Changes in shoulder torque timing and direction during withdrawal reflexes in the impaired upper limb of hemiparetic stroke subjects

Julius P A Dewald*, J. D. Given, R. F. Beer, William Z Rymer

*Corresponding author for this work

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

Flexion withdrawal responses in the impaired/unimpaired upper limbs of hemiparetic stroke subjects were studied to determine the relationship between cutaneous afferent input and abnormal muscle synergies. A mildly noxious electrical stimulus was applied to the index finger while concurrently measuring relevant EMG and joint torque responses. The reflex response in the impaired arm was significantly altered. EMG and torque onsets were delayed at both the shoulder and elbow across all subjects along with torque reversals in two of the three shoulder torques (adduction-abduction in 4/8 subjects and shoulder extension-shoulder flexion in 6/8 subjects). Similar results have been observed during the characterization of spatial EMG profiles and during the execution of maximum voluntary torques. It follows that cutaneous and other sources of tonic sensory input may strongly influence muscle coactivation patterns in the impaired upper extremity of hemiparetic stroke subjects.

Original languageEnglish (US)
Pages (from-to)603-604
Number of pages2
JournalAnnual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings
Volume2
StatePublished - Dec 1 1996
EventProceedings of the 1996 18th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Part 2 (of 5) - Amsterdam, Neth
Duration: Oct 31 1996Nov 3 1996

ASJC Scopus subject areas

  • Signal Processing
  • Biomedical Engineering
  • Computer Vision and Pattern Recognition
  • Health Informatics

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