FIbromyalgia anD GenetIcs Subgroups (FIDGIS)
Condition: Fibromyalgia
MeSH terms: Fibromyalgia; Myofascial Pain Syndromes
Study type: Interventional

Summary: 
      Fibromyalgia syndrome (FS) is characterized by widespread pain and affect 0.5 to 5 % of the
      general population, with a higher prevalence in women. Recognized as disease by World Health
      Organization since 1992, FS concern 1.2 to 2 million of French people and his etiology need
      to be clarified. This affection is characterized by a higher sensitivity to nociceptive
      stimulus, articular and muscular pain and associated to: fatigue, headache, sleep disorders,
      depression and irritated bowel syndrome. The presentation of this symptoms varied according
      to the patient with a heterogeneity of the clinical, physical, social and psychologic
      conditions and of the therapeutic responses.

      Faced to the heterogeneity of FS, various hypotheses about the development mechanisms exist.
      Central sensitization could be one of the key mechanisms of FS, it is described as a loss of
      the natural balance between the transmission of a painful stimulus to the central nervous
      system and pain-inhibiting mechanisms, which results in permanent or chronic pain.

      Moreover, work on the familial character of FS suggests that a genetic component may be
      involved in its development, but the identification of a genetic determinant is difficult
      given the multifactorial nature and complexity of FS.

      The objective of this study is to characterize the predispositions of central sensitization
      and genetics in patients with FS compared to a control group, matched in age, sex and
      menopausal status.
    

Detailed description: 
      This is an exploratory case control pathophysiology study of psychophysical (central
      sensitization assessment) and genetic (candidate gene panel) characteristics.

      The main objectives of this study are :

      Primary: Evaluate the central nociception sensitization characteristics and genetic
      determinants in fibromyalgic syndrome, comparing a group of patients to matched healthy
      controls.

      Secondary :

        -  1) Characterize genetic predispositions of central sensitization in patients with FS
           compared to matched healthy controls, including confirmation of known genetic markers
           and potential identification of new genetic variants involved,

        -  2) Compare in the area of central sensitization the population of patients with FS and
           matched healthy controls,

        -  3) Compare in the domain of temporal summation the population of patients with FS and
           matched healthy controls,

        -  4) Describe in the clinical field the characteristics of the FS patient population,

        -  5) Compare in the areas of quality of life, anxiety/depression and comorbidities,
           characteristics of the FS patient population and matched healthy controls,

        -  6) Compare epigenetic biomarkers of the FS patient population with healthy matched
           controls,

        -  7) Study of the role of the gut microbiota in patients with FS (bio banking)

        -  8) Compare in the areas of pain, sound and light sensitivity the population of patients
           with FS and matched healthy controls.
    

Intervention name(s): Electrophysiological measurement of reflex nociceptive flexion threshold (RIII reflex) using Nicolet Vicking device
Intervention type(s): Device
Intervention description(s): 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
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Intervention model description: Exploratory case control pathophysiology study of psychophysical (central sensitization assessment) and genetic (candidate gene panel) characteristics.
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Fibromyalgia syndrome; Chronic pain; Widespread pain; genetics; central sensitization