Test-Retest and Inter-Examiner Reliability of a Novel Bedside Quantitative Sensory Testing Battery in Postherpetic Neuralgia Patients

sEMG Biofeedback for Episodic Migraines: A Pilot Randomized Clinical Trial

The aim of this study was to assess the feasibility and potential effectiveness of a 6-week virtual sEMG biofeedback intervention for patients with episodic migraines. Patients with episodic migraines were randomized to treatment with a novel surface EMG (sEMG) at-home biofeedback device or a treatment as usual control group; they completed validated baseline and post-intervention assessments of migraine related disability (migraine-specific quality of life, anxiety and depression). Participants also underwent a series of Quantitative Sensory Testing (QST) procedures referring to several different tests that quantitatively assess responses to mechanical stimuli during two separate visits (baseline and post intervention). No adverse events were reported during the study. Compared to the treatment as usual comparison group, patients in the sEMG biofeedback group reported lower migraine disability (p < 0.05). Compared to baseline, participants in the sEMG biofeedback group demonstrated statistically significant reductions in anxiety (p < 0.01), and significant increases in quality of life (p < 0.001), and significant decreases in temporal summation (p < 0.05) assessed by QST. No significant changes were observed in any of the outcomes in the control comparison group (p > 0.05). No significant changes were observed in migraine frequency in either of the two groups (p > 0.05). In addition, mediation analyses revealed that changes in migraine related quality of life mediated group effects on changes in migraine disability. Virtual sEMG biofeedback shows promise as a potential therapy for reducing disability, anxiety and depression and improving quality of life in individuals with episodic migraines. These results demonstrate the feasibility of a digital intervention for migraines and set the basis for conducting a future, larger scale randomized controlled trial to confirm these preliminary findings.

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.

Comprehensive quantitative sensory testing shows altered sensory function in women with chronic pelvic pain: results from the Translational Research in Pelvic Pain (TRiPP) Study

ABSTRACT

Chronic pelvic pain (CPP), despite its high prevalence, is still relatively poorly understood mechanistically. This study, as part of the Translational Research in Pelvic Pain (TRiPP) project, has used a full quantitative sensory testing (QST) paradigm to profile n = 85 women with and without CPP (endometriosis or bladder pain specifically). We used the foot as a control site and abdomen as the test site. Across 5 diagnostically determined subgroups, we found features which are common across different aetiologies, eg, gain of function in pressure pain threshold (PPT) when assessing responses from the lower abdomen or pelvis (referred pain site). However, disease-specific phenotypes were also identified, eg, greater mechanical allodynia in endometriosis, despite there being large heterogeneities within diagnostic groups. The most common QST sensory phenotype was mechanical hyperalgesia (>50% across all the groups). A "healthy' sensory phenotype was seen in <7% of CPP participants. Specific QST measures correlated with sensory symptoms assessed by the painDETECT questionnaire (pressure-evoked pain [painDETECT] and PPT [QST] [ r = 0.47, P < 0.001]; mechanical hyperalgesia (painDETECT) and mechanical pain sensitivity [MPS from QST] [ r = 0.38, P = 0.009]). The data suggest that participants with CPP are sensitive to both deep tissue and cutaneous inputs, suggesting that central mechanisms may be important in this cohort. We also see phenotypes such as thermal hyperalgesia, which may be the result of peripheral mechanisms, such as irritable nociceptors. This highlights the importance of stratifying patients into clinically meaningful phenotypes, which may have implications for the development of better therapeutic strategies for CPP.

Personalized treatment of neuropathic pain: Where are we now?

BACKGROUND

The treatment of neuropathic pain remains a major unmet need that the development of personalized and refined treatment strategies may contribute to address.

DATABASE

In this narrative review, we summarize the various approaches based on objective biomarkers or clinical markers that could be used.

RESULTS

In principle, the validation of objective biomarkers would be the most robust approach. However, although promising results have been reported demonstrating a potential value of genomics, anatomical or functional markers, the clinical validation of these markers has only just begun. Thus, most of the strategies documented to date have been based on the development of clinical markers. In particular, many studies have suggested that the identification of specific subgroups of patients presenting with specific combinations of symptoms and signs would be a relevant approach. Two main approaches have been used to identify relevant sensory profiles: quantitative sensory testing and specific patients reported outcomes based on description of pain qualities.

CONCLUSION

We discuss here the advantages and limitations of these approaches, which are not mutually exclusive.

SIGNIFICANCE

Recent data indicate that various new treatment strategies based on predictive biological and/or clinical markers could be helpful to better personalized and therefore improve the management of neuropathic pain.

