The lidocaine patch 5% effectively treats all neuropathic pain qualities: results of a randomized, double-blind, vehicle-controlled, 3-week efficacy study with use of the neuropathic pain scale

Is Lidocaine Patch Beneficial for Postoperative Pain?: A Meta-analysis of Randomized Clinical Trials

OBJECTIVES

The aim of this meta-analysis was to evaluate whether a lidocaine patch is beneficial for postoperative pain as an option for multimodal analgesia.

METHODS

Information was obtained from PubMed, Embase, and the Cochrane Central Register of Controlled Trials for clinical randomized controlled trials of lidocaine patches for postoperative pain (as of March 2022). Two researchers independently completed study screening, risk bias assessment, and data extraction. Review Manager (version 5.4, Cochrane Collaboration) was used to conduct the meta-analysis. The evaluation metrics were postoperative pain scores, opioid consumption, and patient satisfaction.

RESULTS

Sixteen randomized controlled trials were included, and data from 918 patients were available. Pain scores differed between the 2 groups at 12, 24, and 48 hours postoperatively, and the pain scores of the lidocaine patch group were significantly lower (mean difference [MD]=-1.32 [95% CI, -1.96 to -0.68], P <0.0001; I2 =92%) at 12 hours after the operation; (MD=-1.23 [95% CI, -1.72 to -0.75], P <0.00001; I2 =92%) at 24 hours after the operation; and (MD=-0.25 [95% CI,-0.29 to -0.21], P <0.00001; I2 =98%) at 48 hours after the operation. In addition, the lidocaine patch group had decreased opioid requirements (MD=-3.57 [95% CI, -5.06 to -2.09], P <0.00001; I2 =96%). The lidocaine patch group seemed to be more satisfied, but there was no statistically significant difference (risk ratio, 1.50 [95% CI, 0.74 to 3.05], P =0.26) between the groups.

DISCUSSION

Lidocaine patches are beneficial for postoperative pain and can be used in multimodal analgesia to reduce opioid use, but there is no significant increase in patient satisfaction with pain control. More data are needed to support this conclusion due to the large heterogeneity in the present study.

Immersive interactive virtual walking reduces neuropathic pain in spinal cord injury: findings from a preliminary investigation of feasibility and clinical efficacy

ABSTRACT

Chronic neuropathic pain (NP) is a common and often debilitating secondary condition for persons with spinal cord injury (SCI) and is minimally responsive to existing pharmacological and nonpharmacological treatments. The current preliminary investigation describes the feasibility and initial comparative efficacy of an interactive virtual reality walking intervention, which is a novel extension of visual feedback/illusory walking therapies shown to reduce SCI NP. Virtual reality walking intervention builds on previous research by, for the first time, allowing individuals with SCI NP to volitionally control virtual gait to interact with a fully immersive virtual environment. The current pilot study compared this interactive, virtual walking intervention to a passive, noninteractive virtual walking condition (analogous to previous illusory walking interventions) in 27 individuals with complete paraplegia (interactive condition, n = 17; passive condition, n = 10; nonrandomized design). The intervention was delivered over 2 weeks in individuals' homes. Participants in the interactive condition endorsed significantly greater reductions in NP intensity and NP-related activity interference preintervention to postintervention. Notable improvements in mood and affect were also observed both within individual sessions and in response to the full intervention. These results, although preliminary, highlight the potentially potent effects of an interactive virtual walking intervention for SCI NP. The current study results require replication in a larger, randomized clinical trial and may form a valuable basis for future inquiry regarding the mechanisms and clinical applications of virtual walking therapies.

Pharmacologic Management of Neuropathic Pain

This article aims to provide the practitioner with therapeutic options to treat a broad spectrum of acute and chronic orofacial pain syndromes. The focus will be nonsurgical that the oral health care physician can implement to treat this population of patients. The World Health Organization estimated that more than 1 in every 3 people suffers from acute or chronic pain. This article is primarily devoted to medication management once the diagnosis of neuropathic pain, a true trigeminal neuralgia, or a variant of trigeminal neuralgia often referred to as traumatic neuropathic pain or traumatic trigeminal neuralgia.

Topical Lidocaine for Chronic Pain Treatment

Topical lidocaine is widely used in current practice for a variety of pain conditions. This literature review shows that its limited absorption and relative lack of systemic adverse events are an attractive analgesic option for a number of vulnerable patients. Topical lidocaine has been approved by health authorities for the treatment of post-herpetic neuralgia in a number of countries, and studies present some degree of evidence of its efficacy and safety in postsurgical pain, diabetic peripheral neuropathy, carpal tunnel syndrome, chronic lower back pain and osteoarthritis. Topical lidocaine may be a great alternative alone or in addition to systemic drugs and non-pharmacological approaches for an optimized pain management and in multimodal analgesia.

Efficacy of transdermal 4% lidocaine patches for postoperative pain management after arthroscopic rotator cuff repair: a prospective trial

Background

Postoperative pain management continues to be a challenging aspect of patient care. Lidocaine patches have shown efficacy in reducing pain in other surgical specialties and mixed results in orthopedic trials. We sought to determine the effectiveness of nonprescription lidocaine patches in reducing postoperative pain after arthroscopic rotator cuff repair

Methods

Patients undergoing primary arthroscopic rotator cuff repair were recruited from 3 surgeons at a single institution. All patients of each surgeon were randomized to a lidocaine patch or control group, with crossover occurring at the midpoint. Experimental group patients received 26 4% lidocaine gel-patches. They were provided written and visual instructions to begin wearing the lidocaine patches during daytime on postoperative day (POD) 2. They were to be switched every 8 hours and removed overnight. Control group patients received normal standard of care but did not receive a placebo control. Exclusion criteria included workmen’s compensation claims, age <18 years, history of myocardial infarction, and history of lidocaine or adhesive allergies. The American Shoulder and Elbow Surgeons shoulder survey was completed preoperatively and 2-, 6-weeks, 3-, 4.5-, and 6-months postoperatively. A 14-day visual analog scale pain and medication log was completed three times daily following repair. All patients received interscalene nerve block with bupivacaine and general anesthesia.

