Approaches to neuropathic amputation-related pain: narrative review of surgical, interventional, and medical treatments.

BACKGROUND/IMPORTANCE: Neuropathic amputation-related pain can consist of phantom limb pain (PLP), residual limb pain (RLP), or a combination of both pathologies. Estimated of lifetime prevalence of pain and after amputation ranges between 8% and 72%. OBJECTIVE: This narrative review aims to summarize the surgical and non-surgical treatment options for amputation-related neuropathic pain to aid in developing optimized multidisciplinary and multimodal treatment plans that leverage multidisciplinary care. EVIDENCE REVIEW: A search of the English literature using the following keywords was performed: PLP, amputation pain, RLP. Abstract and full-text articles were evaluated for surgical treatments, medical management, regional anesthesia, peripheral block, neuromodulation, spinal cord stimulation, dorsal root ganglia, and peripheral nerve stimulation. FINDINGS: The evidence supporting most if not all interventions for PLP are inconclusive and lack high certainty. Targeted muscle reinnervation and regional peripheral nerve interface are the leading surgical treatment options for reducing neuroma formation and reducing PLP. Non-surgical options include pharmaceutical therapy, regional interventional techniques and behavioral therapies that can benefit certain patients. There is a growing evidence that neuromodulation at the spinal cord or the dorsal root ganglia and/or peripheral nerves can be an adjuvant therapy for PLP. CONCLUSIONS: Multimodal approaches combining pharmacotherapy, surgery and invasive neuromodulation procedures would appear to be the most promising strategy for preventive and treating PLP and RLP. Future efforts should focus on cross-disciplinary education to increase awareness of treatment options exploring best practices for preventing pain at the time of amputation and enhancing treatment of chronic postamputation pain.

Long-Term Outcomes After Spinal Cord Stimulator Placement in Patients with Pre-procedural Active Opioid Use Versus Patients Who Were Opioid-Naïve.

BACKGROUND: Outcome optimization after the placement of a spinal cord stimulator (SCS) is critical. The objective of this study was to determine if an association existed between pre-procedural opioid use (compared to patients who were opioid-naïve) and postoperative long-term outcomes following SCS placement. OBJECTIVE: To examine the impact of preprocedural opioid use on long-term outcomes after SCS therapy. STUDY DESIGN: Cohort study utilizing a nationwide database. SETTING: Retrospective. METHODS: With the use of data from HCA Healthcare's national database, a retrospective cohort study was performed to analyze differences in outcomes between opioid-naïve patients and preoperative opioid users who underwent SCS placements. The primary outcome of interest was device explantation at 6 months and 12 months. Secondary outcome measurements included reoperations and readmissions at 6 months and 12 months, as well as operative complications. Multivariable logistic regression models were performed to analyze the association of preoperative opioid use with those outcomes. The odds ratio (OR), 95% confidence intervals (CI), and P values were reported for the independent variables. RESULTS: The final study population consisted of 13,893 patients who underwent SCS placements. In univariate analyses, patients who used opioids preoperatively had higher 6-month (3.6% vs. 2.6%) and one-year removal rates (3.6% vs. 2.8%) (all P < 0.009). On multivariable logistic regression, those using opioids preoperatively had higher odds of removal at 6 months (OR = 1.290, 95% CI 1.05-1.58, P = 0.01) and at one year (OR = 1.23, 95% CI 1.01-1.50, P = 0.04). There was no difference between patients requiring preoperative opioids and patients who were opioid-naive as far as the odds of 6- or 12-month readmissions were concerned. Compared to the opioid-naive group, patients requiring preoperative opioids had increased odds of reoperation at 6 months (OR = 1.2, 95% CI 1.02-1.40, P = 0.03). There were no differences in the odds of complications between both cohorts. LIMITATIONS: Opioid use in this study was defined as using opioids preoperatively in the 30 days leading up to surgery. CONCLUSION: Patients requiring preoperative opioids before SCS placements had increased odds of SCS explantation at 6 months and 12 months, as well as increased odds of reoperation at 6 months.

Pain Education and Knowledge (PEAK) Consensus Guidelines for Neuromodulation: A Proposal for Standardization in Fellowship and Training Programs.

The need to be competent in neuromodulation is and should be a prerequisite prior to completing a fellowship in interventional pain medicine. Unfortunately, many programs lack acceptable candidates for these advanced therapies, and fellows may not receive adequate exposure to neuromodulation procedures. The American Society of Pain and Neuroscience (ASPN) desires to create a consensus of experts to set a minimum standard of competence for neurostimulation procedures, including spinal cord stimulation (SCS), dorsal root ganglion stimulation (DRG-S), and peripheral nerve stimulation (PNS). The executive board of ASPN accepted nominations for colleagues with excellence in the subject matter of neuromodulation and physician education. This diverse group used peer-reviewed literature and, based on grading of evidence and expert opinion, developed critical consensus guides for training that all accredited fellowship programs should adopt. For each consensus point, transparency and recusal were used to eliminate bias, and an author was nominated for evidence grading oversight and bias control. Pain Education and Knowledge (PEAK) Consensus Guidelines for Neuromodulation sets a standard for neuromodulation training in pain fellowship training programs. The consensus panel has determined several recommendations to improve care in the United States for patients undergoing neuromodulation. As neuromodulation training in the United States has evolved dramatically, these therapies have become ubiquitous in pain medicine. Unfortunately, fellowship programs and the Accreditation Council for Graduate Medical Education (ACGME) pain program requirements have not progressed training to match the demands of modern advancements. PEAK sets a new standard for fellowship training and presents thirteen practice areas vital for physician competence in neuromodulation.

