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Fibromyalgia, a generalized musculoskeletal pain disorder, is characterized by chronic pain, unrefreshing sleep, fatigue, and neuropsychological impairment by the ACR criteria (1999, 2010, 2016). It often presents comorbid with hypertension, sleep apnoea, anxiety irritable bowel syndrome, sleeping disorders, depression or chronic fatigue syndrome. Few effective treatments exist. FM patients are prescribed regular aerobic exercise, weight control, antidepressants, pain medication, operant and cognitive-behavioural pain therapy (OT/CBT), multimodal pain therapy, and alternative therapies – often with little success. The aetiology of this pain disorder is still under ongoing scientific debate, although there is some evidence that sympatico-vagal disbalances may be important. Several studies show reduced heart rate variability (HRV) and diminished baroreflex sensitivity (BRS) in fibromyalgia patients.
At the Institute for Medical Psychology in Marburg (Germany), a 5-week, 20-hour, treatment has been created, consisting of cardiac gated peripheral electrical stimulation on the hand combined with OT - called SET (Systolic Extinction-Training). SET was compared with 2 control conditions and showed strong benefits on primary pain outcomes (see IMMPACT) - pain relief, improved physical functioning, and depressive mood affective distress. The aim of this dissertation is to explore the mechanism of SET and more specifically pain relief through BRS and HRV improvement in FM.
Female FM patients (initially 80 and after drop-outs n=57) enrolled in tailored randomized controlled therapy study to assessing the efficacy of SET. Before and after treatment, patients were assessed through a multiphasic psychophysiological stress experiment. Only patients with a hypertonic hypertensive stress reactivity pattern were included in the study, because a pilot study in our institute showed, that these FM patients were able to benefit from SET.
The results verified our hypotheses. Significant increase of BRS and HRV, suggesting an increase of parasympathetic activity, was seen after therapy with SET. Patients of the
experimental group reacted to physical stressors (pressure induced pain) and mental stressors (mental arithmetic’s) with a significant higher BRS than before SET and with less or no pain.
According to the literature, operant conditioning can improve BRS. SET activates the brain through learning and BRS through painful and pain free cardiac gated stimuli. Patients relearn a healthy reaction to stress stimuli, where a rise in blood pressure triggers the baroreflex arc - a feedback loop via the NTS, which leads to activation of the parasympathetic nervous system and endogenous pain relief.
Future replication of the SET RCT are needed to show a long-lasting and permanent effect of the SET with a larger sample size, a follow-up data over 12 months, and a treatment in multiple centres. These preliminary results suggest that SET has a high potential to become an effective therapy for FM and other chronic pain diseases.