Results

80 (40 control, 40 lidocaine) patients were enrolled, with 53 completing follow-up. Groups were demographically similar in age (P = .22), gender (P = .20), and body mass index (P = .77). They were similar in tear pattern (P = .95), concomitant acromioplasty (P = .44), concomitant biceps tenodesis (P = .07), and number of anchors used (P = .25). There was no difference in American Shoulder and Elbow Surgeons scores at any time points (range P = .28-P = .97). Reported 14-day pain logs were not different between study groups at any time points (range P = .07-P = .99). There was no difference in opioid consumption in the first 14 days after surgery (P = .38). The lidocaine group reported less satisfaction with their pain management beginning in the evening of POD 2 (P = .05). This continued until the afternoon of POD 8 (P = .03).

Conclusion

Transdermal 4% lidocaine patches are not effective in reducing pain or opioid consumption after arthroscopic rotator cuff repair and were associated with reduced patient satisfaction.

The Safety of Medications used to Treat Peripheral Neuropathic Pain, Part 2 (Opioids, Cannabinoids and Other Drugs): review of Double-Blind, Placebo-Controlled, Randomized Clinical Trials

INTRODUCTION

Peripheral neuropathic pain is a disabling condition for patients and a challenge for physicians. Although many drugs have been assessed in scientific studies, few have demonstrated clear clinical efficacy against neuropathic pain. Moreover, the paucity of data regarding their safety raises the question of the benefit-risk ratio when used in patients experiencing peripheral neuropathies.

AREAS COVERED

We conducted a review of double-blind, placebo-controlled, randomized clinical trials to assess the safety of medications used to treat peripheral neuropathic pain. This second review was focused on opioids, cannabinoids, and other medications. The aim was to provide an overview of the treatment-emergent adverse events (TEAEs) (≥10%) and the serious adverse effects described in clinical trials.

EXPERT OPINION

Opioids and cannabinoids had significantly more TEAEs than placebos. Locally administered analgesics, such as capsaicin, lidocaine, botulinum toxin A seemed to have the most acceptable safety with only local adverse effects. The results for NMDA antagonists were inconclusive since no safety report was available. Less than half of the studies included presented a good description of TEAEs that included a statistical comparison versus a placebo group. Major methodological improvements must be made to ameliorate the assessment of medication safety in future clinical trials.

A randomized controlled trial of cognitive behavioral therapy compared with diabetes education for diabetic peripheral neuropathic pain

A randomized controlled trial compared cognitive behavioral therapy (CBT) and diabetes education (ED) as an adjunctive treatment for diabetic peripheral neuropathic pain (DPNP). We examined change from baseline to 12- and 36-week follow-up in overall pain intensity (NRS), neuropathic pain intensity/quality, pain interference, and mental health functioning, among others. Although CBT participants demonstrated improvement in pain intensity NRS, there were no between-condition differences at either follow-up. CBT reduced neuropathic pain intensity at 12-weeks more than ED. At 36-weeks, CBT was superior to ED for improving pain interference and mental health functioning. Results provide evidence of benefit of CBT for DPNP.

ClinicalTrials.gov Identifier: NCT00830011

Topical Treatment of Localized Neuropathic Pain in the Elderly

The prevalence of neuropathic pain in the older population has been reported to be very high and is most commonly localized to a circumscribed area. Treatment failure is frequent in neuropathic pain and is accompanied by central side effects with recommended oral drugs acting on the central nervous system. A number of topical pharmaceuticals are available on prescription and also sold over the counter. This review in persons aged older than 60 years shows the efficacy of lidocaine 5% and capsaicin 8% for localized neuropathic pain while results with other pharmaceuticals are rather inconsistent. Local application of drugs has a very limited systemic effect and the pharmacological advantages of local over systemic treatment are particularly interesting in older persons who often have comorbidities and take multiple medications. However, more information is needed on the efficacy and safety of lidocaine 5% and capsaicin 8% in older old persons and on the long-term effects of these pharmaceuticals. These studies should also pave the way for research and development in the field of topical analgesics with a satisfactory level of evidence-based medicine.

The Efficacy, Effectiveness and Safety of 5% Transdermal Lidocaine Patch for Chronic Low Back Pain: A Narrative Review

Local anesthetics, such as the 5% transdermal lidocaine patch (5LP), have been frequently used in the treatment of musculoskeletal pain, especially chronic low back pain (CLBP). This review compiles the literature available on the efficacy, effectiveness, and safety of 5LP when used for the management of CLBP. A systematic search method revealed seven articles that fit the inclusion criteria. For each study, efficacy, effectiveness, and adverse events data were extracted. We found no randomized controlled trials with substantial evidence to support the use of 5LP in CLBP, despite the presence of nonrandomized noncontrolled trials suggesting its effectiveness for relief of pain. Future randomized controlled trials with clinically useful outcomes are needed to assess the efficacy, effectiveness, and safety of 5LP for CLBP more appropriately.

A Retrospective Case Series Reporting the Outcomes of Avance Nerve Allografts in the Treatment of Peripheral Nerve Injuries

BACKGROUND

Acellular nerve allografts are a viable treatment modality for bridging nerve gaps. Several small studies have demonstrated results equal to those of autologous grafts; however, there is information lacking with regard to outcomes for wider indications. The authors evaluated the outcomes of patients treated with a nerve allograft in a variety of clinical situations.

METHODS

A retrospective chart analysis was completed between April of 2009 and October of 2017. Inclusion criteria were age 18 years or older at the time of surgery and treatment with a nerve allograft. Patients were excluded if they had not been followed up for a minimum of 6 months. The modified Medical Research Council Classification was used to monitor motor and sensory changes in the postoperative period.

RESULTS

Two hundred seven nerve allografts were used in 156 patients; of these, 129 patients with 171 nerve allografts fulfilled the inclusion criteria. Seventy-seven percent of patients achieved a sensory outcome score of S3 or above and 36 percent achieved a motor score of M3 or above. All patients with chronic pain had improvement of their symptoms. Graft length and diameter were negatively correlated with reported outcomes. One patient elected to undergo revision surgery, and the original graft was shown histologically to have extensive central necrosis. Anatomically, allografts used for lower limb reconstruction yielded the poorest results. All chronic patients had a significantly lower postoperative requirement for analgesia, and allografts were effective in not only reducing pain but also restoring a functional level of sensation.