Biobehavioral Assessments in BACPAC: Recommendations, Rationale, and Methods

The Biobehavioral Working Group of BACPAC was charged to evaluate a range of psychosocial, psychophysical, and behavioral domains relevant to chronic low back pain, and recommend specific assessment tools and procedures to harmonize biobehavioral data collection across the consortium. Primary references and sources for measure selection were the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials, the Minimum Data Set from the National Institutes of Health (NIH) Research Task Force on Standards for Chronic Low Back Pain, the Patient-Reported Outcomes Measurement Information System, and NeuroQOL. The questionnaire's recommendations supplemented the NIH HEAL Common Data Elements and BACPAC Minimum Data Set. Five domains were identified for inclusion: Pain Characteristics and Qualities; Pain-Related Psychosocial/Behavioral Factors; General Psychosocial Factors; Lifestyle Choices; and Social Determinants of Health/Social Factors. The Working Group identified best practices for required and optional Quantitative Sensory Testing of psychophysical pain processing for use in BACPAC projects.

Does Your Bedside Neurological Examination for Suspected Peripheral Neuropathies Measure Up?

SYNOPSIS: Neurological testing is essential for screening and diagnosing suspected peripheral neuropathies. Detecting changes in somatosensory and motor nerve function can also have direct implications for management decisions. Nevertheless, there is considerable variation in what is included in a bedside neurological examination and how it is performed. Neurological examinations are often used as screening tools to detect neurological deficits but not used to their full potential for monitoring progress or deterioration. Here, we advocate for better use of the neurological examination within a clinical reasoning framework. Constrained by the lack of research in this field, our Viewpoint is based on neuroscientific principles. We highlight 6 challenges for clinicians when conducting neurological examinations and propose ways to overcome these challenges in clinical practice. We challenge widely held ideas about how the results of neurological examinations for peripheral neuropathies are interpreted and how the examinations are performed in practice. J Orthop Sports Phys Ther 2023;53(3):107-112. Epub: 28 October 2022. doi:10.2519/jospt.2022.11281.

Biofeedback EMG alternative therapy for chronic low back pain (the BEAT-pain study)

Objective

The aim of this study was to assess the feasibility and potential effectiveness of an 8-week virtual EMG biofeedback intervention for patients with CLBP.

Methods

Patients with CLBP completed validated baseline and post-intervention assessments of pain intensity and interference (Brief Pain Inventory), back pain-related disability (Oswestry Disability Index), anxiety and depression (Hospital Anxiety and Depression Scale). Participants underwent a series of Quantitative Sensory Testing (QST) procedures assessing responses to mechanical stimuli during two separate visits (baseline and post-intervention). In addition, we assessed, using surface EMG, the muscle tension in the trapezius, latissimus, and low back muscles at each session. Patients were randomized into the EMG biofeedback intervention or usual care group. Factorial analysis of variance including the interaction between treatment group and time was used to analyze the changes in pain intensity (primary outcome), pain interference, disability (secondary outcomes), anxiety, and depression (secondary outcomes).

Results

Compared to the treatment as usual comparison group, patients in the EMG biofeedback group reported lower pain intensity after completing the intervention (mean group difference 0.9, 95% CI -1.07, -0.32; p≤0.01). Compared to baseline, participants in the EMG biofeedback group demonstrated statistically significant reductions in pain interference (mean difference 1.3, 95% CI 0.42, 2.1; p≤0.01), disability (mean difference 4.32, 95% CI 1.2, 7.3; p≤0.01), and significant increases in low back pain thresholds (mean difference 0.5, 95% CI -0.87, -0.05; p≤0.01), assessed by QST. However, no significant group by time effects were observed for secondary outcomes: pain interference, disability, and low back pain thresholds. In addition, significant changes were observed in muscle tension for the trapezius, latissimus, and low back muscles in the EMG biofeedback group (p<0.001).

Conclusions

Virtual EMG biofeedback shows promise as a potential therapy for reducing pain and disability in individuals with chronic nonspecific low back pain.

Test-retest reliability of a simple bedside-quantitative sensory testing battery for chronic neuropathic pain

Introduction

The sensory phenotype is believed to provide information about the underlying pathophysiological mechanisms and to be used in the diagnosis and treatment of chronic neuropathic pain. However, the use of standardized quantitative sensory testing (QST) protocols is limited due to high expenditures of time and costs. Thus, a simple bedside-QST battery was recently developed showing good agreement when compared with laboratory QST. The aim of this study was to preliminary validate this bedside-QST protocol.

