Systolic extinction training (SET) — which combines behavior therapy to reduce pain and physical interference with training to improve blood pressure response to stress — leads to long-term reductions in pain severity in women with fibromyalgia (FM), a clinical trial shows.
SET benefits are considered t0 result from a reduction in the hypertensive stress response, the natural response to stress that is dysfunctional in nearly half of fibromyalgia patients.
The study “Efficacy of Systolic Extinction Training in Fibromyalgia Patients With Elevated Blood Pressure Response to Stress: A Tailored Randomized Controlled Trial” was published in the journal Arthritis Care & Research.
Stress and pain can increase blood pressure in some fibromyalgia patients with so-called hypertensive stress response — an unbalanced response which leads to widespread pain, and increases the risk for high blood pressure (hypertension) and cardiovascular disease.
Long-term stress can lead to persistent elevated blood pressure, reduced ability to regulate blood pressure, and persistent widespread pain. In fact, nearly half of fibromyalgia patients (48%) have this kind of response to stress.
Stressor-related information from all major sensory systems is conveyed to the brain through different neuronal pathways, and generate fast responses through reflexes.
A rise in blood pressure activates pressure receptors (baroreceptors) at the carotid arteries — those carrying oxygen-rich blood from the heart to the brain — that will relay impulses to the nucleus tractus solitarius (NTS), a brainstem region bearing a cluster of sensory nerve cell bodies.
This region plays a critical role in integrating reflexes that control cardiovascular function, as well as pain, sleep, and anxiety.
In healthy individuals, acute pain leads to an increase in blood pressure and heart rate, which, in turn, trigger nerve impulses through the NTS that will help slow down the heart rate in order to bring blood pressure back to normal.
This is a natural response activated by the brain to minimize the harmful effects of stress, which depends on the system’s sensitivity to pressure receptors, a property termed baroreflex sensitivity.
In contrast, people with chronic pain, such as those with fibromyalgia and hypertensive stress response, develop increased pain and persistently high levels of blood pressure.
Some therapies can help control and minimize these types of impairments in the pain regulatory system and NTS reflex response.
One is operant therapy (OT), a behavioral therapy that focuses on the extinction of pain behaviors and the development of adaptive behaviors.
Another is baroreflex training (BRT) stimulation, which is designed to improve baroreflex sensitivity by delivering non-painful, mildly painful, and severely painful electrical stimuli after the systolic peak — the peak of pressure when the heart contracts to pump blood to the rest of the body.
Systolic extinction training (SET) combines BRT (to improve baroreflex sensitivity) with OT (to reduce pain behaviors and physical interference).
Baroreflex sensitivity can also be increased with aerobic exercise. Cardiovascular fitness training is believed to reactivate diminished baroreflex sensitivity while improving metabolism and — important for pain reduction — mental health, and physical relaxation.
In this study, the researchers investigated the benefit of SET for restoring arterial baroreflex sensitivity, reducing pain, and improving physical function in female FM patients with elevated cardiovascular risks (those who were older, with diabetes, high cholesterol, and/or high blood pressure).
They compared the magnitude and long-term effectiveness of this approach with two other treatments that have shown to benefit FM patients: operant therapy-transcutaneous electrical nerve stimulation (OT-TENS) and aerobic exercise-baroreflex training (AE-BRT).
Sixty‐two female patients with FM, ages 34 to 79, were randomized to receive SET (21 patients), OT‐TENS (20), or AE‐BRT (21) in two-hour weekly sessions for five weeks.
Outcome assessments of physical and laboratory exams, pain rating scales, and baroreflex sensitivity calculations were performed before treatment, at the end of the five weeks of treatment, and one year of follow-up.
OT, within the context of SET or OT-TENS, consisted of sessions led by a psychologist and a rheumatologist, and included a series of exercises to be practiced at home. OT-TENS combined OT with electrical stimulation of varying pain intensities.
AE-BRT combined BRT with moderate to vigorous intensity exercise on a cycle ergometer.
The data revealed that patients receiving SET experienced greater reductions in pain intensity and interference, which was maintained one year after treatment, compared with patients receiving OT‐TENS or AE‐BRT.
At one year follow-up, SET resulted in clinically meaningful pain reductions in 82% of the patients. In contrast, OT‐TENS led to significant pain reductions in 39% of the patients, and AE‐BRT led to pain reductions in 14%.
Of note, the SET group showed a significant improvement in baroreflex sensitivity, with a 57% increase at the end of the five weeks of training, which continued to be 48% higher one year after treatment.
Consistent with the improvements in pain perception, a clinically significant reduction of pain severity was associated with improvements in baroreflex sensitivity following SET treatment.
Neither the AE‐BRT or OT‐TENS group showed significant changes in baroreflex sensitivity over time.
“SET resulted in statistically significant, clinically meaningful, and long‐lasting pain remission and interference compared to OT‐TENS and AE‐BRT,” the researchers wrote.
“These results suggest that BRS [baroreflex sensitivity] modification is the primary mechanism of improvement. Replication of our results using larger samples and extension to other chronic pain conditions appear to be warranted.”