Neuropathic pain in burn patients - A common problem with little literature: A systematic review

BACKGROUND

The prevalence of neuropathic pain (NP) in burn patients is reported in the literature to be as high as 80%1. Given the complexity of NP in burn patients and the wide range of treatments available, a systematic review of the literature is warranted to summarize our current understanding of management and treatment of NP in this population.

METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The following databases were queried to identify relevant articles: PubMed, Cochrane, Embase, Scopus, Ovid, and Web of Science. The main outcome measures were incidence and management of NP. Secondary outcomes included risk factors for NP.

RESULTS

Included articles presented findings from 11 different countries, capturing outcomes for 4366 patients. Risk factors for neuropathic pain in burn patients were identified, including older age, alcohol and substance abuse, current daily smoking, greater % total body surface area burns (TBSA), and longer hospitalizations. Pharmacologic treatments included gabapentin/pregabalin (n = 7), ascorbic acid (n = 1), and lidocaine (n = 1). Overall, the studies showed varied results regarding the efficacy of pharmacological treatments. While certain studies demonstrated gabapentanoids to be effective in reducing neuropathic symptoms, others found conflicting results. With regards to non-pharmacologic treatments, electroconvulsive therapy (n = 1), electropuncture (n = 1), nerve release/reconstruction (n = 2), and somatosensory feedback rehabilitation (n = 1) were used and demonstrated promise in reducing pain intensity and improving functionality.

CONCLUSIONS

Despite NP afflicting the majority of burn patients long after their injury, this systematic review demonstrates insufficient evidence on the pathophysiology, outcomes, and risk factors in NP, as well as the efficacy of various therapies. Future prospective and randomized studies evaluating the etiology of these factors can substantially improve our treatment strategies. This can allow for the development of well-delineated and evidence-based protocols in NP management in hopes of improving quality of life and both psychological and physical function in burn patients.

Burn Injury Complications Impacting Rehabilitation

Successful post-burn rehabilitation requires an understanding of a wide range of complications to maximize functional recovery. This article reviews a range of potential challenges including burn scar contracture, amputation, peripheral nerve injury, heterotopic ossification, dysphagia, altered skin physiology, pain, and pruritis. The overall focus is to serve as a guide for post-injury therapy and rehabilitation spanning the phases of care and considering evidence-based approaches, prevention, and treatment with an ultimate goal of aiding in the functional recovery and long-term quality of life for burn survivors.

Prescribing of Gabapentinoids with or without opioids after burn injury in the US, 2012-2018

Burn injury pain manifests as a combination of inflammatory, nociceptive, and neuropathic features. While opioids are the mainstay of burn pain management, non-opioid medications, such as gabapentinoids, have also been considered as they target the central nervous system. Increased opioid adverse events and overdose deaths in the United States led to the 2014 and 2016 guidelines to reduce opioid prescribing and consider alternatives, such as gabapentinoids. In the context of burn, the rate of gabapentinoid prescribing at the national level is unknown and it is unclear whether any shift has occurred in prescribing practices over time. We conducted a population level cohort study of adult burn patients from 2012 to 2018 to evaluate the rates and determinants of gabapentinoid prescribing, with and without opioids. Of 98,001 patients with burn, 22,521 (22.98%) received opioids and/or gabapentinoids (GABA). GABA represented 2.4% of prescriptions in 2012, but increased to 7.2% by 2018, while GABA-opioid co-prescriptions increased from 2.3% to 5.1%. The rate of increase in GABA prescriptions was higher for those aged 50-65 years or residing in the South. After adjustment, GABA was 44% more likely to be prescribed in 2017 and 2018 compared to 2012 and 2013, opioids were 38% less likely, while co-prescribing did not show a statistically significant change. Our study showed a modest increase in gabapentinoids' outpatient prescribing for burn patients after the 2014 and 2016 guidelines, indicating more opportunities for prescribers to expand non-opioid pain management in this population.

