title: Preliminary Evaluation of the Pathomechanisms of Dysphagia After Occipitospinal Fusion: Kinematic Analysis by Videofluoroscopic Swallowing Study.
abstract: METHODS
  Kinematic analysis of swallowing function using videofluoroscopic swallowing study (VFSS).
  
  
  OBJECTIVE
  The aims of this study were to analyze swallowing process in the patients who underwent occipitospinal fusion (OSF) and elucidate the pathomechanism of dysphagia after OSF.
  
  
  BACKGROUND
  Although several hypotheses about the pathomechanisms of dysphagia after OSF were suggested, there has been little tangible evidence to support these hypotheses since these hypotheses were based on the analysis of static radiogram or CT. Considering that swallowing is a compositive motion of oropharyngeal structures, the etiology of postoperative dysphagia should be investigated through kinematic approaches.
  
  
  METHODS
  Each four patients with or without postoperative dysphagia (group D and N, respectively) participated in this study. For VFSS, all patients were monitored to swallow 5-mL diluted barium solution by fluoroscopy, and then dynamic passing pattern of the barium solution was analyzed. Additionally, O-C2 angle (O-C2A) was measured for the assessment of craniocervical alignment.
  
  
  RESULTS
  O-C2A in group D was -7.5 degrees, which was relatively smaller than 10.3 degrees in group N (P = 0.07). In group D, all cases presented smooth medium passing without any obstruction at the upper cervical level regardless of O-C2A, whereas the obstruction to the passage of medium was detected at the apex of mid-lower cervical ocurvature, where the anterior protrusion of mid-lower cervical spine compressed directly the pharyngeal space. In group N, all cases showed smooth passing of medium through the whole process of swallowing.
  
  
  CONCLUSIONS
  This study presented that postoperative dysphagia did not occur at the upper cervical level even though there was smaller angle of O-C2A and demonstrated the narrowing of the oropharyngeal space towing to direct compression by the anterior protrusion of mid-lower cervical spine was the etiology of dysphagia after OSF. Therefore, surgeon should pay attention to the alignment of mid-cervical spine as well as craniocervical junction during OSF.
  
  
  METHODS
  4.
authors.affiliation: Department of Orthopaedic Surgery, Kobe Rosai Hospital, Kobe, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kaneyama
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Sumi
authors.forename: Masato
authors.initials: M
authors.lastname: Takabatake
authors.forename: Koichi
authors.initials: K
authors.lastname: Kasahara
authors.forename: Aritetsu
authors.initials: A
authors.lastname: Kanemura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Koh
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hirata
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000601:surgery*; D003679:Deglutition; D003680:Deglutition Disorders / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery*; D005260:Female; D005471:Fluoroscopy / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography / Q000379:methods; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods