title: Corticomotor control of the genioglossus in awake OSAS patients: a transcranial magnetic stimulation study.
abstract: BACKGROUND
  Upper airway collapse does not occur during wake in obstructive sleep apnea patients. This points to wake-related compensatory mechanisms, and possibly to a modified corticomotor control of upper airway dilator muscles. The objectives of the study were to characterize the responsiveness of the genioglossus to transcranial magnetic stimulation during respiratory and non-respiratory facilitatory maneuvers in obstructive sleep apnea patients, and to compare it to the responsiveness of the diaphragm, with reference to normal controls.
  
  
  METHODS
  Motor evoked potentials of the genioglossus and of the diaphragm, with the corresponding motor thresholds, were recorded in response to transcranial magnetic stimulation applied during expiration, inspiration and during maximal tongue protraction in 13 sleep apnea patients and 8 normal controls.
  
  
  RESULTS
  In the sleep apnea patients: 1) combined genioglossus and diaphragm responses occurred more frequently than in controls (P < 0.0001); 2) the amplitude of the genioglossus response increased during inspiratory maneuvers (not observed in controls); 3) the latency of the genioglossus response decreased during tongue protraction (not observed in controls). A significant negative correlation was found between the latency of the genioglossus response and the apnea-hypopnea index; 4) the difference in diaphragm and genioglossus cortico-motor responses during tongue protraction and inspiratory loading differed between sleep apnea and controls.
  
  
  CONCLUSIONS
  Sleep apnea patients and control subjects differ in the response pattern of the genioglossus and of the diaphragm to facilitatory maneuvers, some of the differences being related to the frequency of sleep-related events.
authors.affiliation: Centre de recherche, Hôpital Laval, Institut universitaire de cardiologie et de pneumologie de l'Université Laval, Quebec City, Quebec, Canada. frederic.series@med.ulaval.ca
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sériès
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Thomas
authors.initials: T
authors.lastname: Similowski
mesh_terms: D000328:Adult; D003964:Diaphragm / Q000503:physiopathology*; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009119:Muscle Contraction; D015656:Respiratory Mechanics; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D014059:Tongue / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014851:Wakefulness
references.citation: Am Rev Respir Dis. 1989 Sep;140(3):724-8
references.pmid: 2782743
references.citation: Intern Med. 1998 Feb;37(2):134-40
references.pmid: 9550592
references.citation: J Physiol. 2007 Nov 15;585(Pt 1):135-46
references.pmid: 17916615
references.citation: J Physiol. 2005 Apr 15;564(Pt 2):549-62
references.pmid: 15695240
references.citation: Electroencephalogr Clin Neurophysiol. 1998 Apr;109(2):114-8
references.pmid: 9741801
references.citation: Eur J Neurosci. 2004 Jun;19(11):3099-104
references.pmid: 15182318
references.citation: J Appl Physiol (1985). 2003 Feb;94(2):453-61
references.pmid: 12391044
references.citation: Am J Respir Crit Care Med. 1997 Sep;156(3 Pt 1):867-73
references.pmid: 9310006
references.citation: Thorax. 2007 Oct;62(10):861-7
references.pmid: 17412778
references.citation: Eur Respir J. 1996 Jun;9(6):1224-31
references.pmid: 8804942
references.citation: Respir Physiol Neurobiol. 2006 Dec;154(3):406-18
references.pmid: 16406377
references.citation: Am J Respir Crit Care Med. 1999 May;159(5 Pt 1):1551-5
references.pmid: 10228125
references.citation: J Appl Physiol Respir Environ Exerc Physiol. 1980 Oct;49(4):638-42
references.pmid: 6777347
references.citation: J Clin Invest. 1992 May;89(5):1571-9
references.pmid: 1569196
references.citation: FASEB J. 1996 Jun;10(8):897-904
references.pmid: 8666167
references.citation: Respir Physiol Neurobiol. 2002 Apr;130(2):161-8
references.pmid: 12380006
references.citation: J Physiol. 1971 Jun;215(2):557-75
references.pmid: 4336048
references.citation: Am J Respir Crit Care Med. 2001 Dec 1;164(11):2025-30
references.pmid: 11739130
references.citation: J Sleep Res. 2004 Mar;13(1):31-6
references.pmid: 14996032
references.citation: Electroencephalogr Clin Neurophysiol. 1997 Feb;105(1):15-23
references.pmid: 9118834
references.citation: J Appl Physiol (1985). 2004 Sep;97(3):902-12
references.pmid: 15133007
references.citation: J Appl Physiol (1985). 2003 Jul;95(1):26-34
references.pmid: 12639850
references.citation: Exp Physiol. 2007 Jul;92(4):739-47
references.pmid: 17412750
references.citation: J Sleep Res. 2004 Jun;13(2):159-63
references.pmid: 15175096
references.citation: J Appl Physiol (1985). 1990 Aug;69(2):443-50
references.pmid: 2228853
references.citation: Neuroscience. 2002;110(4):711-22
references.pmid: 11934478
references.citation: Respir Physiol. 1999 Sep 15;117(2-3):85-95
references.pmid: 10563437
references.citation: Exp Physiol. 1991 Mar;76(2):159-200
references.pmid: 2059424
references.citation: J Appl Physiol (1985). 1985 Apr;58(4):1378-82
references.pmid: 3988690
references.citation: J Appl Physiol (1985). 2003 Oct;95(4):1453-9
references.pmid: 12832431
references.citation: Am J Respir Crit Care Med. 1996 Dec;154(6 Pt 1):1771-7
references.pmid: 8970369
references.citation: J Clin Invest. 1995 Jan;95(1):20-5
references.pmid: 7814616
references.citation: BMC Physiol. 2006 Jul 29;6:7
references.pmid: 16875504