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Abstract

Background & Aims: Different studies report diminished baroreflex sensitivity (BRS) in fibromyalgia (FM) patients that interferes the signal relay to the nucleus tractus solitaries (NTS) associated with increased peripheral sympathetic stress responses and central sensitization in a hypertensive subgroup of FM. The present study examined central components of pain processing before and after systolic extinction training (SET) that combines operant behavioral therapy with baroreceptor training. SET aims at newprogramming of the NTS reflex arc in FM. Methods: 68 FM patients treated with SET, placebo-controlled, and compared with 32 healthy controls (HC). Evoked potentials (N50, N150, P260 and P390) to electrical stimuli of 3 different intensities were evaluated during either the systolic or diastolic peak of the cardiac cycle. Clinical pain, pain threshold and pain tolerance were assessed pre-, post- and at follow-up. Results: FM showed a pretreatment attenuation of early evoked potentials (N50, N150) that increased to HC levels after treatment (p<0.01). In addition, in FM both early and late evoked potentials were influenced by stimulus intensity (all p�s<0.01) before but not after treatment. At 6-12 months, the magnitudes of potentials evoked by all stimuli were similar to that evoked in HC at baseline. BRS, pain threshold and tolerance significantly increased after therapy and 82% of FM reported pain remission still 12 months after SET. Conclusions: Cardiac gated peripheral afferent stimulation combined with behavioral treatment may induce changes in central pain processing that lead to pain remission. SET activates both sensory and cognitive-affective brain regions to re-program pain inhibitory mechanisms.

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