Methods

Patients experiencing chronic pain with neuropathic features (n = 60) attended 3 visits. During the first visit, laboratory QST and bedside-QST were performed by the same trained investigator. Three hours and 3 weeks later, bedside-QST was repeated. Patients completed questionnaires regarding their pain (intensity, quality), depression/anxiety, and quality of life. Test-retest reliability and convergent/divergent validity were investigated.

Results

Most of the bedside-QST parameters, including also those recommended in our first study as being indicative for sensory phenotypes, revealed a moderate to excellent test-retest reliability. Overall, results for short-term reliability and interval-scaled parameters were slightly better. Most of the bedside-QST parameters did not correlate with the depression and anxiety score, suggesting a good divergent validity.

Conclusions

Bedside-QST has good criterion and divergent validity as well as reliability. This battery consists of 5 low-cost devices that can be quickly and easily used to characterize the sensory phenotype of patients with neuropathic pain. A combination of bedside-QST parameters can be used to investigate patients' subgroups with specific pathophysiological mechanisms and to identify treatment responders.

Precision Medicine in Neuropathic Pain

Neuropathic pain is a common chronic pain condition that is caused by a lesion or disease of the somatosensory nervous system. The multitude of sensory negative and positive sensations and associated comorbidities have a major impact on quality of life of affected patients. Current treatment options often only lead to a partial pain relief or are even completely ineffective. In addition, many clinical trials for the development of new drugs have not met the primary endpoint. Therefore, there is still an unmet clinical need in neuropathic pain syndromes. One reason for this therapeutic dilemma could be the heterogeneity of neuropathic pain with a variety of pathophysiological pain mechanisms that are expressed differently in each patient regardless of the underlying disease etiology. Reclassification of neuropathic pain syndromes therefore focuses on the underlying mechanisms of pain development rather than the disease etiology. A priori stratification of patients based on these individual mechanisms could allow the identification of potential treatment responders and thus realize the concept of a mechanism-based treatment. As no biomarkers for pain mechanisms have been discovered yet, one has to rely on surrogate markers that are thought to be closely related to these mechanisms. In this chapter, we present promising predictive biomarkers, focusing in particular on sensory symptoms and signs assessed by patient-reported outcome measures and sensory testing, and discuss how these tools might be used in clinical trials in the future.

Small-Fiber-Neuropathien

Die Small-Fiber-Neuropathie (SFN) ist eine Erkrankung des peripheren Nervensystems aufgrund einer isolierten oder vorwiegenden Schädigung dünn myelinisierter Aδ-Fasern und/oder unmyelinisierter C‑Fasern. Für die sichere Diagnose einer SFN ist neben der klinischen Symptomatik mit Schmerzen und Sensibilitätsstörungen, typischerweise mit distal betonter Ausbreitung, der apparative Nachweis einer Rarefizierung oder einer Funktionsstörung der dünn myelinisierten Aδ-Fasern und/oder der unmyelinisierten C‑Fasern gefordert. Im vorliegenden Beitrag wird eine Übersicht über die diagnostischen Verfahren zum Nachweis einer SFN sowie über mögliche Ursachen und Behandlungsoptionen gegeben.

Understanding the Psychological, Physiological, and Genetic Factors Affecting Precision Pain Medicine: A Narrative Review

PURPOSE

Precision pain medicine focuses on employing methods to assess each patient individually, identify their risk profile for disproportionate pain and/or the development of chronic pain, and optimize therapeutic strategies to target specific pathological processes underlying chronic pain. This review aims to provide a concise summary of the current body of knowledge regarding psychological, physiological, and genetic determinants of chronic pain related to precision pain medicine.

METHODS

Following the Scale for the Assessment of Narrative Review Articles (SANRA) criteria, we employed PubMed/Medline to identify relevant articles using primary database search terms to query articles such as: precision medicine, non-modifiable factors, pain, anesthesiology, quantitative sensory testing, genetics, pain medicine, and psychological.

RESULTS

Precision pain medicine provides an opportunity to identify populations at risk, develop personalized treatment strategies, and reduce side effects and cost through elimination of ineffective treatment strategies. As in other complex chronic health conditions, there are two broad categories that contribute to chronic pain risk: modifiable and non-modifiable patient factors. This review focuses on three primary determinants of health, representing both modifiable and non-modifiable factors, that may contribute to a patient's profile for risk of developing pain and most effective management strategies: psychological, physiological, and genetic factors.

