Fibromyalgia (FM) is a syndrome that is characterized by generalized musculoskeletal pain,
fatigue, unrepairable sleep, cognitive alterations, depressive and neurovegetative symptoms,
whose neurobiological process is multiple and complex. Although it is of great relevance to
the individual and to society, this pathology often does not receive the necessary attention
by the organs that define the priorities of health care. Population prevalence, according to
the criteria of the American Society of Rheumatology, reaches 5.4%, and the costs of care,
taxes and early retirement due to disability are estimated at more than the US $ 29 billion
per year in the United States. It is known that conventional pharmacological therapies
produce insignificant responses in more than 50% of patients. It is postulated that these
high rates of failure are due in part to a lack of knowledge about pathophysiological
mechanisms. What is known so far is that the peripheral mechanisms contribute to the FM
picture, but dysfunction in central neurobiological pathways surely commands the process,
perpetuating the dysfunctional process that includes central sensitization (CS). CS comprises
the symptoms of fibromyalgia syndrome that culminates in a state of hypersensitivity that
expresses the imbalance of the excitation/inhibition processes that sustain this condition of
non-pathological pain. Functional alterations of the motor cortex and its connections with
subcortical structures that constitute the neuromatrix of pain have now been demonstrated.
Functional magnetic resonance imaging (fMRI), using the resting-state fMRI (rs-fMRI)
technique, has also demonstrated that high intrinsic functional connectivity (IFC) is related
to pain intensity on FM.
Considering the central component of FM, the focus of research on current therapeutic
approaches has been techniques that may modify the dysfunctional neuroplasticity process,
such as transcranial direct current (tDCS) stimulation in order to counteract the dysfunction
responsible for triggering and maintain the symptoms of FM. Although this technique is
gaining space in research and in the clinical scenario, many questions remain to be answered,
such as time of treatment, place to be stimulated and neurophysiological clarification of the
mechanisms involved.
Based on the presented scenario, the present project was organized, being a double-blinded
parallel randomized controlled trial with 20 female patients with FM diagnosed according to
the criteria of the American Society of Rheumatology (2010 - reviewed in 2016) between 19 and
65 years of age, randomized to receive active or simulated anodic pole over the left
dorsolateral prefrontal cortex (DLPFC) (10 patients in each group). Twenty 20 minute
sessions, with a current intensity of 2 milliampere, will be performed.
In order to respond to the objectives of this study, the IFC will be evaluated before and
after the intervention, through rs-fMRI using seed-based correlation analysis (SCA). The
investigators have a secondary objective to correlate structural connectivity through the
technique of diffusion tensors imaging (DTI) with measures of pain, functional capacity,
depressive symptoms and catastrophism to pain.
The hypothesis is that in FM there is a syndrome of dysfunction in basal IFC and that the
tDCS has a neuromodulatory effect capable of reducing connectivity between brain areas
related to chronic pain and other neuropsychiatric components of FM, such as the
ventrolateral thalamus, cortex motor, prefrontal cortex, insular cortex, hippocampus,
periaqueductal gray matter, among others. The investigators believe that a higher
cortico-thalamic IFC and between regions with high density of opioid receptors have a
positive predictive response in the treatment of tDCS.
If the hypothesis is proven, the IFC data may serve as a biological marker associated with
the perception of pain and its clinical presentation, and consequently, open the possibility
of including IFC as a diagnostic parameter and therapeutic response. In addition to the
possible contribution to knowledge production, this project aims to transfer the technology
acquired and developed to the community, and thus benefit millions of people suffering from
chronic FM pain with limited diagnostic and therapeutic perspectives, as well as extending
the knowledge acquired for other neuropsychiatric disorders, such as depression.