Neuropathic pain needs systematic classification

Steroid hormones in pain: Mechanistic underpinnings and therapeutic perspectives

Pain is a complex sensory and emotional experience that severely affects an individual's quality of life and health status. Steroid hormones, as important regulatory substances in the human body, are extensively involved in various physiological and pathological processes. In recent years, remarkable progress has been made in the research of steroid hormones in the field of pain. They play a crucial role in the occurrence, development, and treatment of pain. This review comprehensively elaborates on the roles and therapeutic mechanisms of steroid hormones in pain, explores the performances of glucocorticoids, mineralocorticoids, sex hormones, etc. in different pain models, as well as the molecular mechanisms by which they regulate pain through genomic and non-genomic effects, aiming to provide a theoretical basis for the clinical treatment of pain.

Clinical Diagnosis and Treatment of Chronic Pain

More than 600 million people globally are estimated to be living with chronic pain. It is one of the most common complaints seen in an outpatient setting, with over half of patients complaining of pain during a visit. Failure to properly diagnose and manage chronic pain is associated with substantial morbidity and mortality, especially when opioids are involved. Furthermore, it is a tremendous financial strain on the healthcare system, as over USD 100 billion is spent yearly in the United States on healthcare costs related to pain management and opioids. This exceeds the costs of diabetes, heart disease, and cancer-related care combined. Being able to properly diagnose, manage, and treat chronic pain conditions can substantially lower morbidity, mortality, and healthcare costs in the United States. This review will outline the current definitions, biopsychosocial model, subclassifications, somatosensory assessments, imaging, clinical prediction models, and treatment modalities associated with chronic pain.

The invisible cost of pain management by the current International Classification of Diseases coding system: a study in a tertiary care inpatient setting

ABSTRACT

The International Classification of Diseases ( ICD ) is applied worldwide for public health data collection among other use cases. However, the current version of the ICD ( ICD-10 ), to which the reimbursement system is linked in many countries, does not represent chronic pain properly. This study aims to compare the ICD-10 with the ICD-11 in hospitalized patients in terms of specificity, clinical utility, and reimbursement for pain management. The medical records of hospitalized patients consulted for pain management at Siriraj Hospital, Thailand, were reviewed, and all pain-related diagnoses were coded into ICD-10 and ICD-11 . The data of 397 patients showed unspecified pain was coded 78% in the ICD-10 and only 0.5% in the ICD-11 version. The difference gap in the proportion of unspecified pain between the 2 versions is wider than in the outpatient setting. The 3 most common codes for ICD-10 were other chronic pain, low back pain, and pain in limb. The 3 most common codes for ICD-11 were chronic cancer pain, chronic peripheral neuropathic pain, and chronic secondary musculoskeletal pain. As in many other countries, no pain-related ICD-10 codes were coded for routine reimbursement. The simulated reimbursement fee remained the same when adding 397 pain-related codings, even if the cost of pain management, such as cost of labor, existed. Compared with the ICD-10 version, the ICD-11 is more specific and makes pain diagnoses more visible. Thus, shifting from ICD-10 to ICD-11 has the potential to improve both the quality of care and the reimbursement for pain management.

Effect of novel Matrix Rhythm Therapy (MaRhyThe®) on neuropathic pain and maximum plantar pressure distribution among type 2 diabetes mellitus patients with peripheral neuropathy

Background

There is a need for a non-pharmacological approach to reduce pain and plantar pressure in diabetic peripheral neuropathy (DPN). Matrix Rhythm Therapy (MaRhyThe®) is a therapeutic modality that works on the principle of physiologic rhythmic oscillations of the body cells. This study aimed to evaluate the effect of MaRhyThe® on neuropathic pain and maximum plantar pressure distribution among type 2 diabetes mellitus patients with peripheral neuropathy.

Materials and methods

A total of 33 participants with DPN were recruited for the study based on inclusion criteria. Maximum plantar pressure was recorded using Win-Track 11K005, and the pain score was obtained using a visual analogue scale. Ten sessions of MaRhyThe® were given to all the participants. Outcome measures were evaluated at the baseline and after 10th session. Paired t-test was performed to analyze the changes in outcome measures.

Results

Participants of DPN were recruited with the average age of 64 ± 9 years, and an average duration of diabetes was 14 ± 9 years were included. Results of the present study found significant improvement in neuropathic pain and plantar pressure in post intervention assessment. (p < 0.05).

Conclusion

In the present study, we found that MaRhyThe® is effective in reducing neuropathic pain and maximum plantar pressure in type 2 diabetes mellitus with peripheral neuropathy.

Possible Neuropathic Pain in Clinical Practice-Review on Selected Diagnostic Tools and Its Further Challenges

BACKGROUND

Neuropathic pain (NeP) is a wide group of conditions provoked by many different causes and with different patterns. The creation of a grading system was intended to determine the level of certainty that the pain is of neuropathic nature.

METHODS

The aim of this review is to update previously published data on some NeP questionnaires and their measurement properties. The selection of articles is based on the basic neurological units. To assess the usefulness and credibility of the questionnaires, the authors searched for a commonly used measure of reliability, as well as sensitivity and specificity.

RESULTS

Studies regarding the usefulness and credibility of questionnaires used in NeP were realized. Different patient cohorts, etiologies and sample sizes, do not allow for an unambiguous comparison of the presented scales; however, all of these studies found good measures of reliability, specificity and sensitivity.

CONCLUSIONS

NeP tools seem to be beneficial screening instruments that should be utilized by specialists and general practitioners to improve the recognition of "possible" NeP and to determine the epidemiology of this disorder. They have been developed to distinguish perceived pain into neuropathic and non-neuropathic, and, therefore, patients with a mixed pain can still present a diagnostic challenge. Clinical examination and interview play an essential role in the diagnostic process and monitoring, and cannot be neglected.

The Influence of Dietary Supplementations on Neuropathic Pain

Neuropathic pain is defined as pain caused by a lesion or disease of the somatosensory nervous system and affects 7-10% of the worldwide population. Neuropathic pain can be induced by the use of drugs, including taxanes, thus triggering chemotherapy-induced neuropathic pain or as consequence of metabolic disorders such as diabetes. Neuropathic pain is most often a chronic condition, and can be associated with anxiety and depression; thus, it negatively impacts quality of life. Several pharmacologic approaches exist; however, they can lead numerous adverse effects. From this perspective, the use of nutraceuticals and diet supplements can be helpful in relieve neuropathic pain and related symptoms. In this review, we discuss how diet can radically affect peripheral neuropathy, and we focus on the potential approaches to ameliorate this condition, such as the use of numerous nutritional supplements or probiotics.

Association of opioid fills with centers for disease control and prevention opioid guidelines and payer coverage policies: physician, insurance and geographic factors

Background The Centers for Disease Control and Prevention (CDC) issued guidelines and certain healthcare payers have made pharmacy coverage changes (PCC) focusing on regulating prescription opioids. Aim We evaluated differences in the rate of first-time opioid fills at doses ≥ 50 morphine milligram equivalents (MME)/day and first-time opioid fills with benzodiazepine fill overlap following the CDC guidelines and following a PCC between provider types, geographic locations, and insurance types. Method We used OptumLabs® Data Warehouse claims data between 2014 and 2018. Subjects were opioid naïve non-cancer care patients, 18 years and older who had an identified chronic pain condition ICD diagnosis within 2 weeks prior to their first-time opioid fill. We used multiple treatment period segmented regression analysis with interaction terms to test the differences between primary care providers (PCPs) and specialist providers (SPs), urban and rural primary care service areas (PCSAs), and Medicare Advantage (MA) and commercially insured patients (CIPs) in their first-time opioid fill patterns. Results Prescribing first-time opioid fills at doses ≥ 50MME/day declined following the CDC guidelines and PCC, the decline was greater among SPs than PCPs and in rural PCSAs than urban PCSAs. Also, following the CDC guidelines, the decline was greater among MA patients however following the PCC the decline was greater among CIPs. There were no differences in rate of first-time opioid fill with benzodiazepine overlap between groups. Conclusion Responses to the CDC opioid guidelines and a PCC differed between PCPs and SPs, urban and rural PCSAs, and when prescribing to MA and CIPs. Understanding these differences is important to help inform future guidelines.

