Pain
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In order to assess the function of endogenous mechanisms modulating somatosensory input in fibromyalgia (FM), the effect of vibratory stimulation (VS) and heterotopic noxious conditioning stimulation (HNCS) on perception of various somatosensory modalities was assessed. Ten female FM patients and 10 healthy, age-matched, females participated. VS (100 Hz) was applied to the left forearm for 45 min and quantitative sensory testing (QST) was performed within the vibrated area and in the right thigh before, during and 45 min following vibration. ⋯ Decreased sensitivity to non-painful cold (P < 0.001) and non-painful warmth (P < 0.001) was seen during and following (P < 0.001; P < 0.05, respectively) the tourniquet in both groups alike. HPTs and perception of suprathreshold heat pain remained unaffected in both groups. In conclusion, FM patients did not differ from healthy controls in their response to vibration, but no modulation of pressure pain was induced by HNCS, as opposed to controls, suggesting a dysfunction in systems subserving 'diffuse noxious inhibitory controls' (DNIC).