Priming pharyngeal motor cortex by repeated paired associative stimulation: implications for dysphagia neurorehabilitation

Neurorehabil Neural Repair. 2013 May;27(4):355-62. doi: 10.1177/1545968312469837. Epub 2013 Jan 8.

Abstract

Background: Several stimulation parameters can influence the neurophysiological and behavioral effects of paired associative stimulation (PAS), a neurostimulation paradigm that repeatedly pairs a peripheral electrical with a central cortical (transcranial magnetic stimulation [TMS]) stimulus. This also appears to be the case when PAS is applied to the pharyngeal motor cortex (MI), with some variability in excitatory responses, questioning its translation into a useful therapy for patients with brain injury.

Objective: To investigate whether repeated PAS in both "responders" and "nonresponders" could enhance cortical excitability in pharyngeal MI more robustly.

Methods: Based on their responses after single PAS, healthy participants were stratified into 2 groups of "responders" and "nonresponders" and underwent 2 periods (60 minutes inter-PAS interval) of active and sham PAS in a randomized order. Neurophysiological measurements with single TMS pulses from pharyngeal motor representation were collected up to 90 minutes after the second PAS period.

Results: Repeated PAS increased cortical excitability up to 95% at 60 minutes following the second PAS in both the "responders" and "nonresponders." Moreover, cortical excitability in the "nonresponders" was significantly different after repeated PAS compared with single and sham application (P = .02; z = -2.2).

Conclusions: Double dose PAS switched "nonresponders" to "responders." These results are important for PAS application to dysphagic stroke patients who do not initially respond to a single application.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Deglutition Disorders / etiology
  • Deglutition Disorders / rehabilitation
  • Electric Stimulation / instrumentation
  • Electric Stimulation / methods
  • Electromyography / instrumentation
  • Electromyography / methods
  • Evoked Potentials, Motor / physiology
  • Female
  • Humans
  • Male
  • Motor Cortex / physiology*
  • Pharyngeal Muscles / physiology*
  • Stroke / complications
  • Stroke Rehabilitation
  • Time Factors
  • Transcranial Magnetic Stimulation / instrumentation
  • Transcranial Magnetic Stimulation / methods*