Evidence for normative intracortical inhibitory recruitment properties in cervical dystonia

Rebekah L.S. Summers, Mo Chen, Colum D. MacKinnon, Teresa J. Kimberley

Research output: Contribution to journalArticle

Abstract

Objective: Dystonia is associated with reduced intracortical inhibition as measured by the cortical silent period (cSP); however, this may be due to abnormal cSP threshold or input-output properties. This study evaluated cSP recruitment properties in people with cervical dystonia (CD). Methods: Bilateral electromyographic recordings were collected in the upper trapezius muscle in response to transcranial magnetic stimulation of the left and right primary motor cortex in a group with CD (n = 19) and controls (n = 21). cSP threshold, cSP input-output properties at stimulation intensities from 1 to 1.4x the cSP threshold, ipsilateral silent period duration (iSP) and timing and magnitude of the contralateral and ipsilateral motor evoked potential (MEP) were assessed. Results: The cSP threshold, input-output properties, and contralateral MEP magnitude were not significantly different between groups (all p > 0.07). Hemispheric symmetry was present in the control group while the CD group had reduced iSP (p < 0.01) and a trend for reduced ipsilateral MEP response (p = 0.053) in the left hemisphere. Conclusions: Recruitment properties of intracortical inhibition are similar between control and CD groups. Transcallosal inhibition is asymmetric between hemispheres in people with CD. Significance: Evidence of normative intracortical inhibition recruitment properties challenge the commonly held view that cortical inhibition is reduced in dystonia.

Original languageEnglish (US)
Pages (from-to)1272-1279
Number of pages8
JournalClinical Neurophysiology
Volume131
Issue number6
DOIs
StatePublished - Jun 2020

Keywords

  • Cortical excitability
  • Cortical silent period
  • Dystonia
  • Motor evoked potential
  • Transcallosal inhibition
  • Transcranial magnetic stimulation

PubMed: MeSH publication types

  • Journal Article

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