title: Characterizing the mechanisms of central and peripheral forms of neurostimulation in chronic dysphagic stroke patients.
abstract: BACKGROUND
  Swallowing problems following stroke may result in increased risk of aspiration pneumonia, malnutrition, and dehydration.
  
  
  OBJECTIVE
  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.
authors: Gastrointestinal Centre, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester (Part of the Manchester Academic Health Sciences Centre [MAHSC]), Salford Royal Hospital, Clinical Sciences Building, Salford M6 8HD, UK.
authors: Emilia
authors: E
authors: Michou
authors: Gastrointestinal Centre, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester (Part of the Manchester Academic Health Sciences Centre [MAHSC]), Salford Royal Hospital, Clinical Sciences Building, Salford M6 8HD, UK.
authors: Satish
authors: S
authors: Mistry
authors: Gastrointestinal Centre, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester (Part of the Manchester Academic Health Sciences Centre [MAHSC]), Salford Royal Hospital, Clinical Sciences Building, Salford M6 8HD, UK.
authors: Samantha
authors: S
authors: Jefferson
authors: Stroke Medicine, Institute of Cardiovascular Sciences, University of Manchester (Part of the Manchester Academic Health Sciences Centre [MAHSC]), Salford Royal Hospital Foundation Trust, Salford M6 8HD, UK.
authors: Pippa
authors: P
authors: Tyrrell
authors: Gastrointestinal Centre, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester (Part of the Manchester Academic Health Sciences Centre [MAHSC]), Salford Royal Hospital, Clinical Sciences Building, Salford M6 8HD, UK. Electronic address: shaheen.hamdy@manchester.ac.uk.
authors: Shaheen
authors: S
authors: Hamdy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003680:Deglutition Disorders / Q000503:physiopathology* / Q000628:therapy*; D004599:Electric Stimulation Therapy; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009473:Neuronal Plasticity / Q000502:physiology; D010614:Pharynx / Q000294:innervation / Q000503:physiopathology; D020521:Stroke / Q000150:complications; D050781:Transcranial Magnetic Stimulation
keywords: Chronic dysphagia; MEP; MI; MT; NIHSS; National Institute of Health Stroke Scale; Neurostimulation; PAS; PEG; PES; Plasticity; Stroke; cPA; cumulative penetration aspiration; motor cortex; motor evoked potentials; motor threshold; paired associative stimulation; percutaneous endoscopic gastrostomy; pharyngeal electrical stimulation; rTMS; repetitive transcranial magnetic stimulation