Reciprocal inhibition becomes facilitation after spinal cord injury: Clinical application of a system identification approach

M. M. Mirbagheri, L. D. Duffell, D. Kotsapouikis, Lynn M Rogers

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Alteration in spinal inputs from descending pathways following spinal cord injury (SCI) affects different mechanisms including reciprocal Ia inhibition. However, whether there is a consistent pattern of change in reciprocal inhibition following SCI is uncertain. Typical attempts to evaluate reciprocal inhibition have been restricted to electrophysiological measurements, which may have limited translation to function. Our objective was to address the uncertainty regarding changes in reciprocal inhibition after SCI by quantitatively evaluating reciprocal inhibition of ankle extensors from ankle flexors using our novel, more functionally relevant system identification approach. To evaluate reciprocal inhibition using the system identification technique, a series of small-amplitude PseudoRandom Binary Sequence (PRBS) perturbations were applied to the ankle when subjects contracted their dorsiflexors. Depression of reflex stiffness with tibialis anterior (TA) activation was evaluated as reciprocal inhibition. Our results showed that reflex stiffness decreased continuously as dorsiflexor torque increased in the healthy control subjects whereas it remained almost unchanged in the SCI subjects, indicating the absence of reciprocal inhibition in patients. This pattern was consistent with the results obtained from electrophysiological measures in a exploratory control experiment revealing depression of the control H-reflex but no change to the SCI H-reflex. These findings suggest that our system identification mechanical technique is a reliable and valid approach for evaluating reciprocal inhibition. Furthermore, our results demonstrate that reciprocal inhibition can diminish or change to reciprocal facilitation after SCI, which in turn can result in reflex hyperexcitability and unwanted activity of ankle extensors triggered by TA activity. This suggests that reciprocal facilitation may play a major role in pathophysiology of spasticity and impaired function.

Original languageEnglish (US)
Title of host publication2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages4395-4398
Number of pages4
Volume2014
ISBN (Electronic)9781424479290
DOIs
StatePublished - Nov 2 2014
Event2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014 - Chicago, United States
Duration: Aug 26 2014Aug 30 2014

Publication series

Name2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014

Other

Other2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014
CountryUnited States
CityChicago
Period8/26/148/30/14

Keywords

  • ankle
  • facilitation
  • reciprocal inhibition
  • reflex
  • spasticity
  • spinal cord injury
  • stiffness
  • system identification

ASJC Scopus subject areas

  • Health Informatics
  • Computer Science Applications
  • Biomedical Engineering
  • Medicine(all)

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  • Cite this

    Mirbagheri, M. M., Duffell, L. D., Kotsapouikis, D., & Rogers, L. M. (2014). Reciprocal inhibition becomes facilitation after spinal cord injury: Clinical application of a system identification approach. In 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014 (Vol. 2014, pp. 4395-4398). [6944598] (2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/EMBC.2014.6944598