(326) Classification of brain activity response to painful heat stimuli in fibromyalgia patients and healthy controls

Abstract

Hypersensitivity and other alterations in sensory processing occur in patients suffering from fibromyalgia syndrome, although the exact nature of how sensory processing contributes to these differences remains unclear. Investigating differences in acute pain processing in fibromyalgia could potentially help uncover mechanisms by which chronic pain processing is modified in fibromyalgia patients. Our recent study used a multivariate approach to demonstrate that brain activity can be used to validate various levels of painful and non-painful heat stimuli in healthy individuals.1 Our goal here was to extend this approach to classify levels of painful heat stimuli in a chronic pain population. Subjects (10 healthy controls, 9 fibromyalgia patients) completed a quantitative sensory testing (QST) session to determine individualized temperatures evoking pain levels of 5 and 7 (visual analog scale, VAS, 0-10). Functional MRI scans and VAS pain ratings were collected while subjects underwent painful heat stimuli on their lower right leg, using individualized temperatures to match heat pain levels across patients and healthy controls. Our preliminary conventional analyses show significant differences in brain activity in response to moderate (VAS pain level 5) and high (VAS pain level 7) levels of heat pain across all subjects. Further analyses will aim to use a multivariate approach (support vector machine, SVM) to classify levels of painful heat stimuli and distinguish between brain activity evoked by acute pain in fibromyalgia patients versus in healthy controls. Our future goal is to identify a signature pattern of brain activity response to acute heat pain that is able to differentiate between fibromyalgia patients and healthy controls. (1. Brown, J.E., et al., Towards a physiology-based measure of pain: patterns of human brain activity distinguish painful from non-painful thermal stimulation. PLoS One, 2011. 6(9): p. e24124.)