Huysmans E.1,2, Ickmans K.1,3, Van Dyck D.4, Nijs J.1,3, Gidron Y.5,6, Roussel N.7, Polli A.1, Moens M.5,8,9, Goudman L.8,9, De Kooning M.1,3,7
1Vrije Universiteit Brussel, Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy (KIMA), Brussels (Jette), Belgium, 2Vrije Universiteit Brussel, Department of Public Health (GEWE), Brussels (Jette), Belgium, 3Universitair Ziekenhuis Brussel, Department of Physical Medicine and Physiotherapy, Brussels (Jette), Belgium, 4Private Practice, Tom Cools, Schelle, Belgium, 5Vrije Universiteit Brussel, Center for Neurosciences, Brussels (Jette), Belgium, 6Vrije Universiteit Brussel, Department of Pharmacology and Pharmacokinetics, Brussels (Jette), Belgium, 7Universiteit Antwerpen, Faculty of Medicine, Antwerpen (Wilrijk), Belgium, 8Universitair Ziekenhuis Brussel, Department of Neurosurgery, Brussels (Jette), Belgium, 9Vrije Universiteit Brussel, Department of Manual Therapy (MANU), Brussels (Jette), Belgium

Background: Chronic nonspecific low back pain (CLBP) is a major problem in today's society. Central sensitization (CS) can be present in certain patients with CLBP and might explain their pain and symptoms. (Nijs et al., 2014; Nijs et al., 2015) It remains to be established why CS is only present in some patients with CLBP. Genetic predisposition and influence of psychosocial and cognitive behavioral factors, such as, depressive feelings, pain catastrophizing or fear avoidance behavior, and more specifically kinesiophobia have been reported in patients with CLBP. These factors may enhance central hyperexcitability through the activation of limbic brain regions, which in turn contributes to and sustains CS. (Roussel et al., 2013; Lloyd et al., 2008)

Purpose: The first objective was to analyze the associations between symptoms of CS and pain behavior, functioning, pain intensity, illness perceptions, kinesiophobia and pain catastrophizing in people with CLBP. Secondly, this study aimed to compare the aforementioned outcomes between patients either showing or not showing clinically relevant symptoms of CS.

Methods: Participants with CLBP for at least three months were included in this cross-sectional study. Outcome measures were the amount of symptoms of CS (Central Sensitization Inventory), pain behavior (1-minute stair climbing test), functioning (Quebec Back Pain Disability Scale), pain intensity (100mm Visual Analogue Scale), pain catastrophizing (Pain Catastrophizing Scale), kinesiophobia (Tampa Scale for Kinesiophobia) and illness perceptions (Brief Illness Perception Questionnaire). Pearson’s correlations were used to analyze associations between symptoms of CS and the remaining outcomes. Additionally, a between groups analysis was performed to compare patients with and without clinically relevant symptoms of CS.

Results: Data from 38 subjects were analyzed. Significant associations were found between symptoms of CS and all other outcomes, especially with current pain (r=0.510; p=0.001), mean pain during the last seven days (r=0.505; p=0.001) and pain catastrophizing (r=0.518; p=0.001). Patients with clinically relevant symptoms of CS (n=12) scored significantly worse on all outcomes compared to persons with less symptoms of CS (n=26), except for the Quebec Back Pain Disability Scale (p=0.128).

Conclusion(s): In patients suffering from CLBP significant relations between the presence of symptoms of CS and pain, pain behavior, functioning, pain catastrophizing, kinesiophobia and illness perceptions were found. These results are in line with findings of previous trials in different chronic pain populations. A clinically relevant amount of symptoms of CS was only present in a subgroup of the investigated sample. In general, patients showing more symptoms of CS had significantly worse scores on the outcome measures compared to patients with less symptoms of CS.

Implications: By unraveling the relationship between certain biopsychosocial factors and CS in patients with CLBP, more targeted interventions could be integrated in their treatment, which might lead to better outcomes for this population. On the one hand biopsychosocial factors might contribute to, cause and maintain the CS process. On the other hand, CS, whether partly genetic or learned, might also be a driving force of such biopsychosocial factors. This study is a first attempt to unravel these relationships and mechanisms, on which larger studies can build further.

Funding acknowledgements: Study funded by Nervomatrix Ltd.,Israel.
Eva Huysmans, is a PhD fellow of the Agency for Innovation by Science and Technology,Belgium.

Topic: Pain & pain management

Ethics approval: The protocol was approved by the local ethics committee of the Universitair Ziekenhuis Brussel/Vrije Universitiet Brussel.

All authors, affiliations and abstracts have been published as submitted.

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