Transcutaneous Electrical Nerve Stimulation (TENS) in Patients With Postacute Sequelae of Sars-CoV-2

The purpose of the pilot study is to examine acceptability and proof of concept effectiveness of a wireless TENS technology to address PASC associated FM. Sample size (n=30) is convenient and designed to explore acceptability and feasibility. Participants, who satisfy the inclusion and exclusion criteria and sign the informed consent form will be randomly assigned with ratio of 1:1 into two groups. One group will utilize TENS high-dose devices (Intervention group, IG); the other group will utilize TENS low-dose devices (Placebo group, PG). The baseline measurements will be performed, and the patients will take the programmed device home for a duration of 4 weeks. Then, the patients will come back after four weeks (4W). At this 4th week visit, both groups will be unblinded and the IG will keep their high-dose TENS device and the PG group will switch from a low-dose TENS to a high-dose TENS device. Both groups will continue to deliver 3-5 hour of stimulation daily, until their final 8th week follow up visit (8W). The primary outcome will be pain. Secondary outcomes include fatigue, limb strength and perfusion, gait assessment (cadence, stride time, double support), balance, pulse oximetry, and quality of life. The coordinator will utilize a weekly spreadsheet showing utilization (therapy sessions/day, logged in the Quell health Cloud) so compliance can be monitored and those that are not using the device can be encouraged.

Postacute Sequelae of Sars-CoV-2 (PASC) is an emerging entity that has been clearly recognized by musculoskeletal pain, fatigue, cognitive, and sleep disturbances, among other symptoms, in patients who have recovered from severe Sars-CoV-2 infection. Hospitalized survivors have reported a significant excess burden of many of these symptoms up to 8 months after discharge. Particularly in the lower extremity, musculoskeletal illness has been associated with prolonged immobilization, high-risk comorbidities, and the use of glucocorticoids that is commonly administered to these patients. These manifestations are the cardinal symptoms of fibromyalgia (FM), a condition thought to be caused by hyperactive sensory signaling due to central sensitization as well as deficient endogenous pain inhibition, triggered among others, by viral infections. Consequently, FM sequelae are one of the most common long-term complications seen in PASC. Thus, it is expected to impose a serious burden on different medical specialties in a near future. In a population that has persistent lack of symptom resolution such as FM, adherence to therapy could be challenging. Patients with constant pain, fatigue, and sleep disturbances, are difficult to keep motivated, especially those pain-medication dependents that often present low quality of life. One practical solution to address the symptomatology characteristic of FM is the use of transcutaneous electrical stimulation therapy (TENS). Studies have demonstrated its ability to manage pain and fatigue in patients with peripheral neuropathy and FM, and has shown to effectively improve lower-extremity perfusion and oxygen delivery in patients with ischemic lesions. However, TENS has not yet been explored for PASC. Since this technology is dose-dependent, the investigators propose a practical daily-basis therapy that patients with persistent associated FM due to previous COVID-19 infection could apply at home, thus, addressing PASC without relying only on medication. In this matter, Neurometrix Inc. (Woburn, MA, USA) has created a wireless TENS device (Quell®) to address pain, gait, sleep, and fatigue. This technology is placed in the lower-extremity and works through the stimulation of nerves that carry non-painful sensations (A-beta fibers) by closing a neurological "gate" in the spinal cord, thus, reducing transmission from pain nerves (A-delta and C fibers) to the brain. This device utilizes a wireless technology manageable through a smart phone application (Quell App) that also tracks symptom-status. Moreover, Baylor College of Medicine has created the Post-COVID-19 Clinic (McNair Campus, BCM St Luke's, Houston, TX, USA) supervised by specialists in critical and pulmonary care. This Clinic has a high volume of patients that present with PASC, particularly those with associated FM (i.e., persistent muscle pain, fatigue, weakness, atrophy, sleep problems, and/or anxiety). Therefore, the investigators believe Baylor institution is a suitable place to perform this pilot study.

Eligibility Criteria:
Inclusion Criteria:

* Previous COVID-19 infection
* Persistent symptoms of pain, fatigue, weakness, or poor gait and balance that were not present before COVID-19 infection
* Willing to attend clinic for assessments

Exclusion Criteria:

* Severe cognitive decline reduces their ability to interact with the TENS mobile app
* Major visual or hearing weakness reduces the ability to interact with TENS mobile app
* Unable to walk independently for a distance of 10 meter
* Major foot problems such as active lower extremity wounds, major foot deformity (e.g., Charcot Foot), previous major amputations, and claudication
* Demand-type cardiac pacemaker, implanted defibrillator, or other implanted electronic devices; and any conditions that may interfere with outcomes or increase the risk of the use TENS based on the judgement of clinicians