RESUMEN
OBJECTIVES: Practitioners rely heavily on flexible endoscopic visualization of the true vocal folds during a repeated "sniff-ee" maneuver to assess vocal fold mobility. However, the human eye lacks the temporal and spatial precision required to accurately gauge fine differences in maximal glottal angle. This study compared differences in maximal glottal angle variables during "sniff-ee" maneuvers across patients with various voice and laryngeal breathing disorders. METHODS: We retrospectively measured glottal angle from flexible laryngoscopy examinations in six groups of patients with voice and upper airway disorders: laryngeal dystonia/essential tremor (LD/ET), vocal fold lesions, vocal fold atrophy, paradoxical vocal fold motion disorder (PVFMD), muscle tension dysphonia (MTD), and healthy controls. Maximum glottal angle (GAMAX) and average glottal angle (GAAVG) were calculated during three serial "sniff-ee" maneuvers for all participants. Individual disorder groups (MTD, PVFMD, LD/ET, atrophy, and lesion) and broader disorder types (functional and organic) were compared to healthy controls using simple linear regression analyses. RESULTS: No significant difference in either GAMAX or GAAVG was found between controls and the disorder subgroups or broader disorder type (function and organic). However, there were statistically significant differences in the variability of GAMAX in both PVFMD (6.2° more variability; P < 0.001) and LD/ET (5.8° more variability; P < 0.001) compared to healthy controls. CONCLUSION: Patients diagnosed with LD/ET and PVFMD both demonstrated significantly more variability in their GAMAX compared to healthy controls, suggesting that movement consistency or coordination may be relatively compromised in these patient groups. Further research is warranted to investigate the sensitivity and specificity of glottal angle variability in diagnosing PVFMD and LD in clinical or research settings. LEVEL OF EVIDENCE: 4 SHORT SUMMARY: Laryngeal examinations from five patient groups were compared to those from healthy controls. Patients with paradoxical vocal fold motion disorder and laryngeal movement disorders exhibited significantly greater variability of glottal angle during sniff maneuver compared to healthy controls.