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.