CONCLUSIONS

This study supports the wider application of allografts in managing nerve problems. However, caution must be applied to the use of long grafts with larger diameters.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Systematic review and network meta-analysis of the efficacy and safety of lidocaine 700 mg medicated plaster vs. pregabalin

Objective: Neuropathic pain prevalence is estimated between 7% and 10% of the population. International guidelines recommend a variety of drugs at different therapy lines for pain relief. However, side effect profiles, for example, prompted the UK government recently to classify pregabalin and gabapentin as class C drugs. Lidocaine 700 mg medicated plaster (LMP) might be a safer alternative. A systematic review assessed how LMP and pregabalin compared in terms of efficacy and safety. The review focused on pain reduction, quality of life and adverse events in peripheral neuropathic pain (PNP) i.e. post-herpetic neuralgia, diabetic peripheral neuropathy, post-surgical/trauma, or other PNP conditions.Methods: Electronic databases were searched as well as a number of other sources up to November 2018. Sensitive strategies were used, with no restriction by language or publication status. Two independent reviewers screened records and extracted data with consensus determining final decisions. Risk of bias was assessed using the Cochrane Collaboration 2011 checklist for RCTs. Full network meta-analysis was conducted to compare LMP to pregabalin 300/600 mg in terms of pain reduction, quality of life, as well as serious adverse events and selected adverse events. Trials with enriched enrolment design were excluded.Results: Searches retrieved 7,104 records. In total 111 references pertaining to 43 RCTs were included for data extraction. Bayesian network meta-analysis of several pain outcomes showed no clear difference in efficacy between treatments However, LMP was clearly advantageous in terms of dizziness and any adverse event vs. pregabalin 600 mg/day and discontinuations vs. pregabalin 300 mg/day or 600 mg/day, as well as being associated with improved quality of life (albeit in this case based on weak evidence).Conclusions: LMP was found to be similar to pregabalin in reducing pain in all populations but had a better adverse events profile.

Assessment and Management of Chronic Pain in the Seriously Ill

The intent of this article is to help clinicians to have practical knowledge and skills related to both assessment and pharmacotherapy of chronic pain in the seriously ill patients. Treating patients with chronic pain and progressive disease should include assessment of "total pain" (physical, psychological, and spiritual suffering) and the care givers as part of treatment team. Effective management of chronic pain starts with thorough assessment and diagnosis of the pain syndrome. A worldwide consensus endorses use of multimodal approach and opioid pharmacotherapy as the mainstay approach to moderate to severe pain in cancer and pain associated with serious illness.

A Comprehensive Algorithm for Management of Neuropathic Pain

BACKGROUND

The objective of this review was to merge current treatment guidelines and best practice recommendations for management of neuropathic pain into a comprehensive algorithm for primary physicians. The algorithm covers assessment, multidisciplinary conservative care, nonopioid pharmacological management, interventional therapies, neurostimulation, low-dose opioid treatment, and targeted drug delivery therapy.

METHODS

Available literature was identified through a search of the US National Library of Medicine's Medline database, PubMed.gov. References from identified published articles also were reviewed for relevant citations.

RESULTS

The algorithm provides a comprehensive treatment pathway from assessment to the provision of first- through sixth-line therapies for primary care physicians. Clear indicators for progression of therapy from firstline to sixth-line are provided. Multidisciplinary conservative care and nonopioid medications (tricyclic antidepressants, serotonin norepinephrine reuptake inhibitors, gabapentanoids, topicals, and transdermal substances) are recommended as firstline therapy; combination therapy (firstline medications) and tramadol and tapentadol are recommended as secondline; serotonin-specific reuptake inhibitors/anticonvulsants/NMDA antagonists and interventional therapies as third-line; neurostimulation as a fourth-line treatment; low-dose opioids (no greater than 90 morphine equivalent units) are fifth-line; and finally, targeted drug delivery is the last-line therapy for patients with refractory pain.

CONCLUSIONS

The presented treatment algorithm provides clear-cut tools for the assessment and treatment of neuropathic pain based on international guidelines, published data, and best practice recommendations. It defines the benefits and limitations of the current treatments at our disposal. Additionally, it provides an easy-to-follow visual guide of the recommended steps in the algorithm for primary care and family practitioners to utilize.

Provider Perspectives on Topical Analgesics

Topical analgesics are effective and alternative means to systemic therapy, often minimizing the adverse drug effects and complications of systemic analgesic use. Despite the number of available topical analgesics, there is little direction provided in practice guidelines on their appropriate use and little is known about patterns of their prescribing. To begin understanding these knowledge gaps, we sought provider perspectives on topical analgesic use at a large academic medical center. This electronic survey seeks to explore the perceptions and prescription patterns of topical analgesics among prescribers in a large academic medical center, where the availability of topical analgesics varies. Among topical analgesics, lidocaine (78%) is prescribed more frequently than nonsteroidal anti-inflammatory drugs (NSAIDs; 41%) or morphine (3%). Formulations and indications of use varied between faculty physicians and nonfaculty providers. Reasons for prescribing were largely based on anecdotal experience. Based on the survey results, it is clear that more topical agents are needed to manage pain; however, so too is guidance on appropriate prescribing.

Management of chronic neuropathic pain with single and compounded topical analgesics

The goal of our review was to emphasize important aspects that physicians should take into consideration when prescribing topical analgesics as part of chronic neuropathic pain treatment. We discuss the dermatopharmacokinetics and microstructural components of the skin, differences between topical and transdermal drug delivery, and topical medication effects on peripheral neuropathy and central sensitization. Even though the US FDA approved topical analgesics are 8%-capsaicin and 5%-lidocaine patches for treating postherpetic neuralgia, there are many other studies conducted on the efficacy of topical ketamine cream, clonidine gel, topical gabapentin, topical baclofen and topical phenytoin for peripheral neuropathic pain, either alone or in combination with other formulations. Furthermore, we discuss new compounded topical analgesics that are becoming more popular and that are showing promising results in the management of chronic peripheral neuropathies. However, more studies are needed for elucidation of the role of topical analgesics and their effects, especially when combined with other treatments.

