Structural and functional MRI studies of pain behaviour, selective attention and fear of pain in pain-free volunteers and chronic low back pain patients

The aim of the original work presented in this thesis was to investigate morphological and functional differences in clinical and control populations, which may negatively impact the experience of pain. Firstly, morphological differences were investigated between groups of healthy controls and chronic low back pain (CLBP) patients. Included in the latter were subgroups of patients not previously investigated in the current morphological literature, those with and without pain behaviour. We investigated differences in gray matter (GM) volume between groups using an automated whole brain technique, and a manual method applied to two regions of interest, namely prefrontal cortex and insular cortex. A deficit in GM volume of right dorsal prefrontal cortex between CLBP patients and controls was found, with a further deficit in left insular cortex for CLBP patients with concomitant pain behaviour. Secondly, we conducted two studies using functional magnetic resonance imaging (fMRI) and a task of selective attention. Our initial investigation provided a proof of principle regarding the suitability of a semantic dot probe task within the fMRI environment. Pain-free participants were grouped based upon fear of pain scores. The results indicated differential behavioural and functional results between the groups. The thesis culminates with an fMRl study investigating selective attention in CLBP patients with pain behaviour. The clinical group were tested prior to and on completion of an intensive multidisciplinary pain management programme (PMP), with the aim of assessing if selective attention is sensitive to cognitive interventions. Selective attentional bias was demonstrated in the clinical group for pain-related trials at both testing sessions, although the direction of attention differed. Similarly, fMRI results showed differences in neural correlates for task performance between groups, with pre-PMP results demonstrating a reliance on semantic and memory processes. The fmdings suggest that fear of pain may be a vulnerability factor in the transition from acute to chronic pain and furthermore, CLBP patients with pain behaviour have structural, functional and behavioural differences which may negatively impact their ability to cope with their pain condition.EThOS - Electronic Theses Online ServiceGBUnited Kingdo