Complex Regional Pain Syndrome: Practical Diagnostic and Treatment Guidelines, 5th Edition.

There have been some modest recent advancements in the research of Complex Regional Pain Syndrome, yet the amount and quality of the work in this complicated multifactorial disease remains low (with some notable exceptions; e.g., the recent work on the dorsal root ganglion stimulation). The semi-systematic (though in some cases narrative) approach to review is necessary so that we might treat our patients while waiting for "better research." This semi-systematic review was conducted by experts in the field, (deliberately) some of whom are promising young researchers supplemented by the experience of "elder statesman" researchers, who all mention the system they have used to examine the literature. What we found is generally low- to medium-quality research with small numbers of subjects; however, there are some recent exceptions to this. The primary reason for this paucity of research is the fact that this is a rare disease, and it is very difficult to acquire a sufficient sample size for statistical significance using traditional statistical approaches. Several larger trials have failed, probably due to using the broad general diagnostic criteria (the "Budapest" criteria) in a multifactorial/multi-mechanism disease. Responsive subsets can often be identified in these larger trials, but not sufficient to achieve statistically significant results in the general diagnostic grouping. This being the case the authors have necessarily included data from less compelling protocols, including trials such as case series and even in some instances case reports/empirical information. In the humanitarian spirit of treating our often desperate patients with this rare syndrome, without great evidence, we must take what data we can find (as in this work) and tailor a treatment regime for each patient.

Comparisons of Monopolar Lesion Volumes with Hypertonic Saline Solution in Radiofrequency Ablation: A Randomized, Double-Blind, Ex Vivo Study.

BACKGROUND: Chronic degeneration of the zygapophyseal joints in the cervical or lumbar spine are common causes of axial back pain. Radiofrequency (RF) ablation is a treatment modality in the denervation of facet joint-related pain. Although multiple factors have been theorized to contribute to the size of the optimal RF lesion, the addition of hypertonic saline solution has been posited to create larger RF lesion sizes. OBJECTIVES: This study compares lesion of 20-gauge RF monopolar probe using 2% lidocaine, 0.9% normal saline solution, and 3% saline solution administered through the RF needle prior to ablation, with subsequent lesion sizes recorded. STUDY DESIGN: Randomized, double-blinded, ex vivo study using clinically relevant conditions. SETTING: Procedural laboratory in an academic institution. METHODS: RF ablation lesions were reproduced in room temperature (21°C ± 2°C) chicken breast specimens with 20-gauge monopolar RF probes inserted. RF was applied for 90 seconds at 80°C after injection of 1 mL of either 2% lidocaine, 2% lidocaine and 0.9% normal saline solution in a 1:1 ratio, or 2% lidocaine and 3% saline solution in a 1:1 ratio. Tissues were dissected, measured, and ellipsoid volumes of burn calculated. Homogeneity of variances was assessed via the Bartlett's test, and heteroskedasticity with the studentized Breusch-Pagan test. One-way analysis of variance (ANOVA) (alpha of 0.05) was used to evaluate statistical significance between volume means across groups. When the null hypothesis of no difference in burn volume between samples could not be rejected, a predefined equivalence volume of ± 0.05 cm3 was used with Welch's 2 one-sided t-tests (TOST) with a Bonferroni adjusted alpha of 0.0167 to evaluate for null acceptance. RESULTS: The mean lesion volume for monopolar RF with 1 mL 2% lidocaine was 0.16 cm3. Monopolar RF with 1 mL 2% lidocaine + 0.9% normal saline solution had a mean lesion volume of 0.15 cm3, and treatment with 1 mL 2% lidocaine + 3% saline solution measured 0.17 cm3. ANOVA failed to reject the null, and TOST accepted as equivalent all 3 comparisons. LIMITATIONS: In vivo anatomy and physiology of a human organism was not used for this study. Samples were not warmed to physiologic temperature. Randomization resulted in slightly unequal sample sizes, although all groups were of sufficient size that the central limit theorem should apply. CONCLUSIONS: Three commonly used solutions were found to have equivalent lesion sizes from monopolar probe RF ablation. KEY WORDS: Radiofrequency, ablation, lesion shape, lesion size, monopolar RF, hypertonic saline solution.