RESUMEN
BACKGROUND: The search for effective treatments for fibromyalgia (FM) has continued for years. The present study premises that thalamocortical dysrhythmia is implicated in fibromyalgia and that low-frequency sound stimulation (LFSS) can play a regulatory function by driving neural rhythmic oscillatory activity. OBJECTIVE: To assess the effect of LFSS on FM. METHOD: The present open-label study with no control group used a repeated-measures design with no noncompleters. Nineteen female volunteers (median age 51 years; median duration of FM 5.76 years) were administered 10 treatments (twice per week for five weeks). Treatments involved 23 min of LFSS at 40 Hz, delivered using transducers in a supine position. Measures (repeated before and after treatment) included the Fibromyalgia Impact Questionnaire, Jenkins Sleep Scale, Pain Disability Index, sitting and standing without pain (in minutes), cervical muscle range of motion and muscle tone. Mean percentages were calculated on end of treatment self-reports of improvement on pain, mood, insomnia and activities of daily living. RESULTS: Significant improvements were observed with median scores: Fibromyalgia Impact Questionnaire, 81% (P<0.0001); Jenkins Sleep Scale, 90% (P<0.0001); and Pain Disability Index, 49.1% (P<0.0001). Medication dose was reduced in 73.68% of patients and completely discontinued in 26.32%. Time sitting and standing without pain increased significantly (P<0.0001). Cervical muscle range of motion increased from 25% to 75% (P=0.001), while muscle tone changed from hypertonic to normal (P=0.0002). CONCLUSION: In the present study, the LFSS treatment showed no adverse effects and patients receiving the LFSS treatment showed statistically and clinically relevant improvement. Further phase 2 and 3 trials are warranted.