It has been proposed that fibromyalgia can be understood as a disorder of central sensitisation and dysregulation (CD) and that characteristic somatic symptoms are the result of 'central augmentation'. We examined this hypothesis by analysing sensory and non-sensory variables in the context of the updated (2010) American College of Rheumatology definition of fibromyalgia and the fibromyalgianess (polysymptomatic distress) scale.
We studied 11,288 patients, including those with fibromyalgia, rheumatoid arthritis (RA) and osteoarthritis (OA). We divided somatic symptoms into sensory (hearing difficulties) and evaluative (easy bruising and hair loss) non-sensory symptoms, and included a non-symptom that was neutral as to psychological content or meaning (influenza vaccination). Data were analysed by logistic regression and adjusted for age and sex.
Fibromyalgia patients reported more sensory and non-sensory symptoms than patients with RA and OA, but not more non-symptoms. At all levels of fibromyalgianess (or fibromyalgia intensity) the probability of sensory and non-sensory symptoms was similar across all rheumatic diseases, and this association occurred in FM criteria (+) and criteria (-) patients. No association was noted with the non-symptom control question.
While the CD hypothesis is consistent with hearing problems in fibromyalgia, there is no medical explanation for the evaluative symptoms of hair loss and bruising being increased. The associations between fibromyalgia/fibromyalgianess and evaluative (not sensory) symptoms must occur through mechanisms other than central sensitization and augmentation, and are consistent with over-reporting that has a psychological basis. However, augmentation of sensory symptoms does not preclude simultaneous over-reporting.