Fibromyalgia is a multidimensional disease, as many factors contribute to its development
(biological, genetic, psychosocial). As a result, it demands a multifaceted approach,
from patient education to pharmacological treatment etc. Regarding the pharmacotherapy,
that should be aimed at a mechanism-oriented fashion. [7] Consistent with this approach,
centrally acting medications can be effective in fibromyalgia, particularly
antidepressants and anticonvulsants, which increase the presence of pain-inhibitory
neurotransmitters by facilitating descending pathways and decreasing dorsal horn
sensitization, or decreasing systemic hyperexcitability. Clinical trials have failed to
conclusively provide overall benefits of specific therapies to treat fibromyalgia.
Therefore, current pharmacological treatments for patients suffering from this syndrome
are mainly directed to palliate some symptoms, with relevant clinical benefits
experienced only by a minority of individuals.
In those treated with pharmacotherapy, a 50% reduction in pain intensity is generally
achieved only by 10% to 25%. However, some treatments seem to significantly improve the
quality of life of certain FM patients. Only a few drugs have been approved for use in
the treatment of FM by the US Food and Drug Administration (FDA), whereas no drug has
been approved for this indication by the European Medicines Agency. Thus patients with FM
frequently need to be treated on an off-label basis. Currently, only 25% to 40% pain
reduction is granted by drugs and meaningful relief occurs in only 40% to 60%, in part
due to dose-limiting adverse effects and incomplete drug efficacy. These limitations in
clinical practice have led some to hypothesize that a combination of different analgesic
drugs acting through different mechanisms may provide superior outcomes compared to
monotherapy. Moreover, drugs should be started at low doses and cautiously titrated
because severalpatients, either do not tolerate or benefit from drug therapy. Because
sleep disturbance, pain and psychological distress are the most amenable to drug therapy,
drugs should be chosen to manage the individual's predominant symptoms. Currently,
several drugs are frequently used alone or in combination to manage FM symptoms. However,
the US FDA indicated for FM only three: two selective serotonin and norepinephrine
reuptake inhibitors (SNRIs), duloxetine and milnacipran as well as an anticonvulsant,
pregabalin. Although clinical evidence demonstrating the efficacy or effectiveness of
opioids analgesics is scanty, these molecules are widely used for the treatment of FM.
However, the long-term use of opioids in FM has been discouraged by several medical
guidelines. As a result, there comes a need of a new treatment of fibromyalgia syndrome,
which will be effective, safe, easily applied, with almost no side effects and low cost.
Non-invasive neuromodulation techniques are gaining more and more the interest of the
scientific society as regards a variety of medical conditions, such as chronic pain,
epilepsy, rheumatoid arthritis. Transcutaneous Vagus Nerve Stimulation (tVNS) is one of
these new techniques.
The parasympathetic vagus nerve (10th cranial nerve) innervates multiple internal organs
and integrates sensory, motor, and autonomic information by four vagal nuclei. The
primary central relay of vagal afferents is the nucleus of the solitary tract in the
brainstem, and several branches of this nucleus, project to different brain areas. The
myelinated A- and B-fibers of the vagal nerve send somatosensory, motor, and autonomic
signals, and the complex system of vagal projections is involved in inflammatory, immune,
nociceptive, and emotional processes. A relevant role of the vagal nerve in pain
processing is the transmission of peripheral inflammation signals to the central nervous
system. Neuromodulatory activity has been identified in areas related to the sensory and
emotional processing of pain, such as the insular cortex and the Anterior Cingulate
Cortex (ACC), after vagal stimulation, which reveals that the central system of pain
processing receives vagal afferences. In 1988 the first human implant of a vagal
stimulating device was performed. In 1997, the US Food and Drug Administration (FDA)
approved the use of Vagal Nerve Stimulation (VNS) as anadjunctive treatment for medically
refractory epilepsy. Vagus nerve stimulation is a FDA-approved treatment for different
pathologies. The regulation of the autonomic and immune systems and a specific effect on
chemical mediators of inflammation are relevant physiological mechanisms of the VNS.