Association of 3 CDC opioid prescription guidelines for chronic pain and 2 payer pharmacy coverage changes on opioid initiation practices

BACKGROUND: Due to the US opioid epidemic, in March of 2016, the Centers for Disease Control and Prevention (CDC) published new guidelines for primary care providers on opioid prescribing for chronic pain. Payer coverage changes were also implemented to help modify opioid prescribing behavior. Whether these initiatives were associated with changes in opioid initiation patterns is unknown. OBJECTIVE: To assess the association between 3 of the 2016 CDC guidelines and 2 subsequent payer pharmacy coverage changes with changes in opioid initiation behavior across different provider specialties. METHODS: We conducted a real-world evidence study using claims data from OptumLabs Data Warehouse between January of 2014 and December of 2018. Subjects were continuously enrolled opioid naive patients, aged at least 18 years, who had at least 1 chronic pain diagnosis within 2 weeks before their first (first-time) opioid prescription. The study used multiple treatment period segmented regression analysis to evaluate the association, across different provider specialties, between the CDC guideline release and the payer pharmacy coverage changes with immediate change in level and overall change in the rate of first-time extended-release opioid prescriptions, firsttime opioid prescriptions at doses of at least 50 MME (morphine milligram equivalent) per day, and first-time opioid prescriptions with overlapping benzodiazepine prescription. RESULTS: The CDC guidelines were not associated with any change in the rate of first-time prescriptions of extended-release opioids. However, a January 2017 payer pharmacy coverage change was associated with a reduction over time in first-time extended-release opioid prescription rates by 22.15 in every 100,000 prescriptions (CI = -40.04 to -2.92, P = 0.013). The CDC guidelines were associated with an immediate decline in level of first-time opioid prescription at doses of at least 50 MME per day by 74.00 in every 10,000 prescriptions (CI = -124.86 to -23.13, P = 0.004) and an increased rate of decline over time by 13.64 in every 10,000 prescriptions (CI = -17.07 to -10.21, P < 0.001). These associations varied across provider types and specialties. The March 2018, payer coverage change was associated with an immediate reduction in level of first-time opioid prescriptions at doses of at least 50 MME per day across all specialties and an increased reduction over time among surgeons. The CDC guidelines were associated, respectively, with a reduction in the rate of overlapping first-time opioid prescriptions with benzodiazepines among family medicine, internal medicine, surgeons, emergency medicine providers, and providers with unknown specialty by 6.11, 5.10, 2.89, 11.43, and 9.11 in every 10,000 prescriptions monthly (CI = -9.48 to -2.73, -9.86 to -0.35, -5.40 to -0.38, -17.26 to -5.61 and -11.96 to -6.25, respectively, P < 0.001, P = 0.035, P = 0.024, P < 0.001 and P < 0.001). CONCLUSIONS: Some specialist providers also adopted the CDC guidelines, and the response to the guidelines differed across various provider specialties. Some CDC guidelines were associated with a reduction in high-risk first-time opioid prescriptions. Payer pharmacy coverage changes reinforced the guidelines both in situations where the CDC guidelines did and did not show any association. DISCLOSURE: This research was funded by Agency for Healthcare Research and Quality (R01 HS025164; PI: Karaca-Mandic). Karaca-Mandic reports grants from the American Cancer Society and Sempre Health, along with fees from Tactile Medical and Precision Health Economics, unrelated to this study. The other authors have nothing to disclose.

Comparing the ICD-11 chronic pain classification with ICD-10: how can the new coding system make chronic pain visible? A study in a tertiary care pain clinic setting

ABSTRACT

Pain is a frequent reason for patients to ask for medical services. However, systematic information about the extent and impact of pain, especially in developing countries, has not been available up to now. We evaluated whether the 11th edition of the International Statistical Classification of Diseases and Related Health Problems (ICD) can fill this gap by coding all electronic out-patient medical records of the pain clinic at Siriraj Hospital in Thailand in 2019 (8714 visits), using the ICD-10 and ICD-11 browsers referenced on the WHO websites. The 3 most frequent pain-related codes in ICD-10 were R52.2 "other chronic pain" (29%), M54.5 "low back pain" (18%), and M79.6 "pain in limb" (13%). In ICD-11, the 3 most frequent codes were MG30.31 "chronic secondary musculoskeletal pain associated with structural changes" (28%), MG30.51 "chronic peripheral neuropathic pain" (26%), and MG30.10 "chronic cancer pain" (23%). Thus, using the currently valid ICD-10 system, roughly one-third of patient encounters were coded as "other chronic pain," and the next 2 were specifying the pain region rather than any underlying cause. By contrast, ICD-11 coding of the same patients identified underlying causes (bones and joints, somatosensory nervous system, cancer, or surgery), which provide guidance towards differential patient management. In our pain clinic, most patients suffered from chronic cancer pain, chronic neuropathic pain, and chronic secondary musculoskeletal pain, which were poorly defined or nonexistent in the current ICD-10 coding system. Compared with the ICD-10, the ICD-11 provides more detailed diagnostic categories and is more informative for clinical use, research, and resource allocation for pain-related conditions.

Pregabalin for neuropathic pain in primary care settings: recommendations for dosing and titration

Pregabalin is one of the first-line treatments approved for the management of neuropathic pain (NeP). While many patients benefit from treatment with pregabalin, they are often treated with suboptimal doses, possibly due to unfamiliarity around prescribing the drug and/or side effects that can occur with up-titration. This narrative review discusses key aspects of initiating, titrating, and managing patients prescribed pregabalin therapy, and addresses concerns around driving and the potential for abuse, as well as when to seek specialist opinion. To ensure that patients derive maximum therapeutic benefit from the drug, we suggest a 'low and slow' dosing approach to limit common side effects and optimize tolerability alongside patients' expectations. When requiring titration to higher doses, we recommend initiating 'asymmetric dosing,' with the larger dose in the evening. Fully engaging patients in order for them to understand the expected timeline for efficacy and side effects (including their resolution), can also help determine the optimal titration tempo for each individual patient. The 'low and slow' approach also recognizes that patients with NeP are heterogeneous in terms of their optimal therapeutic dose of pregabalin. Hence, it is recommended that general practitioners closely monitor patients and up-titrate according to pain relief and side effects to limit suboptimal dosing or premature discontinuation.

Neuropathic Pain and Rehabilitation: A Systematic Review of International Guidelines

Background: Neuropathic pain is an injury or disease of the central and/or peripheral somatosensory nervous system, and it has a significant impact on quality of life, especially since it is often refractory to treatment. Rehabilitative intervention is considered in various guidelines on neuropathic pain treatment, although not in an organic nor detailed way. The aim of this systematic review was to analyze the most indicated therapeutic strategies, providing rehabilitative recommendations in the management of neuropathic pain. Methods: A systematic review was performed according to PRISMA guidelines. The scientific search, carried out until July 2020, considered guidelines in English language of the last thirteen years. Results: Six guidelines were analyzed, from which emerges that a multidisciplinary approach, comprehensive of pharmacologic and nonpharmacologic interventions, should drive neuropathic pain management. A relevant role in non-pharmacological intervention is played by rehabilitation, through an adequate tailored rehabilitation program and physical therapies. Conclusion: This analysis highlights the importance of rehabilitation but also the lack of evidence on various rehabilitative practices. Arises hence the need for further studies in this field to better define a rehabilitative treatment strategy.

Challenges of neuropathic pain: focus on diabetic neuropathy

Neuropathic pain is a frequent condition caused by a lesion or disease of the central or peripheral somatosensory nervous system. A frequent cause of peripheral neuropathic pain is diabetic neuropathy. Its complex pathophysiology is not yet fully elucidated, which contributes to underassessment and undertreatment. A mechanism-based treatment of painful diabetic neuropathy is challenging but phenotype-based stratification might be a way to develop individualized therapeutic concepts. Our goal is to review current knowledge of the pathophysiology of peripheral neuropathic pain, particularly painful diabetic neuropathy. We discuss state-of-the-art clinical assessment, validity of diagnostic and screening tools, and recommendations for the management of diabetic neuropathic pain including approaches towards personalized pain management. We also propose a research agenda for translational research including patient stratification for clinical trials and improved preclinical models in relation to current knowledge of underlying mechanisms.

Epidemiology of Chronic Pain in the Latium Region, Italy: A Cross-Sectional Study on the Clinical Characteristics of Patients Attending Pain Clinics

In Italy, chronic pain affects more than a quarter of the population, whereas the average European prevalence is 21%. This high prevalence might be due to the high percentage of Italian people who do not receive treatment, even after the passing of law 38/2010 (the right to access pain management in Italy), which created a regional network for the diagnosis and treatment of noncancer chronic pain. Italian epidemiologic studies on chronic pain are scanty, and this observational, multicenter, cross-sectional study is the first to investigate the clinical characteristics of patients who attended the pain management clinics in the Latium Region, Italy, for the management of their noncancer chronic pain. A total of 1,606 patients (mean age 56.8 years, standard deviation ± 11.4), 67% women, were analyzed. Severe pain was present in 54% of the sample. Women experienced pain and had it in two or more sites more often than men (57% vs. 50%, p = .02; and 55.2% vs. 45.9%, p < .001, respectively). Chronic pain was musculoskeletal (45%), mixed (34%), and neuropathic (21%). In more than 60% of the cases, chronic pain was continuous, and in 20% it had lasted for more than 48 months; long-lasting pain was often neuropathic. Low back (33.4%) and lower limbs (28.2%) were the main locations. Severe intensity of pain was statistically significantly associated with female gender (odds ratio [OR] 1.39; 95% confidence interval [CI] 1.06-1.84); with International Classification of Diseases, Ninth Revision, codes for chronic pain syndrome (OR 2.14; 95% CI 1.55-2.95); and with continuous pain (OR 2.02; 95% CI 1.54-2.66). Neuropathic pain and mixed pain were significantly associated with number of sites, and a trend seemed to be present (OR 2.11 and 3.02 for 2 and 3 + sites; 95% CI 1.59-2.79 and 2.00-4.55, respectively).

Pregabalin for neuropathic pain in adults

BACKGROUND

This review updates part of an earlier Cochrane Review titled "Pregabalin for acute and chronic pain in adults", and considers only neuropathic pain (pain from damage to nervous tissue). Antiepileptic drugs have long been used in pain management. Pregabalin is an antiepileptic drug used in management of chronic pain conditions.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of pregabalin for chronic neuropathic pain in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase for randomised controlled trials from January 2009 to April 2018, online clinical trials registries, and reference lists.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing pregabalin (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and biases. Primary outcomes were: at least 30% pain intensity reduction over baseline; much or very much improved on the Patient Global Impression of Change (PGIC) Scale (moderate benefit); at least 50% pain intensity reduction; or very much improved on PGIC (substantial benefit). We calculated risk ratio (RR) and number needed to treat for an additional beneficial (NNTB) or harmful outcome (NNTH). We assessed the quality of the evidence using GRADE.

