Determining Predictive Outcome Factors for a Multimodal Treatment Program in Low Back Pain Patients: A Retrospective Cohort Study.

OBJECTIVE: The purpose of this study was to determine the factors predictive of outcomes in a multifaceted rehabilitation program for acute and chronic low back pain (LBP) patients. METHODS: A retrospective cohort study was performed on 565 LBP patients (153 acute and 412 chronic) who participated in a multimodal treatment program at an outpatient clinic in Belgium between 2007 and 2010. The predictive value of several factors, including age, sex, body mass index, fat percentage, Oswestry Disability Index score, Beck Depression Index score, Numeric Pain Rating Scale score for back and leg pain intensity, and Tampa Scale for Kinesiophobia score on favorable treatment outcomes was examined using logistic regression analysis. RESULTS: The results from the multivariate regression indicated that a higher score on the Tampa Scale for Kinesiophobia (odds ratio [OR] = 0.92) decreases the odds of a favorable outcome following a multimodal treatment program in acute LBP. Older age (OR = 0.97), low LBP intensity (OR = 1.191), and higher scores on the Beck Depression Index (OR = 0.96) and the Oswestry LBP Disability Index (OR = 0.93) decreased the odds of a favorable treatment outcome in chronic LBP. CONCLUSIONS: The findings of this study indicate that factors predictive of a (un)favorable treatment outcome differ between acute and chronic LBP. Specifically, kinesiophobia is predictive of poor treatment outcome in acute LBP. In chronic LBP, older age, low LBP intensity, and higher degrees of depression and LBP-related disability are predictive of poor treatment outcome. Therapists should consider assessing these predictive factors at intake to tailor the content of the multimodal treatment program to individual patient needs.

Prevalence of cerebral palsy and factors associated with cerebral palsy subtype: A population-based study in Belgium.

AIM: To report on the prevalence, neuroimaging patterns, and function of children with cerebral palsy (CP) in Belgium for birth years 2007-2012, and identify distinctive risk indicators and differences in outcome between CP subtypes. METHODS: Antenatal and perinatal/neonatal factors, motor and speech function, associated impairments, and neuroimaging patterns were extracted from the Belgian Cerebral Palsy Register. Prevalence was estimated per 1000 (overall, ante/perinatal, spastic, dyskinetic CP) or 10,000 (post-neonatal, ataxic CP) live births. Multinomial logistic regression analyses were performed to ascertain the effects of antenatal/perinatal/neonatal factors and neuroimaging patterns on the likelihood of dyskinetic or ataxic CP relative to spastic CP, and test the likelihood of the occurrence of impaired motor and speech function and associated impairments in dyskinetic or ataxic CP relative to spastic CP. RESULTS: In total, 1127 children with CP were identified in Belgium. The birth prevalence of overall CP was 1.48 per 1000 live births. The likelihood of dyskinetic CP increases if the child was born to a mother aged ≥35 years, mechanically ventilated, and had predominant grey matter injury, while an increased likelihood of ataxic CP is associated with ≥2 previous deliveries. Children with dyskinetic and ataxic CP are more likely to function with impairments in motor, speech, and intellectual abilities. CONCLUSION: Distinctive risk indicators and differences in outcome between CP subtypes were identified. These factors can be incorporated into clinical practice to facilitate early, accurate, and reliable classification of CP subtype, and may lead to individually tailored neonatal care and other (early) intervention options.

Modulation of the nociceptive flexion reflex by conservative therapy in patients and healthy people: a systematic review and meta-analysis.

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.

The influence of physical activity on the nociceptive flexion reflex in healthy people.

