A novel tool for the assessment of pain: validation in low back pain

Probiotic and high-fat diet: effects on pain assessment, body composition, and cytokines in male and female adolescent and adult rats

Obesity in adolescence is increasing in frequency and is associated with elevated proinflammatory cytokines and chronic pain in a sex-dependent manner. Dietary probiotics may mitigate these detrimental effects of obesity. Using a Long-Evans adolescent and adult rat model of overweight (high-fat diet (HFD) - 45% kcal from fat from weaning), we determined the effect of a single-strain dietary probiotic [Lactiplantibacillus plantarum 299v (Lp299v) from weaning] on the theoretically increased neuropathic injury-induced pain phenotype and inflammatory cytokines. We found that although HFD increased fat mass, it did not markedly affect pain phenotype, particularly in adolescence, but there were subtle differences in pain in adult male versus female rats. The combination of HFD and Lp299v augmented the increase in leptin in adolescent females. There were many noninteracting main effects of age, diet, and probiotic on an array of cytokines and adipokines with adults being higher than adolescents, HFD higher than the control diet, and a decrease with probiotic compared with placebo. Of particular interest were the probiotic-induced increases in IL12p70 in female adolescents on an HFD. We conclude that a more striking pain phenotype could require a higher and longer duration caloric diet or a different etiology of pain. A major strength of our study was that a single-strain probiotic had a wide range of inhibiting effects on most proinflammatory cytokines. The positive effect of the probiotic on leptin in female adolescent rats is intriguing and worthy of exploration.NEW & NOTEWORTHY A single-strain probiotic (Lp299v) had a wide range of inhibiting effects on most proinflammatory cytokines (especially IL12p70) measured in this high-fat diet rat model of mild obesity. The positive effect of probiotic on leptin in female adolescent rats is intriguing and worthy of exploration.

Reliability of a clinical sensory test battery in patients with spine-related leg and arm pain

BACKGROUND

The current standard to evaluate the presence of somatosensory dysfunctions is quantitative sensory testing, but its clinical utility remains limited. Low-cost and time-efficient clinical sensory testing (CST) batteries have thus been developed. Recent studies show moderate to substantial reliability in populations with neuropathic pain. This study evaluates the inter- and intra-tester reliability of people with spine-related leg and arm pain, representing mixed pain mechanisms.

METHODS

Fifty-three patients with spine-related leg (n = 41) and arm pain (n = 12) attended three CST sessions. The CST battery consisted of eleven tests, determining loss and gain of sensory nerve function. CST was performed by the same investigator twice and by an additional investigator to determine inter- and intra-tester reliability. Fleiss' (inter-tester) and Cohen's (intra-tester) kappa were calculated for dichotomized and intraclass correlation coefficients (ICC) for continuous outcomes.

RESULTS

Fleiss' kappa varied among modalities from fair to substantial (κ = 0.23-0.66). Cold, warm, and vibration detection thresholds and cold and pressure pain thresholds reached kappa >0.4 (moderate to substantial reliability). Cohen's kappa ranged from moderate to substantial (κ = 0.45-0.66). The reliability of the windup ratio was poor (ICC <0.18).

CONCLUSION

CST modalities with moderate to substantial inter-tester reliability could be of benefit as a screening tool. The moderate to substantial intra-tester reliability for all sensory modalities (except windup ratio) supports their potential use in clinical practice and research to monitor somatosensory changes over time in patients with spine-related limb pain of mixed pain mechanisms.

SIGNIFICANCE

We already know that most modalities of clinical sensory test (CST) batteries achieve moderate to substantial inter- and intra-tester reliability in populations with neuropathic pain. This study evaluates the reliability of a CST battery in populations with mixed pain mechanisms. We found inter-tester reliability varied from poor to substantial for sensory modalities, questioning the value of some CST modalities. The CST battery showed moderate to substantial intra-tester reliability, suggesting its usefulness to monitor sensory changes over time in this cohort.

The Effectiveness and Optimal Dose of Resistance Training in Patients With Subacute and Persistent Low Back-Related Leg Pain: A Systematic Review

A subgroup of patients with low back pain (LBP) suffers from low back-related leg pain (LBLP), which can be classified as radicular pain, or somatic referred pain without nerve root involvement. LBLP is considered an obstacle to recovery and a strong negative prognostic factor for medium- and long-term disability. In this review, we aimed to investigate the effectiveness and optimal dose of resistance training (RT) in patients with subacute or persistent LBLP to provide clinical recommendations for practice. This systematic review was conducted by adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the recommendations of the Cochrane Collaboration. We conducted a literature search on PubMed, PEDro, Cochrane Library, Scopus, and Web of Science databases. Only randomized controlled trials (RCTs) involving patients ≥18 years of age were included. The risk of bias in the included studies was assessed using "the Cochrane Collaboration's tool for assessing risk of bias" (RoB) and the inter-rater agreement for full-text selection was evaluated using Cohen's Kappa (K). The search elicited a total of 4.537 records, and two RCTs involving a total of 196 participants were identified through a selection process based on title, abstract, and full-text assessment. Both studies had a low to moderate risk of bias. The inter-examiner concordance index for the selection of full text was excellent (K=1). RT seems to be an effective and safe intervention for patients with LBLP, but its long-term effectiveness, superiority over other types of exercise-based therapies, and optimal dosage still constitute a gray area in the literature.

1. Lumbosacral radicular pain

INTRODUCTION

Patients suffering lumbosacral radicular pain report radiating pain in one or more lumbar or sacral dermatomes. In the general population, low back pain with leg pain extending below the knee has an annual prevalence that varies from 9.9% to 25%.

METHODS

The literature on the diagnosis and treatment of lumbosacral radicular pain was reviewed and summarized.

RESULTS

Although a patient's history, the pain distribution pattern, and clinical examination may yield a presumptive diagnosis of lumbosacral radicular pain, additional clinical tests may be required. Medical imaging studies can demonstrate or exclude specific underlying pathologies and identify nerve root irritation, while selective diagnostic nerve root blocks can be used to confirm the affected level(s). In subacute lumbosacral radicular pain, transforaminal corticosteroid administration provides short-term pain relief and improves mobility. In chronic lumbosacral radicular pain, pulsed radiofrequency (PRF) treatment adjacent to the spinal ganglion (DRG) can provide pain relief for a longer period in well-selected patients. In cases of refractory pain, epidural adhesiolysis and spinal cord stimulation can be considered in experienced centers.

CONCLUSIONS

The diagnosis of lumbosacral radicular pain is based on a combination of history, clinical examination, and additional investigations. Epidural steroids can be considered for subacute lumbosacral radicular pain. In chronic lumbosacral radicular pain, PRF adjacent to the DRG is recommended. SCS and epidural adhesiolysis can be considered for cases of refractory pain in specialized centers.

Diagnostic clinical prediction rules for categorising low back pain: A systematic review

BACKGROUND

Low back pain (LBP) is a common complex condition, where specific diagnoses are hard to identify. Diagnostic clinical prediction rules (CPRs) are known to improve clinical decision-making. A review of LBP diagnostic-CPRs by Haskins et al. (2015) identified six diagnostic-CPRs in derivation phases of development, with one tool ready for implementation. Recent progress on these tools is unknown. Therefore, this review aimed to investigate developments in LBP diagnostic-CPRs and evaluate their readiness for implementation.

METHODS

A systematic review was performed on five databases (Medline, Amed, Cochrane Library, PsycInfo, and CINAHL) combined with hand-searching and citation-tracking to identify eligible studies. Study and tool quality were appraised for risk of bias (Quality Assessment of Diagnostic Accuracy Studies-2), methodological quality (checklist using accepted CPR methodological standards), and CPR tool appraisal (GRade and ASsess Predictive).

RESULTS

Of 5021 studies screened, 11 diagnostic-CPRs were identified. Of the six previously known, three have been externally validated but not yet undergone impact analysis. Five new tools have been identified since Haskin et al. (2015); all are still in derivation stages. The most validated diagnostic-CPRs include the Lumbar-Spinal-Stenosis-Self-Administered-Self-Reported-History-Questionnaire and Diagnosis-Support-Tool-to-Identify-Lumbar-Spinal-Stenosis, and the StEP-tool which differentiates radicular from axial-LBP.

CONCLUSIONS

This updated review of LBP diagnostic CPRs found five new tools, all in the early stages of development. Three previously known tools have now been externally validated but should be used with caution until impact evaluation studies are undertaken. Future funding should focus on externally validating and assessing the impact of existing CPRs on clinical decision-making.

Comparison of intermittent theta burst stimulation and high-frequency repetitive transcranial magnetic stimulation on spinal cord injury-related neuropathic pain: A sham-controlled study

OBJECTIVE

To compare the effects of intermittent theta burst stimulation (iTBS) and high-frequency repetitive transcranial magnetic stimulation (rTMS) on spinal cord injury-related neuropathic pain with sham controls, using neuropathic pain-specific evaluation tools.

DESIGN

A randomized, double-blind, sham-controlled trial.

SETTING

Rehabilitation medicine department of a university hospital.