MAIN RESULTS

We included 45 studies lasting 2 to 16 weeks, with 11,906 participants - 68% from 31 new studies. Oral pregabalin doses of 150 mg, 300 mg, and 600 mg daily were compared with placebo. Postherpetic neuralgia, painful diabetic neuropathy, and mixed neuropathic pain predominated (85% of participants). High risk of bias was due mainly to small study size (nine studies), but many studies had unclear risk of bias, mainly due to incomplete outcome data, size, and allocation concealment.Postherpetic neuralgia: More participants had at least 30% pain intensity reduction with pregabalin 300 mg than with placebo (50% vs 25%; RR 2.1 (95% confidence interval (CI) 1.6 to 2.6); NNTB 3.9 (3.0 to 5.6); 3 studies, 589 participants, moderate-quality evidence), and more had at least 50% pain intensity reduction (32% vs 13%; RR 2.5 (95% CI 1.9 to 3.4); NNTB 5.3 (3.9 to 8.1); 4 studies, 713 participants, moderate-quality evidence). More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (62% vs 24%; RR 2.5 (95% CI 2.0 to 3.2); NNTB 2.7 (2.2 to 3.7); 3 studies, 537 participants, moderate-quality evidence), and more had at least 50% pain intensity reduction (41% vs 15%; RR 2.7 (95% CI 2.0 to 3.5); NNTB 3.9 (3.1 to 5.5); 4 studies, 732 participants, moderate-quality evidence). Somnolence and dizziness were more common with pregabalin than with placebo (moderate-quality evidence): somnolence 300 mg 16% versus 5.5%, 600 mg 25% versus 5.8%; dizziness 300 mg 29% versus 8.1%, 600 mg 35% versus 8.8%.Painful diabetic neuropathy: More participants had at least 30% pain intensity reduction with pregabalin 300 mg than with placebo (47% vs 42%; RR 1.1 (95% CI 1.01 to 1.2); NNTB 22 (12 to 200); 8 studies, 2320 participants, moderate-quality evidence), more had at least 50% pain intensity reduction (31% vs 24%; RR 1.3 (95% CI 1.2 to 1.5); NNTB 22 (12 to 200); 11 studies, 2931 participants, moderate-quality evidence), and more had PGIC much or very much improved (51% vs 30%; RR 1.8 (95% CI 1.5 to 2.0); NNTB 4.9 (3.8 to 6.9); 5 studies, 1050 participants, moderate-quality evidence). More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (63% vs 52%; RR 1.2 (95% CI 1.04 to 1.4); NNTB 9.6 (5.5 to 41); 2 studies, 611 participants, low-quality evidence), and more had at least 50% pain intensity reduction (41% vs 28%; RR 1.4 (95% CI 1.2 to 1.7); NNTB 7.8 (5.4 to 14); 5 studies, 1015 participants, low-quality evidence). Somnolence and dizziness were more common with pregabalin than with placebo (moderate-quality evidence): somnolence 300 mg 11% versus 3.1%, 600 mg 15% versus 4.5%; dizziness 300 mg 13% versus 3.8%, 600 mg 22% versus 4.4%.Mixed or unclassified post-traumatic neuropathic pain: More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (48% vs 36%; RR 1.2 (1.1 to 1.4); NNTB 8.2 (5.7 to 15); 4 studies, 1367 participants, low-quality evidence), and more had at least 50% pain intensity reduction (34% vs 20%; RR 1.5 (1.2 to 1.9); NNTB 7.2 (5.4 to 11); 4 studies, 1367 participants, moderate-quality evidence). Somnolence (12% vs 3.9%) and dizziness (23% vs 6.2%) were more common with pregabalin.Central neuropathic pain: More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (44% vs 28%; RR 1.6 (1.3 to 2.0); NNTB 5.9 (4.1 to 11); 3 studies, 562 participants, low-quality evidence) and at least 50% pain intensity reduction (26% vs 15%; RR 1.7 (1.2 to 2.3); NNTB 9.8 (6.0 to 28); 3 studies, 562 participants, low-quality evidence). Somnolence (32% vs 11%) and dizziness (23% vs 8.6%) were more common with pregabalin.Other neuropathic pain conditions: Studies show no evidence of benefit for 600 mg pregabalin in HIV neuropathy (2 studies, 674 participants, moderate-quality evidence) and limited evidence of benefit in neuropathic back pain or sciatica, neuropathic cancer pain, or polyneuropathy.Serious adverse events, all conditions: Serious adverse events were no more common with placebo than with pregabalin 300 mg (3.1% vs 2.6%; RR 1.2 (95% CI 0.8 to 1.7); 17 studies, 4112 participants, high-quality evidence) or pregabalin 600 mg (3.4% vs 3.4%; RR 1.1 (95% CI 0.8 to 1.5); 16 studies, 3995 participants, high-quality evidence).

AUTHORS' CONCLUSIONS

Evidence shows efficacy of pregabalin in postherpetic neuralgia, painful diabetic neuralgia, and mixed or unclassified post-traumatic neuropathic pain, and absence of efficacy in HIV neuropathy; evidence of efficacy in central neuropathic pain is inadequate. Some people will derive substantial benefit with pregabalin; more will have moderate benefit, but many will have no benefit or will discontinue treatment. There were no substantial changes since the 2009 review.

The IASP classification of chronic pain for ICD-11: chronic neuropathic pain

The upcoming 11th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD) of the World Health Organization (WHO) offers a unique opportunity to improve the representation of painful disorders. For this purpose, the International Association for the Study of Pain (IASP) has convened an interdisciplinary task force of pain specialists. Here, we present the case for a reclassification of nervous system lesions or diseases associated with persistent or recurrent pain for ≥3 months. The new classification lists the most common conditions of peripheral neuropathic pain: trigeminal neuralgia, peripheral nerve injury, painful polyneuropathy, postherpetic neuralgia, and painful radiculopathy. Conditions of central neuropathic pain include pain caused by spinal cord or brain injury, poststroke pain, and pain associated with multiple sclerosis. Diseases not explicitly mentioned in the classification are captured in residual categories of ICD-11. Conditions of chronic neuropathic pain are either insufficiently defined or missing in the current version of the ICD, despite their prevalence and clinical importance. We provide the short definitions of diagnostic entities for which we submitted more detailed content models to the WHO. Definitions and content models were established in collaboration with the Classification Committee of the IASP's Neuropathic Pain Special Interest Group (NeuPSIG). Up to 10% of the general population experience neuropathic pain. The majority of these patients do not receive satisfactory relief with existing treatments. A precise classification of chronic neuropathic pain in ICD-11 is necessary to document this public health need and the therapeutic challenges related to chronic neuropathic pain.

Predicting factors of outcome in multidisciplinary treatment of chronic neuropathic pain

Purpose

Evidence of the effectiveness of multidisciplinary treatment with a focus on neuropathic pain is still rare. The present study investigated whether multidisciplinary treatment leads to improvement of neuropathic pain in outcome (pain intensity and disability) and psychological (depression, pain acceptance, and catastrophizing) variables at posttreatment and 3-month follow-up. We examined whether and to what extent psychological changes can predict long-term outcome at 3-month follow-up, when other variables are controlled for (baseline characteristics and changes in pain parameters).

Patients and methods

Patients suffering from a chronic neuropathic pain condition (n=141) attended an inpatient multidisciplinary program lasting about 15 continuous days with self-report data collected at pretreatment, posttreatment, and 3-month follow-up.

Results

Repeated-measures ANOVAs showed a significant improvement of pain intensity, disability, pain acceptance, catastrophizing, and depression at posttreatment. These improvements remained stable over the 3-month follow-up for all variables except for depression. The inclusion of psychological changes in multiple regression analyses greatly increased the variance in outcome, explained by baseline characteristics and changes in pain parameters.

Conclusion

The results could help clinicians to determine which variables should be emphasized during inpatient treatment and during the follow-up period, in order to maintain the gains after an inpatient multidisciplinary treatment for neuropathic pain.

Perspective

The present study demonstrates the beneficial effects of an inpatient multidisciplinary program for neuropathic pain and further question the resistant nature of neuropathic pain to treatment. The results add evidence to the relevance of cognitive-behavioral models of pain positing an important role for pain-related thoughts and emotions in long-term outcome following multidisciplinary pain treatment.

The effects of a dopamine agonist (apomorphine) on experimental and spontaneous pain in patients with chronic radicular pain: A randomized, double-blind, placebo-controlled, cross-over study

BACKGROUND

Although evidence suggests that dopaminergic systems are involved in pain processing, the effects of dopaminergic interventions on pain remains questionable. This randomized, double blinded, placebo-controlled, cross-over study was aimed at exploring the effect of the dopamine agonist apomorphine on experimental pain evoked by cold stimulation and on spontaneous pain in patients with lumbar radicular (neuropathic) pain.

