 83 limbs, comprising 95 specimens of neuromas and 125 specimens of nerves located proximal to the neuromas or from controls.

CONCLUSIONS

Our approach outlines the methods combining specimen collection and examination, including both macroscopic and molecular biological features, with PROMs, encompassing physical and psychological aspects, along with clinical metadata obtained through clinical teams and chart review.