Alternatives to Opioids in the Pharmacologic Management of Chronic Pain Syndromes: A Narrative Review of Randomized, Controlled, and Blinded Clinical Trials

Chronic pain exerts a tremendous burden on individuals and societies. If one views chronic pain as a single disease entity, then it is the most common and costly medical condition. At present, medical professionals who treat patients in chronic pain are recommended to provide comprehensive and multidisciplinary treatments, which may include pharmacotherapy. Many providers use nonopioid medications to treat chronic pain; however, for some patients, opioid analgesics are the exclusive treatment of chronic pain. However, there is currently an epidemic of opioid use in the United States, and recent guidelines from the Centers for Disease Control (CDC) have recommended that the use of opioids for nonmalignant chronic pain be used only in certain circumstances. The goal of this review was to report the current body of evidence-based medicine gained from prospective, randomized-controlled, blinded studies on the use of nonopioid analgesics for the most common noncancer chronic pain conditions. A total of 9566 studies were obtained during literature searches, and 271 of these met inclusion for this review. Overall, while many nonopioid analgesics have been found to be effective in reducing pain for many chronic pain conditions, it is evident that the number of high-quality studies is lacking, and the effect sizes noted in many studies are not considered to be clinically significant despite statistical significance. More research is needed to determine effective and mechanism-based treatments for the chronic pain syndromes discussed in this review. Utilization of rigorous and homogeneous research methodology would likely allow for better consistency and reproducibility, which is of utmost importance in guiding evidence-based care.

Topical Treatment of Peripheral Neuropathic Pain: Applying the Evidence

CONTEXT

Patients with peripheral neuropathic pain (NP) may only achieve partial pain relief with currently recommended first-line oral treatments, which are also associated with systemic adverse events. Topical treatments are currently considered second- or third-line options, but a recent pharmacologic treatment algorithm has called for broader first-line use of these agents. This has highlighted a need to communicate the benefits associated with topical agents, in particular around the efficacy, targeted local action, and limited systemic availability resulting in minimal systemic adverse events and drug-drug interactions.

OBJECTIVES

This review aims to evaluate the evidence base for topical therapies currently used to treat peripheral NP, discuss the evidence comparing these treatments head-to-head with oral standard of care, and evaluate how they fit into treatment regimens in the "real world."

METHODS

This is a narrative review.

RESULTS

Two topical treatments are currently licensed: lidocaine 5% medicated plaster (post-herpetic neuralgia) and the capsaicin 8% patch (peripheral NP). When compared head to head with the oral standard of care (pregabalin), the lidocaine 5% medicated plaster provided similar relief of pain associated with post-herpetic neuralgia but did not meet the primary predefined criteria for noninferiority. The capsaicin 8% patch, however, demonstrated noninferior efficacy when compared head-to-head with pregabalin across a wide range of peripheral NP etiologies. Importantly, both treatments demonstrated effective pain relief without the systemic adverse events associated with oral therapies.

CONCLUSION

First-line use of topical agents may be of particular benefit in patients where the safety and tolerability of oral therapy is a concern.

Pain Management in Elderly Patients

In elderly patients, persistent pain negatively impacts quality of life. An interdisciplinary approach to pain management and emphasis on quality improvement will help to achieve better therapeutic outcomes. Managing pain in the geriatric population is challenging because of age-related changes in pain perception, cognition, pharmacokinetics, and drug effects. Improvement and maintenance of physical and emotional function is the goal. Pharmacotherapy should be initiated conservatively and titrated to effective doses with minimal adverse effects. Milder pain should be treated with non-opioid analgesics with a progression toward opioids and/or adjuvant medications as the pain intensifies. Acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and adjuvant medications represent most of the analgesic agents used in pain management. Knowing the underlying mechanism of pain will help guide pharmacologic therapy. The patient should be monitored initially, with every dose change, and periodically to assess efficacy and severity of adverse effects.

Management of Pain in Complex Nerve Injuries

Traumatic nerve injuries can be devastating and life-changing events, leading to functional morbidity and psychological stress and social constraints. Even in the event of a successful surgical repair with recovered motor function, pain can result in continued disability and poor quality of life. Pain after nerve injury can also prevent recovery and return to preinjury life. It is difficult to predict which patients will develop persistent pain; once incurred, pain can be even challenging to manage. This review seeks to define the types of pain following peripheral nerve injuries, investigate the pathophysiology and causative factors, and evaluate potential treatment options.

Orofacial Pain: Pharmacologic Paradigms for Therapeutic Intervention

Pain is a universal experience with profound effects on the physiology, psychology, and sociology of the population. Orofacial pain (OFP) conditions are especially prevalent and can be severely debilitating to a patient's health-related quality of life. Evidence-based clinical trials suggest that pharmacologic therapy may significantly improve patient outcomes either alone or when used as part of a comprehensive treatment plan for OFP. The aim of this article is to provide therapeutic options from a pharmacologic perspective to treat a broad spectrum of OFP. Clinical-based systemic and topical applied pharmaceutical approaches are presented to treat the most common OFP syndromes.

Novel Treatment of Radicular Pain With a Multi-Mechanistic Combination Topical Agent: A Case Series and Literature Review

Introduction

Pharmacologic treatment of radicular pain with oral medications is limited by adverse effects and concern for dependence. While topical formulations have been explored in pain research, there is no published literature evaluating the efficacy in radicular pain. We present the first three cases of radicular pain successfully treated with a topical formulation of diclofenac, ibuprofen, baclofen, cyclobenzaprine, bupivacaine, gabapentin, and pentoxifylline (T7).

Case Presentation

Case series evaluating T7 for treatment of radicular pain in a single, outpatient pain center. Pain was rated on the numeric rating scale (NRS) on initial evaluation and follow up after a trial of T7. One to two grams of T7 was applied to the affected area 3 - 4 times daily in addition to the patient’s baseline pharmacologic management. Three patients with median age of 50 (range, 39 to 65) and diagnosis of cervical and/or lumbosacral radicular pain participated. Two of the three had chronic radicular pain despite use of analgesic agents, spinal injections and failed spinal surgery syndrome. Each reported subjective improvement in radicular pain, function and sleep. There was an average decrease in NRS score consistent with 30% - 40% global improvement in symptoms, clinically significant based on the minimal clinically important difference for radicular pain. T7 was well tolerated without adverse reactions. Surgery was prevented or delayed in all cases.