METHODS

Data was collected from 35 patients with chronic lumbar radiculopathy (18 men, mean age 56.2±13 years). The following parameters were evaluated before (baseline) and 30, 75 and 120 minutes subsequent to a subcutaneous injection of 1.5 mg apomorphine or placebo: cold pain threshold and tolerance in the painful site (ice pack, affected leg) and in a remote non-painful site (12°C water bath, hand), and spontaneous (affected leg) pain intensity (NPS, 0-100).

RESULTS

One-hundred and twenty minutes following apomorphine (but not placebo) injection, cold pain threshold and tolerance in the hand increased significantly compared to baseline (from a median of 8.0 seconds (IQR = 5.0) to 10 seconds (IQR = 9.0), p = 0.001 and from a median of 19.5 seconds (IQR = 30.2) to 27.0 seconds (IQR = 37.5), p<0.001, respectively). In addition, apomorphine prolonged cold pain tolerance but not threshold in the painful site (from a median of 43.0 seconds (IQR = 63.0) at baseline to 51.0 seconds (IQR = 78.0) at 120 min, p = 0.02). Apomorphine demonstrated no superiority over placebo in reducing spontaneous pain intensity.

CONCLUSION

These findings are in line with previous results in healthy subjects, showing that apomorphine increases the ability to tolerate cold pain and therefore suggesting that dopaminergic interventions can have potential clinical relevance.

Cannabis-based medicines for chronic neuropathic pain in adults

BACKGROUND

This review is one of a series on drugs used to treat chronic neuropathic pain. Estimates of the population prevalence of chronic pain with neuropathic components range between 6% and 10%. Current pharmacological treatment options for neuropathic pain afford substantial benefit for only a few people, often with adverse effects that outweigh the benefits. There is a need to explore other treatment options, with different mechanisms of action for treatment of conditions with chronic neuropathic pain. Cannabis has been used for millennia to reduce pain. Herbal cannabis is currently strongly promoted by some patients and their advocates to treat any type of chronic pain.

OBJECTIVES

To assess the efficacy, tolerability, and safety of cannabis-based medicines (herbal, plant-derived, synthetic) compared to placebo or conventional drugs for conditions with chronic neuropathic pain in adults.

SEARCH METHODS

In November 2017 we searched CENTRAL, MEDLINE, Embase, and two trials registries for published and ongoing trials, and examined the reference lists of reviewed articles.

SELECTION CRITERIA

We selected randomised, double-blind controlled trials of medical cannabis, plant-derived and synthetic cannabis-based medicines against placebo or any other active treatment of conditions with chronic neuropathic pain in adults, with a treatment duration of at least two weeks and at least 10 participants per treatment arm.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data of study characteristics and outcomes of efficacy, tolerability and safety, examined issues of study quality, and assessed risk of bias. We resolved discrepancies by discussion. For efficacy, we calculated the number needed to treat for an additional beneficial outcome (NNTB) for pain relief of 30% and 50% or greater, patient's global impression to be much or very much improved, dropout rates due to lack of efficacy, and the standardised mean differences for pain intensity, sleep problems, health-related quality of life (HRQoL), and psychological distress. For tolerability, we calculated number needed to treat for an additional harmful outcome (NNTH) for withdrawal due to adverse events and specific adverse events, nervous system disorders and psychiatric disorders. For safety, we calculated NNTH for serious adverse events. Meta-analysis was undertaken using a random-effects model. We assessed the quality of evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 16 studies with 1750 participants. The studies were 2 to 26 weeks long and compared an oromucosal spray with a plant-derived combination of tetrahydrocannabinol (THC) and cannabidiol (CBD) (10 studies), a synthetic cannabinoid mimicking THC (nabilone) (two studies), inhaled herbal cannabis (two studies) and plant-derived THC (dronabinol) (two studies) against placebo (15 studies) and an analgesic (dihydrocodeine) (one study). We used the Cochrane 'Risk of bias' tool to assess study quality. We defined studies with zero to two unclear or high risks of bias judgements to be high-quality studies, with three to five unclear or high risks of bias to be moderate-quality studies, and with six to eight unclear or high risks of bias to be low-quality studies. Study quality was low in two studies, moderate in 12 studies and high in two studies. Nine studies were at high risk of bias for study size. We rated the quality of the evidence according to GRADE as very low to moderate.Primary outcomesCannabis-based medicines may increase the number of people achieving 50% or greater pain relief compared with placebo (21% versus 17%; risk difference (RD) 0.05 (95% confidence interval (CI) 0.00 to 0.09); NNTB 20 (95% CI 11 to 100); 1001 participants, eight studies, low-quality evidence). We rated the evidence for improvement in Patient Global Impression of Change (PGIC) with cannabis to be of very low quality (26% versus 21%;RD 0.09 (95% CI 0.01 to 0.17); NNTB 11 (95% CI 6 to 100); 1092 participants, six studies). More participants withdrew from the studies due to adverse events with cannabis-based medicines (10% of participants) than with placebo (5% of participants) (RD 0.04 (95% CI 0.02 to 0.07); NNTH 25 (95% CI 16 to 50); 1848 participants, 13 studies, moderate-quality evidence). We did not have enough evidence to determine if cannabis-based medicines increase the frequency of serious adverse events compared with placebo (RD 0.01 (95% CI -0.01 to 0.03); 1876 participants, 13 studies, low-quality evidence).Secondary outcomesCannabis-based medicines probably increase the number of people achieving pain relief of 30% or greater compared with placebo (39% versus 33%; RD 0.09 (95% CI 0.03 to 0.15); NNTB 11 (95% CI 7 to 33); 1586 participants, 10 studies, moderate quality evidence). Cannabis-based medicines may increase nervous system adverse events compared with placebo (61% versus 29%; RD 0.38 (95% CI 0.18 to 0.58); NNTH 3 (95% CI 2 to 6); 1304 participants, nine studies, low-quality evidence). Psychiatric disorders occurred in 17% of participants using cannabis-based medicines and in 5% using placebo (RD 0.10 (95% CI 0.06 to 0.15); NNTH 10 (95% CI 7 to 16); 1314 participants, nine studies, low-quality evidence).We found no information about long-term risks in the studies analysed.Subgroup analysesWe are uncertain whether herbal cannabis reduces mean pain intensity (very low-quality evidence). Herbal cannabis and placebo did not differ in tolerability (very low-quality evidence).

AUTHORS' CONCLUSIONS

The potential benefits of cannabis-based medicine (herbal cannabis, plant-derived or synthetic THC, THC/CBD oromucosal spray) in chronic neuropathic pain might be outweighed by their potential harms. The quality of evidence for pain relief outcomes reflects the exclusion of participants with a history of substance abuse and other significant comorbidities from the studies, together with their small sample sizes.

Tramadol for neuropathic pain in adults

BACKGROUND

This review is an update of a review of tramadol for neuropathic pain, published in 2006; updating was to bring the review in line with current standards. Neuropathic pain, which is caused by a lesion or disease affecting the somatosensory system, may be central or peripheral in origin. Peripheral neuropathic pain often includes symptoms such as burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or an increased sensitivity to normally painful stimuli. Neuropathic pain is a common symptom in many diseases of the peripheral nervous system.

OBJECTIVES

To assess the analgesic efficacy of tramadol compared with placebo or other active interventions for chronic neuropathic pain in adults, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase for randomised controlled trials from inception to January 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing tramadol (any route of administration) with placebo or another active treatment for neuropathic pain, with subjective pain assessment by the participant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH), using standard methods. We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We identified six randomised, double-blind studies involving 438 participants with suitably characterised neuropathic pain. In each, tramadol was started at a dose of about 100 mg daily and increased over one to two weeks to a maximum of 400 mg daily or the maximum tolerated dose, and then maintained for the remainder of the study. Participants had experienced moderate or severe neuropathic pain for at least three months due to cancer, cancer treatment, postherpetic neuralgia, peripheral diabetic neuropathy, spinal cord injury, or polyneuropathy. The mean age was 50 to 67 years with approximately equal numbers of men and women. Exclusions were typically people with other significant comorbidity or pain from other causes. Study duration for treatments was four to six weeks, and two studies had a cross-over design.Not all studies reported all the outcomes of interest, and there were limited data for pain outcomes. At least 50% pain intensity reduction was reported in three studies (265 participants, 110 events). Using a random-effects analysis, 70/132 (53%) had at least 50% pain relief with tramadol, and 40/133 (30%) with placebo; the risk ratio (RR) was 2.2 (95% confidence interval (CI) 1.02 to 4.6). The NNT calculated from these data was 4.4 (95% CI 2.9 to 8.8). We downgraded the evidence for this outcome by two levels to low quality because of the small size of studies and of the pooled data set, because there were only 110 actual events, the analysis included different types of neuropathic pain, the studies all had at least one high risk of potential bias, and because of the limited duration of the studies.Participants experienced more adverse events with tramadol than placebo. Report of any adverse event was higher with tramadol (58%) than placebo (34%) (4 studies, 266 participants, 123 events; RR 1.6 (95% CI 1.2 to 2.1); NNH 4.2 (95% CI 2.8 to 8.3)). Adverse event withdrawal was higher with tramadol (16%) than placebo (3%) (6 studies, 485 participants, 45 events; RR 4.1 (95% CI 2.0 to 8.4); NNH 8.2 (95% CI 5.8 to 14)). Only four serious adverse events were reported, without obvious attribution to treatment, and no deaths were reported. We downgraded the evidence for this outcome by two or three levels to low or very low quality because of small study size, because there were few actual events, and because of the limited duration of the studies.

