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Coppieters I.1, De Pauw R.1, Caeyenberghs K.2, Danneels L.1, Kregel J.1, Lenoir D.3, Meeus M.1,4, Cagnie B.1
1Ghent University, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent, Belgium, 2Australian Catholic University, School of Psychology, Faculty of Health Sciences, Melbourne, Australia, 3Ghent University, Department of Rehabilitation Sciences and Physiotherapy, Ghent, Belgium, 4University of Antwerp, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Antwerp, Belgium
Background: Patients with chronic whiplash associated disorders (CWAD) are characterized by persistent pain of traumatic origin, cognitive deficits and central sensitization (CS). Previous neuroimaging studies revealed altered grey matter volume (GMV) in traumatic brain injury patients and chronic pain patients with other central sensitivity syndromes. Furthermore, these studies showed relations between altered GMV, and symptoms of cognition and pain. It can therefore be hypothesized that GMV alterations also play a role in the diversity and persistence of complaints in CWAD. However, brain alterations as well as the impact of trauma remain poorly investigated in these patients.
Purpose: The present study aimed to quantify alterations in regional GMV in CWAD compared to non-traumatic chronic idiopathic neck pain (CINP) patients and healthy controls. Additionally, relations between regional GMV, and measures of cognition, pain, and CS were examined.
Methods: Ninety-three women (28 healthy controls, 34 CINP, 31 CWAD) were enrolled. First, T1-weighted Magnetic Resonance Images (MRI) of the brain were acquired. Cortical and subcortical regions involved in processing of cognition and pain were examined to evaluate GMV alterations. Next, cognitive deficits, maladaptive pain cognitions and CS symptoms were assessed. Finally, local and distant hyperalgesia, and efficacy of conditioned pain modulation were examined. Analyses of Covariance with age as covariate were performed to explore differences in GMV.
Results: Regional GMV (orbitofrontal, supramarginal, posterior cingulate cortex) was decreased in CWAD compared to healthy controls (p=0.023; p=0.012; p=0.047). In addition, GMV of the superior parietal and posterior cingulate cortex was decreased in CWAD compared to CINP patients (p=0.008; p=0.035). Lower GMV in cognitive and pain processing regions correlated with higher cognitive deficits, maladaptive pain cognitions, CS symptoms, and local hyperalgesia in CWAD patients (rs= -0.515 to -0.657; p 0.01). Furthermore, lower GMV in cognitive and pain processing regions correlated with higher cognitive deficits in CINP patients (rs= -0.499 to -0.619; p 0.01).
Conclusion(s): The present innovative study provides the first evidence for decreased GMV in cortical regions associated with pain and cognitive processing in patients with CWAD compared to CINP and healthy women. In contrast, GMV alterations were not observed in the CINP group. Additionally, lower GMV in cognitive and pain processing regions was correlated with higher cognitive deficits, maladaptive pain cognitions, CS symptoms, and local hyperalgesia in CWAD, and only correlated with cognitive deficits in CINP. These findings indicate a possible negative role of trauma in CWAD. The underlying neurobiological mechanisms of these GMV alterations remain to be elucidated. No conclusions can be drawn on the causality of the observed relations. Accordingly, further research is warranted.
Implications: Cognitive deficits, maladaptive pain cognitions, and features of CS seem to be associated with distinct GMV decrease in regions implicated in processing of cognition and pain in CWAD patients. Therefore, assessment and therapy approaches for CWAD should address the brain and take into account neuroplasticity of the central nervous system. Pain neuroscience education and cognitive behavioural therapy are recommended and are demonstrated to reverse regional GMV decreases related with reduced pain and cognitive deficits in other central sensitivity syndromes.
Funding acknowledgements: Iris Coppieters is funded by the Special Research Fund of Ghent University (BOF-Ghent; BOF13/DOC/276).
Topic: Musculoskeletal: spine
Ethics approval: The local Ethics Committee of the Ghent University Hospital (EC/2013/1053) approved the research protocol.
All authors, affiliations and abstracts have been published as submitted.
