Bodily Changes and Sensory Sensitivity in Complex Regional Pain Syndrome and Fibromyalgia

Pain. 2020 Jun;161(6):1361-1370. doi: 10.1097/j.pain.0000000000001830.

Abstract

Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions of unexplained origins. In addition to symptoms in the diagnostic criteria, patients can report changes to vision and other sensations or bodily functions. It is unclear whether these are greater than would be expected due to normal ageing, living with chronic pain generally, or common comorbidities of chronic pain such as depression or anxiety. We administered an on-line survey evaluating the frequencies and types of self-reported somatic symptoms, bodily changes, and sensory sensitivity in respondents with CRPS (n = 390), fibromyalgia (n = 425), and both CRPS and fibromyalgia ("CRPS+fibromyalgia"; n = 88) compared to respondents with other chronic pain conditions (n = 331) and pain-free controls (n = 441). The survey assessed somatic symptoms (Patient Health Questionnaire-15), bodily changes, pain/discomfort/distress triggers, and pain intensifiers. We conducted analysis of covariance's with age, sex, Patient Health Questionnaire-9 (measuring depression), Generalized Anxiety Disorder-7, pain duration in years, hours of pain per day, and number of pain-related medical diagnoses as covariates. After controlling for covariates, respondents with CRPS and/or fibromyalgia reported more somatic symptoms, changes in movement and biological responses, pain/discomfort/distress triggers, and pain intensifiers than pain(-free) control groups. Fibromyalgia specifically related to changes in vision and hearing, urinary/intestinal function, and drinking and eating. Complex regional pain syndrome related to changes in hair, skin, and nails; and infection and healing. The CRPS+fibromyalgia group presented with features of both disorders with minimal additional stressors or symptoms over and above these. Our findings suggest that CRPS and fibromyalgia share underlying pathophysiologies, although specific mechanisms might be different.