AUTHORS' CONCLUSIONS

There is only modest information about the use of tramadol in neuropathic pain, coming from small, largely inadequate studies with potential risk of bias. That bias would normally increase the apparent benefits of tramadol. The evidence of benefit from tramadol was of low or very low quality, meaning that it does not provide a reliable indication of the likely effect, and the likelihood is very high that the effect will be substantially different from the estimate in this systematic review.

Gabapentin for chronic neuropathic pain in adults

BACKGROUND

Gabapentin is commonly used to treat neuropathic pain (pain due to nerve damage). This review updates a review published in 2014, and previous reviews published in 2011, 2005 and 2000.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of gabapentin in chronic neuropathic pain in adults.

SEARCH METHODS

For this update we searched CENTRAL), MEDLINE, and Embase for randomised controlled trials from January 2014 to January 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trials registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing gabapentin (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). We performed a pooled analysis for any substantial or moderate benefit. Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH). We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We included four new studies (530 participants), and excluded three previously included studies (126 participants). In all, 37 studies provided information on 5914 participants. Most studies used oral gabapentin or gabapentin encarbil at doses of 1200 mg or more daily in different neuropathic pain conditions, predominantly postherpetic neuralgia and painful diabetic neuropathy. Study duration was typically four to 12 weeks. Not all studies reported important outcomes of interest. High risk of bias occurred mainly due to small size (especially in cross-over studies), and handling of data after study withdrawal.In postherpetic neuralgia, more participants (32%) had substantial benefit (at least 50% pain relief or PGIC very much improved) with gabapentin at 1200 mg daily or greater than with placebo (17%) (RR 1.8 (95% CI 1.5 to 2.1); NNT 6.7 (5.4 to 8.7); 8 studies, 2260 participants, moderate-quality evidence). More participants (46%) had moderate benefit (at least 30% pain relief or PGIC much or very much improved) with gabapentin at 1200 mg daily or greater than with placebo (25%) (RR 1.8 (95% CI 1.6 to 2.0); NNT 4.8 (4.1 to 6.0); 8 studies, 2260 participants, moderate-quality evidence).In painful diabetic neuropathy, more participants (38%) had substantial benefit (at least 50% pain relief or PGIC very much improved) with gabapentin at 1200 mg daily or greater than with placebo (21%) (RR 1.9 (95% CI 1.5 to 2.3); NNT 5.9 (4.6 to 8.3); 6 studies, 1277 participants, moderate-quality evidence). More participants (52%) had moderate benefit (at least 30% pain relief or PGIC much or very much improved) with gabapentin at 1200 mg daily or greater than with placebo (37%) (RR 1.4 (95% CI 1.3 to 1.6); NNT 6.6 (4.9 to 9.9); 7 studies, 1439 participants, moderate-quality evidence).For all conditions combined, adverse event withdrawals were more common with gabapentin (11%) than with placebo (8.2%) (RR 1.4 (95% CI 1.1 to 1.7); NNH 30 (20 to 65); 22 studies, 4346 participants, high-quality evidence). Serious adverse events were no more common with gabapentin (3.2%) than with placebo (2.8%) (RR 1.2 (95% CI 0.8 to 1.7); 19 studies, 3948 participants, moderate-quality evidence); there were eight deaths (very low-quality evidence). Participants experiencing at least one adverse event were more common with gabapentin (63%) than with placebo (49%) (RR 1.3 (95% CI 1.2 to 1.4); NNH 7.5 (6.1 to 9.6); 18 studies, 4279 participants, moderate-quality evidence). Individual adverse events occurred significantly more often with gabapentin. Participants taking gabapentin experienced dizziness (19%), somnolence (14%), peripheral oedema (7%), and gait disturbance (14%).

AUTHORS' CONCLUSIONS

Gabapentin at doses of 1800 mg to 3600 mg daily (1200 mg to 3600 mg gabapentin encarbil) can provide good levels of pain relief to some people with postherpetic neuralgia and peripheral diabetic neuropathy. Evidence for other types of neuropathic pain is very limited. The outcome of at least 50% pain intensity reduction is regarded as a useful outcome of treatment by patients, and the achievement of this degree of pain relief is associated with important beneficial effects on sleep interference, fatigue, and depression, as well as quality of life, function, and work. Around 3 or 4 out of 10 participants achieved this degree of pain relief with gabapentin, compared with 1 or 2 out of 10 for placebo. Over half of those treated with gabapentin will not have worthwhile pain relief but may experience adverse events. Conclusions have not changed since the previous update of this review.

Morphine for chronic neuropathic pain in adults

BACKGROUND

Neuropathic pain, which is caused by a lesion or disease affecting the somatosensory system, may be central or peripheral in origin. Neuropathic pain often includes symptoms such as burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or an increased sensitivity to normally painful stimuli. Neuropathic pain is a common symptom in many diseases of the nervous system. Opioid drugs, including morphine, are commonly used to treat neuropathic pain. Most reviews have examined all opioids together. This review sought evidence specifically for morphine; other opioids are considered in separate reviews.

OBJECTIVES

To assess the analgesic efficacy and adverse events of morphine for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase for randomised controlled trials from inception to February 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of two weeks' duration or longer, comparing morphine (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH). We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables.

MAIN RESULTS

We identified five randomised, double-blind, cross-over studies with treatment periods of four to seven weeks, involving 236 participants in suitably characterised neuropathic pain; 152 (64%) participants completed all treatment periods. Oral morphine was titrated to maximum daily doses of 90 mg to 180 mg or the maximum tolerated dose, and then maintained for the remainder of the study. Participants had experienced moderate or severe neuropathic pain for at least three months. Included studies involved people with painful diabetic neuropathy, chemotherapy-induced peripheral neuropathy, postherpetic neuralgia criteria, phantom limb or postamputation pain, and lumbar radiculopathy. Exclusions were typically people with other significant comorbidity or pain from other causes.Overall, we judged the studies to be at low risk of bias, but there were concerns over small study size and the imputation method used for participants who withdrew from the studies, both of which could lead to overestimation of treatment benefits and underestimation of harm.There was insufficient or no evidence for the primary outcomes of interest for efficacy or harm. Four studies reported an approximation of moderate pain improvement (any pain-related outcome indicating some improvement) comparing morphine with placebo in different types of neuropathic pain. We pooled these data in an exploratory analysis. Moderate improvement was experienced by 63% (87/138) of participants with morphine and 36% (45/125) with placebo; the risk difference (RD) was 0.27 (95% confidence interval (CI) 0.16 to 0.38, fixed-effects analysis) and the NNT 3.7 (2.6 to 6.5). We assessed the quality of the evidence as very low because of the small number of events; available information did not provide a reliable indication of the likely effect, and the likelihood that the effect will be substantially different was very high. A similar exploratory analysis for substantial pain relief on three studies (177 participants) showed no difference between morphine and placebo.All-cause withdrawals in four studies occurred in 16% (24/152) of participants with morphine and 12% (16/137) with placebo. The RD was 0.04 (-0.04 to 0.12, random-effects analysis). Adverse events were inconsistently reported, more common with morphine than with placebo, and typical of opioids. There were two serious adverse events, one with morphine, and one with a combination of morphine and nortriptyline. No deaths were reported. These outcomes were assessed as very low quality because of the limited number of participants and events.

AUTHORS' CONCLUSIONS

There was insufficient evidence to support or refute the suggestion that morphine has any efficacy in any neuropathic pain condition.

Methadone for neuropathic pain in adults

BACKGROUND

This review replaces an earlier review, "Methadone for chronic non-cancer pain in adults". This review serves to update the original and includes only studies of neuropathic pain. Methadone belongs to a class of analgesics known as opioids, that are considered the cornerstone of therapy for moderate-to-severe postsurgical pain and pain due to life-threatening illnesses; however, their use in neuropathic pain is controversial. Methadone has many characteristics that differentiate it from other opioids, which suggests that it may have a different efficacy and safety profile.

OBJECTIVES

To assess the analgesic efficacy and adverse events of methadone for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the following databases: CENTRAL (CRSO), MEDLINE (Ovid), and Embase (Ovid), and two clinical trial registries. We also searched the reference lists of retrieved articles. The date of the most recent search was 30 November 2016.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing methadone (in any dose, administered by any route, and in any formulation) with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently considered trials for inclusion in the review, assessed risk of bias, and extracted data. There were insufficient data to perform pooled analyses. We assessed the overall quality of the evidence for each outcome using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included three studies, involving 105 participants. All were cross-over studies, one involving 19 participants with diverse neuropathic pain syndromes, the other two involving 86 participants with postherpetic neuralgia. Study phases ranged from 20 days to approximately eight weeks. All administered methadone orally, in doses ranging from 10 mg to 80 mg daily. Comparators were primarily placebo, but one study also included morphine and tricyclic antidepressants.The included studies had several limitations related to risk of bias, particularly incomplete reporting, selective outcome reporting, and small sample sizes.There were very limited data for our primary outcomes of participants with at least 30% or at least 50% pain relief. Two studies reported that 11/29 participants receiving methadone achieved 30% pain relief versus 7/29 participants receiving placebo. Only one study presented data in a manner that allowed us to calculate the number of participants with at least 50% pain relief. None of the 19 participants achieved a 50% reduction in pain intensity, either when receiving methadone or when receiving placebo. No study provided data for our other primary outcomes of Patient Global Impression of Change scale (PGIC) much or very much improved (equivalent to at least 30% pain relief) and PGIC very much improved (equivalent to at least 50% pain relief).For secondary efficacy outcomes, one study reported maximum and mean pain intensity and pain relief, and reported statistically significant improvements versus placebo for all outcomes with 20 mg daily doses of methadone, but not with 10 mg daily doses. The second study reported differences in pain reduction between methadone (n = 26) and morphine (n = 38) and found morphine to be statistically superior. The third study reported the number of responders (variously defined) for several pain and functional outcomes and found methadone to be statistically superior to placebo for the outcomes of categorical pain intensity and evoked pain. In the two studies that reported data, 0/29 participants withdrew due to lack of efficacy, whereas 4/29 participants withdrew due to adverse events while taking methadone versus 3/29 while taking placebo.One study reported incidences for several individual adverse events, but found a statistically significant increased incidence for methadone over placebo for only one event, dizziness. The other studies did not report data in a manner that enabled us to analyze adverse events. There were no serious adverse events or deaths reported.We assessed the quality of the evidence as very low for all efficacy and safety outcomes using GRADE, primarily because of the heterogeneity of study designs and populations, short durations, cross-over methodology, and few participants and events.