A review of the most impactful published pharmacotherapy-pertinent literature of 2019 and 2020 for clinicians caring for patients with thermal or inhalation injury

Keeping abreast with current literature can be challenging, especially for practitioners caring for patients sustaining thermal or inhalation injury. Practitioners caring for patients with thermal injuries publish in a wide variety of journals, which further increases the complexity for those with resource limitations. Pharmacotherapy research continues to be a minority focus in primary literature. This review is a renewal of previous years' work to facilitate extraction and review of the most recent pharmacotherapy-centric studies in patients with thermal and inhalation injury. Sixteen geographically dispersed, board-certified pharmacists participated in the review. A MeSH-based, filtered search returned 1,536 manuscripts over the previous 2-year period. After manual review and exclusions, only 98 (6.4%) manuscripts were determined to have a potential impact on current pharmacotherapy practices and included in the review. A summary of the 10 articles that scored highest are included in the review. Nearly half of the reviewed manuscripts were assessed to lack a significant impact on current practice. Despite an increase in published literature over the previous 2-year review, the focus and quality remain unchanged. There remains a need for investment in well-designed, high impact, pharmacotherapy-pertinent research for patients sustaining thermal or inhalation injuries.

Neuropathic agents in the management of pruritus in burn injuries: a systematic review and meta-analysis

Objectives

Pruritus is a common and often distressing complication after a burn injury. The purpose of this review is to explore the efficacy of drugs classically used to treat neuropathic pain in the management of pruritus after burn injury.

Methods

A systematic literature search of medical databases was conducted to find studies investigating drugs listed in the National Institute for Health and Care Excellence (NICE) guideline (CG173, "neuropathic pain in adults") for the management of pruritus after burn injury in patients of any age. Controlled studies were stratified by the drug class studied and their risk of bias before conducting meta-analysis. A narrative review of case series or observational studies was presented. Severity of pruritus at any time point, with all quantitative and qualitative measures, was included.

Results

Fifteen studies were included in the final analysis, 10 investigated the use of gabapentinoids, 4 studied doxepin, and 1 local anesthetic agents. Meta-analysis of three randomized controlled trials (RCTs) demonstrated that the use of gabapentinoids was associated with an improvement in mean VAS (Visual Analog Scale) 0-10 scores of 2.96 (95% confidence interval (95% CI) 1.20 to 4.73, p<0.001) when compared with placebo or antihistamine. A meta-analysis of four RCTs investigating topical doxepin showed an improvement in mean VAS scores of 1.82 (95% CI 0.55 to 3.09, p<0.001). However, when excluding two studies found to be at high risk of bias, no such improvement was found (-0.32, 95% CI -1.64 to -0.99, p=0.83).

Conclusion

This study suggests that gabapentinoids are beneficial in the management of burn-related pruritus. There is a lack of evidence to suggest that doxepin is an effective treatment. Topical local anesthetic agents may be safe and beneficial, but studies are scarce.

Level of evidence

Systematic review, level II.

A Retrospective Analysis of Gabapentinoid and Opioids to Opioid Monotherapy for Pain Relief in Patients with Chronic Neck and Low Back Pain

OBJECTIVE

We compared the reduction in pain and opioid consumption in patients with chronic spinal pain on concomitant gabapentinoids and opioids with patients using opioids only.

DESIGN

This was a retrospective chart review of patients with chronic neck or low back pain who were on opioids with at least a 24-month follow-up.

SETTING

Single-center pain clinic in an urban setting.

SUBJECTS

167 patients with chronic spinal pain lasting at least six months.

METHODS

Patients on gabapentin or pregabalin were included in the gabapentinoid group, while the other patients were included in the non-gabapentinoid group. Primary outcome was assessment of pain scores measured via a numeric rating scale (NRS), and secondary outcomes were response to the treatment (>2 point reduction on NRS) and daily opioid use measured in morphine milliequivalents.

