Published online Feb 28, 2016. doi: 10.4329/wjr.v8.i2.192
Peer-review started: August 1, 2015
First decision: September 28, 2015
Revised: October 24, 2015
Accepted: December 18, 2015
Article in press: December 18, 2015
Published online: February 28, 2016
AIM: 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.
CONCLUSION: Using videofluoroscopy, this study shows rtHNC patients have worse swallowing outcomes associated with reduced hyolaryngeal mechanics and pharyngeal constriction compared with controls.
Core tip: Quality videofluoroscopic imaging of barium swallows is useful to determine swallowing outcomes for safe and efficient swallowing, conventional kinematics, and underlying functional anatomy associated with outcomes. This retrospective study of radiation therapy head and neck cancer (rtHNC) patients compared with age and gender matched controls and found that swallowing outcomes were significantly worse in rtHNC patients. Conventional kinematics indicated a reduction in laryngeal elevation. Computational analysis of swallowing mechanics using coordinate data of anatomical landmarks is here used to visualize impaired functional anatomy associated with poor outcomes in order to suggest particular targets for rehabilitation.