AUTHORS' CONCLUSIONS

The three studies provide very limited, very low quality evidence of the efficacy and safety of methadone for chronic neuropathic pain, and there were too few data for pooled analysis of efficacy or harm, or to have confidence in the results of the individual studies. No conclusions can be made regarding differences in efficacy or safety between methadone and placebo, other opioids, or other treatments.

[Efficacy, tolerability and safety of cannabinoids for chronic neuropathic pain: A systematic review of randomized controlled studies]

BACKGROUND

Recently published systematic reviews came to different conclusions with respect to the efficacy, tolerability and safety of cannabinoids for treatment of chronic neuropathic pain.

MATERIAL AND METHODS

A systematic search of the literature was carried out in MEDLINE, the Cochrane central register of controlled trials (CENTRAL) and clinicaltrials.gov up until November 2015. We included double-blind randomized placebo-controlled studies (RCT) of at least 2 weeks duration and with at least 9 patients per treatment arm comparing medicinal cannabis, plant-based or synthetic cannabinoids with placebo or any other active drug treatment in patients with chronic neuropathic pain. Clinical endpoints of the analyses were efficacy (more than 30 % or 50 % reduction of pain, average pain intensity, global improvement and health-related quality of life), tolerability (drop-out rate due to side effects, central nervous system and psychiatric side effects) and safety (severe side effects). Using a random effects model absolute risk differences (RD) were calculated for categorical data and standardized mean differences (SMD) for continuous variables. The methodological quality of RCTs was rated by the Cochrane risk of bias tool.

RESULTS

We included 15 RCTs with 1619 participants. Study duration ranged between 2 and 15 weeks. Of the studies 10 used a plant-derived oromucosal spray with tetrahydrocannabinol/cannabidiol, 3 studies used a synthetic cannabinoid (2  with nabilone and 1  with dronabinol) and 2 studies used medicinal cannabis. The 13 studies with parallel or cross-over design yielded the following results with 95 % confidence intervals (CI): cannabinoids were superior to placebo in the reduction of mean pain intensity with SMD - 0.10 (95 % CI - 0.20- - 0.00, p = 0.05, 13 studies with 1565 participants), in the frequency of at least a 30 % reduction in pain with an RD of 0.10 [95 % CI 0.03-0.16, p = 0.004, 9 studies with 1346 participants, number needed to treat for additional benefit (NNTB) 14, 95 % CI 8-45] and in the frequency of a large or very large global improvement with an RD of 0.09 (95 % CI 0.01-0.17, p = 0.009, 7 studies with 1092 participants). There were no statistically significant differences between cannabinoids and placebo in the frequency of at least a 50 % reduction in pain, in improvement of health-related quality of life and in the frequency of serious adverse events. Patients treated with cannabinoids dropped out more frequently due to adverse events with an RD of 0.04 [95 % CI 0.01-0.07, p = 0.009, 11 studies with 1572 participants, number needed to treat for additional harm (NNTH) 19, 95 % CI 13-37], reported central nervous system side effects more frequently with an RD of 0.38 (95 % CI 0.18-0.58, p = 0.0003, 9 studies with 1304 participants, NNTH 3, 95 % CI 2-4) and psychiatric side effects with an RD of 0.11 (95 % CI 0.06-0.16, p < 0.0001, 9 studies with 1304 participants, NNTH 8, 95 % CI 7-12).

CONCLUSION

Cannabinoids were marginally superior to placebo in terms of efficacy and inferior in terms of tolerability. Cannabinoids and placebo did not differ in terms of safety during the study period. Short-term and intermediate-term therapy with cannabinoids can be considered in selected patients with chronic neuropathic pain after failure of first-line and second-line therapies.

Topical capsaicin (high concentration) for chronic neuropathic pain in adults

BACKGROUND

This review is an update of 'Topical capsaicin (high concentration) for chronic neuropathic pain in adults' last updated in Issue 2, 2013. Topical creams with capsaicin are used to treat peripheral neuropathic pain. Following application to the skin, capsaicin causes enhanced sensitivity, followed by a period with reduced sensitivity and, after repeated applications, persistent desensitisation. High-concentration (8%) capsaicin patches were developed to increase the amount of capsaicin delivered; rapid delivery was thought to improve tolerability because cutaneous nociceptors are 'defunctionalised' quickly. The single application avoids noncompliance. Only the 8% patch formulation of capsaicin is available, with a capsaicin concentration about 100 times greater than conventional creams. High-concentration topical capsaicin is given as a single patch application to the affected part. It must be applied under highly controlled conditions, often following local anaesthetic, due to the initial intense burning sensation it causes. The benefits are expected to last for about 12 weeks, when another application might be made.

OBJECTIVES

To review the evidence from controlled trials on the efficacy and tolerability of topically applied, high-concentration (8%) capsaicin in chronic neuropathic pain in adults.

SEARCH METHODS

For this update, we searched CENTRAL, MEDLINE, Embase, two clinical trials registries, and a pharmaceutical company's website to 10 June 2016.

SELECTION CRITERIA

Randomised, double-blind, placebo-controlled studies of at least 6 weeks' duration, using high-concentration (5% or more) topical capsaicin to treat neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. Where pooled analysis was possible, we used dichotomous data to calculate risk ratio and numbers needed to treat for one additional event, using standard methods.Efficacy outcomes reflecting long-duration pain relief after a single drug application were from the Patient Global Impression of Change (PGIC) at specific points, usually 8 and 12 weeks. We also assessed average pain scores over weeks 2 to 8 and 2 to 12 and the number of participants with pain intensity reduction of at least 30% or at least 50% over baseline, and information on adverse events and withdrawals.We assessed the quality of the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included eight studies, involving 2488 participants, two more studies and 415 more participants than the previous version of this review. Studies were of generally good methodological quality; we judged only one study at high risk of bias, due to small size. Two studies used a placebo control and six used 0.04% topical capsaicin as an 'active' placebo to help maintain blinding. Efficacy outcomes were inconsistently reported, resulting in analyses for most outcomes being based on less than complete data.For postherpetic neuralgia, we found four studies (1272 participants). At both 8 and 12 weeks about 10% more participants reported themselves much or very much improved with high-concentration capsaicin than with 'active' placebo, with point estimates of numbers needed to treat for an additional beneficial outcome (NNTs) of 8.8 (95% confidence interval (CI) 5.3 to 26) with high-concentration capsaicin and 7.0 (95% CI 4.6 to 15) with 'active' placebo (2 studies, 571 participants; moderate quality evidence). More participants (about 10%) had average 2 to 8-week and 2 to 12-week pain intensity reductions over baseline of at least 30% and at least 50% with capsaicin than control, with NNT values between 10 and 12 (2 to 4 studies, 571 to 1272 participants; very low quality evidence).For painful HIV-neuropathy, we found two studies (801 participants). One study reported the proportion of participants who were much or very much improved at 12 weeks (27% with high-concentration capsaicin and 10% with 'active' placebo). For both studies, more participants (about 10%) had average 2 to 12-week pain intensity reductions over baseline of at least 30% with capsaicin than control, with an NNT of 11 (very low quality evidence).For peripheral diabetic neuropathy, we found one study (369 participants). It reported about 10% more participants who were much or very much improved at 8 and 12 weeks. One small study of 46 participants with persistent pain following inguinal herniorrhaphy did not show a difference between capsaicin and placebo for pain reduction (very low quality evidence).We downgraded the quality of the evidence for efficacy outcomes by one to three levels due to sparse data, imprecision, possible effects of imputation methods, and susceptibility to publication bias.Local adverse events were common, but not consistently reported. Serious adverse events were no more common with active treatment (3.5%) than control (3.2%). Adverse event withdrawals did not differ between groups, but lack of efficacy withdrawals were somewhat more common with control than active treatment, based on small numbers of events (six to eight studies, 21 to 67 events; moderate quality evidence, downgraded due to few events). No deaths were judged to be related to study medication.

