Understanding the impact of widespread pain on women's health and wellbeing

Chronic pelvic pain is highly burdensome in women, yet too often, treatments targeting the periphery are ineffective at managing such pain. While advances have been made in improving our understanding of chronic pelvic pain, an underexplored area is extra-pelvic, or widespread pain. Within this thesis, I used body maps, validated questionnaires, and psychophysical pain testing (i.e. conditioned pain modulation and quantitative sensory testing) to characterise widespread pain and its associated burden in women with chronic pelvic pain. In a small cohort of women with endometriosis and chronic pelvic pain, I used the body map to characterise extra-pelvic pain. In this cohort I investigated the relationship between widespread pain and psychological health measures, such as pain catastrophizing, depression, and anxiety. I further investigated the number of comorbid pain conditions and other comorbidities, and importantly, reproductive outcomes, with respect to widespread pain. I found a significant relationship between widespread pain and poor psychological health; however, no significant association was observed with the other factors. This chapter generated important hypotheses upon which this thesis is grounded. The relationship between chronic pain and reproductive outcomes is not well understood. In this thesis, I explored the relationship between reproductive outcomes and chronic pain, as well as different classes of pain conditions, using data from the UK Biobank. Chronic pain was shown to be associated with an increased odds of miscarriage, and further, when stratifying chronic pain conditions by their underlying mechanisms, those with an inflammatory chronic pain diagnosis had an increased odds of being nulliparous. Sensory perturbations have been demonstrated in individuals with widespread pain. In this thesis, I investigated sensory perception and descending pain modulation in women with chronic pelvic pain and a widespread pain phenotype. However, contrary to my hypotheses, minimal alterations in sensory processes were observed with increasing pain spread. Finally, conditioned pain modulation is a widely used paradigm to understand descending pain inhibition. However, protocol standardisation, reliability and covariates influencing conditioned pain modulation are not well established. In this thesis, I explored the reliability and covariates which may influence a well-established conditioned pain modulation paradigm in women with chronic pelvic pain and healthy controls. Although the paradigm was reliable in this cohort, I could not identify a single covariate which explained why so few women exhibited inhibition. Overall, the aim of this thesis was to advance our understanding of widespread pain in women with chronic pelvic pain. Adequate management of all their symptoms is of the utmost importance to women suffering from such pain, and novel methods of pain phenotyping, such as widespread pain, may shed light on areas of clinical importance which could ultimately improve patient outcomes.