Laryngeal Elevation Velocity as a Candidate Dynamic Marker of Swallowing Safety in Postradiotherapy Dysphagia: A Preliminary Exploratory Study.

Background/Objectives: To investigate laryngeal elevation velocity (LEV) as a candidate physiological marker of swallowing safety in post-radiotherapy dysphagia patients with cricopharyngeal muscle dysfunction (CPMD), we examined its association with airway safety and whether the LEV-upper esophageal sphincter (UES) opening relationship differed before versus after botulinum toxin injection, used here as a within-subject physiological perturbation. Methods: This retrospective cohort study included 18 post-radiotherapy patients with nasopharyngeal carcinoma (NPC) and CPMD who underwent botulinum toxin injection into the cricopharyngeal muscle (median total dose, 30 U; range, 20-40 U) and completed videofluoroscopic swallowing studies (VFSSs) before and after intervention. Primary outcomes were the Penetration-Aspiration Scale (PAS) and UES opening diameter; secondary outcomes included the Functional Oral Intake Scale (FOIS), laryngeal elevation (LE) and LEV. Associations were evaluated using generalized estimating equations (GEEs) with LEV × treatment interaction terms to assess whether they differed across pre- and post-injection states. Results: Following botulinum toxin injection, FOIS scores improved significantly (median, 4 to 5; p < 0.001), with concurrent increases in LEV (median, 149.86 to 201.12 C2-4%/s; p = 0.027) and UES diameter (median, 21.10 to 23.30 C2-4%; p = 0.039); PAS scores and laryngeal elevation displacement did not change significantly. Higher LEV was associated with lower odds of unsafe airway invasion (PAS 5-8) in univariate analysis (odds ratio per 100-unit increase, 0.38; 95% confidence interval [CI], 0.17-0.86; p = 0.021). A significant LEV × treatment interaction was observed for UES diameter (p = 0.021). Conclusions: In post-radiotherapy NPC patients with CPMD, higher LEV was associated with airway safety, and the LEV-UES relationship differed across pre- and post-injection states. Although the study design does not permit conclusions about treatment efficacy, LEV may represent a candidate load-sensitive marker of swallowing safety, warranting further investigation.