Whiplash injuries: how a momentary impact can result in long-term consequences: Investigating psychosocial characteristics, pain processing and cerebral mechanisms following a whiplash injury

Onderzoeksoutput: PhD Thesis

Samenvatting

The current dissertation tried to unravel the contributing pathophysiological mechanisms behind the complex clinical picture of patients suffering from chronic whiplash associated disorders (CWAD). Previous studies have provided ample evidence for the importance of central sensitization (CS) in chronic pain patients in general, and in patients with CWAD in specific. In addition, previous studies have indicated the importance of brain characteristics in the understanding of the symptomatology reported by patients with chronic (neck) pain. Moreover, many researchers have hypothesized a link between pain, cerebral mechanisms, and psychosocial variables. To elucidate these pathophysiological mechanisms and relationships, we investigated outcomes of quantitative sensory testing (QST), brain connectivity, somatosensory processing and psychosocial characteristics of chronic pain patients in general, and of patients with CWAD in specific. In addition, we formulated guidelines for the classification, assessment and treatment of patients with WAD.
This dissertation was structurally divided into three parts, and will be discussed as such hereafter.
PART I: Psychosocial characteristics and pain processing in patients with CWAD The first study aimed to investigate the relationships between psychosocial characteristics and pain processing in patients with CWAD, and investigated differences in QST outcomes between patients with CWAD and healthy controls. Based on the results of this study, we were able to identify the importance of self-reported outcome measures, and more specifically of self-reported psychological measures, in relation to QST outcomes (including pain thresholds and temporal summation) in patients suffering from CWAD. Results of decreased pain thresholds at both wrists and increased self-reported symptoms of CS suggested a role for CS in the underlying pathophysiological processes of CWAD.
PART II: Cerebral mechanisms in chronic pain patients in general, and patients with CWAD in specific The first objective of part II was to investigate differences in brain connectivity, based on graph measures, between chronic pain patients and healthy controls. This systematic review included the general chronic pain population due to a lack of such studies in patients with CWAD. Differences between chronic pain patients and healthy controls could mostly be observed in global graph measures of connectivity. Differences in nodal graph measures were observed, but were mostly based on single studies. Both the global as nodal changes in connectivity often involved the limbic network or other regions involved in emotions and cognitions. Additionally, significant correlations were found between several nodal and global graph measures, and clinical outcomes related to pain, disability and motor control, which indicates the relevance of looking at the brain of chronic pain patients on a network level.
The second objective of part II was to investigate the processing of nociceptive stimulation in the chronic pain population in general (based on a systematic review), and in patients with CWAD in specific (based on an original study), using electroencephalography (EEG). From the systematic review it could be concluded that differences in characteristics of event-related potentials (namely amplitude and latency) between chronic pain patients and healthy controls can mostly be found in those patients suffering from neuropathic pain or other types of chronic pain that involve small fibre dysfunction. Relationships between the EEG outcomes and perceived pain intensity, as a result of the nociceptive stimulation, were only reported in a very limited amount of studies, and a (positive) relation was only found by 1 study which was performed in a group of patients with fibromyalgia. As expected, this correlation indicated that a stronger amplitude of the event-related potential coincided with the experience of a stronger nociceptive stimulus.
A translation of this latter research to the CWAD population revealed a prolonged latency of the P3 component, which is suggestive for decreased integrity of the nociceptive pathway, or impairment of small fibre function. In addition, the characteristics of event-related potentials seemed to be influenced by the intensity of the applied stimulus, the severity of self-reported symptoms of CS, and the intensity of the worst pain reported during the past week.
PART III: A therapeutic approach for patients suffering from WAD The last part of this dissertation aimed to provide guidelines for classification, assessment and treatment of patients with WAD, based on the results of an umbrella review. It could be concluded that current clinical practice guidelines for patients with WAD mostly recommend classification based on the Quebec task force guidelines and the stage of the disorder. Treatment recommendations are currently only tailored to the stage of the disorder, and mainly include education, multimodal care and exercise therapy. It can therefore be concluded that current guidelines for patients with WAD are not as extensive as recommendations for other patient populations and that further research into the added value of patient-tailored approaches is needed.
Given the methodological considerations raised in this dissertation, future additional research is needed to corroborate the current findings. Future studies using QST outcomes should include stimuli of different modalities and should include both static as dynamic QST measures. For future assessment of functioning of the nociceptive afferent pathways, the use of laser-evoked potentials (which can selectively recruit Aδ- and C-fibres instead of Aβ-fibres) should be preferred over somatosensory evoked potentials. Lastly, future studies including patients suffering from CWAD should consider to evaluate small fibre integrity to enable adequate interpretations of study results concerning somatosensory processing.
Originele taal-2English
Toekennende instantie
  • Vrije Universiteit Brussel
  • Ghent University
Begeleider(s)/adviseur
  • Cagnie, Barbara, Promotor, Externe Persoon
  • Meeus, Mira, Promotor, Externe Persoon
  • Ickmans, Kelly, Promotor
  • Coppieters, Iris, Promotor
Datum van toekenning30 mrt 2022
StatusPublished - 2022

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