EFNS guidelines on pharmacological treatment of neuropathic pain

Empirically Supported Use of Psychiatric Medications in Adolescents and Adults with IBD

BACKGROUND

The use of psychotropic medications, particularly antidepressants, is common in patients with inflammatory bowel disease (IBD) in spite of a lack of their robust efficacy in this population. This review provides an overview of the use trends of different classes of antidepressant and anti-anxiety medication and their effects on mood, nervous system function, gastrointestinal physiology and immunity drawing from the literature available in the general population, other medical conditions, and when available, patients with IBD. It also covers the evidence base for the actions, efficacy, and potential complications of antidepressants organized by different classes.

METHODS

We conducted a PubMed search of articles relating the different drug classes probed to the terms above in different populations of interest. All types of articles were accepted including case reports and series, open and randomized trials, reviews, and expert opinion. We also examined the reference lists of the publications found.

RESULTS

Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) are the most commonly prescribed agents for anxiety and depression in patients with IBD, though their efficacy for these conditions in the general population are mild to moderate at best. SSRIs are generally well tolerated, though at higher doses, they, like most antidepressant classes, can be associated with activation, serotonergic syndrome, and increased suicidal ideation. TCAs have many more serious side effects but have some shown efficacy for functional GI symptoms. A newer class, the serotonin noradrenergic reuptake inhibitors (SNRIs), can be effective for refractory depression, anxiety and chronic pain syndromes with a side effect profile similar to both SSRIs and more mild manifestations of TCAs. Mirtazapine has moderate efficacy for depression if sedation and weight gain side effects are tolerated and some small support for use in nausea and vomiting. Bupropion targets dopamine and noradrenaline reuptake and has moderate efficacy for depression, and some small support for use in fatigue and smoking cessation. Buspirone has an indication for generalized anxiety disorder though studies show only a minimal benefit. It has some growing evidence for use in functional dyspepsia. Most of these agents have physiological effects on the brain, immune system, and gastrointestinal tract (with the exception of bupropion) hence their therapeutic and side effects manifested in these systems.

CONCLUSION

Antidepressant medications are frequently prescribed for depression, anxiety disorders, and chronic pain syndromes, but overall support for their efficacy is modest at best. Psychological interventions have growing support for having much more robust effects without the side effects of antidepressants and should be considered first-line treatment or at least an adjunct to psychotropic medications for these conditions.

Comparative clinical study of gabapentin and pregabalin for postoperative analgesia in laparoscopic cholecystectomy

Background:

Reduction in central sensitization by gabapentinoids that include gabapentin and pregabalin may reduce acute postoperative pain.

Aims:

The aim of this study is to evaluate postoperative analgesic benefit and efficacy in patients administered with oral gabapentin or pregabalin as premedication for laparoscopic cholecystectomy under general anesthesia.

Settings and Design:

Randomized, prospective, and comparative study.

Materials and Methods:

In this study, recruited patients were randomly allocated in three groups. Groups A, B, and C received 2 capsules of B complex, 3 capsules of 300 mg gabapentin each, and 2 capsules of 75 mg pregabalin, respectively, each in 30 patients of each group, 1 h before induction of anesthesia. Postoperative efficacy among these three groups was compared with respect to increase in duration of analgesia, reduction in postoperative pain scores, total postoperative requirements of analgesics and side effects.

Statistical Analysis:

Mean and standard deviation were calculated. Test of analysis between two groups was done by t-test and among three groups by analysis of variance, and then P value was calculated.

Results:

Pregabalin and gabapentin group had lower visual analog scale (VAS) score (P < 0.05), prolonged timing of first rescue analgesic (4.67 ± 14.79 vs. 158 ± 13.10 vs. 343.16 ± 9.69) min, and less opioid consumption (169.87 ± 20.32 vs. 116.13 ± 14.08 vs. 64.67 ± 16.69) mg compared to placebo group. Between the gabapentinoids, pregabalin group had lower VAS score, prolonged timing of first rescue analgesic, and less opioids consumption than the gabapentin group.

Conclusion:

It is concluded in this study that pregabalin group had lower VAS score, prolonged timing of first rescue analgesic, and less opioids consumption than the gabapentin group. Both gabapentinoids had better postoperative analgesic profile than placebo.

The efficacy of pregabalin in patients with moderate and severe pain due to diabetic peripheral neuropathy

Objective To compare the therapeutic response to pregabalin in patients with moderate or severe painful diabetic peripheral neuropathy (pDPN). Research design and methods Data were pooled from 11 placebo-controlled trials to evaluate the efficacy of pregabalin flexible or fixed dose (150, 300 or 600 mg/day) in pDPN patients with mean baseline pain scores of ≥4 to <7 (moderate) or ≥7 to ≤10 (severe). Last observation carried forward imputation was used. Study number/ClinicalTrials.gov identifier 1008-014/-, 1008-029/-, 1008-040/-, 1008-131/-, 1008-149/-, 1008-000-155/-, A0081030/NCT00156078, A0081060/NCT00159679, A0081071/NCT00143156, A0081081/NCT00301223, A0081163/NCT00553475. Main outcome measures Pregabalin-mediated change in pain, pain-related sleep interference (PRSI) and patient global impression of change (PGIC) were compared versus placebo and between moderate and severe pain cohorts. Adverse events (AEs) were reported. Results At baseline, 1816 patients had moderate pain (pregabalin, n = 1189) and 1119 patients had severe pain (pregabalin, n = 720). Pregabalin significantly reduced pain scores at endpoint compared with placebo when patients of all pain levels were combined (all doses; p < 0.05). In the moderate and severe pain cohorts, pregabalin treatment (300, 600 mg/day or flexible) significantly reduced mean pain scores at endpoint compared with placebo (p < 0.01). Pain reduction was greatest in patients with severe baseline pain compared with moderate baseline pain (pregabalin 300, 600 mg/day or flexible; p < 0.0001). Pregabalin improved PRSI and PGIC in the moderate and severe cohorts compared with placebo. The greatest improvement in PRSI also occurred in the severe cohort. Treatment-emergent AEs, most commonly dizziness, somnolence and peripheral edema, occurred more frequently in patients treated with pregabalin compared with placebo. Conclusions Pregabalin was effective in pDPN patients with both moderate and severe baseline pain. Patients with severe pain exhibited greater improvements in pain and PRSI than patients with moderate pain. Pain severity may, in part, predict therapeutic response to pregabalin.

