Surface Electromyographic Mapping of the Orbicularis Oculi Muscle for Real-Time Blink Detection

Abstract

IMPORTANCE Facial paralysis is a life-altering condition that significantly impairs function, appearance, and communication. Facial rehabilitation via closed-loop pacing represents a potential but as yet theoretical approach to reanimation. A first critical step toward closed-loop facial pacing in cases of unilateral paralysis is the detection of healthy movements to use as a trigger to prosthetically elicit automatic artificial movements on the contralateral side of the face.OBJECTIVES To test and to maximize the performance of an electromyography (EMG)-based blink detection system for applications in closed-loop facial pacing. DESIGN, SETTING, AND PARTICIPANTSBlinking was detected across the periocular region by means of multichannel surface EMG at an academic neuroengineering and medical robotics laboratory among 15 healthy volunteers. MAIN OUTCOMES AND MEASURESReal-time blink detection was accomplished by mapping the surface of the orbicularis oculi muscle on one side of the face with a multichannel surface EMG. The biosignal from each channel was independently processed; custom software registered a blink when an amplitude-based or slope-based suprathreshold activity was detected. The experiments were performed when participants were relaxed and during the production of particular orofacial movements. An F1 score metric was used to analyze software performance in detecting blinks. RESULTSThe maximal software performance was achieved when a blink was recorded from the superomedial orbit quadrant. At this recording location, the median F1 scores were 0.89 during spontaneous blinking, 0.82 when chewing gum, 0.80 when raising the eyebrows, and 0.70 when smiling. The overall performance of blink detection was significantly better at the superomedial quadrant (F1 score, 0.75) than at the traditionally used inferolateral quadrant (F1 score, 0.40) (P < .05).CONCLUSIONS AND RELEVANCE Electromyographic recording represents an accurate tool to detect spontaneous blinks as part of closed-loop facial pacing systems. The early detection of blink activity may allow real-time pacing via rapid triggering of contralateral muscles. Moreover, an EMG detection system can be integrated in external devices and in implanted neuroprostheses. A potential downside to this approach involves cross talk from adjacent muscles, which can be notably reduced by recording from the superomedial quadrant of the orbicularis oculi muscle and by applying proper signal processing.LEVEL OF EVIDENCE NA.

Effects of Low‐Intensity Contractions of Different Craniofacial Muscles in Healthy Participants – An Experimental Cross‐Over Study

“…Orbicularis‐oris activity, when pressing lips together, also evokes activation in other peri‐oral muscles (ie, depressor anguli oris, depressor labii, and mentalis) . Orbicularis‐oculi activity, the performance of blink detection, is better at the superomedial quadrant than at the inferolateral quadrant . It seems that the superomedial quadrant activity is associated with movements of both frontalis and temporalis muscles.…”

“…41 Orbicularis-oculi activity, the performance of blink detection, is better at the superomedial quadrant than at the inferolateral quadrant. 42 It seems that the superomedial quadrant activity is associated with movements of both frontalis and temporalis muscles. Thus, it is suggested that orbicularis-oculi contractions can induce headaches, whereas orbicularis-oris contractions may not tend to cause the symptoms at the superomedial quadrant.…”

A Study of the Electrical Properties of the Buccal Area using Facial Surface Electromyography※

“…Considering the existing studies, A. Frigerio et al 4) proposed a measurement method especially for the orbicularis oculi muscle. N. P. Schumann et al 5) analyzed the movement of the muscles during has recommended sensor locations and placements in various muscles.…”

Facial nerve electrodiagnostics for patients with facial palsy: a clinical practice guideline

“…sEMG is non-invasive, painless, and the number of surface electrodes used and therefore the number of facial muscles analyzed simultaneously, is unlimited. sEMG allows a detailed analysis of the coordinated muscle activation needed for specific tasks and emotional expressions [45,46]. If several surface electrodes are placed on the same facial muscle, the intramuscular pattern of muscle recruitment can be analyzed.…”