PARTICIPANTS

Thirty-three patients with spinal cord injury-related neuropathic pain.

INTERVENTIONS

Patients were randomly allocated to one of three groups (real iTBS, real rTMS, and sham rTMS). Each patient underwent five sessions of assigned stimulation.

OUTCOME MEASURES

Before and after completion of the five sessions, patients were evaluated using the self-completed Leeds Assessment of Neuropathic Symptoms and Signs, Numeric Rating Scale, Neuropathic Pain Symptom Inventory, and Neuropathic Pain Scale.

RESULTS

Real iTBS and real rTMS reduced pain levels after stimulation according to all the evaluation tools, and the changes were significant when compared to the values of the sham rTMS group. No significant differences were found between the real iTBS and real rTMS groups.

CONCLUSION

Both iTBS and rTMS were effective in reducing spinal cord injury-related neuropathic pain. When safety, convenience, and compliance are considered, iTBS would have an advantage over rTMS in clinical situations with spinal cord injury-related neuropathic pain.Trial Registration: This trial was registered with the Clinical Research Information Service (registration no. KCT0004976).

Clinical characteristics of ankylosing spondylitis patients depending on neuropathic pain

Introduction

Neuropathic pain (NP) in ankylosing spondylitis (AS) is an important factor that complicates patients' everyday activities and leads to a decrease of life quality. Detection and diagnosis of NP can be facilitated by the use of screening instruments, and the comparative assessment of the sensitivity of different scales is important for improving the diagnosis and personalizing the treatment of AS.The aim of the study was to analyze prevalence of NP in patients with AS and clinical features of AS patients depending on the presence of NP.

Material and methods

We examined 94 patients with NP and 48 patients without pain in AS using the following questionnaires: LANSS, DN4, StEP, BASFI, BASMI, BASDAI, HAQ, ASAS HI/EF and BAS-G.

Results

The prevalence of NP according to LANSS was 51.7% in women and 32.7% in men (p = 0.048); according to DN4 - 58.6% and 32.7%, respectively (p = 0.010). Disease activity and functional disability of the patients were higher in the group of patients with NP than in the group of patients without NP according to the BASDAI, BASFI, BASMI, HAQ, ASAS HI/EF and BAS-G. Significance of differences between groups was at the level of p < 0.01.

Conclusions

The prevalence of NP in AS is alarmingly high. Even with low scores on screening scales, patients showed signs of NP, which may indicate higher prevalence of NP. Neuropathic pain is more associated with the activity of the disease, greater loss of functional capacity and a decrease in indicators of the general state of health, which allows it to be considered as an aggravating factor regarding these manifestations.

Neuropathic pain questionnaires for back pain, what do we know?

INTRODUCTION

Low back pain is a global public health concern, with an estimated lifetime prevalence of 84%. Axial low back pain refers to pain confined to an area in the low back and is different to radicular pain which radiates to extremities. Axial low back pain has traditionally been considered as nociceptive. However, research suggests it may have neuropathic components. Neuropathic axial low back pain is an unresolved, hotly contested topic due to controversies surrounding its aetiology, diagnosis, clinical course, prognosis and treatment options.

PURPOSE

The reference standard for diagnosing neuropathic pain is by medical history and clinical assessment (i.e., sensory testing), with optional neuropathic screening tools and selective, further diagnostic tests when clinically needed. Neuropathic screening tools are not always specific for neuropathic radiating low back pain, let alone neuropathic axial low back pain. Additionally, not all have been validated for the English language (e.g., PainDETECT). Research also suggests the percentage of patients identified as having neuropathic radiating low back pain may be dependent on the combination of reference standards used.

IMPLICATIONS

There is a need for research that works towards improving understanding of neuropathic axial low back pain and developing a standardised, validated and reliable system for assessing and identifying this condition. This body of research will promote earlier stratification and more rapid referral for appropriate treatment, and improve awareness, assessment and visibility of this condition amongst healthcare practitioners and in healthcare settings. This will lead to transformations in Pathways and health guidelines, ultimately improving patient outcomes.

Can radiological findings detect neuropathic pain in patients with osteoarthritis of the knee undergoing surgery?

OBJECTIVES

The mechanism underlying neuropathic pain (NP) in osteoarthritis (OA) of the knee is not completely understood. This study aimed to investigate whether possible NP in patients with knee OA undergoing knee surgery is associated with specific radiological findings.

METHODS

This study included 197 patients who underwent knee surgery for symptomatic knee OA. Clinical evaluation was performed using the Central Sensitization Inventory (CSI), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and PainDETECT questionnaire. Radiological evaluation was performed using the hip-knee-ankle (HKA) angle, posterior tibial slope (PTS), varus and valgus laxities, and magnetic resonance imaging OA Knee Score (MOAKS). Radiological findings were compared between patients with possible and unlikely NP. Logistic regression analysis was performed to identify the predictive factors for NP.

RESULTS

There were 163 and 34 patients with unlikely NP and with possible NP, respectively. The percentage of patients with CSI score ≥ 40 was significantly higher in the possible NP group than in the unlikely NP group (17.6% vs. 6.1%). Patients with possible NP had worse WOMAC scores than patients with unlikely NP. There were no significant positive associations between the possible NP and radiological findings in knee OA. Regression analysis showed no predictive factors for possible NP.

CONCLUSIONS

Possible NP is not associated with specific radiological findings in knee OA. Patients with possible NP may mediate CS and experience more severe symptoms, including decreased knee function and lower quality of life, than patients with unlikely NP.

Symptom descriptors and patterns in lumbar radicular pain caused by disc herniation: a 1-year longitudinal cohort study

OBJECTIVE

The objective of the present study was to explore the diversity, quality, severity and distribution of symptoms in patients with radicular pain and a lumbar disc herniation.

DESIGN

Longitudinal cohort study.

SETTING

Hospital-based back clinic.

PARTICIPANTS

Ninety patients referred to secondary healthcare with (a) low back-related leg pain, (b) age between 18 and 65 years and (c) MRI confirmed lumbar disc herniation at a relevant side and level.

OUTCOME MEASURES

Neuropathic pain symptoms were assessed using the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2) and the painDETECT Questionnaire. In a subsample classified with neuropathic pain, in-depth interviews were performed, and symptomatic areas were drawn on standardised body charts.

RESULTS

At baseline, the most frequently used painDETECT symptom descriptor was numbness sensation, reported by 94%, followed by sudden pain attacks and tingling or prickling. The mean (SD) SF-MPQ-2 score (0-10) for aching pain was 5.9 (2.8); numbness 4.3 (3.3); tingling 4.0 (3.4); burning 2.6 (3.1); pain caused by light touch 1.5 (2.6). Leg pain was rated as extremely bothersome by 73%, numbness and tingling by 38%, weakness by 24% and back pain by 17%. In the subsample (n=52), deep-lying pain and non-painful abnormal sensations were frequent, at 71% and 85%. Drawings demonstrated substantial overlap between symptoms from compromised L5 and the S1 nerve roots. Painful and non-painful symptoms improved at approximately the same rate. At the 1-year follow-up, 45% (14/31) of patients who had received disc surgery, and 34% (18/53) of those who had received conservative treatment reported no bothersome back pain, leg pain, numbness/tingling or weakness.

CONCLUSION

Patients reported several highly bothersome symptoms, but not all are described as painful. The overall symptom profile of lumbar disc-related radicular pain differs from other neuropathic pain conditions with limited allodynia and thermal hyperalgesia. Symptomatic areas for the L5 and S1 nerve roots have a large overlap.

Fatty acid amide hydrolase activity in the dorsal periaqueductal gray attenuates neuropathic pain and associated dysautonomia

The complexity of neuropathic pain and its associated comorbidities, including dysautonomia, make it difficult to treat. Overlap of anatomical regions and pharmacology of sympathosensory systems in the central nervous system (CNS) provide targets for novel treatment strategies. The dorsal periaqueductal gray (dPAG) is an integral component of both the descending pain modulation system and the acute stress response and is critically involved in both analgesia and the regulation of sympathetic activity. Local manipulation of the endocannabinoid signaling system holds great promise to provide analgesia without excessive adverse effects and also influence autonomic output. Inhibition of fatty acid amide hydrolase (FAAH) increases brain concentrations of the endocannabinoid N-arachidonoylethanolamine (AEA) and reduces pain-related behaviors in neuropathic pain models. Neuropathic hyperalgesia and reduced sympathetic tone are associated with increased FAAH activity in the dPAG, which suggests the hypothesis that inhibition of FAAH in the dPAG will normalize pain sensation and autonomic function in neuropathic pain. To test this hypothesis, the effects of systemic or intra-dPAG FAAH inhibition on hyperalgesia and dysautonomia developed after spared nerve injury (SNI) were assessed in male and female rats. Administration of the FAAH inhibitor PF-3845 into the dPAG reduces hyperalgesia behavior and the decrease in sympathetic tone induced by SNI. Prior administration of the CB1 receptor antagonist AM281, attenuated the antihyperalgesic and sympathetic effects of FAAH inhibition. No sex differences were identified. These data support an integrative role for AEA/CB1 receptor signaling in the dPAG contributing to the regulation of both hyperalgesia behavior and altered sympathetic tone in neuropathic pain.