Transcranial magnetic stimulation as a new tool to control pain perception

Treatment for chronic pain is frequently unsuccessful or characterized by side-effects. The high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has been suggested in the management of refractory chronic pain. Various studies have shown that HF-rTMS sessions of long-duration applied at primary motor cortex induce pain relief through mechanisms of plastic changes. Efficacy of rTMS mostly depends on stimulation parameters, but this aspect requires better characterization. A rationale to target other cortical areas exists. Current data are promising, but a careful analysis of stimulation settings and maintenance treatment design are need.

Intraoral administration of botulinum toxin for trigeminal neuropathic pain

This article presents 2 cases of different neuropathic trigeminal pain conditions treated with intraoral botulinum toxin injections. There is a growing body of evidence to support the use of this substance when administered subcutaneously in the treatment of neuropathic pain, such as in extraoral injections for trigeminal neuralgia. However, reports of intraoral submucosal administration are still lacking. In the 2 cases presented here, neuropathic pain was refractory to treatment with an important intraoral peripheral component, so onabotulinum toxin A was introduced as an adjuvant therapy. The technique, doses, and dilution are discussed. The patients reported significant reductions in pain frequency and intensity, with minimal side effects of temporary mucosal dryness and smile droopiness. The analgesic benefits of botulinum toxin may be utilized to address intraoral neuropathic pain. Further studies are needed to confirm safety and effectiveness in larger samples.

Current Ideas on the Treatment Of Diabetic Neuropathies

Diabetic neuropathies are common and their prevalence is rising with the growth in the global prevalence of type 2 diabetes. Several patterns of neuropathy have now been described, with diabetic sensorimotor polyneuropathy (DPN) being the most common. Autonomic neuropathy, entrapment neuropathies including carpal tunnel syndrome and ulnar neuropathy at the elbow pose additional burdens. DPN can be detected in over half of all diabetic subjects and approximately 20% of all patients with DPN also experience neuropathic pain, a complication with major impacts on quality of life. Currently, the only available treatments for DPN are optimal glucose control and pain management, whereas interventions, beyond optimizing hyperglycemic control, to address the underlying polyneuropathy are not available. Here we review current treatment options and new literature relating to DPN, with an emphasis on novel and emerging treatments.

Amitriptyline and phenytoin prevents memory deficit in sciatic nerve ligation model of neuropathic pain

BACKGROUND

Phenytoin and amitriptyline are often reported to attenuate pain in chronic conditions. Information on their ability to ameliorate cognitive impairment associated with neuropathic pain remains unclear due to mixed results from studies. This study investigated the effects of phenytoin and amitriptyline on memory deficit associated with neuropathic pain.

METHODS

Twenty-eight adult male Wistar rats were randomly divided into four groups: A, B, C, and D (n=7). Groups A, B, C, and D served as sham control, sciatic nerve ligated untreated, sciatic nerve ligated receiving amitriptyline (5 mg/kg), and sciatic nerve ligated receiving phenytoin (10 mg/kg) respectively. Treatments lasted for 14 days, after which both 'Y' maze and novel object recognition test (NOR) were performed. On the last day of treatment, the animals were anesthetized and their brain excised, and the prefrontal cortices and sciatic nerve were processed histologically using hematoxylin and eosin.

RESULTS

There was memory impairment in the sciatic nerve ligated untreated group which was statistically significant (p<0.05) when compared to the phenytoin-treated, amitriptyline-treated, and sham control groups using the 'Y' maze and NOR tests. Histological quantification showed that the prefrontal cortices of the ligated animals showed increased neural population in comparison to normal control. These increases were significantly marked in the untreated ligated group. Sciatic nerve of untreated ligated group showed high demyelination and axonal degeneration which was ameliorated in the treated animals.

CONCLUSIONS

The administration of amitriptyline and phenytoin can ameliorate neuronal injury, demyelination, and memory impairment associated with neuropathic pain in Wistar rats.

Efficacy and Safety of Gabapentin vs. Carbamazepine in the Treatment of Trigeminal Neuralgia: A Meta-Analysis

To evaluate the safety and efficacy of gabapentin in comparison with carbamazepine in the treatment of trigeminal neuralgia, a meta-analysis of randomized controlled trials was performed. Two reviewers independently selected studies, assessed study quality, and extracted data. Sixteen randomized controlled trials that included 1,331 patients were assessed. The meta-analysis showed that the total effective rate of gabapentin therapy group was similar with carbamazepine therapy group (OR = 1.600, 95% CI 1.185, 2.161, P = 0.002). While the effective rate of gabapentin therapy for 4 weeks was higher than that of carbamazepine therapy (OR = 1.495, 95% CI 1.061, 2.107, P = 0.022, heterogeneity: x² = 7.12, P = 0.625, I² = 0.0%), the life satisfaction improvement is also better in the gabapentin therapy group after a 4-week treatment (SMD = 0.966, 95% CI 0.583, 1.348, P < 0.001). Furthermore, our meta-analysis suggested that the adverse reaction rate of gabapentin therapy group was significantly lower than that of carbamazepine therapy group (OR = 0.312, 95% CI 0.240, 0.407, P < 0.001). In conclusion, present trials comparing gabapentin with carbamazepine are all poor in terms of methodological quality. Based on the available evidence, it is not possible to draw conclusions regarding the efficacy and side effects of gabapentin being superior to carbamazepine.

