title: Submental Muscle Activity is Delayed and Shortened During Swallowing Following Stroke.
abstract: OBJECTIVE
  To evaluate the activities of the submental muscles using surface electromyography (sEMG) in patients presenting with dysphagia secondary to middle cerebral artery (MCA) infarction, and to compare the results with those in healthy volunteers.
  
  
  METHODS
  Retrospective study design.
  
  
  METHODS
  A dysphagia clinic at a tertiary care university hospital.
  
  
  METHODS
  Twenty-one patients presenting with dysphagia after unilateral MCA infarction were recruited into the study within 2 months of stroke onset. To serve as a control group, 13 healthy volunteers were enrolled.
  
  
  METHODS
  The primary sEMG parameters were swallowing onset, pretrigger duration, swallowing duration, and swallowing amplitude. Swallowing functional outcome was evaluated using the Videofluoroscopic Dysphagia Scale and the American Speech-Language-Hearing Association National Outcome Measurement System.
  
  
  RESULTS
  Patients with MCA infarction demonstrated significantly delayed swallowing onset (P < .001) and shorter swallowing duration (P = .003) compared with the controls. Duration from the start of sEMG activity and actual laryngeal elevation also was delayed in the patient group (P = .042). At a cut-off point of 0.13 seconds for swallowing onset, sensitivity was 85.7% and specificity was 69.2%. For swallowing duration, sensitivity was 84.6% and specificity was 66.7% with 1.05 seconds as the cut-off point.
  
  
  CONCLUSIONS
  Patients with MCA infarction showed not only delayed swallowing onset and pretrigger duration, but also shorter duration of sEMG activity compared with those in healthy volunteers. Our results suggest that dysphagia after stroke might be further compromised by delayed laryngeal response especially after the start of suprahyoid muscle activity, which represents impaired laryngeal protection mechanism.
authors.affiliation: Department of Rehabilitation Medicine, National Rehabilitation Center, Seoul, Republic of Korea.
authors.forename: Hye-Ri
authors.initials: HR
authors.lastname: Kim
authors.affiliation: Department of Rehabilitation Medicine, Gangdong Kyunghee University Hospital, Seoul, Republic of Korea.
authors.forename: Seung Ah
authors.initials: SA
authors.lastname: Lee
authors.affiliation: Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Keewon
authors.initials: K
authors.lastname: Kim
authors.affiliation: Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Ja-Ho
authors.initials: JH
authors.lastname: Leigh
authors.affiliation: Department of Rehabilitation Medicine, Gangwon-Do Rehabilitation Hospital, Chuncheon, Gangwon-Do, Republic of Korea.
authors.forename: Tai Ryoon
authors.initials: TR
authors.lastname: Han
authors.affiliation: Department of Rehabilitation Medicine, Seoul National University College of Medicine, Republic of Korea.
authors.forename: Byung-Mo
authors.initials: BM
authors.lastname: Oh
mesh_terms: D000368:Aged; D003679:Deglutition / Q000502:physiology*; D003680:Deglutition Disorders / Q000209:etiology / Q000503:physiopathology*; D004576:Electromyography; D005152:Facial Muscles / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D013997:Time Factors