The history of pain measurement in humans and animals

Pain needs to be measured in order to be studied and managed. Pain measurement strategies in both humans and non-human animals have varied widely over the years and continue to evolve. This review describes the historical development of human and animal algesiometry.

A Review of the Clinical and Therapeutic Implications of Neuropathic Pain

Understanding neuropathic pain presents several challenges, given the various mechanisms underlying its pathophysiological classification and the lack of suitable tools to assess its diagnosis. Furthermore, the response of this pathology to available drugs is still often unpredictable, leaving the treatment of neuropathic pain still questionable. In addition, the rise of personalized treatments further extends the ramified classification of neuropathic pain. While a few authors have focused on neuropathic pain clustering, by analyzing, for example, the presence of specific TRP channels, others have evaluated the presence of alterations in microRNAs to find tailored therapies. Thus, this review aims to synthesize the available evidence on the topic from a clinical perspective and provide a list of current demonstrations on the treatment of this disease.

Validation of Complete Hindi Version of Douleur Neuropathique 4 Questionnaire for Assessment of Neuropathic Pain

Objectives:

The Douleur Neuropathique 4 (DN4) questionnaire is a widely used tool for the diagnosis of neuropathic pain (NP). The aim was to validate the Complete Hindi version of DN4 (CH-DN4) questionnaire.

Materials and Methods:

A systematic translation process was used to translate the original English DN4 into Hindi. The Hindi version was validated among patients appearing in the pain clinic of a tertiary hospital in the capital of Delhi by two different raters. We assessed the internal consistency, test–retest reliability, and inter-rater agreement, validity, sensitivity, specificity, positive and negative predictive values, and area under the curve (AUC).

Results:

A total of 285 participants, out of which 153 had NP and 132 had non NP (NNP) were included in the study. The results showed our CH-DN4 to have good diagnostic accuracy, a score of ≥ 3.5 was found to be the best cut–off for the diagnosis of NP, with a sensitivity of 0.78, specificity of 0.76, a positive predictive value of 78.5%, and a negative predictive value of 74.5%. Cronbach’s α was 0.82 (95% confidence interval: 0.80–0.84), and interclass correlation coefficients was 0.95. The AUC was >0.8 indicating excellent discrimination between NP and NNP.

Conclusion:

The CH-DN4 questionnaire has been found to be a reliable and valid screening tool with an excellent power to discriminate between NP and NNP.

Heterogeneity in patterns of pain development after nerve injury in rats and the influence of sex

The genesis of neuropathic pain is complex, as sensory abnormalities may differ between patients with different or similar etiologies, suggesting mechanistic heterogeneity, a concept that is largely unexplored. Yet, data are usually grouped for analysis based on the assumption that they share the same underlying pathogenesis. Sex is a factor that may contribute to differences in pain responses. Neuropathic pain is more prevalent in female patients, but pre-clinical studies that can examine pain development in a controlled environment have typically failed to include female subjects. This study explored patterns of development of hyperalgesia-like behavior (HLB) induced by noxious mechanical stimulation in a neuropathic pain model (spared nerve injury, SNI) in both male and female rats, and autonomic dysfunction that is associated with chronic pain. HLB was analyzed across time, using both discrete mixture modeling and rules-based longitudinal clustering. Both methods identified similar groupings of hyperalgesia trajectories after SNI that were not evident when data were combined into groups by sex only. Within the same hyperalgesia development group, mixed models showed that development of HLB in females was delayed relative to males and reached a magnitude similar to or higher than males. The data also indicate that sympathetic tone (as indicated by heart rate variability) drops below pre-SNI level before or at the onset of development of HLB. This study classifies heterogeneity in individual development of HLB and identifies sexual dimorphism in the time course of development of neuropathic pain after nerve injury. Future studies addressing mechanisms underlying these differences could facilitate appropriate pain treatments.

Do chronic low back pain subgroups derived from dynamic quantitative sensory testing exhibit differing multidimensional profiles?

OBJECTIVES

The relationship of pain sensitivity with pain and disability in low back pain (LBP) is complicated. It has been suggested increased understanding of dynamic quantitative sensory testing (QST) might be useful in increasing understanding of these relationships. This study aimed to create subgroups based on participant responses to dynamic QST, profile these subgroups based on multidimensional variables (including clinical measures of pain and disability, psychological and lifestyle variables and static QST), and investigate the association of subgroup membership with levels of pain intensity, LBP-related disability and disability risk at 12-month follow up.

METHODS

Participants (n=273) with dominant axial chronic non-specific LBP with duration of pain >3 months were included in this study. At baseline, eligible participants completed a self-report questionnaire to collect demographic, clinical, psychological and lifestyle data prior to dynamic and static QST. Dynamic QST measures were conditioned pain modulation (CPM) and temporal summation (TS). At 12-months follow up, clinical data were collected, including pain intensity and LBP-related disability. Sub-groups were formed by cross-tabulation. Analysis was undertaken to profile dynamic QST subgroup on demographic, clinical, psychological, lifestyle and static QST measures. Associations between dynamic QST subgroups and follow-up clinical variables were examined.

RESULTS

Based on dynamic QST, participants were allocated into four subgroups; normal CPM and normal TS (n=34, 12.5%); normal CPM and facilitated TS (n=6, 2.2%); impaired CPM and normal TS (n=186, 68.1%); impaired CPM and facilitated TS (n=47, 17.2%). At baseline no differences were demonstrated between subgroups across most clinical variables, or any psychological or lifestyle measures. The two subgroups with impaired CPM were more likely to have a higher number of painful body areas. Cold pain sensitivity was heightened in both the subgroups with facilitated TS. Subgroups did not differ across pain intensity, LBP-related disability and disability risk stratification at follow-up.

CONCLUSIONS

The profiles of people with axial LBP did not vary significantly across dynamic QST subgroups, save for those in groups with impaired CPM being more likely to have more widespread symptoms and those with facilitated TS having heightened cold pain sensitivity. Further, subgroup membership was not related to future pain and disability. The role of dynamic QST profiles in LBP remains unclear. Further work is required to understand the role of pain sensitivity in LBP. The utility of dynamic QST subgrouping might not be in determining of future disability. Future research might focus on treatment modifying effects of dynamic QST subgroups.

Pathophysiology of neuropathic pain

Background: Neuropathic pain is notoriously difficult to manage properly, not only because of its varied nature and the absence of objective diagnostic tools but also because of extensive reciprocal neuronal interactive pathogenic mechanism from the molecular level to patient’s own psychophysical characteristics. This paper briefly reviews the pathophysiology of neuropathic pain to the level of clinicians’ interest and its potential in clinical practiceCurrent Concepts: Recent research progress now allows us to obtain a bird view of neuropathic pain pathophysiology: peripheral and central sensitization. For peripheral sensitization, a local inflammatory milieu of the injured nerve primarily drives sequential phenotypic changes, which are critical and shared by both neuropathic and inflammatory pain. Central sensitization is led either by the hyperexcitability of the second-order afferent neuron itself or loss of physiological inhibitory control of the transmission of pain signal to the higher nervous system. Peripheral and central sensitization work synergistically but can also introduce neuropathic pain alone.Discussion and Conclusion: The cause of neuropathic pain is diverse, and understanding of its pathophysiology is still insufficient to realize a mechanism-based approach to clinical phenotypes or therapeutic applications. In dealing with chronic neuropathic pain, it is highly desirable to assess key aspects of a patient’s pain based on a plausible mechanism and select the best management method accordingly.

Evaluation and diagnosis of neuropathic pain

Background: Thorough evaluation and an accurate diagnosis of neuropathic pain are essential for effective treatment. The therapeutic approach and choice of medication for neuropathic pain are different from those for other kinds of nociceptive pain. Therefore, this study aimed to present the current evaluation and diagnostic methods for neuropathic pain.Current Concepts: Grading of the certainty of the presence of neuropathic pain according to the results of clinical history, neurological examination, and confirmatory tests improves the diagnosis of neuropathic pain. The Leeds Assessment of Neuropathic Symptoms and Signs, Neuropathic Pain Questionnaire, Douleur Neuropathique en 4 Questions, and PainDETECT are mainly used for neuropathic pain screening. During physical examination, sensory nerve function tests are more critical than other nervous system examination items, including the test of the sense of touch with a cotton swab and the sense of vibration with a tuning fork. In addition, pain sensation using pins and temperature sensation using cold metal are tested to check for nociceptive pathway abnormalities. Diagnostic tests include imaging tests, nerve conduction tests, and other neurophysiological tests, such as quantitative sensory function tests, autonomic nerve function tests, and blood tests.Discussion and Conclusion: To diagnose neuropathic pain, physicians should first determine whether patient symptoms match the characteristics of neuropathic pain. If there is a possibility of neuropathic pain, physicians should perform a neurological screening examination and a proper diagnostic test to identify the cause of pain.