BACKGROUND: The nociceptive flexion reflex (NFR) is a spinal reflex induced by painful stimuli resulting in an appropriate withdrawal response. The NFR is considered to be an objective physiological correlate of spinal nociception. Previous research has already demonstrated that physical activity (PA) can influence pain assessments. To date, no studies have directly examined the relationship between PA and spinal nociception. Hence, this study aimed to investigate whether the NFR threshold can be predicted by report-based and monitor-based measures of PA in healthy adults. METHODS: PA and the NFR threshold of 58 healthy adults were assessed. PA was evaluated by self-report using the International Physical Activity Questionnaire and by monitor-based accelerometry data. The NFR threshold was elicited through transcutaneous electrical stimulation of the sural nerve and quantified by the biceps femoris muscle electromyogram. Hierarchical linear regression analyses were performed to determine the relationship between PA and the NFR, while controlling for confounders. RESULTS: Monitor-based measured step count and activities of moderate- to vigorous-intensity predicted the NFR threshold accounting for 23.0% (p = .047) to 37.1% (p = .002) of the variance. Larger amounts of step counts and higher participation in moderate- to vigorous-intensity activities predicted higher NFR thresholds. Monitor-based activities of sedentary intensity predicted the NFR threshold accounting for 35.8% (p = .014) to 35.9% (p = .014) of the variance. Spending more time per day on activities of sedentary intensity predicted lower NFR thresholds. CONCLUSIONS: The study provides preliminary evidence indicating that a physically active lifestyle may reduce spinal nociception in healthy adults, while a sedentary lifestyle enhances spinal nociception. SIGNIFICANCE: The present study provides preliminary evidence that the influencing effects of physical activity on pain are the result of a strong descending control and do not purely rely on supraspinal mechanisms. These study results highlight the importance of considering physical activity levels when evaluating nociceptive processing, given the prognostic value of physical activity in spinal nociception. Furthermore, this study encourages future research to examine the effects of moderate- to vigorous-intensity exercise programmes on spinal nociception in chronic pain populations.

Does muscular or mental fatigue have an influence on the nociceptive flexion reflex? A randomized cross-over study in healthy people.

BACKGROUND: The nociceptive flexion reflex (NFR) is a spinally-mediated withdrawal reflex occurring in response to noxious stimuli and is used as an electrophysiological marker of spinal nociception. Although it is well-documented that the NFR is subject to powerful modulation of several personal factors, the effects of experimentally induced fatigue on the NFR have not yet been examined. Hence, this study aimed to characterize if and how fatigue affects spinal nociception in healthy adults. METHODS: The NFR of 58 healthy people was measured prior to and following rest and two fatiguing tasks performed in randomized order. The NFR was elicited by transcutaneous electrical stimulation of the sural nerve and objectified by electromyographic recordings from the biceps femoris muscle. An isokinetic fatiguing protocol was used to induce localized muscle fatigue of the hamstrings. The modified incongruent Stroop-word task was used to provoke mental fatigue. A linear mixed model analysis was performed to assess the influence of fatigue on the NFR. RESULTS: Low-to-moderate levels experimentally induced localized muscle and mental fatigue did not affect the NFR in healthy adults. These results suggest that descending pain inhibitory processes to dampen spinal nociception are resistant to the effects of localized muscle and mental fatigue. CONCLUSIONS: The relative robustness of the NFR to fatigue may be beneficial in both clinical and research settings where the influence of confounders complicates interpretation. Furthermore, the findings possibly help enhance our understanding on why even demanding cognitive/physical exercise-based treatment programs form effective treatment strategies for patients with chronic pain. SIGNIFICANCE: The present study unraveled that low-to-moderate levels experimentally induced localized muscle and mental fatigue did not affect the NFR. These results suggest that descending pain inhibitory processes to dampen spinal nociception are resistant to the effects of localized muscle and mental fatigue. This relative robustness of the NFR may be beneficial in a clinical setting in which the evaluation of spinal nociception that is unaffected by clinical symptoms of fatigue may be useful (e.g. chronic fatigue syndrome, cancer-related fatigue, etc.).

Pain sensitivity is reduced by exercise training: Evidence from a systematic review and meta-analysis.

BELAVY, D. L., J. Van Oosterwijck, M. Clarkson, E. Dhondt, N. L. Mundell, C. Miller and P. J. Owen. NEUROSCI BIOBEHAV REV 21(1) XXX-XXX, 2020. Exercise training is capable of reducing pain in chronic pain syndromes, yet its mechanisms are less well established. One mechanism may be via the impact of exercise on increasing a person's pain threshold. Here we show, via meta-analysis of fifteen exercise training studies in pain syndromes that exercise training leads to increased pressure pain thresholds (low to moderate quality evidence). We also find low to moderate quality evidence exists that exercise training was more effective than non-exercise interventions, such as pain education, massage and stress management for improving pain sensitivity. Further, the effect of exercise was greater locally at the site of pain and less so at remote regions. These finding suggest that adaptations in central inhibition occur over time with exercise training and, more widely, add to the mechanistic understanding of how effective interventions can improve pain in chronic pain syndromes.

Predicting treatment adherence and outcome to outpatient multimodal rehabilitation in chronic low back pain.

