Swallowing problems following stroke may result in increased risk of aspiration pneumonia, malnutrition, and dehydration.
Objective/hypothesis
Our hypothesis was that three neurostimulation techniques would produce beneficial effects on chronic dysphagia following stroke through a common brain mechanism that would predict behavioral response.
Methods
In 18 dysphagic stroke patients (mean age: 66 ± 3 years, 3 female, time-post-stroke: 63 ± 15 weeks [±SD]), pharyngeal electromyographic responses were recorded after single-pulse transcranial magnetic stimulation (TMS) over the pharyngeal motor cortex, to measure corticobulbar excitability before, immediately, and 30 min, after real and sham applications of neurostimulation. Patients were randomized to a single session of either: pharyngeal electrical stimulation (PES), paired associative stimulation (PAS) or repetitive TMS (rTMS). Penetration-aspiration scores and bolus transfer timings were assessed before and after both real and sham interventions using videofluoroscopy.
Results
Corticobulbar excitability of pharyngeal motor cortex was beneficially modulated by PES, PAS and to a lesser extent by rTMS, with functionally relevant changes in the unaffected hemisphere. Following combining the results of real neurostimulation, an overall increase in corticobulbar excitability in the unaffected hemisphere (P = .005, F1,17 = 10.6, ANOVA) with an associated 15% reduction in aspiration (P = .005, z = −2.79) was observed compared to sham.
Conclusions
In this mechanistic study, an increase in corticobulbar excitability the unaffected projection was correlated with the improvement in swallowing safety (P = .001, rho = −.732), but modality-specific differences were observed. Paradigms providing peripheral input favored change in neurophysiological and behavioral outcome measures in chronic dysphagia patients. Further larger cohort studies of neurostimulation in chronic dysphagic stroke are imperative.
Keywords
Chronic dysphagia
Stroke
Neurostimulation
Plasticity
Abbreviations
cPA
cumulative penetration aspiration
MEP
motor evoked potentials
MT
motor threshold
NIHSS
National Institute of Health Stroke Scale
PAS
paired associative stimulation
PEG
percutaneous endoscopic gastrostomy
PES
pharyngeal electrical stimulation
rTMS
repetitive transcranial magnetic stimulation
MI
motor cortex
Cited by (0)
Funding: Supported by the Wellcome Trust (WT081741MA). EM was recipient of the Greek State Foundation Scholarship and FSF NIHR North West Stroke Research Network. SJ was funded through a grant from Action Medical.
Contributors and authorships: EM (blinded to interventions), SJ (blinded to interventions), SM assisted in the studies. EM and SJ analyzed data and wrote the paper. EM, SM, SJ and PT helped in interpretation of data. SH was the Chief Investigator, wrote the grants to support the studies, helped write the paper and interpret the analysis.
Disclosures: Nothing to disclose.
The study was sponsored by the University of Manchester, UK, which did not have a role in the study design or in the collection, analysis, or interpretation of data.
