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Abstract: The nociceptive withdrawal reflex (NWR) is a spinal withdrawal reflex induced by painful stimulation. It is a measure of spinal hyperexcitability, which is believed to contribute to chronic musculoskeletal pain (MSKP) and headache. Previous syntheses of the evidence for alterations in the NWR in patients with chronic MSKP and headache needed a comprehensive update. This systematic review and meta-analysis was performed after the Preferred Items for Systematic reviews and Meta-Analyses guidelines. Studies examining NWR-related outcome measures in patients with chronic MSKP and headache compared to pain-free controls were identified through electronic database searches and included after screening against predefined eligibility criteria. Standardized mean differences or mean differences and 95% confidence intervals (CI) were calculated. Thirty-one studies were included in the systematic review and 25 in the meta-analysis. Moderate-quality evidence was found indicating lower NWR threshold (-3.68; 95% CI, -4.56 to -2.80; P < 0.001), larger NWR area (standardized mean difference = 0.69; 95% CI, 0.37-1.01; P < 0.001), and shorter NWR latency (mean difference = -13.68; 95% CI, -22.69, -4.67; P = 0.003) in patients compared to controls. These findings remained robust when performing meta-regressions based on subgroups (ie, headache, fibromyalgia, whiplash-associated disorder, and osteoarthritis). Low-quality evidence demonstrated facilitated temporal summation of NWR threshold (-2.48; 95% CI, -3.13 to -1.83; P < 0.001) in patients compared to controls. Spinal hyperexcitability as evidenced by lowered NWR threshold values and temporal summation of the NWR is present in patients with chronic MSKP and headache. No evidence was found for alterations in NWR duration and NWR magnitude. Future research is needed to address the gap in research on NWR-related outcome measures other than NWR threshold., (Copyright © 2024 International Association for the Study of Pain.)

Objective: Previous studies evaluating interdisciplinary multimodal interventions for chronic spinal pain often excluded patients with comorbid mental disorders. This study aims to assess the effectiveness of an outpatient secondary care interdisciplinary multimodal integrative healthcare program for individuals experiencing co-occurring chronic spinal pain and mental disorders., Methods: Participants were 944 patients with chronic spinal pain and comorbid mental disorders. Primary outcomes were health-related quality of life, assessed using the Research and Development-36 (RAND-36), and pain-related disability, assessed using the Quebec Back Pain Disability Scale (QBPDS). Secondary outcomes included pain intensity, pain catastrophizing, kinesiophobia, fatigue, lumbar mobility, and isometric strength. Data were collected during the healthcare program at four time points: pretreatment (T0), midway through 20-week treatment (T1), end of 20-week treatment (T2), and at completion of 12-month relapse prevention program (T3). Multilevel regression analyses were conducted to examine the effects of the healthcare program on primary outcomes over time., Results: The 20-week treatment period yielded significant improvements in both mental ( B = 0.44, t (943) = 19.42, p < .001) and physical component summary scores ( B = 0.45, t (943) = 18.24, p < .001) of the RAND-36, as well as in QBPDS total score ( B = -0.77, t (943) = -26.16 p < .001). Pretreatment scores indicated the presence of problematic fatigue, kinesiophobia, and clinical levels of pain catastrophizing, all of which resolved by the end of the 12-month relapse prevention program., Conclusions: An interdisciplinary multimodal integrative healthcare program seems effective for patients with chronic spinal pain and comorbid mental disorders., (Copyright © 2024 by the American Psychosomatic Society.)

Abstract: The nociceptive flexion reflex (NFR) is a spinally mediated withdrawal response and is used as an electrophysiological marker of descending modulation of spinal nociception. Chemical and pharmacological modulation of nociceptive neurotransmission at the spinal level has been evidenced by direct effects of neurotransmitters and pharmacological agents on the NFR. Largely unexplored are, however, the effects of nonpharmacological noninvasive conservative interventions on the NFR. Therefore, a systematic review and meta-analysis was performed and reported following the PRISMA guidelines to determine whether and to what extent spinal nociception measured through the assessment of the NFR is modulated by conservative therapy in patients and healthy individuals. Five electronic databases were searched to identify relevant articles. Retrieved articles were screened on eligibility using the predefined inclusion criteria. Risk of bias was investigated according to Version 2 of the Cochrane risk-of-bias assessment tool for randomized trials. The evidence synthesis for this review was conducted in accordance with the Grading of Recommendations Assessment, Development and Evaluation. Thirty-six articles were included. Meta-analyses provided low-quality evidence showing that conservative therapy decreases NFR area and NFR magnitude and moderate-quality evidence for increases in NFR latency. This suggests that conservative interventions can exert immediate central effects by activating descending inhibitory pathways to reduce spinal nociception. Such interventions may help prevent and treat chronic pain characterized by enhanced spinal nociception. Furthermore, given the responsiveness of the NFR to conservative interventions, the NFR assessment seems to be an appropriate tool in empirical evaluations of treatment strategies.PROSPERO registration number: CRD42020164495., (Copyright © 2021 International Association for the Study of Pain.)

