The Impact Of Auricular Vagus Nerve Stimulation On Pain And Life Quality In Patients With Fibromyalgia Syndrome

Fibromyalgia syndrome (FMS) is a syndrome, characterized by chronic widespread pain that continues for a minimum of 3 months and pain felt upon 11 out of 9 pairs of identified sore points. It is often accompanied by systemic symptoms such as fatigue, sleep disorders, cognitive dysfunction and depression . Moreover, headache, dysmenorrhea, irritable bowel syndrome, restless leg syndrome, chest pain, jaw pain, stomach ache, sensitive skin, mitral valve prolapses, Sicca symptoms, Raynaud phenomenon and female urethral syndrome accompany the clinical picture in many patients with FMS . This syndrome, the etiology of which is unknown, is commonly seen in women and the age of onset is usually 30 - 50 . Its prevalence among the general population is reported to be between 2.9 - 4.7 percent . While it is often seen in the adult population, it can also be observed in childhood or later age . Recent research studies show that various anomalies in genetic structure, autonomic nervous system (ANS), neurotransmitters, hypothalamic-hypophyseal-adrenal axe hormones, oxidative stress, pain modulation centers, central sensitization and muscular structure occur in FMS . The etiology of FMS is still not fully understood; nonetheless, the data reveals that this syndrome may stem from dysfunctionality in ANS . Sympathetic nervous system (SNS) dominance is widespread in FMS, chronic fatigue, irritable bowel syndrome and interstitial cystitis . A highly peripheral sympathetic tone causes regional ischemia, which in turn causes widespread pain. Therapeutic interventions that result in vasodilatation (e.g. exercise) and appropriate autonomic changes are proven to be effective for reducing pain levels .

The "great and perfect protector" of the body, the vagus nerve includes a neuro-endocrine-immune network that ensures homeostasis. The vagus nerve, which has reciprocal neural connections with more than one region of the brain, serves a control center that combines sensitive information and provides appropriate feedback responses. Recent studies show that the vagus nerve also encompasses inflammation, mood and pain regulation. All of these can be modulated with vagus nerve stimulation. Vagus nerve stimulation can generate a neuromodulating effect to activate other natural protective paths to improve health . The development of vagus nerve stimulation began in the 19th century. A number of new electrical stimulation devices have now been developed. Non-invasive transcutaneal devices stimulate the vagus nerve through the auricular branch or from the carotid. Moreover, they are used in the treatment of various disorders, such as epilepsy, pain and headache . Recent pre-clinical studies have shown that vagus nerve stimulation heavily modulates pain in humans and is quite effective. The use of a medical device allows the auricular branch of the vagus nerve to be stimulated without surgical intervention. Consequently, it has been found that the threshold of pain is elevated and mechanical pain sensitivity is reduced .

As a result of these completed studies, there is a possibility that FMS is a disease, which occurs through ANS impairment. Vagus nerve stimulation could be used as an additional treatment method to improve the ANS impairment. However, as there are no studies that investigate vagus nerve stimulation in FMS, this study is designed and executed.

MATERIAL AND METHOD

Our study, in which the researchers investigated the impact of auricular vagus nerve stimulation on pain and life quality in patients with FMS, was conducted in Beykoz Public Hospital's Department of Physiotherapy and Rehabilitation. A total of 60 female patients within the age range 18 - 50, with diagnosed FMS by a physiatrist according to 2010 ACR criteria, were included in this study. Only females were included to make groups homogenous and ended the age range at 50 to avoid comorbid illnesses seen in elderly people and also menopause. Pregnants, perimenopausal and postmenaopausal women are not included, also those experiencing any comorbid illnesses like neurological deficits, diabetes, neuropathic disorders, chronic inflammation, immune deficiency, cardiac disorders and current vitamin D intake were excluded from the study. In addition those who started using new drugs in the last month and during the study were not included. Patients who experienced vasovagal syncope in their past could not participate in the study.