Imbalanced corticospinal and reticulospinal contributions to spasticity in humans with spinal cord injury

Sina Sangari, Monica A. Perez*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Damage to the corticospinal and reticulospinal tract has been associated with spasticity in humans with upper motor neuron lesions. We hypothesized that these descending motor pathways distinctly contribute to the control of a spastic muscle in humans with incomplete spinal cord injury (SCI). To test this hypothesis, we examined motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation over the leg representation of the primary motor cortex, maximal voluntary contractions (MVCs), and the StartReact response (shortening in reaction time evoked by a startling stimulus) in the quadriceps femoris muscle in male and females with and without incomplete SCI. A total of 66.7% of the SCI participants showed symptoms of spasticity, whereas the other 33.3% showed no or low levels of spasticity. We found that participants with spasticity had smaller MEPs and MVCs and larger StartReact compared with participants with no or low spasticity and control subjects. These results were consistently present in spastic subjects but not in the other populations. Clinical scores of spasticity were negatively correlated with MEP-max and MVC values and positively correlated with shortening in reaction time. These findings provide evidence for lesser corticospinal and larger reticulospinal influences to spastic muscles in humans with SCI and suggest that these imbalanced contributions are important for motor recovery.

Original languageEnglish (US)
Pages (from-to)7872-7881
Number of pages10
JournalJournal of Neuroscience
Volume39
Issue number40
DOIs
StatePublished - Oct 2019

Funding

Received May 14, 2019; revised June 22, 2019; accepted July 25, 2019. Author contributions: S.S. and M.A.P. designed research; S.S. and M.A.P. performed research; S.S. and M.A.P. contributedunpublishedreagents/analytictools;S.S.andM.A.P.analyzeddata;S.S.andM.A.P.wrotethefirstdraft of the paper; S.S. and M.A.P. edited the paper; S.S. and M.A.P. wrote the paper. M.A.P. was supported by the National Institute of Neurological Disorders and Stroke and the Veterans Administration. The authors declare no competing financial interests. Correspondence should be addressed to Monica A. Perez at [email protected]. https://doi.org/10.1523/JNEUROSCI.1106-19.2019 Copyright © 2019 the authors

Keywords

  • Corticospinal pathway
  • Muscle weakness
  • Reticulospinal pathway
  • Spasticity
  • Voluntary drive

ASJC Scopus subject areas

  • General Neuroscience

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