Conclusions

This is the first report of the successful treatment of radicular pain with a topical agent. This highlights the need for randomized, prospective study of both single and compounded topical agents for treatment of radicular pain.

Intrathecal clonidine and adenosine: effects on pain and sensory processing in patients with chronic regional pain syndrome

Chronic pain may be accompanied by hyperalgesia and allodynia, and analgesic interventions may reduce these hypersensitivity phenomena. Preclinical data suggest that intrathecal clonidine and adenosine reduce hypersensitivity, but only clonidine reduces pain; therefore, we tested the effects of these interventions in patients with chronic pain. Twenty-two subjects with pain and hyperalgesia in a lower extremity from complex regional pain syndrome were recruited in a double-blind crossover study to receive intrathecal clonidine, 100 μg, or adenosine, 2 mg. Primary outcome measure was proportion with ≥30% reduction in pain 2 hours after injection, and secondary measures were pain report, areas of hypersensitivity, and temporal summation to heat stimuli. Treatments did not differ in the primary outcome measure (10 met success criterion after clonidine administration and 5 after adenosine administration), although they did differ in pain scores over time, with clonidine having a 3-fold greater effect (P = 0.014). Both drugs similarly reduced areas of hyperalgesia and allodynia by approximately 30% and also inhibited temporal summation. The percentage change in pain report did not correlate with the percentage change in areas of hyperalgesia (P = 0.09, r = 0.08) or allodynia (P = 0.24, r = 0.24) after drug treatment. Both intrathecal clonidine and adenosine acutely inhibit experimentally induced and clinical hypersensitivity in patients with chronic regional pain syndrome. Although these drugs do not differ in analgesia by the primary outcome measure, their difference in effect on pain scores over time and lack of correlation between effect on pain and hypersensitivity suggest that analgesia does not parallel antihyperalgesia with these treatments.

Herpes Zoster and Postherpetic Neuralgia: Practical Consideration for Prevention and Treatment

Herpes zoster (HZ) is a transient disease caused by the reactivation of latent varicella zoster virus (VZV) in spinal or cranial sensory ganglia. It is characterized by a painful rash in the affected dermatome. Postherpetic neuralgia (PHN) is the most troublesome side effect associated with HZ. However, PHN is often resistant to current analgesic treatments such as antidepressants, anticonvulsants, opioids, and topical agents including lidocaine patches and capsaicin cream and can persist for several years. The risk factors for reactivation of HZ include advanced age and compromised cell-mediated immunity (CMI). Early diagnosis and treatment with antiviral agents plus intervention treatments is believed to shorten the duration and severity of acute HZ and reduce the risk of PHN. Prophylactic vaccination against VZV can be the best option to prevent or reduce the incidence of HZ and PHN. This review focuses on the pathophysiology, clinical features, and management of HZ and PHN, as well as the efficacy of the HZ vaccine.

Topical analgesics for neuropathic pain in the elderly: current and future prospects

Neuropathic pain (NeP) is a significant medical and socioeconomic burden with limited therapeutic options. Elderly patients exhibit a higher incidence of several NeP conditions and pose a particular challenge due to age-related pharmacokinetic and pharmacodynamic issues, comorbid conditions, and polypharmacy, as well as frailty and cognitive decline. Topical analgesics are of interest because of their comparable efficacy to oral agents, good tolerability and safety, and potential to be add-on therapies to oral treatments. In recent years, two topical formulations for NeP have been approved (5% lidocaine medicated plaster, 8% capsaicin patch) but are not available in all countries. There are controlled trials and a growing body of open-label reports on their use in clinical care. Some studies provide a post hoc analysis of data in relation to older age (≥65 years), which is useful. The body of evidence relating to topical investigational agents is growing and involves controlled trials as well as individual cases. The largest single body of information is for topical ketamine, administered either alone or combined with other agents (particularly amitriptyline), and some large randomized controlled trials report efficacy. Other large trials involve topical clonidine and further ketamine combinations. Compounding analgesics involves challenges, including uncertain composition (two to five ingredients are used) and concentrations (range 0.5-5%), as well as the heterogeneity of data that support choices. Nevertheless, case reports and acceptable response rates in larger cohorts are intriguing, and this area merits further investigation in controlled settings as well as continued documentation of clinical experiences.

Skin Matters: A Review of Topical Treatments for Chronic Pain. Part Two: Treatments and Applications

In Part One of this two-part series, we discussed skin physiology and anatomy as well as generalities concerning topical analgesics. This modality of therapy has lesser side effects and drug-drug interactions, and patients tolerate this form of therapy better than many oral options. Unfortunately, this modality is not used as often as it could be in chronic pain states, such as that from neuropathic pain. Part Two discusses specific therapies, local anesthetics, and other drugs, as well as how a clinician might use specific aspects of a patient's neuropathic pain presentation to help guide them in the selection of a topical agent.

Pain, sleep disturbances, and functional limitations in people living with HIV/AIDS-associated distal sensory peripheral neuropathy

BACKGROUND

Pain, sleep, and functional disturbances are a common occurrence in people living with HIV/AIDS-related distal sensory peripheral neuropathy (PLWHA-DSPN) yet lack group classification and quantification.

METHODS

A total of 46 PLWHA-DSPN were recruited, as part of a 2-group intervention study, to complete the Neuropathic Pain Scale and the Pittsburgh Sleep Quality Index (PSQI) questionnaires. The participant's performance during a forward reach task and walking distance in 6 minutes was recorded as a measure of function.

RESULTS

The pain (60.77 +/- 17.85) and sleep (14.62 +/- 4.28) scores denote marked pain and sleep disturbances, compared to seronegative, age-matched individuals. The ambulation distance was limited (243.99 +/- 141.04 m) and inversely associated with the PSQI-sleep efficiency subscale (rs = -.35, P < .05). The average reaching distances measured (36.07 +/- 7.37 cm) were similar to seronegative, age-matched individuals. Pain, sleep, and functional measures exhibited significant associations.

CONCLUSIONS

The data collected suggest that PLWHA-DSPN report moderate-to-severe pain and significant sleep disturbances and exhibit limited ambulation distances.

Topical lidocaine for neuropathic pain in adults

BACKGROUND

Lidocaine is a local anaesthetic that is sometimes used on the skin to treat neuropathic pain.

