Fibromyalgia (FM) is a chronic pain condition characterized by widespread musculoskeletal pain, tenderness to pressure, and a constellation of symptoms such as fatigue, sleep difficulties, and cognitive dysfunction. Recent evidence showed that FM patients exhibit increased sensitivity to sensory stimulation that is not limited to nociceptive stimuli, such as noxious heat or pressure over thumbnail, but also to non-noxious auditory stimulus. This is likely related to the aversive component of these sensory stimuli, which might underlie such enhanced sensitivity in FM patients. This ongoing study assessed the effect of two sensory stimuli of matched unpleasantness, one painful (blunt pressure) and one non-painful (screeching sound), on insular cortex activation during functional magnetic resonance imaging (fMRI). Eight female FM patients and seven age- and sex-matched healthy controls (HC) participated in two experimental sessions: i. psychophysical testing where both stimuli were presented in an intermingled fashion in order to match their unpleasantness level based on 1) subjective ratings using the pain unpleasantness Gracely Box scale, and 2) a behavioral escape paradigm; ii. fMRI data acquisition using both stimuli at the levels found during the psychophysical session. We hypothesized that both stimuli when matched to unpleasantness subjective ratings would elicit similar insular cortex activations for FM patients and controls. No brain activations were found for blunt pressure in any group, while the auditory stimulus elicited activations in the insular cortex for both groups (FM: MNI coordinates (x,y,z) -47, -17, -4, Z-score = 5.89; HC: MNI coord 42,-23,-1, Z-score = 7.8) as well as in the secondary somatosensory cortex (FM: MNI coord -61, -18, 2, Z-score = 8.64; HC: MNI coord -58, -30, 8, Z-score = 5.96). Our results are consistent with the role of the insular cortex in processing aversive sensorial stimuli. In this preliminary report, both groups exhibited insular cortex activation. Ongoing recruitment of FM and HC subjects is planned reaching a sample size of 60 subjects (30 per group). This should increase this study’s statistical power and allow further exploration of brain activation to painful and non-painful sensory stimuli in the insular and somatosensory cortices.
|Original language||English (US)|
|Media of output||Poster|
|Place of Publication||New Orleans, LA. USA.|
|State||Published - 2012|