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An Implantable System For Chronic In Vivo Electromyography
Published on: April 21, 2020
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Large-scale intramuscular electrode system for chronic electromyography and functional electrical stimulation
Nicole L Holly1, Brady A Hasse2, Katalin M Gothard1,3,4
1Department of Physiology, College of Medicine, University of Arizona, Tucson, Arizona.
Journal of Neurophysiology
|September 21, 2022
Summary
Researchers developed stable intramuscular electrodes for long-term muscle monitoring and electrical stimulation. This system reliably recorded electromyographic signals and evoked muscle forces in nonhuman primates for several months.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Rehabilitation Technology
Background:
- Understanding central nervous system (CNS) control of movement requires monitoring multiple muscles.
- Restoring movement to paralyzed limbs via electrical stimulation necessitates access to numerous limb muscles.
- Intramuscular electrodes are crucial for isolated muscle recording and stimulation.
Purpose of the Study:
- To develop and assess the long-term stability of large arrays of implanted intramuscular electrodes.
- To evaluate the system's efficacy for both recording muscle activity and delivering electrical stimulation.
Main Methods:
- Implanted 58 intramuscular electrodes in 29 upper limb muscles of three macaques.
- Utilized a skull-mounted chamber for electrode connector protection and subcutaneous wire tunneling.
- Employed gold anchors for electrode fixation and an insertion device for deployment.
- Secured chambers to the skull using titanium baseplates in two subjects.
- Recorded electromyographic (EMG) signals during reaching movements up to 15 weeks post-surgery.
- Measured evoked muscle forces in response to electrical stimulation at 4, 8, and 16 weeks post-surgery.
Main Results:
- EMG signals demonstrated stability across multiple sessions, with an average coefficient of variation of 0.24 ± 0.15.
- No significant difference was found in the threshold current required to evoke a response at 16 weeks compared to 4 weeks.
- Peak evoked force at 16 weeks was comparable to that at 4 weeks for a 16 mA stimulus current.
- The system maintained stable recording and stimulation capabilities over several months.
Conclusions:
- The developed intramuscular electrode system offers long-lasting stability for recording and stimulation.
- This technology is suitable for monitoring and stimulating a large number of muscles.
- It holds significant potential for advancing the understanding of natural and evoked movement control.