Clinical practice guidelines for the management of neuropathic pain: a systematic review

BACKGROUND

The management of neuropathic pain (NP) is challenging despite it being the recent focus of extensive research. A number of clinical practice guidelines (CPGs) for the management of NP have been published worldwide over the past 2 decades. This study aimed to assess the quality of these CPGs.

METHODS

We performed a systematic review of published CPGs for the management of NP. Three reviewers independently assessed the quality of the CPGs using the Appraisal of Guidelines Research and Evaluation II (AGREE-II) instrument, and recommendations of CPGs were also appraised.

RESULTS

A total of 16 CPGs were included. Thirteen CPGs were developed using an evidence-based approach, and the remaining CPGs were produced by consensus panels. None of CPGs obtained a score greater than 50% in all six AGREE II instrument domains mainly owing to poor performance in the "Applicability" domain. The highest score of the CPGs was achieved in "Clarity and Presentation" domain, followed by "Scope and Purpose" and "Editorial Independence" domains, and the lowest scores were found the in "Applicability" domain. The majority of the CPG recommendations on the management of patients with NP were relatively consistent, especially regarding the recommendation of stepwise treatment with medication.

CONCLUSIONS

Greater efforts are needed not only to improve the quality of development and presentation of the CPGs, but also to provide more efficacy evidence for the management of patients with NP.

The topical 5% lidocaine medicated plaster in localized neuropathic pain: a reappraisal of the clinical evidence

Topical 5% lidocaine medicated plasters represent a well-established first-line option for the treatment of peripheral localized neuropathic pain (LNP). This review provides an updated overview of the clinical evidence (randomized, controlled, and open-label clinical studies, real-life daily clinical practice, and case series). The 5% lidocaine medicated plaster effectively provides pain relief in postherpetic neuralgia, and data from a large open-label controlled study indicate that the 5% lidocaine medicated plaster is as effective as systemic pregabalin in postherpetic neuralgia and painful diabetic polyneuropathy but with an improved tolerability profile. Additionally, improved analgesia and fewer side effects were experienced by patients treated synchronously with the 5% lidocaine medicated plaster, further demonstrating the value of multimodal analgesia in LNP. The 5% lidocaine medicated plaster provides continued benefit after long-term (≤7 years) use and is also effective in various other LNP conditions. Minor application-site reactions are the most common adverse events associated with the 5% lidocaine medicated plaster; there is minimal risk of systemic adverse events and drug–drug interactions. Although further well-controlled studies are warranted, the 5% lidocaine medicated plaster is efficacious and safe in LNP and may have particular clinical benefit in elderly and/or medically compromised patients because of the low incidence of adverse events.

Alleviation of neuropathic scar pain using autologous fat grafting

Traumatic wounds inflict small- and large-fiber sensory nerve damage, causing neuropathic pain in scar tissue, thus impairing patients' quality of life and leading to the development of psychological disorders. Autologous fat grafting has been clinically shown to improve scar quality, but few studies have explored the effects of this technique on pain. The purpose of this study was to assess the effect of fat grafting on treating neuropathic scar pain. From February 2008 to January 2013, 13 patients who were identified using the Douleur Neuropathique 4 Questions (scores>4/10) were enrolled in this study. The Visual Analog Scale (VAS) and Neuropathic Pain Symptom Inventory (NPSI) were used to evaluate pain preoperatively and 1 week, 4 weeks, and 24 weeks postoperatively. The mechanism of trauma, scar location and size, duration of allodynia, fat graft volume, pharmacologic therapy duration, and total follow-up time were recorded. Thirteen patients experiencing neuropathic pain were enrolled in this study. The mean±SD age was 33.08±16.35 years. The mean duration of pain was 4.29±2.85 months. The mean VAS score before treatment was 7.54±1.05. The mean VAS scores decreased by 4.38±1.66 after 1 week of treatment (P=0.009), 5.38±2.06 after 4 weeks of treatment, and 5.62±2.18 after 24 weeks of treatment. The mean NPSI scores were 49.38±13.25 before treatment, 25±14.4 after 1 week of treatment (P=0.004), 21±17.78 after 4 weeks of treatment, and 14.62±16.88 after 24 weeks of treatment. The 13 patients followed a mean of 24 weeks; 10 (77%) of the patients had improvement of 5 or greater on the VAS score. The mean follow-up period was 19.3±12.26 months (range, 6-38 months). No surgical complications were noted in this series. In our study, both VAS and NPSI scores decreased significantly, revealing that the autologous fat grafting can alleviate neuropathic scar pain 1 week after operation and in the long term.

[Central regulation of pain in patients with joint disease and approaches to therapy]

The paper reviews investigations studies that have demonstrated that chronic pain syndrome is mixed in rheumatic diseases. The nervous system is involved in its pathogenesis with different frequency and different mechanisms. Under the influence of afferent pain impulses from damaged joints, there are changes in the excitability of spinal cord neurons, which is called central sensitization (CS). A number of patients have enhanced CS and clinical manifestations as neuropathic sensitive phenomena. The mixed model of the development of chronic pain in joint diseases and its presence along with nociceptive (inflammatory) and neuropathic pain components may explain the discrepancy between joint inflammatory and structural changes and pain intensity, the presence of distant pain and sensitive disorders in the areas outside the joint, and sometimes the efficiency of anti-inflammatory therapy. The presence of the neuropathic pain component serves as a rationale for combined therapy by adding centrally acting drugs, such as anticonvulsants.