Cage-lid hanging behavior as a translationally relevant measure of pain in mice

ABSTRACT

The development of new analgesic drugs has been hampered by the inability to translate preclinical findings to humans. This failure is due in part to the weak connection between commonly used pain outcome measures in rodents and the clinical symptoms of chronic pain. Most rodent studies rely on the use of experimenter-evoked measures of pain and assess behavior under ethologically unnatural conditions, which limits the translational potential of preclinical research. Here, we addressed this problem by conducting an unbiased, prospective study of behavioral changes in mice within a natural homecage environment using conventional preclinical pain assays. Unexpectedly, we observed that cage-lid hanging, a species-specific elective behavior, was the only homecage behavior reliably impacted by pain assays. Noxious stimuli reduced hanging behavior in an intensity-dependent manner, and the reduction in hanging could be restored by analgesics. Finally, we developed an automated approach to assess hanging behavior. Collectively, our results indicate that the depression of hanging behavior is a novel, ethologically valid, and translationally relevant pain outcome measure in mice that could facilitate the study of pain and analgesic development.

Sensory Perception in Lumbosacral Radiculopathy with Radicular Pain: Feasibility Study of Multimodal Bedside-Suitable Somatosensory Testing

Background

Somatosensory testing could be useful in stratifying pain patients and improving pain treatment guidelines. Bedside-suitable techniques are searched for application in daily clinical practice. This study aimed to characterize chronic unilateral lumbosacral radiculopathy (LSR) patients with radicular pain using multimodal bedside-suitable somatosensory testing.

Materials and methods

We evaluated 50 chronic unilateral LSR patients with radicular pain (LSR group) and 24 controls (Control group). Sensory testing was performed using a battery of bedside sensory tests (10g monofilament, 200–400 mN brush, Lindblom rollers with controlled 25°C and 40°C temperature, and 40g neurological pin and investigator’s finger pressure). Participants had to rate their sensory perceptions on both legs at multiple test points within L3 to S2 dermatomes. Characteristics of the testing process and sensory disturbances were analyzed.

Results

LSR group showed sensory disturbances in 82% of patients. The Control group showed no sensory disturbances. Sensory testing took longer (p < 0.001) in the LSR group (29.3 ± 6.5 minutes per patient) than in the Control group (20.5 ± 5.2). Nine sensory phenotypes were detected in the LSR group according to individual sensory disturbances within 5 superficial tests.

Conclusions

The applied multimodal bedside-suitable somatosensory testing battery is suitable for sensory evaluation and characterization of LSR patients. Grouping of allied sensory phenotypes revealed some tendencies in pain intensity characteristics.

Pinprick and Light Touch Are Adequate to Establish Sensory Dysfunction in Patients with Lumbar Radicular Pain and Disc Herniation

BACKGROUND

The frequency with which sensory disturbances occur in patients with radicular leg pain and disc herniation is not well known, and the efficacy of tests to identify such changes are not firmly established. The presence of sensory disturbances is a key sign of nerve root involvement and may contribute to the diagnosis of a lumbar disc herniation, identify patients for referral to spinal imaging and surgery, and improve disease classification.

QUESTIONS/PURPOSES

In this study, we sought: (1) to determine the frequency with which abnormal sensory findings occur in patients with lumbar disc herniation-related radicular pain, using a standard neurological sensory examination; (2) to determine what particular standard sensory test or combination of tests is most effective in establishing sensory dysfunction; and (3) to determine whether a more detailed in-depth sensory examination results in more patients being identified as having abnormal sensory findings.

METHODS

Between October 2013 and April 2016, 115 patients aged 18 to 65 years referred to secondary health care with radicular leg pain and disc herniation were considered potentially eligible for inclusion in the study. Based on these inclusion criteria, 79% (91) were found eligible. Ten percent (11) were excluded because of other illness that interfered with the study purpose, 3% (3) because of cauda equina syndrome, 2% (2) because of spinal stenosis, 2% (2) because of prior surgery at the same disc level, and 2% (2) because of poor Norwegian language skills. Three percent (4) of the patients did not want to participate in the study. Of the 91 eligible patients, 56% (51) consented to undergo a comprehensive clinical examination and were used for analysis here. The sample for the purposes of the present study was predetermined at 50. These patients were first examined by a standard procedure, including sensory assessment of light touch, pinprick, vibration, and warmth and cold over the back and legs. Second, an in-depth semiquantitative sensory testing procedure was performed in the main pain area to assess sensory dysfunction and improve the detection of potential positive sensory signs, or sensory gain of function more precisely. Sensory loss was defined as sensations experienced as distinctly reduced in the painful side compared with the contralateral reference side. In contrast, sensory gain was defined as sensations experienced as abnormally strong, unpleasant, or painful and distinctly stronger than the contralateral side. Ambiguous test results were coded as a normal response to avoid inflating the findings. The proportions of abnormal findings were calculated for each sensory modality and for all combinations of the standard examination tests.

RESULTS

The standard examination identified at least one abnormal finding in 88% (45 of 51) of patients. Sensory loss was present in 80% (41), while sensory gain was present in 35% (18). The combination of pinprick and light touch identified all patients who were classified as having abnormal findings by the full standard examination. The semiquantitative procedure identified an additional three patients with an abnormal finding.

CONCLUSION

We suggest that the combination of pinprick and light touch assessment is an adequate minimal approach for diagnostic and classification purposes in patients with lumbar radicular pain.

LEVEL OF EVIDENCE

Level I, diagnostic study.

Methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system: a systematic review

ABSTRACT

Mechanism-based classification of pain has been advocated widely to aid tailoring of interventions for individuals experiencing persistent musculoskeletal pain. Three pain mechanism categories (PMCs) are defined by the International Association for the Study of Pain: nociceptive, neuropathic, and nociplastic pain. Discrimination between them remains challenging. This study aimed to build on a framework developed to converge the diverse literature of PMCs to systematically review methods purported to discriminate between them; synthesise and thematically analyse these methods to identify the convergence and divergence of opinion; and report validation, psychometric properties, and strengths/weaknesses of these methods. The search strategy identified articles discussing methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system. Studies that assessed the validity of methods to discriminate between categories were assessed for quality. Extraction and thematic analysis were undertaken on 184 articles. Data synthesis identified 200 methods in 5 themes: clinical examination, quantitative sensory testing, imaging, diagnostic and laboratory testing, and pain-type questionnaires. Few methods have been validated for discrimination between PMCs. There was general convergence but some disagreement regarding findings that discriminate between PMCs. A combination of features and methods, rather than a single method, was generally recommended to discriminate between PMCs. Two major limitations were identified: an overlap of findings of methods between categories due to mixed presentations and many methods considered discrimination between 2 PMCs but not others. The results of this review provide a foundation to refine methods to differentiate mechanisms for musculoskeletal pain.

Masterclass: A pragmatic approach to pain sensitivity in people with musculoskeletal disorders and implications for clinical management for musculoskeletal clinicians

INTRODUCTION

Research on musculoskeletal disorders indicates that pain sensitivity can be an important consideration for musculoskeletal clinicians in the holistic view of a patient presentation. However, diversity in research findings in this field can make this a difficult concept for clinicians to navigate. Limited integration of the concept of pain sensitivity into clinical practice for musculoskeletal clinicians has been noted.

PURPOSE

The purpose of this masterclass is to provide a framework for the consideration of pain sensitivity as a contributing factor in the presentation of people with musculoskeletal pain. It provides pragmatic synthesis of the literature related to pain sensitivity through a lens of how this information can inform clinical practice for musculoskeletal clinicians. Guidance is provided in a 'how to' format for integration of this knowledge into the clinical encounter to facilitate personalised care.

IMPLICATIONS

The relationship of pain sensitivity with pain and disability is not clear or linear. The real importance of pain sensitivity in a clinical presentation may be: (1) the potential for pain sensitivity to modify the effect of common treatments utilised by musculoskeletal clinicians, or (2) the effect of pain sensitivity on the prognosis/course of a disorder. Screening tools and subjective features have been highlighted to indicate when physical assessment of pain sensitivity should be prioritised in the physical examination. A pragmatic blueprint for specific assessment related to pain sensitivity has been outlined. A framework for integrating assessment findings into clinical reasoning to formulate management plans for the pain sensitive patient is provided.

Qualitative Sensory Testing in Outcome Prediction of Transforaminal Epidural Steroid Injection for Chronic Painful Unilateral Lumbosacral Radiculopathy: Prospective Observational Study

BACKGROUND

Transforaminal epidural steroid injection (TFESI) is widely practiced for the treatment of radicular pain. As its effectiveness is still subject to debate, a better patient selection for TFESI is necessary. We aimed to evaluate the potential of bedside-suitable qualitative sensory testing (QualST) to determine the early effectiveness of TFESI for the treatment of chronic lumbosacral radiculopathy (LSR)-related pain.