AUTHORS' CONCLUSIONS

High-concentration topical capsaicin used to treat postherpetic neuralgia, HIV-neuropathy, and painful diabetic neuropathy generated more participants with moderate or substantial levels of pain relief than control treatment using a much lower concentration of capsaicin. These results should be interpreted with caution as the quality of the evidence was moderate or very low. The additional proportion who benefited over control was not large, but for those who did obtain high levels of pain relief, there were usually additional improvements in sleep, fatigue, depression, and quality of life. High-concentration topical capsaicin is similar in its effects to other therapies for chronic pain.

Paracetamol (acetaminophen) with or without codeine or dihydrocodeine for neuropathic pain in adults

BACKGROUND

Paracetamol, either alone or in combination with codeine or dihydrocodeine, is commonly used to treat chronic neuropathic pain. This review sought evidence for efficacy and harm from randomised double-blind studies.

OBJECTIVES

To assess the analgesic efficacy and adverse events of paracetamol with or without codeine or dihydrocodeine for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase from inception to July 2016, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing paracetamol, alone or in combination with codeine or dihydrocodeine, with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE.

MAIN RESULTS

No study satisfied the inclusion criteria. Effects of interventions were not assessed as there were no included studies. We have only very low quality evidence and have no reliable indication of the likely effect.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the suggestion that paracetamol alone, or in combination with codeine or dihydrocodeine, works in any neuropathic pain condition.

Oxycodone for neuropathic pain in adults

BACKGROUND

This is an update of an earlier review that considered both neuropathic pain and fibromyalgia (Issue 6, 2014), which has now been split into separate reviews for the two conditions. This review considers neuropathic pain only.Opioid drugs, including oxycodone, are commonly used to treat neuropathic pain, and are considered effective by some professionals. Most reviews have examined all opioids together. This review sought evidence specifically for oxycodone, at any dose, and by any route of administration. Separate reviews consider other opioids.

OBJECTIVES

To assess the analgesic efficacy and adverse events of oxycodone for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE from inception to 6 November 2013 for the original review and from January 2013 to 21 December 2015 for this update. We also searched the reference lists of retrieved studies and reviews, and two online clinical trial registries. This update differs from the earlier review in that we have included studies using oxycodone in combination with naloxone, and oxycodone used as add-on treatment to stable, but inadequate, treatment with another class of drug.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing any dose or formulation of oxycodone with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. Where pooled analysis was possible, we used dichotomous data to calculate risk ratio and numbers needed to treat for one additional event, using standard methods.We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created a 'Summary of findings' table.

MAIN RESULTS

The updated searches identified one additional published study, and one clinical trial registry report. We included five studies reporting on 687 participants; 637 had painful diabetic neuropathy and 50 had postherpetic neuralgia. Two studies used a cross-over design and three used a parallel group design; all studies used a placebo comparator, although one study used an active placebo (benztropine). Modified-release oxycodone (oxycodone MR) was titrated to effect and tolerability. One study used a fixed dose combination of oxycodone MR and naloxone. Two studies added oxycodone therapy to ongoing, stable treatment with either pregabalin or gabapentin. All studies had one or more sources of potential major bias.No study reported the proportion of participants experiencing 'substantial benefit' (at least 50% pain relief or who were very much improved). Three studies (537 participants) in painful diabetic neuropathy reported outcomes equivalent to 'moderate benefit' (at least 30% pain relief or who were much or very much improved), which was experienced by 44% of participants with oxycodone and 27% with placebo (number needed to treat for one additional beneficial outcome (NNT) 5.7).All studies reported group mean pain scores at the end of treatment. Three studies reported a greater pain intensity reduction and better patient satisfaction with oxycodone MR alone than with placebo. There was a similar result in the study adding oxycodone MR to stable, ongoing gabapentin, but adding oxycodone MR plus naloxone to stable, ongoing pregabalin did not show any additional effect.More participants experienced adverse events with oxycodone MR alone (86%) than with placebo (63%); the number needed to treat for an additional harmful outcome (NNH) was 4.3. Serious adverse events (oxycodone 3.4%, placebo 7.0%) and adverse event withdrawals (oxycodone 11%, placebo 6.4%) were not significantly different between groups. Withdrawals due to lack of efficacy were less frequent with oxycodone MR (1.1%) than placebo (11%), with a number needed to treat to prevent one withdrawal of 10. The add-on studies reported similar results.We downgraded the quality of the evidence to very low for all outcomes, due to limitations in the study methods, heterogeneity in the pain condition and study methods, and sparse data.

AUTHORS' CONCLUSIONS

There was only very low quality evidence that oxycodone (as oxycodone MR) is of value in the treatment of painful diabetic neuropathy or postherpetic neuralgia. There was no evidence for other neuropathic pain conditions. Adverse events typical of opioids appeared to be common.

Clinical Significance of Invasive Motor Cortex Stimulation for Trigeminal Facial Neuropathic Pain Syndromes

BACKGROUND:

Invasive neuromodulation of the cortical surface for various chronic pain syndromes has been performed for &gt;20 years. The significance of motor cortex stimulation (MCS) in chronic trigeminal neuropathic pain (TNP) syndromes remains unclear. Different techniques are performed worldwide in regard to operative procedure, stimulation parameters, test trials, and implanted materials.

OBJECTIVE:

To present the clinical experiences of a single center with MCS, surgical approach, complications, and follow-up as a prospective, noncontrolled clinical trial.

METHODS:

The implantation of epidural leads over the motor cortex was performed via a burr hole technique with neuronavigation and intraoperative neurostimulation. Special focus was placed on a standardized test trial with an external stimulation device and the implementation of a double-blinded or placebo test phase to identify false-positive responders.

RESULTS:

A total of 36 patients with TNP were operated on, and MCS was performed. In 26 of the 36 patients (72%), a significant pain reduction from a mean of 8.11 to 4.58 (on the visual analog scale) during the test trial was achieved (P &lt;.05). Six patients were identified as false-positive responders (17%). At the last available follow-up of 26 patients (mean, 5.6 years), active MCS led to a significant pain reduction compared with the preoperative pain ratings (mean visual analog scale score, 5.01; P &lt;.05).

CONCLUSION:

MCS is an additional therapeutic option for patients with refractory chronic TNP, and significant long-term pain suppression can be achieved. Placebo or double-blinded testing is mandatory.

Hydromorphone for neuropathic pain in adults

BACKGROUND

Opioid drugs, including hydromorphone, are commonly used to treat neuropathic pain, and are considered effective by some professionals. Most reviews have examined all opioids together. This review sought evidence specifically for hydromorphone, at any dose, and by any route of administration. Other opioids are considered in separate reviews.This review is part of an update of a previous review, Hydromorphone for acute and chronic pain that was withdrawn in 2013 because it needed updating and splitting to be more specific for different pain conditions. This review focuses only on neuropathic pain.

OBJECTIVES

To assess the analgesic efficacy of hydromorphone for chronic neuropathic pain in adults, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), via the CRSO; MEDLINE via Ovid; and EMBASE via Ovid from inception to 17 November 2015, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing hydromorphone (at any dose, by any route of administration, or in any formulation) with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation).

MAIN RESULTS

Searches identified seven publications relating to four studies. We excluded three studies. One post hoc (secondary) analysis of a study published in four reports assessed the efficacy of hydromorphone in neuropathic pain, satisfied our inclusion criteria, and was included in the review. The single included study had an enriched enrolment, randomised withdrawal design with 94 participants who were successfully switched from oral morphine to oral hydromorphone extended release (about 60% of those enrolled). These participants were then randomised to continuing hydromorphone for 12 weeks or tapering down the hydromorphone dose to placebo. The methodological quality of the study was generally good, but we judged the risk of bias for incomplete outcome data as unclear, and for study size as high.Since we identified only one study for inclusion, we were unable to carry out any analyses. The included study did not report any of our prespecified primary outcomes, which relate to the number of participants achieving moderate or substantial levels of pain relief. It did report a slightly larger increase in average pain intensity for placebo in the randomised withdrawal phase than for continuing with hydromorphone. It also reported the number of participants who withdrew due to lack of efficacy in the randomised withdrawal phase, which may be an indicator of efficacy. However, in addition to using an enriched enrolment, randomised withdrawal study design, there was an unusual choice of imputation methods for withdrawals (about 50% of participants); the evidence was of very low quality and inadequate to make a judgement on efficacy. Adverse events occurred in about half of participants with hydromorphone, the most common being constipation and nausea. A similar proportion of participants experienced adverse events with placebo, the most common being opioid withdrawal syndrome (very low quality evidence). Most adverse events were mild or moderate in intensity. One in eight participants withdrew while taking hydromorphone during the conversion and titration phase, despite participants being opioid-tolerant (very low quality evidence).We downgraded the quality of the evidence to very low because there was only one study with few participants, it did not report clinically useful efficacy outcomes, and it was a post hoc analysis.

AUTHORS' CONCLUSIONS

There was insufficient evidence to support or refute the suggestion that hydromorphone has any efficacy in any neuropathic pain condition.

Are Pain Ratings Irrelevant?

Pain intensity ratings have been the basis of pain diagnosis and a fundamental tool in pain research, but are not always used. Frequent comments by physicians that pain ratings, sometimes called pain scores, are not useful in clinical practice and comments by basic scientists that pain ratings may measure the wrong thing, have been in significant part supported by a short survey conducted among members of American Pain Society (APS). Though limited by small number of respondents, the findings of this survey and additional comments by members of APS raise critical questions about why pain ratings do not serve the clinical communities. These findings send an urgent call to the pain community to reassess the status of currently used pain ratings and to find solutions to this fundamental issue.