Opioid use in the management of diabetic peripheral neuropathy (DPN) in a large commercially insured population

OBJECTIVE

To examine the proportion of diabetic peripheral neuropathy (DPN) patients receiving pharmacologic DPN treatments and specifically to identify the rates and factors associated with opioid use and first-line opioid use.

METHODS

A 10% sample of IMS-LifeLink claims data from 1998 through 2008 was used. The study population consisted of diabetic patients who met DPN criteria using a validated DPN algorithm. Multivariable logistic regression controlling for demographics, comorbidities, and other clinical characteristics was used to identify factors associated with any DPN pharmacologic treatment, any opioid use, and first-line opioid treatment. Sensitivity analyses were conducted to explore variations in exclusion criteria as well as opioid use definitions.

RESULTS

A total of 666 DPN patients met inclusion criteria and pharmacologic treatment was received by 288 patients (43.24%) and of those, 154 (53.47%) had DPN-related opioid use and 96 (33.33%) received opioid as first-line treatment. Persons with diabetic complications were more likely to use opioids (odds ratio=4.53; 95% confidence interval, 1.09-18.92). Food and Drug Administration-approved DPN agents duloxetine 1.04% (n=3) and pregabalin 5.56% (n=16) had much lower rates of use. DPN-related drug use and DPN-related opioid usage increased as we used less restrictive samples in sensitivity analyses.

CONCLUSIONS

Opioids were the most frequently prescribed first-line agents for DPN. More than 50% of DPN patients remained untreated with pharmacologic agents 1 year after a DPN diagnosis.

The Medicinal Cannabis Treatment Agreement: Providing Information to Chronic Pain Patients Through a Written Document

AIM

Pain practitioners would seem to have an obligation to understand and inform their patients on key issues of the evidence base on cannabinoid therapeutics. One way to fulfill this obligation might be to borrow from concepts developed in the prescription of opioids: the use of a written agreement to describe and minimize risks. Regrettably, the widespread adoption of opioids was undertaken while harmful effects were minimized; obviously, no one wants to repeat this misstep.

OBJECTIVE

This article describes a method of educating patients in a manner analogous to other treatment agreements.

BACKGROUND

Surveys have demonstrated that pain is the most common indication for medical use of cannabis. As more individuals gain access to this botanical product through state ballot initiatives and legislative mandate, the pain specialist is likely to be confronted by patients either seeking such treatment where permitted, or otherwise inquiring about its potential benefits and harms, and alternative pharmaceuticals containing cannabinoids.

METHODS

PubMed searches were conducted using the following keywords: cannabis guidelines, harmful effects of cannabis, medical marijuana, medicinal cannabis, opioid cannabis interaction, cannabis dependence and cannabis abuse

RESULTS

: The authors selected individual tenets a medicinal cannabis patient would be asked to review and acknowledge via signature.

CONCLUSIONS

Undoubtedly, the knowledge base concerning risks will be an iterative process as we learn more about the long-term use of medicinal cannabis. But we should start the process now so that patients may be instructed about our current conception of what the use of medicinal cannabis entails.

Analgesic effect of total flavonoids from Sanguis draxonis on spared nerve injury rat model of neuropathic pain

BACKGROUND

Sanguis draxonis (SD) is a kind of red resin obtained from the wood of Dracaena cochinchinensis (Lour.) S. C. Chen (D. cochinchinensis). The active components of total flavonoids from SD (SDF) have analgesic effect.

AIM

The aim of this study is to evaluate the analgesic effects and potential mechanism of SDF on mechanical hypersensitivity induced by spared nerve injury (SNI) model of neuropathic pain in the rat.

METHODS

SNI model in rats was established and then the rats were treated with SDF intragastric administration for 14 days. Paw withdrawal mechanical threshold (PMWT) in response to mechanical stimulation was measured by von Frey filaments on day 1 before operation and days 1, 3, 5, 7, 9, 11, 14 after operation, respectively. After 14 days, we measured the levels of nitric oxide (NO), nitric oxide synthase (NOS), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-10 (IL-10) in the spinal dorsal horn. In addition, the expression of fibroblast growth factor receptor 3 (FGFR3), phosphorylated cyclic AMP response element-binding protein (p-CREB) and glial fibrillary acidic protein (GFAP) of the spinal dorsal horn was evaluated by western blotting and an immunofluorescence histochemical method, respectively.

RESULTS

Intragastric administration of SDF (100, 200, 400 mg/kg) alleviated significantly SNI-induced mechanical hypersensitivity, as PMWT increased in a dose-dependent manner. Moreover, SDF not only reduced the level of NO, NOS, TNF-α and IL-1β, but also upregulated the level of IL-10 in the spinal dorsal horn of SNI rats. At the same time, SDF (100, 200, 400 mg/kg) could inhibit the expression of FGFR3, GFAP and p-CREB in the spinal dorsal horn.

CONCLUSION

SDF has potentially reduced mechanical hypersensitivity induced by SNI model of neuropathic pain which may be attributed to inhibition of astrocytic function (like release pro-inflammatory cytokines) and NO release as well as p-CREB activation in the spinal dorsal horn.

Pilot evaluation of scrambler therapy for pain induced by bone and visceral metastases and refractory to standard therapies

PURPOSE

Scrambler therapy is a non-invasive neurocutaneous electrical pain intervention, effective for the treatment of neuropathic pain. Currently, few data about the efficacy of this treatment in cancer pain induced by skeletal and visceral metastases are available. The aim of this single-center case series is to evaluate the efficacy of scrambler therapy in reducing this kind of cancer pain after failure of standard treatments, including pharmacological therapies and radiation therapy.