METHODS

Thirty-six patients with chronic painful unilateral LSR were evaluated in a prospective observational study using five standardized sensory tests (10 g monofilament, 200 to 400 mN brush, Lindblom rollers with controlled 25 and 40°C temperature, and 40 g neurological pin). Quality of sensory perceptions on the painful leg was compared to the non-painful leg and rated as normal sensitivity, hyposensitivity, or hypersensitivity. Pain and related characteristics were evaluated before TFESI, 1 week after and 4 weeks after intervention.

RESULTS

Seven sensory phenotypes were distinguished according to individual sets of sensory disturbances acquired with five sensory tests. Patients were grouped into four groups of allied phenotypes (normal sensitivity, hyposensitivity to 1 to 3 modalities, hyposensitivity to 4 to 5 modalities, and hypersensitivity). The whole study group showed significant improvement in most parameters of outcome measurements. Statistical analysis revealed some significant differences between sensory groups in patient-reported treatment effect scales after 4 weeks. We also detected significant differences between sensory groups in repeated measures after 1 and 4 weeks in some pain intensity characteristics and patient-reported treatment effect scales.

CONCLUSION

QualST might be clinically applicable for detecting patient subgroups that could differ in the early treatment results of radicular pain by TFESI.

Patient phenotyping in clinical trials of chronic pain treatments: IMMPACT recommendations

There is tremendous interpatient variability in the response to analgesic therapy (even for efficacious treatments), which can be the source of great frustration in clinical practice. This has led to calls for “precision medicine” or personalized pain therapeutics (ie, empirically based algorithms that determine the optimal treatments, or treatment combinations, for individual patients) that would presumably improve both the clinical care of patients with pain and the success rates for putative analgesic drugs in phase 2 and 3 clinical trials. However, before implementing this approach, the characteristics of individual patients or subgroups of patients that increase or decrease the response to a specific treatment need to be identified. The challenge is to identify the measurable phenotypic characteristics of patients that are most predictive of individual variation in analgesic treatment outcomes, and the measurement tools that are best suited to evaluate these characteristics. In this article, we present evidence on the most promising of these phenotypic characteristics for use in future research, including psychosocial factors, symptom characteristics, sleep patterns, responses to noxious stimulation, endogenous pain-modulatory processes, and response to pharmacologic challenge. We provide evidence-based recommendations for core phenotyping domains and recommend measures of each domain.

Sensory descriptors which identify neuropathic pain mechanisms in low back pain: a systematic review

OBJECTIVE

Descriptors provided by patients with neuropathic low back pain (NLBP) with or without spinally referred leg pain are frequently used by clinicians to help to identify the predominant pain mechanisms. Indeed, many neuropathic screening tools are primarily based on subjective descriptors to determine the presence of neuropathic pain. There is a need to systematically review and analyse the existing evidence to determine the validity of such descriptors in this cohort.

METHODS

Ten databases were systematically searched. The review adhered to PRISMA and CRD guidelines and included a risk of bias assessment using QUADAS-2. Studies were included if they contained symptom descriptors from a group of NLBP patients +/- leg pain. Studies had to include a reference test to identity neuropathic pain from other pain mechanisms.

RESULTS

Eight studies of 3099 NLBP patients were included. Allodynia and numbness were found to discriminate between NLBP and nociceptive LBP in four studies. Autonomic dysfunction, (changes in the colour or appearance of the skin), was also found to discriminate between the groups in two studies. Dysesthesia identified NLBP in 5/7 respectively. Results from studies were equivocal regarding pain described as hot/burning cold and paroxysmal pain in people with NLBP.

CONCLUSION

Subjectively reported allodynia and numbness would suggest a neuropathic pain mechanism in LBP. Dysesthesia would raise the suspicion of NLBP. More research is needed to determine if descriptors suggesting autonomic dysfunction can identify NLBP. There is poor consensus on whether other descriptors can identify NLBP.

Clinical indicators to identify neuropathic pain in low back related leg pain: a modified Delphi study

BACKGROUND

Neuropathic pain (NP) is common in patients presenting with low back related leg pain. Accurate diagnosis of NP is fundamental to ensure appropriate intervention. In the absence of a clear gold standard, expert opinion provides a useful methodology to progress research and clinical practice. The aim of this study was to achieve expert consensus on a list of clinical indicators to identify NP in low back related leg pain.

METHODS

A modified Delphi method consisting of three rounds was designed in accordance with the Conducting and Reporting Delphi Studies recommendations. Recruitment involved contacting experts directly and through expressions of interest on social media. Experts were identified using pre-defined eligibility criteria. Priori consensus criteria were defined for each round through descriptive statistics. Following completion of round 3 a list of clinical indicators that achieved consensus were generated.

RESULTS

Thirty-eight participants were recruited across 11 countries. Thirty-five participants completed round 1 (92.1%), 32 (84.2%) round 2 and 30 (78.9%) round 3. Round 1 identified consensus (Kendall's W coefficient of concordance 0.456; p < 0.001) for 10 clinical indicators out of the original 14, and 9 additional indicators were added to round 2 following content analysis of qualitative data. Round 2 identified consensus (Kendall's W coefficient of concordance 0.749; p < 0.001) for 10 clinical indicators out of 19, and 1 additional indicator was added to round 3. Round 3 identified consensus for 8 indicators (Kendall's W coefficient of concordance 0.648; p < 0.001). Following completion of the third round, an expert derived consensus list of 8 items was generated. Two indicators; pain variously described a burning, electric shock like and/or shooting into leg and pain in association with other neurological symptoms (e.g. pins and needles, numbness, weakness), were found to have complete agreement amongst expert participants.

CONCLUSIONS

Good agreement was found for the consensus derived list of 8 clinical indicators to identify NP in low back related leg pain. This list of indicators provide some indication of the criteria upon which clinicians can identify a NP component to low back related leg pain; further research is needed for stronger recommendations to be made.

Diagnostic utility of patient history, clinical examination and screening tool data to identify neuropathic pain in low back related leg pain: a systematic review and narrative synthesis

BACKGROUND

Low back-related leg pain (LBLP) is a challenge for healthcare providers to manage. Neuropathic pain (NP) is highly prevalent in presentations of LBLP and an accurate diagnosis of NP in LBLP is essential to ensure appropriate intervention. In the absence of a gold standard, the objective of this systematic review was to evaluate the diagnostic utility of patient history, clinical examination and screening tool data for identifying NP in LBLP.

METHODS

This systematic review is reported in line with PRISMA and followed a pre-defined and published protocol. CINAHL, EMBASE, MEDLINE, Web of Science, Cochrane Library, AMED, Pedro and PubMed databases, key journals and the grey literature were searched from inception to 31 July 2019. Eligible studies included any study design reporting primary diagnostic data on the diagnostic utility of patient history, clinical examination or screening tool data to identify NP in LBLP, in an adult population. Two independent reviewers searched information sources, assessed risk of bias (QUADAS-2) and used GRADE to assess overall quality of evidence.

RESULTS

From 762 studies, 11 studies were included. Nine studies out of the 11 were at risk of bias. Moderate level evidence supports a cluster of eight signs (age, duration of disease, paroxysmal pain, pain worse in leg than back, typical dermatomal distribution, worse on coughing/sneezing/straining, finger to floor distance and paresis) for diagnosing lumbosacral nerve root compression, demonstrating moderate/high sensitivity (72%) and specificity (80%) values. Moderate level evidence supports the use of the StEP tool for diagnosing lumbar radicular pain, demonstrating high sensitivity (92%) and specificity (97%) values.

CONCLUSIONS

Overall low-moderate level evidence supports the diagnostic utility of patient history, clinical examination and screening tool data to identify NP in LBLP. The weak evidence base is largely due to methodological flaws and indirectness regarding applicability of the included studies. The most promising diagnostic tools include a cluster of 8 patient history/clinical examination signs and the StEP tool. Low risk of bias and high level of evidence diagnostic utility studies are needed, in order for stronger recommendations to be made.

The development and use of facial grimace scales for pain measurement in animals

The measurement of pain in animals is surprisingly complex, and remains a critical issue in veterinary care and biomedical research. Based on the known utility of pain measurement via facial expression in verbal and especially non-verbal human populations, "grimace scales" were first developed a decade ago for use in rodents and now exist for 10 different mammalian species. This review details the background context, historical development, features (including duration), psychometric properties, modulatory factors, and impact of animal grimace scales for pain.

Imagined Examples of Painful Experiences Provided by Chronic Low Back Pain Patients and Attributed a Pain Numerical Rating Score

Objective

The pain numerical rating scale (NRS) is widely used in pain research and clinical settings to represent pain intensity. For an individual with chronic pain, NRS reporting requires representation of a complex subjective state as a numeral. To evaluate the process of NRS reporting, this study examined the relationship between reported pain NRS levels and imagined painful events reported by study subjects.

Design

A total of 149 subjects with chronic low back pain characterized by the NIH Research Task Force Recommended Minimal Dataset reported current pain NRS and provided imagined examples of painful experiences also attributing to these an NRS. We present a quantitative and qualitative analysis of the 797 pain examples provided by the study subjects.

