Fibromyalgia is a major problem due to issues such as the impact on quality of life and the associated health and social costs. It is characterized by a generalized state of sensitization, with a high level of perceived pain, among other features. Peripheral pain sources potentially exacerbate the central sensitization and its symptoms of chronic diffuse musculoskeletal pain and hyperalgesia. It has been shown that visceral pain enhances the level of central sensitization typical of the syndrome. So, it has been claimed that systematic assessment and treatment of visceral pain comorbidities should be a part of the management strategy in fibromyalgia.~Patients with fibromyalgia present visceral comorbidities. Those comorbidities include that of peridiaphragmatic organs, which are supplied by the phrenic nerve among other innervations. It is known that peridiaphragmatic organs trigger referred pain in the neck area, via the phrenic nerves. So, the phrenic nociceptive afferences can be contributing to enhance the state of sensitization in fibromyalgia. This study aims to analyze the ability of phrenic nerve infiltration to diminish sensitization in subjects suffering fibromyalgia.~For this purpose, the investigators intend to perform a randomized clinical trial, assessing the effects on pain threshold to pressure, visual analogue scale, range of motion and fibromyalgia specific questionnaires. There will be only one intervention session. The experimental group will receive an ultrasound-guided anaesthetic infiltration of the phrenic nerve, while the control group will receive a placebo infiltration. A one-week follow-up, with intermediate measurements, will be carried out to assess the evolution of sensitization and symptomatology.~The results of this study will make it possible to establish the role of phrenic afferences in fibromyalgia sensitization, thus making it possible to specify a specific therapeutic target (phrenic nerve) as well as the importance of visceral treatment in subjects with fibromyalgia.
It is known that nociceptive afferences in visceral pain and visceral disorders increase sensitization in subjects suffering from fibromyalgia. These patients use to present visceral comorbidities. Those comorbidities include that of peridiaphragmatic organs, which are supplied by the phrenic nerve among other innervations. It is known that peridiaphragmatic organs trigger referred pain in the neck area, via the phrenic nerves. So, the phrenic nociceptive afferences can be contributing to enhance the state of sensitization in fibromyalgia. This study aims to analyze the ability of phrenic nerve infiltration to diminish sensitization in subjects suffering fibromyalgia, by means of a randomized controlled trial.