CONCLUSION

Consideration of these three domains is already being integrated into patient care in other specialties, but by understanding the role they play in development and maintenance of chronic pain, we can begin to implement both precision and personalized treatment regimens.

Hierarchical clustering by patient-reported pain distribution alone identifies distinct chronic pain subgroups differing by pain intensity, quality, and clinical outcomes

Background

In clinical practice, the bodily distribution of chronic pain is often used in conjunction with other signs and symptoms to support a diagnosis or treatment plan. For example, the diagnosis of fibromyalgia involves tallying the areas of pain that a patient reports using a drawn body map. It remains unclear whether patterns of pain distribution independently inform aspects of the pain experience and influence patient outcomes. The objective of the current study was to evaluate the clinical relevance of patterns of pain distribution using an algorithmic approach agnostic to diagnosis or patient-reported facets of the pain experience.

Methods and findings

A large cohort of patients (N = 21,658) completed pain body maps and a multi-dimensional pain assessment. Using hierarchical clustering of patients by body map selection alone, nine distinct subgroups emerged with different patterns of body region selection. Clinician review of cluster body maps recapitulated some clinically-relevant patterns of pain distribution, such as low back pain with radiation below the knee and widespread pain, as well as some unique patterns. Demographic and medical characteristics, pain intensity, pain impact, and neuropathic pain quality all varied significantly across cluster subgroups. Multivariate modeling demonstrated that cluster membership independently predicted pain intensity and neuropathic pain quality. In a subset of patients who completed 3-month follow-up questionnaires (N = 7,138), cluster membership independently predicted the likelihood of improvement in pain, physical function, and a positive overall impression of change related to multidisciplinary pain care.

Conclusions

This study reports a novel method of grouping patients by pain distribution using an algorithmic approach. Pain distribution subgroup was significantly associated with differences in pain intensity, impact, and clinically relevant outcomes. In the future, algorithmic clustering by pain distribution may be an important facet in chronic pain biosignatures developed for the personalization of pain management.

Bedside testing for precision pain medicine

PURPOSE OF REVIEW

In recent years, the identification of therapy responders has become an increasing focus of pain research. On the basis of laboratory quantitative sensory testing, subgroups of patients were identified, which have been shown to predict treatment response. However, the high cost and time expenditure limits the use of these lab-QST protocols in clinical practice and large clinical trials.

RECENT FINDINGS

Recently, different bedside testing protocols were developed as easy-to-use alternative for lab-QST. In addition, patients can be subgrouped based on their symptoms by use of patient-reported outcome measures. First results suggest that these approaches can be used to stratify patients into pathophysiological-plausible subgroups predictive for treatment response.

SUMMARY

This review presents recently developed bedside approaches that can be implemented as stratification tools in future clinical trials to realize individualized pain medicine. Being complementary rather than replaceable, future studies should combine questionnaires and sensory testing and apply them prospectively in large clinical trials.

Temporal summation of mechanical pain prospectively predicts movement-evoked pain severity in adults with chronic low back pain

BACKGROUND

Biopsychosocial factors above and beyond pathoanatomical changes likely contribute to the severity of chronic low back pain. A pro-nociceptive endogenous pain modulatory balance (↓inhibition and ↑facilitation) may be an important contributor to chronic low back pain severity and physical function; however, additional research is needed to address this possibility. The objective of this study was to determine whether quantitative sensory tests of endogenous pain inhibition and facilitation prospectively predict movement-evoked pain and cLBP severity self-reported on a validated questionnaire.

METHODS

One hundred thirty-four individuals with chronic low back pain were enrolled in this two-session study. During the first study session, temporal summation of mechanical pain and conditioned pain modulation were assessed at the lumbar spine to determine endogenous pain facilitation and inhibition, respectively. One week later, participants returned for a second study session whereby they reported their pain severity and pain interference using the Brief Pain Inventory-Short Form. Movement-evoked pain and physical function capacity were assessed upon completion of the balance, walking, and transition from sit to stand tests of the Short Physical Performance Battery.

RESULTS

Temporal summation of mechanical pain, but not conditioned pain modulation, significantly and prospectively predicted greater movement-evoked pain and poorer physical function on the Short Physical Performance Battery. Neither temporal summation nor conditioned pain modulation were significantly related to self-reported pain severity or pain interference on the Brief Pain Inventory-Short Form.

CONCLUSIONS

Findings suggest that a pro-nociceptive pain modulatory balance characterized by enhanced pain facilitation may be an important driver of movement-evoked pain severity and poor physical function in individuals with chronic low back pain.

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.