Results

Study subjects tended to be able to imagine both highly painful 10/10 events and non-painful events with relative agreement across subjects. While NRS for the pain examples tended to increase with example severity, for many types of examples there was wide dispersion around the mean pain level. Examination of pain examples indicated unexpected relationships between current pain and the intensity and nature of the imagined painful events.

Conclusions

Our results indicate that the pain NRS does not provide a reliably interpretable assessment of current physical pain intensity for an individual with chronic pain at a specific moment.

Sensitivities to Thermal and Mechanical Stimuli: Adults With Sickle Cell Disease Compared to Healthy, Pain-Free African American Controls

Evidence supports^, but is inconclusive that sensitization contributes to chronic pain in some adults with sickle cell disease (SCD). We determined the prevalence of pain sensitization among adults with SCD pain compared with pain-free healthy adults. In a cross sectional, single session study of 186 African American outpatients with SCD pain (age 18-74 years, 59% female) and 124 healthy age, gender, and race matched control subjects (age 18-69 years, 49% female), we compared responses to standard thermal (Medoc TSA II) and mechanical stimuli (von Frey filaments). Although we observed no significant differences in thermal thresholds between controls and patients, patients with SCD had lower pain thresholds to mechanical stimuli and reported higher pain intensity scores to all thermal and mechanical stimuli at a non-painful body site. Compared with controls, about twice as many patients with SCD showed sensitization: 12% versus 23% at the anterior forearm site (P = .02), and 16% versus 32% across 3 tested sites (P = .004). Among patients with SCD, 18% exhibited some element of central sensitization. Findings indicate that persistent allodynia and hyperalgesia can be part of the SCD pain experience and should be considered when selecting therapies for SCD pain. PERSPECTIVE: Compared with matched healthy controls, quantitative sensory testing in adults with pain and sickle cell disease (SCD) demonstrates higher prevalence of sensitization, including central sensitization. The findings of allodynia and hyperalgesia may indicate neuropathic pain and could contribute to a paradigm shift in assessment and treatment of SCD pain.

Current Evidence for Diagnosis of Common Conditions Causing Low Back Pain: Systematic Review and Standardized Terminology Recommendations

OBJECTIVE

The purpose of this systematic review is to evaluate and summarize current evidence for diagnosis of common conditions causing low back pain and to propose standardized terminology use.

METHODS

A systematic review of the scientific literature was conducted from inception through December 2018. Electronic databases searched included PubMed, MEDLINE, CINAHL, Cochrane, and Index to Chiropractic Literature. Methodological quality was assessed with the Scottish Intercollegiate Guidelines Network checklists.

RESULTS

Of the 3995 articles screened, 36 (8 systematic reviews and 28 individual studies) met final eligibility criteria. Diagnostic criteria for identifying likely discogenic, sacroiliac joint, and zygapophyseal (facet) joint pain are supported by clinical studies using injection-confirmed tissue provocation or anesthetic procedures. Diagnostic criteria for myofascial pain, sensitization (central and peripheral), and radicular pain are supported by expert consensus-level evidence. Criteria for radiculopathy and neurogenic claudication are supported by studies using combined expert-level consensus and imaging findings.

CONCLUSION

The absence of high-quality, objective, gold-standard diagnostic methods limits the accuracy of current evidence-based criteria and results in few high-quality studies with a low risk of bias in patient selection and reference standard diagnosis. These limitations suggest practitioners should use evidence-based criteria to inform working diagnoses rather than definitive diagnoses for low back pain. To avoid the unnecessary complexity and confusion created by multiple overlapping and nonspecific terms, adopting International Association for the Study of Pain terminology and definitions is recommended.

Development of an Evidence-Based Practical Diagnostic Checklist and Corresponding Clinical Exam for Low Back Pain

OBJECTIVE

The purpose of this study was to use scientific evidence to develop a practical diagnostic checklist and corresponding clinical exam for patients presenting with low back pain (LBP).

METHODS

An iterative process was conducted to develop a diagnostic checklist and clinical exam for LBP using evidence-based diagnostic criteria. The checklist and exam were informed by a systematic review focused on summarizing current research evidence for office-based clinical evaluation of common conditions causing LBP.

RESULTS

Diagnostic categories contained within the checklist and exam include nociceptive pain, neuropathic pain, and sensitization. Nociceptive pain subcategories include discogenic, myofascial, sacroiliac, and zygapophyseal (facet) joint pain. Neuropathic pain categories include neurogenic claudication, radicular pain, radiculopathy, and peripheral entrapment (piriformis and thoracolumbar syndrome). Sensitization contains 2 subtypes, central and peripheral sensitization. The diagnostic checklist contains individual diagnostic categories containing evidence-based criteria, applicable examination procedures, and checkboxes to record clinical findings. The checklist organizes and displays evidence for or against a working diagnosis. The checklist may help to ensure needed information is obtained from a patient interview and exam in a variety of primary spine care settings (eg, medical, chiropractic).

CONCLUSION

The available evidence informs reasonable working diagnoses for many conditions causing or contributing to LBP. A practical diagnostic process including an exam and checklist is offered to guide clinical evaluation and demonstrate evidence for working diagnoses in clinical settings.

Concurrent validity of a low-cost and time-efficient clinical sensory test battery to evaluate somatosensory dysfunction

Background

This study describes a low‐cost and time‐efficient clinical sensory test (CST) battery and evaluates its concurrent validity as a screening tool to detect somatosensory dysfunction as determined using quantitative sensory testing (QST).

Method

Three patient cohorts with carpal tunnel syndrome (CTS, n = 76), non‐specific neck and arm pain (NSNAP, n = 40) and lumbar radicular pain/radiculopathy (LR, n = 26) were included. The CST consisted of 13 tests, each corresponding to a QST parameter and evaluating a broad spectrum of sensory functions using thermal (coins, ice cube, hot test tube) and mechanical (cotton wool, von Frey hairs, tuning fork, toothpicks, thumb and eraser pressure) detection and pain thresholds testing both loss and gain of function. Agreement rate, statistical significance and strength of correlation (phi coefficient) between CST and QST parameters were calculated.

Results

Several CST parameters (cold, warm and mechanical detection thresholds as well as cold and pressure pain thresholds) were significantly correlated with QST, with a majority demonstrating >60% agreement rates and moderate to relatively strong correlations. However, agreement varied among cohorts. Gain of function parameters showed stronger agreement in the CTS and LR cohorts, whereas loss of function parameters had better agreement in the NSNAP cohort. Other CST parameters (16 mN von Frey tests, vibration detection, heat and mechanical pain thresholds, wind‐up ratio) did not significantly correlate with QST.

Conclusion

Some of the tests in the CST could help detect somatosensory dysfunction as determined with QST. Parts of the CST could therefore be used as a low‐cost screening tool in a clinical setting.

Significance

Quantitative sensory testing, albeit considered the gold standard to evaluate somatosensory dysfunction, requires expensive equipment, specialized examiner training and substantial time commitment which challenges its use in a clinical setting. Our study describes a CST as a low‐cost and time‐efficient alternative. Some of the CST tools (cold, warm, mechanical detection thresholds; pressure pain thresholds) significantly correlated with the respective QST parameters, suggesting that they may be useful in a clinical setting to detect sensory dysfunction.

Development and validation of a Taiwan version of the DN4-T questionnaire

BACKGROUND

Neuropathic pain (NeP) is often under-recognized, resulting in poor pain management. Therefore, a Taiwan version of the 10-item Douleur Neuropathique 4 (DN4-T) questionnaire was developed to identify patients with NeP from a mixed population of patients with pain.

METHODS

A prospective, nonrandomized, multicenter study was conducted in the Neurology Departments of four Taiwanese medical centers, to develop and validate the DN4-T questionnaire as a diagnostic tool for identifying patients with NeP. Patients who experienced pain for >30 days were classified as having neuropathic, nociceptive, or mixed pain. Patients and physicians also completed the DN4-T questionnaire. The DN4-T scores were assessed with the optimal cut-off score calculated using a receiver operating characteristics (ROC) curve, and sensitivity and specificity assessed and reliability determined statistically using the Cronbach alpha coefficient.

RESULTS

Of the 318 patients who completed the DN4-T questionnaire, 189 patients were diagnosed with NeP, seven patients with mixed pain, and 122 patients with nociceptive pain. For statistical analysis, patients were categorized as having NeP (those with neuropathic pain and mixed pain) or non-neuropathic (nociceptive) pain (non-NeP). Using an optimum DN4-T cut-off score of ≥3 (ranging from 0 to 10, determined by a maximum c index value of 1.54), DN4-T scores provided a sensitivity of 0.77 and specificity of 0.78, for predicting NeP. The predictive power of DN4-T in diagnosing NeP was 0.83 (as determined by area under the curve of the ROC curve), and was significantly predictive of pain type (p < 0.0001) with a concordance of 0.785, a discordance of 0.129, and a Cronbach alpha coefficient of 0.7, suggesting that the DN4-T questionnaire is a useful predictive tool for diagnosing NeP.

CONCLUSION

The DN4-T questionnaire has been reliably translated into Mandarin Chinese and can be used as a diagnostic tool for NeP in conjunction with clinical evaluation.

