Effect of Topical Anesthesia on the Phonation Process During High-Speed Digital Imaging Laryngoscopy in Patients With Laryngopharyngeal Reflux

Standard clinical practice for rigid transoral laryngoscopy, including High‐Speed DigitalImaging (HSDI), includes the elective use of topical anesthesia of the oral cavity andoropharynx; however, clearly defined recommendations and indications for its use arelacking, and its potential effect on the phonation process has not been unequivocallyestablished. Upon application to the oral cavity and oropharynx, anesthetic may draininto the larynx and desensitize the mucosa, potentially affecting sensorimotor aspects oflaryngeal function. Existing studies on the effect of topical anesthesia on phonationduring laryngoscopy are limited and report contradictory findings.This prospective, randomized, double‐blind, placebo‐controlled crossover study assignedeach participant a unique number via random number generator, determining the order ofrecording modalities (even numbers recorded first with topical anesthesia, odd numbersfirst without). Once assigned, the order could not be changed. Randomization and testingorder were concealed from the examiner performing the HSDI recording.Topical anesthesia (lidocaine spray, 100 mg/ml, 0.1 ml per actuation) or physiologicalsaline (placebo) was applied by a junior physician, blinded to the substance used, to thebase of the tongue, posterior pharyngeal wall, and soft palate (one actuation per site).HSDI recording was performed 5 minutes after application. Each participant underwentrecording in both modalities on two consecutive days, a period considered sufficientlyshort to avoid confounding phonotraumatic, hormonal, or health‐related changes.HSDI recordings were performed by an experienced otorhinolaryngologist and phoniatrician(>5 years of experience) using a rigid 90° endoscope (Wolf 5562 HRES ENDOCAM with WolfAuto LP 5132 Hlight light source, Richard Wolf GmbH, Knittlingen, Germany). Participantswere seated upright with the tongue held protruded; the endoscope was passed along themidline of the tongue to visualize the full length of the vocal folds. Participantsphonated the vowel /a/ dynamically and frequentially, and a 2‐second HSDI recording wascaptured. Recordings were reviewed for quality (minimum 1,000 clear, focused, consecutiveimages of the full vocal fold length during the steady phonation phase); inadequaterecordings were repeated. Fundamental frequency and phonation intensity were recorded viaa microphone mounted on the endoscope with software processing. Maximum Phonation Timewas determined from three stopwatch‐timed measurements of sustained /a/ phonation, takenimmediately before and after HSDI recording.Each HSDI recording was independently assessed by two experiencedotorhinolaryngologists/phoniatricians (>5 years of experience) using visual‐perceptualanalysis. Discrepancies in parameter scoring were resolved through joint re‐analysis anddiscussion until consensus was reached before proceeding to the next recording.Assessment was standardized using the Voice‐Vibratory Assessment with Laryngeal Imaging(VALI) form and the European Laryngological Society (ELS) form for glottal closurepattern classification, along with a modified classification of glottal insufficiency.The Reflux Finding Score was re‐determined from recordings according to the Belafsky etal. classification.Participants underwent a follow‐up examination within three months of studyparticipation, during which the Reflux Finding Score (via fiberendoscopy) and RefluxSymptom Index (via questionnaire) were re‐assessed while participants continued regularproton pump inhibitor therapy and hygienic‐dietary measures; participants with persistentpathological findings were excluded from final analysis.Statistical analysis included the Kolmogorov‐Smirnov test for normality of distribution.Normally distributed variables were described using means and standard deviations;non‐normally distributed variables were described using medians and ranges. Differencesbetween recordings with and without topical anesthesia were tested using the pairedt‐test (parametric) or Wilcoxon signed‐rank test (non‐parametric), as appropriate.Spearman correlation and regression analysis were used to explore associations betweenanatomical structures and measured characteristics. A p‐value <0.05 was consideredstatistically significant.