OBJECTIVES

To assess the analgesic efficacy of topical lidocaine for chronic neuropathic pain in adults, and to assess the associated adverse events.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE from inception to 1 July 2014, together with the reference lists of retrieved papers and other reviews. We also searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) search portal to identify additional published or unpublished data.

SELECTION CRITERIA

We included randomised, double-blind studies of at least two weeks' duration comparing any formulation of topical lidocaine with placebo or another active treatment in chronic neuropathic pain. Participants were adults aged 18 and over. We included only full journal publication articles.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks' duration, parallel design); second tier evidence from data that failed to meet one or more of these criteria and that we considered at some risk of bias but with adequate numbers in the comparison; and third tier evidence from data involving small numbers of participants that we considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

We included 12 studies (508 participants) in comparisons with placebo or an active control. Six studies enrolled participants with moderate or severe postherpetic neuralgia, and the remaining studies enrolled different, or mixed, neuropathic pain conditions, including trigeminal neuralgia and postsurgical or post-traumatic neuralgia. Four different formulations were used: 5% medicated patch, 5% cream, 5% gel, and 8% spray. Most studies used a cross-over design, and two used a parallel-group design. Two studies used enriched enrolment with randomised withdrawal. Seven studies used multiple doses, with one to four-week treatment periods, and five used single applications. We judged all of the studies at high risk of bias because of small size or incomplete outcome assessment, or both.There was no first or second tier evidence, and no pooling of data was possible for efficacy outcomes. Only one multiple-dose study reported our primary outcome of participants with ≥ 50% or ≥ 30% pain intensity reduction. Three single-dose studies reported participants who were pain-free at a particular time point, or had a 2-point (of 10) reduction in pain intensity. The two enriched enrolment, randomised withdrawal studies reported time to loss of efficacy. In all but one study, third tier (very low quality) evidence indicated that lidocaine was better than placebo for some measure of pain relief. Pooling multiple-dose studies across conditions demonstrated no clear evidence of an effect of lidocaine on the incidence of adverse events or withdrawals, but there were few events and the withdrawal phase of enriched enrolment designs is not suitable to assess the true impact of adverse events (very low quality evidence).

AUTHORS' CONCLUSIONS

This review found no evidence from good quality randomised controlled studies to support the use of topical lidocaine to treat neuropathic pain, although individual studies indicated that it was effective for relief of pain. Clinical experience also supports efficacy in some patients. Several large ongoing studies, of adequate duration, with clinically useful outcomes should provide more robust conclusions about both efficacy and harm.

Analgesic effects of ketamine infusion therapy in korean patients with neuropathic pain: A 2-week, open-label, uncontrolled study

BACKGROUND

The overexcitation of the N-methyl-D-aspartate receptor complex appears to play a critical role in the development of neuropathic pain, and ketamine acts as an antagonist to that receptor. Some publications have reported on the prominent relief of neuropathic pain with intravenous or subcutaneous ketamine infusions or a single-dose intravenous ketamine injection despite adverse effects.

OBJECTIVES

The primary objective of this study was to determine the analgesic effect of intravenous ketamine infusion therapy for neuropathic pain refractory to conventional treatments. Secondary objectives included identifying the variables related to the analgesic effect and the pain descriptors susceptible to ketamine infusion.

METHODS

This 2-week, open-label, uncontrolled study was conducted in Korean patients with neuropathic pain recruited from the Samsung Seoul Hospital (Seoul, Republic of Korea) outpatient pain management unit. Patients were required to have a pain severity score >5 (visual analog scale [VAS], where 0 = no pain and 10 = worst pain imaginable) over a period of ≥1 month while on standard treatment. The patients were required to have shown no benefit from standard treatment and no pain relief lasting over 1 month. The ketamine infusion therapy was composed of 3 sessions performed consecutively every other day. Midazolam was administered concomitantly to reduce the occurrence of central nervous system-related adverse events (AEs) secondary to ketamine. Each session was as follows: ketamine 0.2 mg/kg and midazolam 0.1 mg/kg were administered intravenously for 5 minutes as a loading dose, followed by a continuous infusion of ketamine 0.5 mg/kg/h and midazolam 0.025 mg/kg/h for 2 hours. AEs were assessed in the following ways: close monitoring of ECG, blood pressure, oxygen saturation, and evaluating the need for treatment of AEs during infu- sion and until discharge by an attending anesthesiologist; an open question about discomfort at the end of each session; spontaneous reports about AEs during each session; and the patients' and caregivers' checklist of AEs occurring at home for 2 weeks after discharge. All the descriptors of pain expressed by the patients in Korean were recorded and translated into appropriate English terminology on the basis of the literature on Korean verbal descriptors of pain. Each of the translated pain descriptors was then classified into 1 of 18 sensory items.

RESULTS

The overall VAS score for pain decreased from a baseline mean (SD) of 7.20 (1.77) to 5.46 (2.29) (P < 0.001) 2 weeks after treatment in 103 patients (53 males and 50 females; mean age, 52.56 [17.33] years) who completed the study. Variables such as age, sex, and the duration and diagnosis of pain were not found to be associated with analgesic effect. Seven of the 18 pain descriptors were found to have a significant response to ketamine infusion treatment between baseline and 2 weeks follow-up: burning pain (P = 0.008); dull, aching pain (P < 0.001); overly sensitive to touch (P = 0.002); stabbing pain (P = 0.008); electric pain (P = 0.031); tingling pain (P < 0.001); and squeezing pain (P < 0.001). A total of 52 patients reported AEs: 33 during infusion and 44 during recovery and up to 2 weeks follow up. The most commonly reported AEs were snoring (15 [15%]) during infusion and dizziness (43 [42%]) during recovery.

CONCLUSIONS

Ketamine infusion therapy was associated with reduced severity of neuropathic pain and generally well tolerated for up to 2 weeks in these patients with neuropathic pain refractory to standard treatment. Variables such as sex, age, and the diagnosis and duration of pain had no association with the analgesic effect of this treatment. Randomized controlled trials are needed to evaluate the efficacy and tolerability of treatment with ketamine infusion.

