Vibroacoustic stimulation — delivering sound-driven vibrations to the skin while seated or lying in bed — can ease fibromyalgia symptoms, depression and everyday pain, as well as improve patients’ sleep, a clinical study suggests.
These findings provide preliminary evidence that a type of treatment called rhythmic sensory stimulation (RSS) may relieve fibromyalgia symptoms, supporting future investigations about the effects of this intervention on chronic pain.
The study “A parallel randomized controlled trial examining the effects of rhythmic sensory stimulation on fibromyalgia symptoms” was published in the journal PLOS ONE.
RSS is a broad term to describe the use of vibrations, sounds, and visual flickering stimuli applied in intermittent pulses or continuous forms.
For example, the application of vibrations to the skin has been used to reduce acute pain and help rehabilitation in a variety of conditions. However, its benefit for chronic pain is less known.
A few studies have looked at the impact of vibroacoustic stimulation in fibromyalgia, using sound-driven vibrations applied to localized body regions or to the whole body.
These studies have focused on the use of rhythmic gamma-frequency (30 – 120 Hz) sound-driven stimulation, but results have been ambiguous.
In this clinical trial (NCT02493348) researchers investigated two questions: if vibroacoustic RSS is effective for reducing the severity of fibromyalgia symptoms, and if changing the stimuli parameters (frequency, time and wave pattern) changes the treatment effect.
Fifty patients with fibromyalgia were assigned randomly to two groups. One group received a continuous vibroacoustic stimulation of constant frequency (40 Hz) for 30 minutes, five days per week, over five weeks, in addition to standard care.
The second group completed the same schedule of sessions, but received a different type of stimulation, consisting of random and intermittent vibroacoustic stimuli.
The stimulation was delivered via a portable consumer device (Sound Oasis Vibroacoustic Therapy System VTS-1000) with a transducer located in the middle back region and stereo speakers placed at ear level.
All sessions were self-administered by participants at home. The device would deliver a mild vibration at the lower-back and shoulder, and head area, as well as a low-level hum.
Participants were instructed to place the device on a comfortable chair or bed and relax, but were allowed to perform other activities (e.g., reading) during sessions.
The results show that the RSS treatment led to a significant decrease in fibromyalgia symptom severity and depression, as measured by specific patient-reported questionnaires.
Moreover, patients also indicated they had better sleep quality at the end of the treatment period.
But the two patient groups, receiving different RSS interventions, had a similar treatment response, with a comparable easing in symptoms.
Of note, pain interference in daily activities changed significantly only in participants receiving the second type of intervention.
No changes were reported by patients in pain severity or quality of life at the end of the treatment compared to the study’s start.
However, regardless of the type of vibroacoustic stimuli applied in either group, participants generally reported a relief in pain severity after each treatment session. This effect was felt at the first week of intervention, but did not get better with time.
“This finding suggests that, while there were some immediate effects on pain relief, these benefits may not have persisted to the point of a clinically meaningful improvement for some patients,” researchers wrote.
The results also indicate that 40% of the patients achieved a clinically relevant symptom decrease in fibromyalgia, defined as a reduction of 14% or more in the Fibromyalgia Impact Questionnaire (FIQ) score.
A small group of 6%, however, claimed their symptoms got worse.
The explanation for variability in treatment responses may lie in individual differences regarding pain severity, location of tender points, hypersensitivity to vibratory stimuli, and associated diseases.
These may be important factors to consider prior to starting an RSS intervention, and require more investigation in larger studies, the scientists said.
According to the team, the findings provide “preliminary evidence that gamma-frequency rhythmic vibroacoustic stimulation [used in group 2] may decrease fibromyalgia symptoms and ease associated comorbidities”.
Some hypotheses have been offered to explain why sensory stimulation is able to relieve pain. The vibratory stimulation may inhibit pain signals before they reach the brain, moving patients’ attention away from pain, or changing the brain’s electrical activity and enhancing neurons’ connectivity.
Researchers added that the beneficial effect on depression was unexpected, but raises the question if this was “associated with a general improvement in the patients’ mood or whether RSS affected common underlying features between depression and fibromyalgia.”
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