Central sensitization and functioning in patients with chronic low back pain: A cross-sectional and longitudinal study

Association of Muscle Strength, Psychological Factors, and Central Sensitization With Movement-Evoked Pain in Patients With Nonspecific Chronic Low Back Pain: The BACKFIT Project

BACKGROUND

People with chronic pain might evade certain movements to prevent their experience of pain. Movement-evoked pain (MEP) might induce lower functionality during daily activities.

HYPOTHESIS

(1) MEP after physical fitness tests would vary depending on the main musculature involved in the test; (2) physical and psychological factors would be associated with MEP in patients with NSCLBP.

STUDY DESIGN

Cross-sectional design.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 104 (69 women) patients aged 51.0 ± 10.3 years with NSCLBP participated. MEP was measured with a visual analog scale (VAS) at baseline and immediately after performing each physical fitness test, that is, the Biering-Sørensen, prone bridging, handgrip, chair-stand, and 8-foot time-up-and-go tests, measuring back extensor, back flexor, upper- and lower-body muscle strength, and motor agility, respectively. Global muscle strength was calculated with normalized index (z-score) procedure. Depression, anxiety, pain catastrophizing, and central sensitization were assessed with the Beck Depression Inventory II, State Trait Anxiety Inventory I, Pain Catastrophizing Scale, and Central Sensitization Inventory (CSI), respectively.

RESULTS

Patients showed greater pain after completion of the Biering-Sørensen (mean difference 95% CI, 0.02, 1.11), prone bridging (0.15, 1.21), lower pain after handgrip (-1.46, -0.52), and the 8-foot time-up-and-go (-1.43, 0.46) tests (all P ≤ 0.04). Lower global muscular strength (β between -0.18 and -0.30), and greater pain catastrophizing (β = 0.16), and CSI scoring (β between 0.18 and 0.27) were associated with greater MEP (all P ≤ 0.04).

CONCLUSION

Greater MEP was observed after tests measuring core musculature strength than after tests measuring distal (limbs) strength and agility. Greater MEP was overall associated with lower muscle strength, greater pain catastrophizing, and central sensitization.

CLINICAL RELEVANCE

Fitness testing might be implemented as a complementary tool for the monitoring of NSCLBP in clinical settings.

To what degree patient-reported symptoms of central sensitization, kinesiophobia, disability, sleep, and life quality associated with 24-h heart rate variability and actigraphy measurements?

OBJECTIVES

Chronic musculoskeletal pain is associated with decreased parasympathetic and increased sympathetic activity in the autonomic nervous system. The objective of this study was to determine the associations between objective measures of heart rate variability (a measure of autonomic nervous system function), actigraphy (a measure of activity and sleep quality), respiration rates, and subjective patient-reported outcome measures (PROMs) of central sensitization, kinesiophobia, disability, the effect of pain on sleep, and life quality.

METHODS

Thirty-eight study subjects were divided into two subgroups, including low symptoms of central sensitization (n = 18) and high symptoms of central sensitization (n = 20), based on patient-reported scores on the Central Sensitization Inventory (CSI). Heart rate variability (HRV) and actigraphy measurements were carried out simultaneously in 24 h measurement during wakefulness and sleep.

RESULTS

A decrease in HRV during the first 2 h of sleep was stronger in the low CSI subgroup compared to the high CSI subgroup. Otherwise, all other HRV and actigraphy parameters and subjective measures of central sensitization, disability, kinesiophobia, the effect of pain on sleep, and quality of life showed only little associations.

DISCUSSION

The high CSI subgroup reported significantly more severe symptoms of disability, kinesiophobia, sleep, and quality of life compared to the low CSI subgroup. However, there were only small and nonsignificant trend in increased sympathetic nervous system activity and poorer sleep quality on the high central sensitization subgroup. Moreover, very little differences in respiratory rates were found between the groups.

Effects of sleep quality on pain, cognitive factors, central sensitization, and quality of life in patients with chronic low back pain

BACKGROUND

Sleep quality in patients with chronic low back pain (CLBP) may affect quality of life (QoL), possibly due to worsening pain, central sensitization (CS), and cognitive factors. However, causal relationship among the factors has not been confirmed yet.

OBJECTIVE

The purpose of this study was to test the hypothesis that sleep quality in patients with CLBP is attributable to pain, cognitive factors, and CS, and influences QoL, by structural covariance analysis.

METHODS

This is a cross-sectional study. Participants were recruited from six health care facilities and 101 patients with CLBP were included. Structural covariance analysis assessed the fit of data to the model using goodness of fit index (GFI), adjusted goodness of fit index (AGFI), comparative fit index (CFI), and mean squared approximation error (RMSEA).

RESULTS

The structural covariance analysis showed that the goodness-of-fit indices were high (GFI = 0.993, AGFI = 0.964, CFI = 1.00, RMSEA < 0.01). Sleep quality was not directly influenced by QoL but rather by CS and cognitive factors.

CONCLUSION

This study suggests that sleep quality in patients with CLBP is indirectly mediated through multiple pathways, including cognitive factors and CS, which may influence QoL.

Impact of central sensitization on pain, disability and psychological distress in patients with knee osteoarthritis and chronic low back pain

BACKGROUND

Central sensitization (CS) is becoming increasingly recognized as a significant factor in many chronic pain conditions, including knee osteoarthritis (KOA) and chronic low back pain (CLBP). Yet it presently remains unclear how strong is the involvement of CS in KOA and CLBP and which factors are involved in CS in these two chronic disabling diseases.

METHODS

This is a cross-sectional study in which included a total of 178 patients with KOA and 118 patients with CLBP. Inclusion criteria for eligible participants for the KOA group were a confirmed diagnosis of KOA according to the American College of Rheumatology criteria, and for the CLBP group a chronic low back pain for more than 3 months. Subjects were excluded if they presented with a diagnosed psychiatric disorder or if they lacked the capacity to provide informed consent, understand study questionnaires or perform physical performance tests. In each group, were assessed; CS-related symptoms using the Central Sentization Inventory (CSI); demographic and clinical characteristics such as disease duration, pain intensity on a visual analog scale, self-reported function using the Lequesne index for KOA patients and the Oswestry Disability index for CLBP patients, and physical performance with the 6 minutes' walk test; as well as psychosocial risk factors using the Patient Health Questionnaire for depression (PHQ-9), the Generalized Anxiety Disorder (GAD-7) and the Pain Catastrophizing Scale (PCS).

RESULTS

CSI scores significantly correlated with pain intensity and disability in KOA and CLBP patients, and were highly correlated with self-reported symptoms of depression, anxiety and pain catastrophizing. Depression significantly predicted the CSI score in both groups.

CONCLUSION

These findings provide further evidence for the impact of CS on pain, function and physical performance in KOA and CLBP patients. Psychosocial symptoms such as pain catastrophizing, anxiety and depression should also be considered as they are also associated with CS.