BACKGROUND: There is a growing need to identify patient pre-treatment characteristics that could predict adherence and outcome following specific interventions. OBJECTIVE: To identify predictors of adherence and outcome to outpatient multimodal rehabilitation in chronic low back pain (CLBP). METHODS: A total of 273 CLBP patients participated in an exercise-based rehabilitation program. Patients who completed ⩾ 70% of the treatment course were classified as adherent. Patients showing a post-treatment reduction of ⩾ 30% in Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) back pain intensity scores were assigned to the favorable outcome group. RESULTS: Multivariate logistic regression revealed that higher age, higher ability to perform low-load activities, and higher degrees of kinesiophobia increased the odds to complete the rehabilitation program. By contrast, lower levels of education and back pain unrelated to poor posture increased the odds for non-adherence. Furthermore, a favorable outcome was predicted in case the cause for LBP was known, shorter symptom duration, no pain in the lower legs, no difficulties falling asleep, and short-term work absenteeism. CONCLUSIONS: Assessment and consideration of patient pre-treatment characteristics is of great importance as they may enable therapists to identify patients with a good prognosis or at risk for non-responding to outpatient multimodal rehabilitation.

Effects of Conditioned Pain Modulation on the Nociceptive Flexion Reflex in Healthy People: A Systematic Review.

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.

Lumbar muscle structure and function in chronic versus recurrent low back pain: a cross-sectional study.

BACKGROUND CONTEXT: Heterogeneity exists within the low back pain (LBP) population. Some patients recover after every pain episode, whereas others suffer daily from LBP complaints. Until now, studies rarely make a distinction between recurrent low back pain (RLBP) and chronic low back pain (CLBP), although both are characterized by a different clinical picture. Clinical experiences also indicate that heterogeneity exists within the CLBP population. Muscle degeneration, like atrophy, fat infiltration, alterations in muscle fiber type, and altered muscle activity, compromises proper biomechanics and motion of the spinal units in LBP patients. The amount of alterations in muscle structure and muscle function of the paraspinal muscles might be related to the recurrence or chronicity of LBP. PURPOSE: The aim of this experimental study is to evaluate differences in muscle structure (cross-sectional area and lean muscle fat index) and muscle activity of the multifidus (MF) and erector spinae (ES) during trunk extension, in patients with RLBP, non-continuous CLBP, and continuous CLBP. STUDY DESIGN AND SETTING: This cross-sectional study took place in the university hospital of Ghent, Belgium. Muscle structure characteristics and muscle activity were assessed by magnetic resonance imaging (MRI). PATIENT SAMPLE: Fifty-five adults with non-specific LBP (24 RLBP in remission, 15 non-continuous CLBP, 16 continuous CLBP) participated in this study. OUTCOME MEASURES: Total cross-sectional area, muscle cross-sectional area, fat cross-sectional area, lean muscle fat index, T2-rest and T2-shift were assessed. METHODS: A T1-weighted Dixon MRI scan was used to evaluate spinal muscle cross-sectional area and fat infiltration in the lumbar MF and ES. Muscle functional MRI was used to evaluate the muscle activity of the lumbar MF and ES during a lumbar extension exercise. Before and after the exercise, a pain assessment was performed. This study was supported by grants from the Special Research Fund of Ghent University (DEF12/AOP/022) without potential conflict of interest-associated biases in the text of the paper. RESULTS: Fat cross-sectional area and lean muscle fat index were significantly higher in MF and ES in continuous CLBP compared with non-continuous CLBP and RLBP (p<.05). No differencesbetween groups were found for total cross-sectional area and muscle cross-sectional area in MF or ES (p>.05). Also, no significant differences between groups for T2-rest were established. T2-shift, however, was significantly lower in MF and ES in RLBP compared with, respectively, non-continuous CLBP and continuous CLBP (p<.05). CONCLUSIONS: These results indicate a higher amount of fat infiltration in the lumbar muscles, in the absence of clear atrophy, in continuous CLBP compared with RLBP. A lower metabolic activity of the lumbar muscles was seen in RLBP replicating a relative lower intensity in contractions performed by the lumbar muscles in RLBP compared with non-continuous and continuous CLBP. In conclusion, RLBP differs from continuous CLBP for both muscle structure and muscle function, whereas non-continuous CLBP seems comparable with RLBP for lumbar muscle structure and with continuous CLBP for lumbar muscle function. These results underline the differences in muscle structure and muscle function between different LBP populations.