RESULTS

Pain scores were reduced in the first six months and plateaued after that in both groups. At the end of 24 months, the average pain score was 6.71 in the gabapentinoid group, while the average pain score was 7.18 in the non-gabapentinoid group. There was no statistical significance between the groups (p = 0.28). There was no difference in response to treatment in gabapentinoid group (33.3%) when compared with non-gabapentinoid group (32.7%). We also failed to find any significant difference in daily opioid usage between the two groups.

CONCLUSION

Gabapentinoids may not lead to reduction in pain or opioid consumption in patients with chronic spinal pain. A careful approach must be adopted while prescribing gabapentinoids in the chronic spinal pain patient population.

Efficacy of opioids and non-opioid analgesics in the treatment of post procedure pain of burned patients: a narrative review

Introduction

Burns are a common trauma that cause acute severe pain in up to 80% of patients. The objective of this narrative review is to evaluate the efficacy of opioids, non-steroidal anti-inflammatory drugs, paracetamol, gabapentinoids, ketamine, and lidocaine in the treatment of acute pain in burn victims.

Methodology

The databases explored were PubMed, Embase, ClinicalTrials, and OpenGrey. The included randomized, controlled clinical trials assessed the analgesic efficacy of these drugs on hospitalized patients, had no age limit, patients were in the acute phase of the burn injury and were compared to placebo or other analgesic drugs. Studies describing deep sedation, chronic opioid use, chronic pain, and patients taken to reconstructive surgeries were excluded. The Jadad scale was used to evaluate quality.

Results

Six randomized controlled clinical trials (397 patients) that evaluated the analgesic efficacy of fentanyl (n = 2), nalbuphine (n = 1), ketamine (n = 1), gabapentin (n = 1), and lidocaine (n = 1) to treat post-procedural pain were included. Fentanyl, nalbuphine, and ketamine were effective, while lidocaine was associated with a slight increase in reported pain and gabapentin showed no significant differences. Two studies were of high quality, one was of medium high quality, and three were of low quality. No studies on the efficacy of NSAIDs or paracetamol were found.

Conclusion

Evidence of efficacy is very limited. Fentanyl, nalbuphine, and ketamine seem to be effective for controlling acute pain in burn patients, whereas gabapentin and lidocaine did not show any efficacy.

Primary management of burn injuries: Balancing best practice with pragmatism

Management of burns is an often-neglected area in training from undergraduate to specialist level. There is, however, a high burden of injury that affects a largely vulnerable population, for example, children, the elderly and epileptics. This CPD article highlights that first aid should include cooling the burn with cool running tap water up to 3-hours post injury (Burnshield may be used if cool running water is not available); removal of all blisters facilitates accurate assessment of the burn size and depth; formulas exist for the resuscitation of acute burn injuries of more than 10% – 15% total body surface area and prophylactic antibiotics should not be administered to patients with acute burns as the prevention of infection should lie with good wound care (including good wound cleaning and the use of topical antimicrobial dressings). A standardised approach to pain management with an incremental pharmacological approach should be followed whilst considering other issues such as neuropathic pain, anxiety and depression.

Therapeutic Approaches for Peripheral and Central Neuropathic Pain

Neuropathic pain is a chronic secondary pain condition, which is a consequence of peripheral or central nervous (somatosensory) system lesions or diseases. It is a devastating condition, which affects around 7% of the general population. Numerous etiological factors contribute to the development of chronic neuropathic pain. It can originate from the peripheral part of the nervous system such as in the case of trigeminal or postherpetic neuralgia, peripheral nerve injury, painful polyneuropathies, or radiculopathies. Central chronic neuropathic pain can develop as a result of spinal cord or brain injury, stroke, or multiple sclerosis. As first-line pharmacological treatment options, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids are recommended. In trigeminal neuralgia, carbamazepine and oxcarbazepine are the first-choice drugs. In drug-refractory cases, interventional, physical, and psychological therapies are available. This review was structured based on a PubMed search of papers published in the field from 2010 until May 2019.