title: Differential changes in human pharyngoesophageal motor excitability induced by swallowing, pharyngeal stimulation, and anesthesia.
abstract: We investigated the effects of water swallowing, pharyngeal stimulation, and oropharyngeal anesthesia on corticobulbar and craniobulbar projections to human swallowing musculature. Changes in pathway excitability were measured via electromyography from swallowed intraluminal pharyngeal and esophageal electrodes to motor cerebral and trigeminal nerve magnetic stimulation. After both water swallowing and pharyngeal stimulation, pharyngoesophageal corticobulbar excitability increased (swallowing: pharynx = 59 +/- 12%, P < 0.001; esophagus = 45 +/- 20%, P < 0.05; pharyngeal stimulation: pharynx = 76 +/- 19%, P < 0.001; esophagus = 45 +/- 23%, P = 0.05), being early with swallowing but late with stimulation. By comparison, craniobulbar excitability increased early after swallowing but remained unaffected by pharyngeal stimulation. After anesthesia, both corticobulbar (pharynx =-24 +/- 10%, P < 0.05; esophagus = -28 +/- 7%, P < 0.01) and craniobulbar excitability showed a late decrease. Thus swallowing induces transient early facilitation of corticobulbar and craniobulbar projections, whereas electrical stimulation promotes delayed facilitation mainly in cortex. With removal of input, both corticobulbar and craniobulbar projections show delayed inhibition, implying a reduction in motoneuron and/or cortical activity.
authors.affiliation: Department of Gastrointestinal Science, University of Manchester, Hope Hospital, Eccles Old Road, Salford M6 8HD, England.
authors.forename: Christopher
authors.initials: C
authors.lastname: Fraser
authors.forename: John
authors.initials: J
authors.lastname: Rothwell
authors.forename: Maxine
authors.initials: M
authors.lastname: Power
authors.forename: Anthony
authors.initials: A
authors.lastname: Hobson
authors.forename: David
authors.initials: D
authors.lastname: Thompson
authors.forename: Shaheen
authors.initials: S
authors.lastname: Hamdy
mesh_terms: D000328:Adult; D000758:Anesthesia; D000779:Anesthetics, Local; D003679:Deglutition / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D004947:Esophagus / Q000294:innervation / Q000502:physiology*; D005260:Female; D006801:Humans; D008012:Lidocaine; D008280:Magnetics; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D010609:Pharyngeal Muscles / Q000294:innervation / Q000502:physiology*; D011712:Pyramidal Tracts / Q000166:cytology / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D014276:Trigeminal Nerve / Q000502:physiology; D014867:Water
chemical_list: D000779:Anesthetics, Local; D014867:Water; D008012:Lidocaine