Selectivity and Resolution of Surface Electrical Stimulation for Grasp and Release

Electrical stimulation of arm and hand muscles can be a functional tool for patients with motor dysfunction. Sufficient stimulation of finger and thumb musculature can support natural grasping function. Yet it remains unclear how different grasping movements can be selectively supported by electrical stimulation. The goal of this study is to determine to what extent activation of individual fingers is possible with surface electrical stimulation for the purpose of rehabilitation following stroke. The extensor digitorum communis (EDC) muscle, flexor pollicis longus (FPL) muscle, and the thenar muscle group, all involved in grasp and release, were selected for stimulation. The evoked forces in individual fingers were measured. Stimulation thresholds and selective ranges were determined for each subject. Electrode locations where the highest selective range occurred were compared between subjects and influences of different isometric wrist positions were assessed. In all subjects selective stimulation of middle finger extension and thumb flexion was possible. In addition, selective stimulation of index and ring finger extension was possible in most cases. In nine out of the ten EDC subjects we were able to stimulate three or all four fingers selectively. However, large variability in electrode locations for high selectivity was observed between the subjects. Within the designs of grasping prostheses and grasping rehabilitation devices, the variability of electrode locations should be taken into account. The results of our study facilitate the optimization of such designs and favour a design which allows individualized stimulation locations.

[1]  A. Monster,et al.  Isometric force production by motor units of extensor digitorum communis muscle in man. , 1977, Journal of neurophysiology.

[2]  A. Prochazka,et al.  The bionic glove: an electrical stimulator garment that provides controlled grasp and hand opening in quadriplegia. , 1997, Archives of physical medicine and rehabilitation.

[3]  T Cameron,et al.  The effect of wrist angle on electrically evoked hand opening in patients with spastic hemiplegia. , 1999, IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society.

[4]  R Thorsen,et al.  Functional control of the hand in tetraplegics based on residual synergistic EMG activity. , 1999, Artificial organs.

[5]  R. Enoka,et al.  Motor unit physiology: Some unresolved issues , 2001, Muscle & nerve.

[6]  Grasping power by means of functional electrical stimulation in a case of C6 complete tetraplegia. , 2003, The Tohoku journal of experimental medicine.

[7]  M. Schieber,et al.  Reduced muscle selectivity during individuated finger movements in humans after damage to the motor cortex or corticospinal tract. , 2004, Journal of neurophysiology.

[8]  Marc H Schieber,et al.  Human finger independence: limitations due to passive mechanical coupling versus active neuromuscular control. , 2004, Journal of neurophysiology.

[9]  M. Popovic,et al.  Multi-field surface electrode for selective electrical stimulation. , 2005, Artificial organs.

[10]  J. Krakauer.  Motor learning: its relevance to stroke recovery and neurorehabilitation. , 2006, Current opinion in neurology.

[11]  R. H. Nathan,et al.  Functional electrical stimulation of the upper limb: Charting the forearm surface , 1979, Medical and Biological Engineering and Computing.

[12]  R. H. Nathan,et al.  FNS of the upper limb: targeting the forearm muscles for surface stimulation , 1990, Medical and Biological Engineering and Computing.

[13]  Thomas Sinkjær,et al.  Cortical excitability changes following grasping exercise augmented with electrical stimulation , 2008, Experimental Brain Research.

[14]  Thierry Keller,et al.  Assessment of finger forces and wrist torques for functional grasp using new multichannel textile neuroprostheses. , 2008, Artificial organs.

[15]  J N A L Leijnse,et al.  Anatomic basis for individuated surface EMG and homogeneous electrostimulation with neuroprostheses of the extensor digitorum communis. , 2008, Journal of neurophysiology.

[16]  Takashi Maeno,et al.  Underactuated five-finger prosthetic hand inspired by grasping force distribution of humans , 2008, 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[17]  Y. Hara,et al.  Neurorehabilitation with new functional electrical stimulation for hemiparetic upper extremity in stroke patients. , 2008, Journal of Nippon Medical School = Nippon Ika Daigaku zasshi.

[18]  Silvestro Micera,et al.  Array electrode design for transcutaneous electrical stimulation: a simulation study. , 2009, Medical engineering & physics.

[19]  C. Lang,et al.  Recovery of thumb and finger extension and its relation to grasp performance after stroke. , 2009, Journal of neurophysiology.

[20]  Hiske van Duinen,et al.  Limited ability to extend the digits of the human hand independently with extensor digitorum , 2009, The Journal of physiology.

[21]  M. Popovic,et al.  Electrical stimulation as a means for achieving recovery of function in stroke patients. , 2009, NeuroRehabilitation.

[22]  M. Popovic,et al.  Automatic determination of the optimal shape of a surface electrode: Selective stimulation , 2009, Journal of Neuroscience Methods.

[23]  M. Morari,et al.  Wearable Neural Prostheses , 2010, IEEE Engineering in Medicine and Biology Magazine.

[24]  M. Morari,et al.  The Influence of Electrode Size on Selectivity and Comfort in Transcutaneous Electrical Stimulation of the Forearm , 2010, IEEE Transactions on Neural Systems and Rehabilitation Engineering.