METHODS

Twenty-five consecutive patients underwent scrambler therapy individually delivered by MC5-A Calmare for 10 daily sessions each of 30-40 min. Pain was measured by a numeric rating scale at baseline, as well as before and after each treatment session.

RESULTS

One hundred percent of patients reached a pain relief ≥50 %. Pain score was reduced from 8.4 at baseline to 2.9 after treatment, with a mean pain relief of 89 %. The sleeping hours improved from 4.4 ± 1.2 to 7.5 ± 1.1. The duration of pain control by scrambler therapy was 7.7 ± 5.3 weeks. No adverse events were observed.

CONCLUSION

Scrambler therapy does not present toxicity and allows opioids dosage reduction, and it is also a repeatable treatment. Present novel data support that scrambler therapy seems to be effective for the treatment of cancer pain. Further evaluation in randomized and controlled clinical trials should be performed to confirm our findings.

Neuropathic pain in brachial plexus injury

BACKGROUND

In Thailand, brachial plexus injury is a common traumatic injury that affects the function of the upper extremity. The current treatments focus mainly on improving the motor and sensory function. Apart from the motor and sensory deficit, these patients usually suffer from pain.

OBJECTIVE

The purpose of this study was to determine the prevalence and factors that relate to neuropathic pain in patients with brachial plexus injury.

METHODS

We collected data from March 2008 to July 2011. The DN4 Questionnaire was used to diagnose neuropathic pain in 95 patients.

RESULTS

The prevalence of neuropathic pain was as high as 76%. Majority of patients presented with hypoesthesia to pin prick, hypoesthesia to touch and numbness. Severity of neuropathic pain was significantly correlated with the type of brachial plexus injury. There was no difference between demographic characteristics of patients.

CONCLUSION

Our study showed that the prevalence of neuropathic pain was high in brachial plexus injured patients. Therefore, surgeons should be aware of this common, yet underestimated, problem in brachial plexus injured patients.

Neuropathic pain in people with cancer (part 2): pharmacological and non-pharmacological management

The aim of this paper is to provide an overview of the management of neuropathic pain associated with cancer and to provide helpful clinical advice for nurses working with patients who may have neuropathic pain. While cancer pain is a mixed-mechanism pain, this article will focus only on neuropathic pain management. The impact of neuropathic pain on patients' quality of life is great and while many patients recover from their cancer, a significant number continue to suffer from a neuropathic pain syndrome. Management of neuropathic pain is significantly different from management of nociceptive pain with respect to pharmacological and non-pharmacological strategies. Neuropathic pain is complex, and as such requires complex management using pharmacological as well as non-pharmacological approaches. Specific drugs for neuropathic pain may be effective for some patients, but not all; therefore, ongoing and comprehensive assessment and management are required. Furthermore, these patients may require trials of several drugs before they find one that works for them. It is important for nurses to understand neuropathic pain, its manifestation, impact on quality of life and management when nursing patients with neuropathic pain associated with cancer.

Outcome measures in randomized-controlled trials of neuropathic pain conditions: a systematic review of systematic reviews and recommendations for practice

OBJECTIVES

Neuropathic pain (NeP) is a prevalent, disabling, multidimensional condition with significant morbidity; however, there appears to be a variable approach in the use of outcome measures in NeP trials. A search of systematic reviews of interventional randomized-controlled trials for NeP was undertaken to investigate the range and types of outcome measures used to determine treatment effects.

METHODS

Keywords and MESH searches were conducted in 5 electronic databases from inception to January 31, 2012. Full-text English-language reviews based on various acute and chronic NeP conditions were included. Two independent reviewers screened papers for inclusion, extracted data, and assessed the quality of reviews. Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to critically appraise the reviews.

RESULTS

A total of 46 studies were identified: the majority of reviews (n=28/46, 61%) scored well on the PRISMA (PRISMA scores of 20-27/27). Change in levels or intensity of pain were used by the majority of studies as the primary outcome measure in intervention studies (n=40/46 studies, 87%). Few studies used a functional outcome measure as either a primary or secondary outcome measure (n=7/46, 15% of studies).

DISCUSSION

These results demonstrate that measures of pain are predominantly used in trials of NeP conditions and highlight the scant usage of functional outcome measures. The lack of standardization for the diagnostic criteria in NeP trials is also an issue that needs to be considered for future research and guideline development.

Informative gene network for chemotherapy-induced peripheral neuropathy

BACKGROUND

Host genetic variability has been implicated in chemotherapy-induced peripheral neuropathy (CIPN). A dose-limiting toxicity for chemotherapy agents, CIPN is also a debilitating condition that may progress to chronic neuropathic pain. We utilized a bioinformatics approach, which captures the complexity of intracellular and intercellular interactions, to identify genes for CIPN.

METHODS

Using genes pooled from the literature as a starting point, we used Ingenuity Pathway Analysis (IPA) to generate gene networks for CIPN.

RESULTS

We performed IPA core analysis for genes associated with platinum-, taxane- and platinum-taxane-induced neuropathy. We found that IL6, TNF, CXCL8, IL1B and ERK1/2 were the top genes in terms of the number of connections in platinum-induced neuropathy and TP53, MYC, PARP1, P38 MAPK and TNF for combined taxane-platinum-induced neuropathy.

CONCLUSION

Neurotoxicity is common in cancer patients treated with platinum compounds and anti-microtubule agents and CIPN is one of the debilitating sequela. The bioinformatic approach helped identify genes associated with CIPN in cancer patients.

Re-branding cannabis: the next generation of chronic pain medicine?