Objectives: The current study assessed the role of hypervigilance for bodily sensations in the back in long-term low back pain problems., Methods: People with chronic low back pain, recurrent low back pain, and no low back pain were compared on the extent to which they attended to somatosensory stimuli on the back during a movement task. To measure hypervigilance, somatosensory event-related potentials (SEPs) to task-irrelevant tactile stimuli on the back were measured when preparing movements in either a threatening or a neutral condition, indicated by a cue signaling possible pain on the back during movement or not., Results: Results showed stronger attending to stimuli on the back in the threat condition than in the neutral condition, as reflected by increased amplitude of the N96 SEP. However, this effect did not differ between groups. Similarly, for all 3 groups the amplitude of the P172 was larger for the threatening condition, suggesting a more general state of arousal resulting in increased somatosensory responsiveness. No significant associations were found between somatosensory attending to the back and theorized antecedents such as pain catastrophizing, pain-related fear, and pain vigilance., Discussion: The current study confirmed that individuals preparing a movement attended more toward somatosensory stimuli at the lower back when anticipating back pain during the movement, as measured by the N96 SEP. However, no differences were found between participants with chronic low back pain or recurrent low back pain, or the pain-free controls.

Nonspecific chronic low back pain (CLBP) is a multifactorial disorder. Pain-related fear and altered movement preparation are considered to be key factors in the chronification process. Interactions between both have been hypothesized, but studies examining the influence of situational fear on movement preparation in low back pain (LBP) are wanting, as well as studies differentiating between recurrent LBP (RLBP) and CLBP. Therefore, this study examined whether experimentally induced pain-related fear influences movement preparation. In healthy controls (n = 32), RLBP (n = 31) and CLBP (n = 30) patients central and peripheral measures of movement preparation were assessed by concurrently measuring trunk muscle anticipatory postural adjustments (APA) with electromyography and contingent negative variation with EEG during performance of rapid arm movements. Two conditions were compared, one without (no fear) and one with (fear) possibility of painful stimulation to the back during rapid arm movements. Visual analogue scales were used to assess pain-related expectations/fear in both conditions. The experimentally induced fear of pain during movement performance led to an increase in contingent negative variation amplitude, which was similar in all 3 groups. Concerning APAs, no effects of fear were found, but group differences with generally delayed APAs in CLBP compared with controls and RLBP patients were evident. These results suggest that with fear, an attentional redirection towards more conscious central movement preparation strategies occurs. Furthermore, differences in movement preparation in patients with RLBP and CLBP exist, which could explain why patients with RLBP have more recovery capabilities than patients with CLBP.

Objectives: The nociceptive flexion reflex (NFR) is a spinal reflex induced by painful stimuli resulting in a withdrawal response. Research has shown that the NFR is inhibited through endogenous pain inhibitory mechanisms, which can be assessed by conditioned pain modulation (CPM) paradigms. Although accumulating research suggests that the NFR can be affected by CPM, no clear overview of the current evidence exists. Therefore, the present review aimed at providing such a synthesis of the literature. In addition, the influence of personal factors on the CPM of the NFR was investigated., Materials and Methods: A systematic review was performed and reported following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Five electronic databases were searched to identify relevant articles. Retrieved articles were screened on eligibility using predefined inclusion criteria. Risk of bias was investigated according to the modified Newcastle-Ottawa Scale. Levels of evidence and strength of conclusion were assigned following the guidelines of the Dutch Institute for Healthcare Improvement., Results: Forty articles were included. There is some evidence that CPM produced by thermal or mechanical stimuli induces inhibitory effects on the NFR. However, inconclusive evidence exists with regard to the effect of electrical conditioning stimuli. While several personal factors do not affect CPM of the NFR, increased cognitive interference is associated with reduced NFR inhibition., Discussion: The present review demonstrates that certain types of nociceptive conditioning stimuli have the potential to depress, at the spinal level, nociceptive stimuli elicited from distant body regions. Although CPM of the NFR seems to be robust to the influence of several personal factors, it can be affected by cognitive influences.

Objectives: There is evidence that education on pain physiology can have positive effects on pain, disability, and catastrophization in patients with chronic musculoskeletal pain disorders. A double-blind randomized controlled trial (RCT) was performed to examine whether intensive pain physiology education is also effective in fibromyalgia (FM) patients, and whether it is able to influence the impaired endogenous pain inhibition of these patients., Methods: Thirty FM patients were randomly allocated to either the experimental (receiving pain physiology education) or the control group (receiving pacing self-management education). The primary outcome was the efficacy of the pain inhibitory mechanisms, which was evaluated by spatially accumulating thermal nociceptive stimuli. Secondary outcome measures included pressure pain threshold measurements and questionnaires assessing pain cognitions, behavior, and health status. Assessments were performed at baseline, 2 weeks, and 3 months follow-up. Repeated measures ANOVAS were used to reveal possible therapy effects and effect sizes were calculated., Results: After the intervention the experimental group had improved knowledge of pain neurophysiology (P<0.001). Patients from this group worried less about their pain in the short term (P=0.004). Long-term improvements in physical functioning (P=0.046), vitality (P=0.047), mental health (P<0.001), and general health perceptions (P<0.001) were observed. In addition, the intervention group reported lower pain scores and showed improved endogenous pain inhibition (P=0.041) compared with the control group., Discussion: These results suggest that FM patients are able to understand and remember the complex material about pain physiology. Pain physiology education seems to be a useful component in the treatment of FM patients as it improves health status and endogenous pain inhibition in the long term.