A parallel randomized controlled trial examining the effects of rhythmic sensory stimulation on fibromyalgia symptoms

Abstract

This double-blind, two-arm parallel randomized controlled trial investigated the effects of gamma-frequency rhythmic sensory stimulation on fibromyalgia. We were interested in whether rhythmic sensory stimulation would promote significant changes in fibromyalgia and associated symptoms, and whether treatment effects would differ between two distinct treatment parameters. Fifty patients with a formal diagnosis of fibromyalgia were randomly assigned to two test groups. One group received vibrotactile stimulation from a continuous sine wave single-frequency stimulation (40 Hz) for 30 minutes, five days per week, over five weeks, concomitant with usual care. The second group completed the same treatment protocol but received a different stimulation, consisting of random and intermittent complex wave gamma-range vibrotactile stimulation. Fibromyalgia symptoms, pain severity and interference, depression symptoms, quality of life and sleep quality were assessed at baseline and post-intervention. Results indicated that there were statistically significant changes from baseline to post-treatment in measures of fibromyalgia symptom severity, pain interference, depression, and sleep quality. However, treatment outcomes did not differ significantly between groups. These findings provide preliminary evidence that gamma-frequency rhythmic vibroacoustic stimulation may decrease fibromyalgia symptoms and ease associated comorbidities, opening new avenues for further investigation of the effects of rhythmic sensory stimulation on chronic pain conditions.

Fig 1. Flowchart of study participants.

Fig 2. Stimulus peak frequencies.

Sound stimulus delivered to group one consisted of continuous single-frequency sine wave with peak frequency at 40 Hz that was amplitude modulated on an 11-second cycle (top figure), plus isochronous auditory stimulation with a 160 Hz tone amplitude modulated at 40 Hz with secondary pitch peaks at 120 Hz and 200 Hz (bottom figure).

Fig 3. Stimulus peak frequencies.

Sound administered as stimulation to group two comprised of randomly intermittent sounds consisting of complex wave gamma-range noise with pitch peaks at approximately 33 Hz and 45 Hz, and a secondary pitch peak at approximately 95 Hz.