At the present research study, we will use the 2016 revision to 2010/2011 ACR
fibromyalgia diagnostic criteria. The treatment of fibromyalgia is based on a
biopsychosocial approach and includes pharmacological and non-pharmacοlogical approaches,
according to the EULAR recommendations. However, patients are still reporting high pain
scores and increased interference with quality of life.
Considering that the vagus nerve controls pain signals towards the central nervous system
and growing evidence of autonomic dysfunction in fibromyalgia in terms of sympathetic
hyperactivity, it can be argued that rebalancing the sympathetic- parasympathetic
activity via vagal stimulation might reduce the intensity of pain and stabilize the
autonomic symptoms of this disease. In addition, an immune system alteration seems to
mediate the interaction between the autonomic nervous system and the chronic inflammatory
state in fibromyalgia, apparently by the influence of inflammatory cytokines and
chemokines. Stimulation of the auricular and cervical branches of the vagus nerve might
reduce such inflammatory overactivity via efferent modulation of the activity of the
inflammatory processes and hereby reduce pain symptoms. The potential of non-invasive
stimulation of the auricular and cervical branches of the vagus nerve in repeated
sessions to improve fibromyalgia symptoms has not been evaluated in randomized,
sham-controlled clinical studies. Transcutaneous stimulation of the auricular and
cervical branches of the vagus nerve (tVNS), are both non-invasive, low-intensity
electric stimulation procedures. According to literature, the effectiveness of these
non-invasive methods might not differ significantly from the invasive vagus nerve
stimulation, while non-invasiveness provides an advantageous safety profile. Since
fibromyalgia involves a dysregulation of the autonomic and immune systems, non-invasive
tVNS is expected to improve the symptoms of fibromyalgia, including chronic,
musculoskeletal, and generalized pain, through modulation of the vegetative and immune
systems. The purpose of the proposed double blind placebo controlled randomized clinical
trial is to investigate the effect of tVNS in Chronic Pain compared to medication and the
future establishment of the given technique in the clinic. The research interest of the
scientific community is growing more and more in recent years. However, research in
thisfield is still in its infancy stages. At the same time the holistic treatment of
chronic pain, including its neurobiological, psychosocial, cognitive and behavioral
components, may become a valuable aid-giver in the best completion of the research
project. Research question and Aim The hypothesis of our study is to evaluate, if the
addition of transcutaneous stimulation of the auricular branch of the vagus nerves in
patients suffering with fibromyalgia can lead to better pain control and quality of life.
To investigate this, we will offer a 2 week treatment (14 sessions) in a double-sham
controlled study.
This study is designed to determine whether the standard pharmacological treatment paired
with 14 sessions of tVNS can improve pain symptomatology in fibromyalgia and the whole
range of FM symptoms, such as depression, anxiety, fatigue etc. by using appropriate
scales as Numerical Rating Scale (NRS), Fibromyalgia Impact Questionnaire (FIQ), Brief
Pain Inventory (BPI), Depression and Anxiety Stress Scale (DASS), Materials and Methods
(binding+sham) Participants Our population will be comprised of fibromyalgia patients
that are originally diagnosed or referred to Aretaieion Pain Clinic. For the diagnosis
(or confirmation of diagnosis) we will be using the ACR (American College of
Rheumatology) 2016 revised criteria.
The present single center double blind sham-controlled randomized clinical trial will be
conducted at the Pain Clinic of Aretaieion University Hospital, National and Kapodistrian
University of Athens. Recruitment Methods Investigators may contact (or be contacted by)
a potential subject by telephone or email or direct contact to discuss participation in
this research protocol. The investigator will provide the subject with all the
information contained in the written consent form and at the same time she will answer
any questions regarding the research and give the subject sample, time to consider
participation in the study, which may require a follow-up phone conversation or an
in-person appointment at the Pain Clinic for a brief study enrollment screening visit.