title: Changes in masticatory muscles activity associated with Eagle's syndrome.
abstract: OBJECTIVE
  This study had the goal of analyzing masseter and temporalis muscles of individuals with Eagle's Syndrome, establishing comparisons with healthy control individuals by means of electromyography, due to the importance of the masticatory musculature upon the various functions of the stomatognathic system and the effects of Eagle's syndrome on this system's functioning.
  
  
  METHODS
  Ten women with Eagle's syndrome and ten healthy controls volunteered to participate in the study. A Myosystem I system, Prosecon Ltda (Uberlândia/MG, Brazil) with 12 channels was used Active differential electrodes were placed on the belly of both masseters and on the anterior temporalis. Firstly, rest position was registered and then the patients were instructed to clench their teeth with maximum strength for four seconds to register the Clenching at Usual Maximum Intercuspation. Next, the clinical conditions of chewing, mandible laterality, and water swallowing were performed.
  
  
  RESULTS
  The normalized data of muscle activity during the different clinical conditions and at rest position were compared by Student's t test, considering two groups: controls and syndrome bearers. The masticatory muscles of every syndrome bearers showed hyperactivity during the analyzed clinical conditions; except for chewing, in which the right masseter did not show greater electromyographic activity.
  
  
  CONCLUSIONS
  It is concluded that individuals with the syndrome showed muscular hyperactivity when compared to healthy individuals, due to the interference of the elongated styloid process, which leads to dysfunctions of the stomatognathic system in the syndrome bearers, with signs and symptoms related to craniofacial pain, dysphagia, otalgy, temporomandibular dysfunctions, and headache.
authors.affiliation: Ribeirão Preto School of Dentistry, São Paulo University, Department of Morphology, Stomatology and Physiology, Ribeirão Preto, SP, Brazil.
authors.forename: S
authors.initials: S
authors.lastname: Siéssere
authors.forename: M
authors.initials: M
authors.lastname: Vitti
authors.forename: L G
authors.initials: LG
authors.lastname: de Sousa
authors.forename: M
authors.initials: M
authors.lastname: Semprini
authors.forename: P C A
authors.initials: PC
authors.lastname: Watanabe
authors.forename: J E C
authors.initials: JE
authors.lastname: Hallak
authors.forename: S C H
authors.initials: SC
authors.lastname: Regalo
mesh_terms: D000328:Adult; D001847:Bone Diseases / Q000503:physiopathology*; D004576:Electromyography; D005157:Facial Pain / Q000503:physiopathology; D005260:Female; D006801:Humans; D008406:Masseter Muscle / Q000503:physiopathology*; D008409:Mastication; D009119:Muscle Contraction; D013577:Syndrome; D013701:Temporal Bone / Q000002:abnormalities* / Q000503:physiopathology*; D013703:Temporal Muscle / Q000503:physiopathology*