Abstract
This study investigated the effect of Transcutaneous Electrical Nerve Stimulation (TENS) for fibromyalgia-like symptoms including chronic widespread pain, fatigue, and gait impairment in twenty-five individuals with Post-Acute Sequelae of Sars-Cov-2 (PASC). Participants were randomized to a high dose (intervention group, IG) or low dose (placebo group, PG) TENS device. Both groups received daily 3–5 hours of TENS therapy for 4-weeks. The Brief Pain Inventory assessed functional interference from pain (BPI-I), and pain severity (BPI-S). The global fatigue index (GFI) assessed functional interference from fatigue. Wearable technology measured gait parameters during three 30-feet consecutive walking tasks. At 4-weeks, the IG exhibited a greater decrease in BPI-I compared to the PG (mean difference = 2.61, p = 0.008), and improved in gait parameters including stride time (4%-8%, test condition dependent), cadence (4%-10%, depending on condition), and double-support phase (12% in dual-task) when compared to baseline. A sub-group meeting the American College of Rheumatology Fibromyalgia diagnostic criteria undergoing high-dose TENS showed GFI improvement at 4-weeks from baseline (mean change = 6.08, p = 0.005). Daily TENS therapy showed potential in reducing functional interference from pain, fatigue, and gait alterations in PASC individuals. The study's limited power could affect the confirmation of certain observations. Extending the intervention period may improve treatment effectiveness.