Chronic low back pain is highly individualised: patterns of classification across three unidimensional subgrouping analyses

BACKGROUND AND AIMS

Chronic low back pain (CLBP) is a complex disorder where central and peripheral nociceptive processes are influenced by factors from multiple dimensions associated with CLBP (e.g. movement, pain sensitivity, psychological). To date, outcomes for treatments matched to unidimensional subgroups (e.g. psychologically-based) have been poor. Therefore, unidimensional subgrouping may not reflect the complexity of CLBP presentations at an individual level. The aim of this study was therefore to explore patterns of classification at an individual level across the three previously-published, data-driven, within-dimension subgrouping studies.

METHODS

Cross-sectional, multidimensional data was collected in 294 people with CLBP. Statistical derivation of subgroups within each of three clinically-important dimensions (pain sensitivity, psychological profile, pain responses following repeated spinal bending) was briefly reviewed. Patterns of classification membership were subsequently tabulated across the three dimensions.

RESULTS

Of 27 possible patterns across these dimensions, 26 were represented across the cohort.

CONCLUSIONS

This result highlights that while unidimensional subgrouping has been thought useful to guide treatment, it is unlikely to capture the full complexity of CLBP. The amount of complexity important for best patient outcomes is currently untested.

IMPLICATIONS

For clinicians this study highlights the high variability of presentations of people with CLBP at the level of the individual. For example, clinician's should not assume that those with high levels of pain sensitivity will also have high psychological distress and have pain summation following repeated spinal bending. A more flexible, multidimensional, clinically-reasoned approach to profile patient complexity may be required to inform individualised, patient-centred care. Such individualised care might improve treatment efficacy. This study also has implications for researchers; highlighting the inadequacy of unidimensional subgrouping processes and methodological difficulties in deriving subgroups across multidimensional data.

Classification and description of chronic pain among HIV positive patients in Uganda

INTRODUCTION

Chronic pain classification in HIV positive patients is essential for diagnosis and treatment. However, this is rarely done despite association with poor outcomes.

METHODS

A cross-sectional survey of 345 consented patients at a specialized HIV care center in Uganda was conducted. Chronic pain was defined as pain of more than two weeks duration. Data was collected using a socio-demographic questionnaire, the IASP classification of chronic pain; the StEP; Mini Mental Status Examination, Patient Health Questionnaire, Mini International Neuropsychiatric Interview and the World Health Organization quality of life instrument brief version. Chi-square, Fisher's exact, t-test and logistic regression analyses were carried out to determine factors associated with chronic pain.

RESULTS

Description of pain aetiology was difficult. Chronic pain was reported in 21.5% of the participants. Non-neuropathic (92.0%) was more common than neuropathic pain (8.0%). Chronic pain was found to be associated with feeling ill [OR=6.57 (3.48 - 12.39)], and worse scores in the quality of life domain for physical health [OR=0.71 (0.60 - 0.83)].

CONCLUSION

People living with HIV/AIDS commonly have chronic pain that is associated with poor quality of life. More sensitive tools are needed to accurately describe chronic pain in resource limited settings.

Analysis of Motor Control in Patients With Low Back Pain: A Key to Personalized Care?

SYNOPSIS

Motor control exercise has been shown to be effective in the management of low back pain (LBP). However, the effect sizes for motor control exercise are modest, possibly because studies have used a one-size-fits-all approach, while the literature suggests that patients may differ in presence or type of motor control issues. In this commentary, we address the question of whether consideration of such variation in motor control issues might contribute to more personalized motor control exercise for patients with LBP. Such an approach is plausible, because motor control changes may play a role in persistence of pain through effects on tissue loading that may cause nociceptive afference, particularly in the case of peripheral sensitization. Subgrouping systems used in clinical practice, which comprise motor control aspects, allow reliable classification that is, in part, aligned with findings in studies on motor control in patients with LBP. Motor control issues may have heuristic value for treatment allocation, as the different presentations observed suggest different targets for motor control exercise, but this remains to be proven. Finally, clinical assessment of patients with LBP should take into account more aspects than motor control alone, including pain mechanisms, musculoskeletal health, and psychosocial factors, and may need to be embedded in a stratification approach based on prognosis to avoid undue diagnostic procedures. J Orthop Sports Phys Ther 2019;49(6):380-388. Epub 12 Jun 2018. doi:10.2519/jospt.2019.7916.

Acute postoperative pain is an independent predictor of chronic postsurgical pain following total knee arthroplasty at 6 months: a prospective cohort study

Background

Approximately 15% of patients report persistent knee pain despite surgical success following total knee arthroplasty (TKA). The purpose of this study was to determine the association of acute-postsurgical pain (APSP) with chronic postsurgical pain (CPSP) 6 months after TKA controlling for patient, surgical and psychological confounding factors.

Methods

Adult patients with osteoarthritis undergoing primary elective tricompartmental TKA, with the operated knee the primary source of preoperative pain, were studied between March 2011 and February 2017. Patients received standard operative management and a perioperative multimodal analgesia regimen. The primary outcome was CPSP at 6 months. The primary variable of interest was the APSP (weighted mean pain score) for 72 hours postoperatively. Patient, surgical and psychological confounders were assessed using binary logistic regression.

Results

245 cases were analyzed. The incidence of CPSP was 14% (95% CI 10% to 19%). Median APSP values were 4.2 (2.2–5.0) in the CPSP group and 2.8 (1.8–3.7) without CPSP, difference 1.4 (95% CI 0.1 to 1.8, p=0.005). The unadjusted odds for CPSP with an increase of 1 in APSP was 1.46 (95% CI 1.14 to 1.87, p=0.002)). After multivariable risk adjustment, the OR for CPSP for an increase of 1 in the APSP was 1.53 (95% CI 1.12 to 2.09, p=0.008).

Conclusions

APSP is a risk factor for CPSP following TKA even after adjusting for confounding variables such as pain catastrophizing, anxiety, depression and functional status. Studies are needed to determine if APSP is a modifiable risk factor for the development of CPSP.

A cross-sectional study to estimate the point prevalence of painful diabetic neuropathy in Eastern Libya

BACKGROUND

Painful Diabetic Neuropathy (PDN) is a complication that affects up to one third of people living with diabetes. There is limited data on the prevalence of PDN from countries in the Middle East and North Africa. The aim of this study was to estimate the point prevalence of PDN in adults in Eastern Libya using the self-report Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) pain scale.

METHODS

We invited patients attending the Benghazi Diabetes Centre who had diabetes for ≥ 5 years to take part in the study. Patients provided consent and completed the Arabic S-LANSS. Anthropometrics, marital status, socioeconomic and education information was recoded and fasting plasma glucose concentration determined.

RESULTS

Four hundred and fifty participants completed the study (age = 19 to 87 years, BMI = 17.6 to 44.2 kg/m2, 224 women). One hundred and ninety five participants (43.3%) reported pain in their lower limbs in the previous 6 months and 190/195 participants (97.4%) reported a S-LANSS score of ≥ 12 suggesting they had neuropathic pain characteristics. Thus, 42.2% (190/450) of participants with diabetes were categorised as experiencing pain with neuropathic characteristics. Mean ± SD duration of diabetes for participants with PDN (20.4 ± 6.5 years) was significantly higher compared with those without PDN (11.1 ± 4.6 years). Participants with PDN smoked tobacco for more years than those without pain (7.9 ± 12.3 years versus 1.1 ± 3.9 years respectively); had significantly higher fasting plasma glucose concentration (143.6 ± 29.3 mg/dl versus 120.0 ± 17.3 mg/dl) and had a significantly higher levels of education and employment status. The most significant predictors of PDN were duration of diabetes (OR = 25.85, 95% CI = 13.56-49.31), followed by smoking for men (OR = 8.28, 95% CI = 3.53-9.42), obesity (OR = 3.96, 95% CI = 2.25-6.96) and high fasting plasma glucose concentration (OR = 3.51, 95% CI = 1.99-6.21).

CONCLUSION

The prevalence of PDN in people with diabetes in Eastern Libya was 42.2%. Risk factors for developing PDN were high fasting plasma glucose concentration, long duration of diabetes, and higher level of educational and employment status.

STarT Back Tool risk stratification is associated with changes in movement profile and sensory discrimination in low back pain: A study of 290 patients

BACKGROUND

Investigation of movement and sensory profiles across STarT Back risk subgroups.

METHODS

A chronic low back pain cohort (n = 290) were classified as low, medium or high risk using the STarT Back Tool, and completed a repeated spinal bending task and quantitative sensory testing. Pain summation, time taken and the number of protective behaviours with repeated bending were measured. Sensory tests included two-point discrimination, temporal summation, pressure/thermal pain thresholds and conditioned pain modulation. Subgroups were profiled against movement and sensory variables.

RESULTS

The high-risk subgroup demonstrated greater pain summation following repeated forward bending (p < 0.001). The medium-risk subgroup demonstrated greater pain summation following repeated backward bending (p = 0.032). Medium- and high-risk subgroups demonstrated greater forward/backward bend time compared to the low-risk subgroup (p = 0.001, p = 0.005, respectively). Medium- and high-risk subgroups demonstrated a higher number of protective behaviours per forward bend compared to the low-risk subgroup (p = 0.008). For sensory variables, only two-point discrimination differed between subgroups, with medium- and high-risk subgroups demonstrating higher thresholds (p = 0.016).