The field of pain medicine is at a crossroads given the epidemic of addiction and overdose deaths from prescription opioids. Cannabis and its active ingredients, cannabinoids, are a much safer therapeutic option. Despite being slowed by legal restrictions and stigma, research continues to show that when used appropriately, cannabis is safe and effective for many forms of chronic pain and other conditions, and has no overdose levels. Current literature indicates many chronic pain patients could be treated with cannabis alone or with lower doses of opioids. To make progress, cannabis needs to be re-branded as a legitimate medicine and rescheduled to a more pharmacologically justifiable class of compounds. This paper discusses the data supporting re-branding and rescheduling of cannabis.

Effects of centrally acting analgesics on spinal segmental reflexes and wind-up

BACKGROUND

The spinal cord is a prime site of action for analgesia. Here we characterize the effects of established analgesics on segmental spinal reflexes. The aim of the study was to look for the pattern of action or signature of analgesic effects on these reflexes.

METHODS

We used a spinal cord in vitro preparation of neonate mice to record ventral root responses to dorsal root stimulation. Pregabalin, clonidine, morphine and duloxetine and an experimental sigma-1 receptor antagonist (S1RA) were applied to the preparation in a cumulative concentration protocol. Drug effects on the wind-up produced by repetitive stimulation of C-fibres and on responses to single A- and C-fibre intensity stimuli were analysed.

RESULTS

All compounds produced a concentration-dependent inhibition of total spikes elicited by repetitive stimulation. Concentrations producing ∼50% reduction in this parameter were (in μM) clonidine (0.01), morphine (0.1), pregabalin (1), duloxetine (10) and S1RA (30). At these concentrations clonidine, pregabalin and S1RA had significant effects on the wind-up index and little depressant effects on responses to single stimuli. Morphine and duloxetine did not depress wind-up index and showed large effects on responses to single stimuli. None of the compounds had strong effects on the amplitude of the non-nociceptive monosynaptic reflex.

CONCLUSIONS

morphine and duloxetine had general depressant effects on spinal reflexes, whereas the effects of clonidine, pregabalin and S1RA appeared to be restricted to signals originated by strong repetitive activation of C-fibres. Results are discussed in the context of reported behavioural effects of the compounds studied.

Neuropathic Pain Components in Patients with Lumbar Spinal Stenosis

PURPOSE

To determine the prevalence and characteristics of neuropathic pain (NP) in patients with lumbar spinal stenosis (LSS) according to subgroup analysis of symptoms.

MATERIALS AND METHODS

We prospectively enrolled subjects with LSS (n=86) who were scheduled to undergo spinal surgery. The patients were divided into two groups according to a chief complaint of radicular pain or neurogenic claudication. We measured patient's pain score using the visual analog scale (VAS), Oswestry Disability Index (ODI) and Leads Assessment of Neuropathic Symptoms and Signs (LANSS). According to LANSS value, the prevalence of NP component pain in patients with LSS was assessed. Statistical analysis was performed to find the relationship between LANSS scores and the other scores.

RESULTS

From our sample of 86 patients, 31 (36.0%) had a NP component, with 24 (63.4%) in the radicular pain group having NP. However, only seven patients (15.6%) in the neurogenic claudication group had NP. The LANSS pain score was not significantly correlated with VAS scores for back pain, but did correlate with VAS scores for leg pain (R=0.73, p<0.001) and with ODI back pain scores (R=0.54, p<0.01).

CONCLUSION

One-third of the patients with LSS had a NP component. The presence of radicular pain correlated strongly with NP. The severity of leg pain and ODI score were also closely related to a NP component. This data may prove useful to understanding the pain characteristics of LSS and in better designing clinical trials for NP treatment in patients with LSS.

Epidemiology of chronic pain in the office of a pain specialist neurologist

Objective The objective of the present report was to describe the working experience of a pain specialist neurologist after concluding a medical residency program on neurology, area of concentration pain. Method A retrospective study was conducted for one year in the office of a pain specialist neurologist. Patients older than 18 years with chronic pain according to the criteria of the International Association for the Study of Pain, were included. Demographic data, chronic pain data and the treatments instituted were investigated. Results A total of 241 medical records were reviewed, mean patient age was 52.4 years and 79 (66.9%) were women, and the mean score on a numeric pain scale was 8.69. The diagnoses were headaches (74.6%), neuropathic pain (17%) and ostheomuscular pain (8.2%). We did not detect cancer pain. Patients received medication and procedures of anesthetic blockade. Conclusion This data can guide new medical residency programs on Neurology, area of concentration pain, to plan activities and studies.

Right secondary somatosensory cortex-a promising novel target for the treatment of drug-resistant neuropathic orofacial pain with repetitive transcranial magnetic stimulation

High-frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex has analgesic effect; however, the efficacy of other cortical targets and the mode of action remain unclear. We examined the effects of rTMS in neuropathic orofacial pain, and compared 2 cortical targets against placebo. Furthermore, as dopaminergic mechanisms modulate pain responses, we assessed the influence of the functional DRD2 gene polymorphism (957C>T) and the catechol-O-methyltransferase (COMT) Val158Met polymorphism on the analgesic effect of rTMS. Sixteen patients with chronic drug-resistant neuropathic orofacial pain participated in this randomized, placebo-controlled, crossover study. Navigated high-frequency rTMS was given to the sensorimotor (S1/M1) and the right secondary somatosensory (S2) cortices. All subjects were genotyped for the DRD2 957C>T and COMT Val158Met polymorphisms. Pain, mood, and quality of life were monitored throughout the study. The numerical rating scale pain scores were significantly lower after the S2 stimulation than after the S1/M1 (P = 0.0071) or the sham (P = 0.0187) stimulations. The Brief Pain Inventory scores were also lower 3 to 5 days after the S2 stimulation than those at pretreatment baseline (P = 0.0127 for the intensity of pain and P = 0.0074 for the interference of pain) or after the S1/M1 (P = 0.001 and P = 0.0001) and sham (P = 0.0491 and P = 0.0359) stimulations. No correlations were found between the genetic polymorphisms and the analgesic effect in the present small clinical sample. The right S2 cortex is a promising new target for the treatment of neuropathic orofacial pain with high-frequency rTMS.

