Acceptability and Feasibility of Surface EMG-Based Gamification Therapy for Motor Relearning after Nerve and Tendon Transfers
Yusha Liu, MD, PhD1, Rafael M.L. Silva, MS2, Jeffrey B. Friedrich, MD1, Dennis S. Kao, MD1, Pierre D. Mourad, PhD1 and Aaron E. Bunnell, MD1, (1)University of Washington, Seattle, WA, (2)University of Washington, Bothell, WA
INTRODUCTION: Brachial plexus injuries and compression neuropathies lead to debilitating upper extremity weakness, and nerve and tendon transfer surgeries are frequently performed in an attempt to restore function. Therapy is critical for recovery; however, these patients face two major challenges. First, they are unable to engage with traditional therapy until evidence of motor recovery is seen on clinical exam, which may be months to a year after nerve transfer surgery. Second, they need to relearn how to appropriately activate their muscles after their nerves or tendons are rerouted, which is often difficult for patients to master. We have developed an innovative surface electromyography (EMG)-based interactive gaming platform that provides biofeedback to show patients their progress in real time.
METHODS: We custom-built a highly sensitive surface EMG device capable of detecting low levels of muscle activation, even during recruitment of a single motor unit, and integrated this with a simple game in which muscle activation greater than a set threshold triggers an action in the virtual gaming environment. Patients who underwent nerve, tendon, and/or free functional muscle transfers were recruited to participate in one supervised session of gamified therapy, and adhesive electrodes were placed on the skin overlying the specific muscle(s) targeted by surgery. Acceptability surveys were administered at the completion of the session.
RESULTS: A variety of upper extremity muscles were tested in a total of eleven patients, ranging two months to three years postoperatively. After receiving brief verbal instructions on how to conceptualize their specific nerve or tendon transfer, all patients quickly learned how to appropriately activate the targeted muscle, and even muscles lacking antigravity muscle strength were able to reliably engage in gameplay. Survey responses showed that patients found our system motivating, enjoyable, and easy to understand, and subjectively felt that its use would speed up their recovery. System usability scale score averaged 81.
CONCLUSIONS: Surface EMG-based therapy has tremendous potential particularly with severe weakness in the earliest stages of recovery, as nascent signals from muscle activation are detectable on EMG long before significant movement can be observed on clinical exam, allowing for earlier initiation of therapy. Furthermore, therapeutic gaming promotes patient engagement, motivation, and compliance. In patients with nerve and tendon transfers, surface EMG-based gamified therapy allows individual muscles of interest to be targeted and promotes motor relearning by providing direct biofeedback of appropriate donor nerve activation causing recipient muscle movement.
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