CONCLUSIONS

This study showed altered movement characteristics and sensory discrimination across SBT risk subgroups in people with CLBP. Membership of the high SBT risk subgroup was associated with greater pain and disability levels, greater pain summation following repeated bending, slower bending times, a greater number of protective behaviours during forward bending, and a higher TPD threshold. Treatment outcomes for higher risk SBT subgroups may be enhanced by interventions specifically targeting movement and sensory alterations.

SIGNIFICANCE

In 290 people with chronic low back pain movement profile and two-point discrimination threshold differed across risk subgroups defined by the STarT Back Tool. Conversely, pain sensitivity did not differ across these subgroups. These findings may add further guidance for targeted care in these subgroups.

Difference between subjects in early chronic phase of low back pain with and without neuropathic component: observational cross-sectional study

BACKGROUND

Neuropathic pain in early chronic low back pain is insufficiently recognized and treated.

AIM

The aim of this study was to establish if there is a difference among chronic low back pain subjects with and without neuropathic pain and healthy subjects, in clinical characteristic and the level of trunk muscle activation.

DESIGN

Cross sectional observational study.

SETTING

Rehabilitation clinic, inpatient and outpatient.

POPULATION

Thirty-three subjects in early chronic phase of low back pain and 26 healthy subjects were included in this research.

METHODS

Clinical characteristics and relative thickness change of lumbar multifidus and transversal abdominal muscle, measured by ultrasound, in neuropathic, non-neuropathic chronic low back pain and healthy subjects were analyzed.

RESULTS

Chronic low back pain subjects with neuropathic pain reported higher level of pain on Visual Analog Scale (VAS) (back pain P=0.016, leg pain P=0.006), had higher Oswestry Disability Score (P=0.029), had lower motor (P=0.001) and sensory leg scores (P=0.000), and decreased level of activation of transversal abdominal muscle (P=0.000) comparing to chronic low back pain group without neuropathic pain. Low back pain subjects with leg pain ≥5 on VAS were 11.2 times more prone to develop neuropathic pain. Motor leg score ≤47 increases this chance 35 times. Sensory leg score ≤25 increases this chance 14 times. Reduced activation of transversal abdominal muscle for 40-50% increases this chance 7-24 times.

CONCLUSIONS

Chronic low back pain subjects with neuropathic pain were more painful and disabled, had lower motor and sensory scores, and lower relative thickness change of transversal abdominal muscle comparing to the low back pain group without neuropathic pain. Self -reported leg pain intensity of 5 or more on VAS, motor score of 47 and less, sensory scores of 25 and less and diminished activation of transversal abdominal muscle significantly increase the chance that chronic low back pain subject has neuropathic component of pain.

CLINICAL REHABILITATION IMPACT

Neuropathic pain in early chronic low back pain subjects might be more readily recognized if patients with radiculopathy and diminished activation of transversal abdominal muscle were regularly screened for neuropathic pain.

Pharmacological target therapy of neuropathic pain and patient-reported outcomes in patients with chronic low back pain in Korea: Results from the NLBP Outcomes Research

A number of studies have demonstrated an association of neuropathic pain and chronic low back pain (CLBP), but the outcome difference in each medical management is poorly understood. This study is aimed to investigate treatment patterns of neuropathic pain in CLBP patients and to explore patient-reported outcomes (PROs) including quality of life (QoL) and functional disability by treatment patterns.Data were extracted from the neuropathic low back pain (NLBP) outcomes research. It was a multicenter and cross-sectional study in which 1200 patients were enrolled at 27 general hospitals, from 2014 to 2015. Of total, 478 patients classified as neuropathic pain were used for this subgroup analysis. The patients were divided into 2 groups according to treatment patterns (with vs. without the targeted therapy [TT] of neuropathic pain). Demographic and clinical features were collected by chart reviews and PROs were measured by patient's survey. QoL was assessed by EuroQoL 5-dimension (EQ-5D) questionnaire. Functional disability was measured by the Quebec Back Pain Disability Scale (QBPDS). Multiple linear regression analyses were conducted to compare the PROs between TT group and non-targeted therapy (nTT) group.Among the NLBP patients (mean age 63years, female 62%), EQ-5D index, EuroQoL-Visual Analog Scale (EQ-VAS), and QBPDS Scores (mean ± standard deviation) were 0.40 ± 0.28, 54.98 ± 19.98, and 46.03 ± 21.24, respectively. Only 142 (29.7%) patients had pharmacological TT of neuropathic pain. Univariate analyses revealed no significant mean differences between TT group and nTT group in the EQ-5D index (0.41 ± 0.27 and 0.39 ± 0.28), EQ-VAS (56.43 ± 18.17 and 54.37 ± 20.69), and QBPDS (45.31 ± 21.32 and 46.31 ± 21.24). After adjustment with covariates, TT group had higher scores of EQ-5D index (β = 0.07; P < 0.01) and EQ-VAS (β = 4.59; P < 0.05) than the nTT group. The TT group's QBPDS score was lower than the nTT group, although its statistical significance still has not been reached (β = -4.13; P = 0.07).We found that considerable proportion of the NLBP patients remains untreated or undertreated. Although TT group had significantly better QoL than nTT group, only 29.7% of NLBP patients had pharmacological TT. Therefore, clinicians should consider using TT for better QoL of neuropathic pain patients.

Avoiding Catch-22: validating the PainDETECT in a in a population of patients with chronic pain

Background

Neuropathic pain is defined as pain caused by a lesion or disease of the somatosensory nervous system and is a major therapeutic challenge. Several screening tools have been developed to help physicians detect patients with neuropathic pain. These have typically been validated in populations pre-stratified for neuropathic pain, leading to a so called “Catch-22 situation:” “a problematic situation for which the only solution is denied by a circumstance inherent in the problem or by a rule”. The validity of screening tools needs to be proven in patients with pain who were not pre-stratified on basis of the target outcome: neuropathic pain or non-neuropathic pain. This study aims to assess the validity of the Dutch PainDETECT (PainDETECT_-Dlv) in a large population of patients with chronic pain.

Methods

A cross-sectional multicentre design was used to assess PainDETECT_-Dlv validity. Included where patients with low back pain radiating into the leg(s), patients with neck-shoulder-arm pain and patients with pain due to a suspected peripheral nerve damage. Patients’ pain was classified as having a neuropathic pain component (yes/no) by two experienced physicians (“gold standard”). Physician opinion based on the Grading System was a secondary comparison.

Results

In total, 291 patients were included. Primary analysis was done on patients where both physicians agreed upon the pain classification (n = 228). Compared to the physician’s classification, PainDETECT_-Dlv had a sensitivity of 80% and specificity of 55%, versus the Grading System it achieved 74 and 46%.

Conclusion

Despite its internal consistency and test-retest reliability the PainDETECT_-Dlv is not an effective screening tool for a neuropathic pain component in a population of patients with chronic pain because of its moderate sensitivity and low specificity. Moreover, the indiscriminate use of the PainDETECT_-Dlv as a surrogate for clinical assessment should be avoided in daily clinical practice as well as in (clinical-) research. Catch-22 situations in the validation of screening tools can be prevented by not pre-stratifying the patients on basis of the target outcome before inclusion in a validation study for screening instruments.

Trial registration

The protocol was registered prospectively in the Dutch National Trial Register: NTR 3030.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1094-4) contains supplementary material, which is available to authorized users.

Clinical Manifestation of Acute, Subacute, and Chronic Low Back Pain in Different Age Groups: Low Back Pain in 35,446 Patients

BACKGROUND

Low back pain (LBP) is a major healthcare problem causing tremendous economic costs.

METHODS

Clinical manifestation of LBP was characterized in 35,446 patients. We focused on the comparison of the acute, subacute, and chronic LBP stage with regard to patients' ages, based on epidemiologic and clinical questionnaires (eg, painDETECT Questionnaire, Pain Disability Index), pain intensity, pain descriptors, and functional impairment.

RESULTS

We found that neuropathic components were most frequent in chronic LBP patients at the ages of 51 to 60 years. Elderly LBP patients showed a decrease in neuropathic and an increase in nociceptive pain. The most frequently reported pain descriptors were "pressure pain" and "pain attacks" through all stages of LBP, whereas "burning" and "prickling" were most frequent in the chronic stage. Patients after back surgery presented neuropathic pain symptoms most frequently and had the highest amount of pain medication intake.

CONCLUSIONS

Burning and prickling were revealed as possible indicators for LBP chronicity. Combined with pain attacks and pressure pain, these 4 pain descriptors might be a promising adjunct to pain intensity in terms of outcome parameters for future LBP studies. The decrease of neuropathic pain syndromes in the elderly might be explained by degenerative processes. The presented work provides important insights on LBP management in the acute, subacute, and chronic stages.