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.

Palliative care in the ambulatory geriatric practice

Geriatrics and palliative care often overlap. This article focuses on 2 areas where the disciplines may differ in their approach. The first is planning for extreme illness and death, with explicit acknowledgment that limiting therapy might be a good idea. This situation is likely to have a different impact in the course of a routine geriatrics visit than in a palliative care context. The second is pain management, especially chronic pain. In patients with sharply limited life expectancy, the risk/benefit equation tilts easily toward narcotic use. In frail elders working to remain independent, the calculus may be quite different.

Prevalence and determinants of cannabinoid prescription for the management of chronic noncancer pain: a postal survey of physicians in the Abitibi-Témiscamingue region of Quebec

BACKGROUND

Few studies have been conducted to explore physicians' prescription practices and attitudes toward the use of cannabinoids in Canada.We measured the prevalence and identified determinants of cannabinoid prescription for the management of chronic noncancer pain among physicians in southwestern Quebec.

METHODS

In February 2013, we conducted a postal survey using a modified Dillman method that involved physicians practising in the Abitibi-Témiscamingue region of Quebec. We used multivariate logistic regression models to identify determinants of cannabinoid prescription.

RESULTS

A total of 166 physicians of 318 practising in the region participated in the survey (response rate 52.2%). The prevalence of cannabinoid prescription was 27.3% (45/165) for any indication and 23.0% (38/165) for the management of chronic noncancer pain; 91.1% (41/45) of the physicians prescribed cannabinoids to 5 or fewer patients. Of the 38 physicians who prescribed cannabinoids for chronic noncancer pain, 35 (92.1%) prescribed nabilone, 7 (18.4%) medical marijuana and 2 (5.3%) nabiximols. The principal determinant of cannabinoid prescription was the physician's level of comfort with prescribing cannabinoids (adjusted odds ratio 1.25, 95% confidence interval 1.01-1.55, per 1-point increase in comfort level measured on 10-point scale). Respondents reported that continuing medical education (CME) activities could increase their comfort level. They also indicated a need for guidelines or algorithms that included cannabinoid use as well as more studies about the efficacy and safety of cannabinoids for the management of chronic noncancer pain.

INTERPRETATION

We found that cannabinoids were not often prescribed for the management of chronic noncancer pain and that survey respondents were not comfortable with prescribing this drug class. This degree of discomfort could be addressed by CME activities, more effective dissemination of guidelines and more evidence regarding cannabinoid use for the management of chronic noncancer pain.

Pharmacotherapy for neuropathic pain in adults: a systematic review and meta-analysis

BACKGROUND

New drug treatments, clinical trials, and standards of quality for assessment of evidence justify an update of evidence-based recommendations for the pharmacological treatment of neuropathic pain. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), we revised the Special Interest Group on Neuropathic Pain (NeuPSIG) recommendations for the pharmacotherapy of neuropathic pain based on the results of a systematic review and meta-analysis.

METHODS

Between April, 2013, and January, 2014, NeuPSIG of the International Association for the Study of Pain did a systematic review and meta-analysis of randomised, double-blind studies of oral and topical pharmacotherapy for neuropathic pain, including studies published in peer-reviewed journals since January, 1966, and unpublished trials retrieved from ClinicalTrials.gov and websites of pharmaceutical companies. We used number needed to treat (NNT) for 50% pain relief as a primary measure and assessed publication bias; NNT was calculated with the fixed-effects Mantel-Haenszel method.

FINDINGS

229 studies were included in the meta-analysis. Analysis of publication bias suggested a 10% overstatement of treatment effects. Studies published in peer-reviewed journals reported greater effects than did unpublished studies (r(2) 9·3%, p=0·009). Trial outcomes were generally modest: in particular, combined NNTs were 6·4 (95% CI 5·2-8·4) for serotonin-noradrenaline reuptake inhibitors, mainly including duloxetine (nine of 14 studies); 7·7 (6·5-9·4) for pregabalin; 7·2 (5·9-9·21) for gabapentin, including gabapentin extended release and enacarbil; and 10·6 (7·4-19·0) for capsaicin high-concentration patches. NNTs were lower for tricyclic antidepressants, strong opioids, tramadol, and botulinum toxin A, and undetermined for lidocaine patches. Based on GRADE, final quality of evidence was moderate or high for all treatments apart from lidocaine patches; tolerability and safety, and values and preferences were higher for topical drugs; and cost was lower for tricyclic antidepressants and tramadol. These findings permitted a strong recommendation for use and proposal as first-line treatment in neuropathic pain for tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors, pregabalin, and gabapentin; a weak recommendation for use and proposal as second line for lidocaine patches, capsaicin high-concentration patches, and tramadol; and a weak recommendation for use and proposal as third line for strong opioids and botulinum toxin A. Topical agents and botulinum toxin A are recommended for peripheral neuropathic pain only.

INTERPRETATION

Our results support a revision of the NeuPSIG recommendations for the pharmacotherapy of neuropathic pain. Inadequate response to drug treatments constitutes a substantial unmet need in patients with neuropathic pain. Modest efficacy, large placebo responses, heterogeneous diagnostic criteria, and poor phenotypic profiling probably account for moderate trial outcomes and should be taken into account in future studies.