Randomized Trial of Lower Extremity Splinting to Manage Neuropathic Pain and Sleep Disturbances in People Living with HIV/AIDS

Background/Aims:

Distal symmetrical peripheral neuropathy (DSPN) and sleep disturbances are among the most common complications reported in people living with the human immunodeficiency virus infection and acquired immunodeficiency syndrome (PLWHA). DSPN-pain is predominantly managed by using systemic agents with little evidence supporting their analgesic efficacy. The purpose of this study is to evaluate the effect of nighttime lower extremity splinting application on DSPN-related pain and sleep disturbances compared to a parallel splint liner application in PLWHA.

Methods:

Forty-six PLWHA and DSPN were randomized to nighttime wearing of bilateral lower extremity splints or the liners only. Pain and sleep outcomes were measured at baseline, week 3, and week 6. The pain was measured using the Neuropathic Pain Scale and sleep using the Pittsburgh Sleep Quality Index.

Results:

Pain and sleep scores improved in both groups over time. The median percentage pain reduction at week 6 was 8% in the liner group and 34% in the splint group. The change in pain scores in the splint group was found to be significant over time, P < .0005. The contrast between the splint and liner groups was underpowered (26%) and was not found to be significant, P > .05. Sleep scores improved 20% from baseline to the end of the study in both groups; all participants were classified as poor sleepers.

Conclusion:

The 6-week use of nighttime splints reduces DSPN-pain possibly by providing peripheral inhibition of external stimuli. Future studies are needed to validate this inhibitory intervention to manage DSPN in PLWHA and other neuropathic conditions.

Health economic evidence of 5% lidocaine medicated plaster in post-herpetic neuralgia

BACKGROUND

Post-herpetic neuralgia (PHN) is the most common and most debilitating complication of herpes zoster, and involves considerable associated costs.

OBJECTIVE

This paper presents results from nine health economic studies undertaken in eight European countries that compared lidocaine medicated plaster with gabapentin and/or pregabalin in PHN. It aims to support the increasing need for published cost-effectiveness data for health care decision-making processes in Europe.

METHODS

All studies were based on a similar core Markov model with data derived from clinical trials, local Delphi panels, and official national price and tariff lists. The main outcome measure was cost per quality-adjusted life year gained; time without pain or intolerable adverse events was also included as a secondary outcome measure. All studies focused on an elderly population of patients with PHN who had insufficient pain relief with standard analgesics and could not tolerate or had contraindications to tricyclic antidepressants.

RESULTS

Despite considerable differences in many of the variables used, the results showed remarkable similarity and suggested that use of lidocaine medicated plaster offered cost-savings in many of the countries studied, where it proved a highly cost-effective alternative to both gabapentin and pregabalin.

CONCLUSION

Lidocaine medicated plaster is a cost-effective alternative to gabapentin and pregabalin in the treatment of PHN. These savings are largely the result of the superior safety profile of the lidocaine medicated plaster.

WITHDRAWN: Topical lidocaine for the treatment of postherpetic neuralgia

BACKGROUND

This is an update of the original Cochrane review published in Issue 2, 2007. The cause of postherpetic neuralgia is damage to peripheral neurons, dorsal root ganglia, and the dorsal horn of the spinal cord, secondary to herpes zoster infection (shingles). In postherpetic neuralgia, peripheral neurons discharge spontaneously and have lowered activation thresholds, and exhibit an exaggerated response to stimuli. Topical lidocaine dampens peripheral nociceptor sensitisation and central nervous system hyperexcitability, and may benefit patients with postherpetic neuralgia.

OBJECTIVES

To examine efficacy and safety of topical lidocaine in the treatment of postherpetic neuralgia.

SEARCH METHODS

We searched the Cochrane Pain, Palliative and Supportive Care Group Trials Register, CENTRAL, MEDLINE, EMBASE, LILACS, SIGLE, Citation Index, the reference lists of all eligible trials, key textbooks, and previous systematic reviews. Last search conducted April 2011.

SELECTION CRITERIA

Randomised or quasi‐randomised trials comparing topical applications of lidocaine in patients of all ages with postherpetic neuralgia (pain persisting at the site of shingles at least one month after the onset of the acute rash).

DATA COLLECTION AND ANALYSIS

Two review authors extracted data, and a third checked them.

MAIN RESULTS

In the original review three studies involving 182 topical lidocaine treated participants and 132 control participants were included. Two studies gave data on pain relief, and the remaining study provided data on secondary outcome measures. The largest study published as an abstract compared topical lidocaine patch to a placebo patch and accounted for 150 of the 314 participants (48%). A meta‐analysis combining two studies identified a significant difference between topical lidocaine and control groups for the primary outcome measure: a mean improvement in pain relief according to a pain relief scale. Topical lidocaine relieved pain better than placebo (P = 0.003). There was a statistical difference between the groups for the secondary outcome measure of mean VAS score reduction (P = 0.03), but this was only for a single small study. There were a similar number of adverse skin reactions in both treatment and placebo groups. The highest recorded blood lidocaine concentration varied between 59 ng/ml and 431 ng/ml between studies. The latter figure is high and the authors of the study suggest that the sample had been contaminated during the assay procedure.

AUTHORS' CONCLUSIONS

Since the last version of this review in Issue 2, 2007 no new studies have been found and the results therefore remain the same. There is still insufficient evidence to recommend topical lidocaine as a first‐line agent in the treatment of postherpetic neuralgia with allodynia. Further research should be undertaken on the efficacy of topical lidocaine for other chronic neuropathic pain disorders, and also to compare different classes of drugs (e.g. topical anaesthetic applications versus anti‐epileptic drugs).

Therapeutic options for the treatment of postherpetic neuralgia: a systematic review

Postherpetic neuralgia (PHN) is a chronic and painful condition that may result in significant disturbances to normal activities and decreases in the quality of life for those affected. Despite the availability of several first- and second-line treatment options, many patients may experience refractory pain. The objectives of this review were to summarize evidence for Food and Drug Administration (FDA)-approved and off-label therapies for the treatment of PHN and to present gaps in the current literature for future research focus. Several agents, including pregabalin, gabapentin, and opioids, have been shown to significantly improve pain when compared with placebo. However, evidence regarding the comparative effectiveness of these treatment alternatives is lacking. In order to choose the optimal treatment, providers should consider issues related to efficacy, safety, and tolerability in conjunction with patient goals, preferences, and adherence issues. Evidence from randomized or observational studies that directly compare agents with each other should help to inform treatment choices.

