title: Controlled study of EMG activity of the jaw closers and openers during mastication in patients with myasthenia gravis.
abstract: Mastication was evaluated in patients with bulbar myasthenia gravis and compared with that of patients with ocular myasthenia gravis, patients in remission who previously suffered from bulbar symptoms, and healthy controls. Bulbar myasthenia gravis may impair mastication due to weakness of the masticatory muscles. The aim of the study was to objectively evaluate the influence of myasthenia gravis on mastication. The subjects chewed a piece of breakfast cake and chewed 1 min on a piece of chewing gum. Surface EMG of the masseter muscle, temporalis muscle and jaw opener muscles was recorded. Statistical analysis revealed that bulbar patients produced significantly less EMG activity in the closing phase of a chewing cycle in both experiments. The EMG of the masseter muscle expressed as percentage of the maximum EMG during maximal clenching showed significantly higher values in the bulbar group than in the other groups. This was not found for the temporalis muscle. It was suggested that bulbar patients use a strategy of limited effort to produce a bolus that can be swallowed. The ocular patients and the patients in remission showed no subclinical impairments in muscle function during chewing.
authors.affiliation: Department of Oral-Maxillofacial Surgery, Prosthodontics and Special Dental Care, University Medical Center Utrecht, The Netherlands. a.vanderbilt@med.uu.nl
authors.forename: A
authors.initials: A
authors.lastname: van der Bilt
authors.forename: F G
authors.initials: FG
authors.lastname: Weijnen
authors.forename: F
authors.initials: F
authors.lastname: Bosman
authors.forename: H W
authors.initials: HW
authors.lastname: van der Glas
authors.forename: J B
authors.initials: JB
authors.lastname: Kuks
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002638:Chewing Gum; D003679:Deglutition / Q000502:physiology; D004576:Electromyography; D005260:Female; D005502:Food; D006801:Humans; D016014:Linear Models; D008297:Male; D008334:Mandible / Q000503:physiopathology; D008406:Masseter Muscle / Q000503:physiopathology; D008409:Mastication / Q000502:physiology*; D008410:Masticatory Muscles / Q000503:physiopathology*; D008875:Middle Aged; D009068:Movement; D009119:Muscle Contraction / Q000502:physiology; D009157:Myasthenia Gravis / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D013703:Temporal Muscle / Q000503:physiopathology
chemical_list: D002638:Chewing Gum