FIbromyalgia anD GenetIcs Subgroups (FIDGIS)

"This intervention measures the response to electrical stimulation of the sural nerve using a pair of percutaneous electrodes placed at the external malleolar retro passage of the nerve (2 cm apart) and connected to the stimulation device (Nicolet Vicking). Reflex muscle responses will be collected using surface electrodes placed on the femoral biceps muscle of the participant and connected to an Electromyogram recording device.~The RIII will be determined twice (rest period between each 10-minute). In order to induce the reflex nociceptive flexion response, repeated cutaneous electrical stimulations (30 to 40) will be applied at the level of the sural nerve following a variable interval of 6 to 10 seconds in order to overcome the phenomena of habituation and predictability. Each stimulus test will consist of a single rectangular pulse of 0.5 ms, of variable intensity (0-100mA) until a reflex nociceptive flexion threshold is detected or a maximum current of 100 mA is reached"