FUNDING

NeuPSIG of the International Association for the Study of Pain.

Combined inhibition of monoacylglycerol lipase and cyclooxygenases synergistically reduces neuropathic pain in mice

BACKGROUND AND PURPOSE

Neuropathic pain is commonly treated with GABA analogues, steroids or non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs inhibit one or more COX isozymes but chronic COX inhibition paradoxically increases gastrointestinal inflammation and risk of unwanted cardiovascular events. The cannabinoids also have analgesic and anti-inflammatory properties and reduce neuropathic pain in animal models. The present study investigated the analgesic effects of inhibiting both monoacylglycerol lipase (MAGL) and COX enzymes, using low doses of both inhibitors.

EXPERIMENTAL APPROACH

Mice subjected to chronic constriction injury (CCI) were tested for mechanical and cold allodynia after administration of the MAGL inhibitor, JZL184, or the non-selective COX inhibitor diclofenac. Then, both drugs were co-administered at fixed dose proportions of 1:3, 1:1 and 3:1, based on their ED50 values. PGs, endocannabinoids and related lipids were quantified in lumbar spinal cord.

KEY RESULTS

Combining low doses of JZL184 and diclofenac synergistically attenuated mechanical allodynia and additively reduced cold allodynia. The cannabinoid CB1 receptor antagonist, rimonabant, but not the CB2 receptor antagonist, SR144528, blocked the analgesic effects of the JZL184 and diclofenac combination on mechanical allodynia, implying that CB1 receptors were primarily responsible for the anti-allodynia. Diclofenac alone and with JZL184 significantly reduced PGE2 and PGF2α in lumbar spinal cord tissue, whereas JZL184 alone caused significant increases in the endocannabinoid metabolite, N-arachidonoyl glycine.

CONCLUSIONS AND IMPLICATIONS

Combining COX and MAGL inhibition is a promising therapeutic approach for reducing neuropathic pain with minimal side effects.

Tapentadol extended release in the management of peripheral diabetic neuropathic pain

Tapentadol, a μ-opioid agonist and norepinephrine reuptake inhibitor, has been found to be an effective medication for a wide variety of chronic pain conditions, including back pain, cancer-related pain, and arthritic pain. It has also been found to have fewer gastrointestinal side effects than more traditional opioid-based therapies. More recently, tapentadol extended release has been demonstrated to be effective in the management of painful diabetic neuropathy, an often debilitating condition affecting approximately one-third of all patients with diabetes. This review highlights the most up-to-date basic and clinical studies by focusing on the mechanisms of action of tapentadol and its clinical efficacy, especially with regard to painful diabetic neuropathy.

Synthesis and biological evaluation of novel sigma-1 receptor antagonists based on pyrimidine scaffold as agents for treating neuropathic pain

The discovery and synthesis of a new series of pyrimidines as potent sigma-1 receptor (σ1R) antagonists, associated with pharmacological antineuropathic pain activity, are the focus of this article. The new compounds were evaluated in vitro in σ-1 and σ-2 receptor binding assays. The nature of the pyrimidine scaffold was crucial for activity, and a basic amine was shown to be necessary according to the known pharmacophoric model. The most promising derivative was 5-chloro-2-(4-chlorophenyl)-4-methyl-6-(3-(piperidin-1-yl)propoxy)pyrimidine (137), which exhibited a high binding affinity to σ1R receptor (Ki σ1 = 1.06 nM) and good σ-1/2 selectivity (1344-fold). In in vivo tests, compound 137 exerted dose-dependent antinociceptive effects in mice formalin model and rats CCI models of neuropathic pain. In addition, no motor impairments were found in rotarod tests; acceptable pharmacokinetic properties were also noted. These data suggest compound 137 may constitute a novel class of drugs for the treatment of neuropathic pain.

Effect of intermittent normobaric hyperoxia for treatment of neuropathic pain in Chinese patients with spinal cord injury

STUDY DESIGN

Prospective, randomized and controlled study.

OBJECTIVES

The aim of the study was to investigate the effect of intermittent normobaric hyperoxia (InHO) for treatment of neuropathic pain in patients with spinal cord injury (SCI).

SETTING

The First Affiliated Hospital of Nanhua University, Hengyang, Hunan Province, China.

METHODS

Patients with SCI from Hunan Province were recruited from the First Affiliated Hospital of Nanhua University. History, duration, localization and characteristics of pain were recorded. Visual analog scale (VAS), the Patient Global Impression of Change (PGIC) and Short Form-36 walk-wheel (SF-36ww) was used to investigate the effect of InHO. Patients were randomly assigned to study and control groups. In study group, patients were exposed to pure oxygen via non-rebreathing reservoir mask, which increased the provided oxygen at a rate of 7 l min^-1 for 1 or 4 h daily in 2 weeks. While in control group, patients breathed air via non-rebreathing reservoir mask at the same rate.

RESULTS

A total of 62 SCI patients with neuropathic pain were included in the study. The mean age of the patients was 36.85±10.71 years. Out of 62 patients, 21 were tetraplegic and 41 were paraplegic. Overall, 14 patients had complete SCI while 48 patients had incomplete injuries. Three groups were similar with respect to age, gender, duration, smoker or not, level and severity of injury. In the 4 h per day InHO groups, a statistically significant reduction of the VAS values was observed (P<0.05). Significant difference was also found in SF-36ww pain scores and PGIC (P<0.05). However, such an effect was not evident in the control group.

CONCLUSION

This study revealed that in treatment of neuropathic pain of SCI patients, InHO may be effective.

PERSPECTIVE

This article presents InHO may effectively complement pharmacological treatment in patients with SCI and neuropathic pain.