A comparison of primed low-frequency repetitive transcranial magnetic stimulation treatments in chronic stroke

Jessica M. Cassidy, Haitao Chu, David C Anderson, Linda E. Krach, LeAnn M Snow, Teresa J Kimberley, PT,, James R Carey

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Background Preceding low-frequency repetitive transcranial magnetic stimulation (rTMS) with a bout of high-frequency rTMS called priming potentiates the after-effects of the former in healthy adults. The utility of primed rTMS in stroke remains under-explored despite its theoretical benefits in enhancing cortical excitability and motor function. Objective To ascertain the efficacy of priming in chronic stroke by comparing changes in cortical excitability and paretic hand function following three types of primed low-frequency rTMS treatments. Methods Eleven individuals with chronic stroke participated in this repeated-measures study receiving three treatments to the contralesional primary motor cortex in randomized order: 6 Hz primed 1 Hz rTMS, 1 Hz primed 1 Hz rTMS, and sham 6 Hz primed active 1 Hz rTMS. Within- and between-treatment differences from baseline in cortical excitability and paretic hand function from baseline were analyzed using mixed effects linear models. Results 6 Hz primed 1 Hz rTMS produced significant within-treatment differences from baseline in ipsilesional cortical silent period (CSP) duration and short-interval intracortical inhibition. Compared to 1 Hz priming and sham 6 Hz priming of 1 Hz rTMS, active 6 Hz priming generated significantly greater decreases in ipsilesional CSP duration. These heightened effects were not observed for intracortical facilitation or interhemispheric inhibition excitability measures. Conclusion Our findings demonstrate the efficacy of 6 Hz primed 1 Hz rTMS in probing homeostatic plasticity mechanisms in the stroke brain as best demonstrated by differences CSP duration and SICI from baseline. Though 6 Hz priming did not universally enhance cortical excitability across measures, our findings pose important implications in non-invasive brain stimulation application in stroke rehabilitation.

Original languageEnglish (US)
Pages (from-to)1074-1084
Number of pages11
JournalBrain Stimulation
Volume8
Issue number6
DOIs
StatePublished - Nov 2015

Keywords

  • Homeostatic plasticity
  • Metaplasticity
  • Priming
  • Repetitive transcranial magnetic stimulation
  • Stroke

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