title: Impaired swallowing mechanics of post radiation therapy head and neck cancer patients: A retrospective videofluoroscopic study.
abstract: OBJECTIVE
  To determine swallowing outcomes and hyolaryngeal mechanics associated with post radiation therapy head and neck cancer (rtHNC) patients using videofluoroscopic swallow studies.
  
  
  METHODS
  In this retrospective cohort study, videofluoroscopic images of rtHNC patients (n = 21) were compared with age and gender matched controls (n = 21). Penetration-aspiration of the bolus and bolus residue were measured as swallowing outcome variables. Timing and displacement measurements of the anterior and posterior muscular slings elevating the hyolaryngeal complex were acquired. Coordinate data of anatomical landmarks mapping the action of the anterior muscles (suprahyoid muscles) and posterior muscles (long pharyngeal muscles) were used to calculate the distance measurements, and slice numbers were used to calculate time intervals. Canonical variate analysis with post-hoc discriminant function analysis was performed on coordinate data to determine multivariate mechanics of swallowing associated with treatment. Pharyngeal constriction ratio (PCR) was also measured to determine if weak pharyngeal constriction is associated with post radiation therapy.
  
  
  RESULTS
  The rtHNC group was characterized by poor swallowing outcomes compared to the control group in regards to: Penetration-aspiration scale (P < 0.0001), normalized residue ratio scale (NRRS) for the valleculae (P = 0.002) and NRRS for the piriform sinuses (P = 0.003). Timing and distance measurements of the anterior muscular sling were not significantly different in the two groups, whereas for the PMS time of displacement was abbreviated (P = 0.002) and distance of excursion was reduced (P = 0.02) in the rtHNC group. A canonical variate analysis shows a significant reduction in pharyngeal mechanics in the rtHNC group (P < 0.0001). The PCR was significantly higher in the test group than the control group (P = 0.0001) indicating reduced efficiency in pharyngeal clearance.
  
  
  CONCLUSIONS
  Using videofluoroscopy, this study shows rtHNC patients have worse swallowing outcomes associated with reduced hyolaryngeal mechanics and pharyngeal constriction compared with controls.
authors.affiliation: William G Pearson Jr, Department of Cellular Biology and Anatomy, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States.
authors.forename: William G
authors.initials: WG
authors.lastname: Pearson
authors.affiliation: William G Pearson Jr, Department of Cellular Biology and Anatomy, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States.
authors.forename: Alisa A
authors.initials: AA
authors.lastname: Davidoff
authors.affiliation: William G Pearson Jr, Department of Cellular Biology and Anatomy, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States.
authors.forename: Zachary M
authors.initials: ZM
authors.lastname: Smith
authors.affiliation: William G Pearson Jr, Department of Cellular Biology and Anatomy, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States.
authors.forename: Dorothy E
authors.initials: DE
authors.lastname: Adams
authors.affiliation: William G Pearson Jr, Department of Cellular Biology and Anatomy, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Langmore
keywords: Anatomy; Fluoroscopy; Head and neck cancer; Post radiation; Swallow mechanics