An Analysis of EMG Electrode Configuration for Targeted Muscle Reinnervation Based Neural Machine Interface

Abstract

Targeted muscle reinnervation (TMR) is a novel neural machine interface for improved myoelectric prosthesis control. Previous high-density (HD) surface electromyography (EMG) studies have indicated that tremendous neural control information can be extracted from the reinnervated muscles by EMG pattern recognition (PR). However, using a large number of EMG electrodes hinders clinical application of the TMR technique. This study investigated a reduced number of electrodes and the placement required to extract sufficient neural control information for accurate identification of user movement intents. An electrode selection algorithm was applied to the HD EMG recordings from each of 4 TMR amputee subjects. The results show that when using only 12 selected bipolar electrodes the average accuracy over subjects for classifying 16 movement intents was 93.0(±3.3)%, just 1.2% lower than when using the entire HD electrode complement. The locations of selected electrodes were consistent with the anatomical reinnervation sites. Additionally, a practical protocol for clinical electrode placement was developed, which does not rely on complex HD EMG experiment and analysis while maintaining a classification accuracy of 88.7±4.5%. These outcomes provide important guidelines for practical electrode placement that can promote future clinical application of TMR and EMG PR in the control of multifunctional prostheses.

Decoding Information From Neural Signals Recorded Using Intraneural Electrodes: Toward the Development of a Neurocontrolled Hand Prosthesis

“…The results showed in this manuscript indicate that some specific "states" (i.e., grip types) can be decoded from intraneural ENG signals. This "high-level" finite state approach has been implemented with very good results in EMG-controlled prostheses [5,13,35]. It is achieved by combining information on the grip together with fixed parameters embedded in the robotic controller (e.g., on the pre-shaping phase of the hand before grasping) and selected by trial and error.…”

“…Motor commands can project to different size motor units, or even to different muscle groups. The sensory information set can be varied and [11] and schematic (right) of the targeted muscle reinnervation technique and of the high density EMG experimental setup used in unilateral short transhumeral amputee subject [13]. In single-unit recordings, the shape of the action potential is generally believed to carry individual and selective information, with the information coded in the action potential rate and population firing distribution; in other words, the signal-to-noise ratio is remarkably superior.…”

“…Among these approaches, Kuiken et al [12][13] developed a new method based on transferring amputees' residual nerves to other muscles in or near the residual limb (see Figure 1). This approach has the advantage of physiologically correlating the nerve function to the function it is controlling in the prosthesis.…”

Improved Myoelectric Prosthesis Control Using Targeted Reinnervation Surgery: A Case Series

“…The goal is to reduce this number of inputs to a more reasonable number (8-16 electrode pairs), while still maintaining similar accuracies. A further discussion of this topic can be found in the companion paper in this issue [23].…”

Performance of pattern recognition myoelectric control using a generic electrode grid with Targeted Muscle Reinnervation patients

“…As such, the physical location, or source, of the pattern is irrelevant as long as the patterns are unique [8]. Evaluating the number of EMG channels and their locations has been previously investigated for transradial amputees [9] and TMR patients [10] using high-density electromyography with channel reduction. These previous results from TMR patients suggest that there is a significant benefit of strategic placement of electrodes over the reinnervated muscle sites when up to 16 movements are recognized by the classifier.…”