Use of 5% lidocaine medicated plaster to treat localized neuropathic pain secondary to traumatic injury of peripheral nerves

OBJECTIVE

The efficacy of 5% lidocaine medicated plaster (LMP) has previously been demonstrated in post-traumatic localized neuropathic pain. This study evaluated the use of LMP in localized neuropathic pain secondary to traumatic peripheral nerve injury.

PATIENTS AND METHODS

This prospective observational study enrolled patients with traumatic injuries to peripheral nerves that were accompanied by localized neuropathic pain of more than 3 months duration. Demographic variables, pain intensity (measured using the numeric rating scale; NRS), answers to the Douleur Neuropathique 4 (DN4) questionnaire, and the size of the painful area were recorded.

RESULTS

Nineteen patients were included, aged (mean ± standard deviation) 41.4 ± 15.7 years. Nerve injuries affected the upper (eight patients) or lower (11 patients) limbs. The mean duration of pain before starting treatment with LMP was 22.6 ± 43.5 months (median 8 months). Mean baseline values included: NRS 6.7 ± 1.6, painful area 17.8 ± 10.4 cm(2) (median 18 cm(2)), and DN4 score 6.7 ± 1.4. The mean duration of treatment with LMP was 19.5 ± 10.0 weeks (median 17.4 weeks). Mean values after treatment were: NRS 2.8 ± 1.5 (≥3 point reduction in 79% of patients, ≥50% reduction in 57.9% of patients) and painful area 2.1 ± 2.3 cm(2) (median 1 cm(2), ≥50% reduction in 94.7% of patients). Functional improvement after treatment was observed in 14/19 patients (73.7%).

CONCLUSION

LMP effectively treated traumatic injuries of peripheral nerves which presented with chronic localized neuropathic pain, reducing both pain intensity and the size of the painful area.

Lidocaine patch (5%) is no more potent than placebo in treating chronic back pain when tested in a randomised double blind placebo controlled brain imaging study

Background

The 5% Lidocaine patch is used for treating chronic neuropathic pain conditions such as chronic back pain (CBP), diabetic neuropathy and complex regional pain syndrome, but is effective in a variable proportion of patients. Our lab has reported that this treatment reduces CBP intensity and associated brain activations when tested in an open labelled preliminary study. Notably, effectiveness of the 5% Lidocaine patch has not been tested against placebo for treating CBP. In this study, effectiveness of the 5% Lidocaine patch was compared with placebo in 30 CBP patients in a randomised double-blind study where 15 patients received 5% Lidocaine patches and the remaining patients received placebo patches. Functional MRI was used to identify brain activity for fluctuations of spontaneous pain, at baseline and at two time points after start of treatment (6 hours and 2 weeks).

Results

There was no significant difference between the treatment groups in either pain intensity, sensory and affective qualities of pain or in pain related brain activation at any time point. However, 50% patients in both the Lidocaine and placebo arms reported a greater than 50% decrease in pain suggesting a marked placebo effect. When tested against an untreated CBP group at similar time points, the patch treated subjects showed significantly greater decrease in pain compared to the untreated group (n = 15).

Conclusions

These findings suggest that although the 5% Lidocaine is not better than placebo in its effectiveness for treating pain, the patch itself induces a potent placebo effect in a significant proportion of CBP patients.

Modified Jaipur block for the treatment of post-herpetic neuralgia

Post-herpetic neuralgia means pain which occurs for longer than one to three months after the resolution of the rash of herpes zoster. We conducted a study of 30 patients having post herpetic neuralgia. All the patients were treated with modified Jaipur block consisting of local subcutaneous infiltration of 2% Xylocaine, 0.5% bupivacaine and methylprednisolone. In our study, it was seen that 20% patients had complete relief of pain after first injection, 60% patients had complete relief of pain after second injection, 10% patients had complete relief of pain after third injection, and only 10% patients did not respond to treatment. The non-responders were either old (over 60 years) or had pain lasting for more than two years.

Painful peripheral neuropathies

BACKGROUND AND OBJECTIVES

Painful neuropathies are common and often difficult to treat. The objective of this report was to review the subject to facilitate diagnosis and pain relief.

CONTENTS

The classification, causes, type of fibers involved, manifestations, diagnosis, adjuvant tests, questionnaires used in the diagnosis, and treatment are described.

CONCLUSIONS

The subject is very broad and involves several causes and treatments that often should be combined to obtain adequate pain control.

Preliminary assessment of a neuropathic pain treatment and referral algorithm for patients with cancer

CONTEXT

The purpose of this case series study was to pilot test an evidence-based neuropathic pain (NP) treatment and referral algorithm for use by oncology nurses when managing cancer-related NP.

OBJECTIVES

The primary study objective was to assess patient-reported outcomes (pain severity, changes in activities of daily living, and satisfaction) resulting from algorithm use.

METHODS

Outpatients (n=20) with cancer-related NP scores ≥4 on a 0-10 numeric rating scale participated in the study. NP assessment, treatment, and referral to ancillary providers were guided by an evidence-based NP algorithm that was implemented by oncology nurse practitioners. Based on efficacy evidenced through randomized clinical trials published at the time of study implementation, the following drugs were included in the algorithm: lidocaine patch, gabapentin, oxycodone, tramadol, morphine, methadone, duloxetine, pregabalin, and nortriptyline. Recommendations for starting dose, dose escalation, drug combinations, treatment duration, and contraindications were included for first-tier drugs. Patient-reported outcomes (pain severity, functional capacity, and satisfaction) were assessed monthly over 12 weeks.

RESULTS

Average NP severity (P=0.001), general activity (P<0.001), mood (P=0.002), walking ability (P=0.01), ability to perform normal work (P=0.002), relationships (P=0.002), sleep (P=0.01), life enjoyment (P<0.001), and patient satisfaction (P=0.003) all improved by 12 weeks.

CONCLUSION

Evidence from this pilot study suggests that NP evidence-based treatment may result in improved symptoms, function, and patient satisfaction. A randomized controlled trial is needed to further assess algorithm efficacy.