Oral nonsteroidal anti-inflammatory drugs for neuropathic pain

BACKGROUND

Although often considered to be lacking adequate evidence, nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used in the management of neuropathic pain. Previous surveys found 18% to 47% of affected people reported using NSAIDs specifically for their neuropathic pain, although possibly not in the United Kingdom (UK).

OBJECTIVES

To assess the analgesic efficacy of oral NSAIDs for chronic neuropathic pain in adults, when compared to placebo or another active intervention, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE from inception to 29 May 2015, together with reference lists of retrieved papers and reviews, and an online trials registry.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks duration or longer, comparing any oral NSAID with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality. We did not carry out any pooled analysis.

MAIN RESULTS

We included two studies involving 251 participants with chronic low back pain with a neuropathic component or postherpetic neuralgia; 209 of these participants were involved in a study of an experimental NSAID not used in clinical practice, and of the remaining 42, only 16 had neuropathic pain. This represented only third tier evidence, and was of very low quality. There was no indication of any significant pain reduction with NSAIDs. Adverse event rates were low, with insufficient events for any analysis.

AUTHORS' CONCLUSIONS

There is no evidence to support or refute the use of oral NSAIDs to treat neuropathic pain conditions.

Buprenorphine for neuropathic pain in adults

BACKGROUND

Opioid drugs, including buprenorphine, are commonly used to treat neuropathic pain, and are considered effective by some professionals. Most reviews have examined all opioids together. This review sought evidence specifically for buprenorphine, at any dose, and by any route of administration. Other opioids are considered in separate reviews.

OBJECTIVES

To assess the analgesic efficacy of buprenorphine for chronic neuropathic pain in adults, and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE from inception to 11 June 2015, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing any oral dose or formulation of buprenorphine with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality. We did not carry out any pooled analyses.

MAIN RESULTS

Searches identified 10 published studies, and one study with results in ClinicalTrials.gov. None of these 11 studies satisfied our inclusion criteria, and so we included no studies in the review.

AUTHORS' CONCLUSIONS

There was insufficient evidence to support or refute the suggestion that buprenorphine has any efficacy in any neuropathic pain condition.

Perspectives on next steps in classification of oro-facial pain - part 1: role of ontology

The purpose of this study was to review existing principles of oro-facial pain classifications and to specify design recommendations for a new system that would reflect recent insights in biomedical classification systems, terminologies and ontologies. The study was initiated by a symposium organised by the International RDC/TMD Consortium Network in March 2013, to which the present authors contributed. The following areas are addressed: problems with current classification approaches, status of the ontological basis of pain disorders, insufficient diagnostic aids and biomarkers for pain disorders, exploratory nature of current pain terminology and classification systems, and problems with prevailing classification methods from an ontological perspective. Four recommendations for addressing these problems are as follows: (i) develop a hypothesis-driven classification structure built on principles that ensure to our best understanding an accurate description of the relations among all entities involved in oro-facial pain disorders; (ii) take into account the physiology and phenomenology of oro-facial pain disorders to adequately represent both domains including psychosocial entities in a classification system; (iii) plan at the beginning for field-testing at strategic development stages; and (iv) consider how the classification system will be implemented. Implications in relation to the specific domains of psychosocial factors and biomarkers for inclusion into an oro-facial pain classification system are described in two separate papers.

Diagnosis and management of neuropathic pain

A recent revision in the definition of neuropathic pain has highlighted this condition as a distinct disease entity. More accurate search for a lesion in the somatosensory nervous system as the pain-generating mechanism will help target the treatment by pharmacological agents. A multidisciplinary approach is recommended, with pharmacotherapy supplemented by psychological therapy and physical rehabilitation, and appropriate interventional treatment for selected refractory cases.

Is an easy and reliable diagnosis of localized neuropathic pain (LNP) possible in general practice? Development of a screening tool based on IASP criteria

BACKGROUND AND OBJECTIVE

Neuropathic pain (NP) is a common type of chronic pain in which 60% of patients present with localized symptoms. Early diagnosis of NP is often a challenge in primary care. Moreover, so far no standard diagnostic procedure for localized NP (LNP) is available. To help general practitioners, a screening tool was developed and evaluated.

RESEARCH DESIGN AND METHODS

The development of the screening tool was based on the grading system principles for NP proposed by the IASP, focusing on medical history and distribution of painful symptoms and sensory signs. It was tested by 31 general practitioners and evaluated against the NP diagnosis of three pain specialists as reference in a single center prospective study in Spain using a cohort study design including an adult population of chronic pain patients. This design avoids spectrum bias where the spectrum of disease is not correctly reflected in the study population.

MAIN OUTCOME MEASURES

General practitioners rated usefulness, simplicity, and time requirements of the tool. Diagnostic accuracy was expressed by sensitivity, specificity, and positive and negative predictive values.

RESULTS

General practitioners consecutively screened 2079 chronic pain patients (mean age 60.7 ± 11.1 years, 69.9% female). Using the tool, 394 patients were diagnosed with LNP. Screening including sensory examination took 7 min (median). General practitioners rated the tool as useful (24/31; 77.4%) or very useful (7/31; 22.6%) for diagnosing LNP and facilitating clinical practice (30/31; 96.8%). Under daily practice conditions, sensitivity and specificity of the tool for detecting LNP was 46.7% and 86.6%, respectively.

CONCLUSIONS

The proposed screening tool was shown to be easy and useful for detecting NP and LNP in chronic pain patients as a fast first assessment tool in primary care, thus facilitating the choice of a topical treatment. LIMITATIONS AND STRENGTHS: The drop-out rate was high but was accounted for by using correction factors in the diagnostic accuracy calculations. A strength is the unselected chronic patient population: spectrum of disease correctly reflects day-to-day clinical practice and is not biased. Diagnostic accuracy of the tool therefore appears to be realistic.

Building a diagnostic algorithm on localized neuropathic pain (LNP) and targeted topical treatment: focus on 5% lidocaine-medicated plaster

Within the broad definition of neuropathic pain, the refinement of clinical diagnostic procedures has led to the introduction of the concept of localized neuropathic pain (LNP). It is characterized by consistent and circumscribed area(s) of maximum pain, which are associated with negative or positive sensory signs and/or spontaneous symptoms typical of neuropathic pain. This description outlines the clinical features (currently lacking in guidelines and treatment recommendations) in patients for whom topical targeted treatment with 5% lidocaine-medicated plaster is suggested as first-line therapy. Few epidemiologic data are present in the literature but it is generally estimated that about 60% of neuropathic pain conditions are localized, and therefore identifiable as LNP. A mandatory clinical criterion for the diagnosis of LNP is that signs and symptoms must be present in a clearly identified and defined area(s). Cartographic recordings can help to define each area and to assess variations. The diagnosis of LNP relies on careful neurological examination more than on pain questionnaires, but it is recognized that they can be extremely useful for recording the symptom profiles and establishing a more targeted treatment. The most widely studied frequent/relevant clinical presentations of LNP are postherpetic neuralgia, diabetic neuropathy, and neuropathic postoperative pain. They successfully respond to treatment with 5% lidocaine-medicated plaster with equal if not better pain control but with fewer side effects versus conventional systemic treatments. Generally, the more localized the pain (ie, the area of an A4 sheet of paper) the better the results of topical treatment. This paper proposes an easy-to-understand algorithm to identify patients with LNP and to guide targeted topical treatments with 5% lidocaine medicated plaster.

PRECISE - pregabalin in addition to usual care for sciatica: study protocol for a randomised controlled trial

Background

Sciatica is a type of neuropathic pain that is characterised by pain radiating into the leg. It is often accompanied by low back pain and neurological deficits in the lower limb. While this condition may cause significant suffering for the individual, the lack of evidence supporting effective treatments for sciatica makes clinical management difficult. Our objectives are to determine the efficacy of pregabalin on reducing leg pain intensity and its cost-effectiveness in patients with sciatica.

Methods/Design

PRECISE is a prospectively registered, double-blind, randomised placebo-controlled trial of pregabalin compared to placebo, in addition to usual care. Inclusion criteria include moderate to severe leg pain below the knee with evidence of nerve root/spinal nerve involvement. Participants will be randomised to receive either pregabalin with usual care (n = 102) or placebo with usual care (n = 102) for 8 weeks. The medicine dosage will be titrated up to the participant’s optimal dose, to a maximum 600 mg per day. Follow up consultations will monitor individual progress, tolerability and adverse events. Usual care, if deemed appropriate by the study doctor, may include a referral for physical or manual therapy and/or prescription of analgesic medication. Participants, doctors and researchers collecting participant data will be blinded to treatment allocation. Participants will be assessed at baseline and at weeks 2, 4, 8, 12, 26 and 52. The primary outcome will determine the efficacy of pregabalin in reducing leg pain intensity. Secondary outcomes will include back pain intensity, disability and quality of life. Data analysis will be blinded and by intention-to-treat. A parallel economic evaluation will be conducted from health sector and societal perspectives.

Discussion

This study will establish the efficacy of pregabalin in reducing leg pain intensity in patients with sciatica and provide important information regarding the effect of pregabalin treatment on disability and quality of life. The impact of this research may allow the future development of a cost-effective conservative treatment strategy for patients with sciatica.

Trial registration

ClinicalTrial.gov, ACTRN 12613000530729