Association between baroreflex function and pressure pain threshold in women with fibromyalgia

The aim of this study is to evaluate the relationship between baroreflex function and pain in women with fibromyalgia syndrome (FMS). Ten women with clinical diagnosis of FMS took part in the research. The ECG and blood pressure were continuously recorded on a beat to beat basis in supine and orthostatic postures. Coherence between SAP and RR variability (K²_SAP-RR) and baroreflex function (index α) were quantified. Pressure pain threshold (PPT) was determined at 18 specific tender points distributed all over the body, using a digital algometer. Correlation analysis showed positive relationship between PPT and K²_SAP-RR sampled at high frequency (HF) band in the orthostatic posture (r = 0.67; p = 0.03). This result suggests that the higher is the coupling between SAP and RR series in HF band during orthostatic posture, the higher is the pressure needed to FMS participants to begin feeling pain.