The Role of Laryngoscopy in the Diagnosis of Spasmodic Dysphonia

IMPORTANCE Spasmodic dysphonia (SD) can be difficult to diagnose, and patients often see multiple physicians for many years before diagnosis. Improving the speed of diagnosis for individuals with SD may decrease the time to treatment and improve patient quality of life more quickly. OBJECTIVE To assess whether the diagnosis of SD can be accurately predicted through auditory cues alone without the assistance of visual cues offered by laryngoscopic examination. DESIGN, SETTING, AND PARTICIPANTS Single-masked, case-control study at a specialized referral center that included patients who underwent laryngoscopic examination as part of a multidisciplinary workup for dysphonia. Twenty-two patients were selected in total: 10 with SD, 5 with vocal tremor, and 7 controls without SD or vocal tremor. INTERVENTIONS The laryngoscopic examination was recorded, deidentified, and edited to make 3 media clips for each patient: video alone, audio alone, and combined video and audio. These clips were randomized and presented to 3 fellowship-trained laryngologist raters ( A. D. R., A. T. H., and A. M. K.), who established the most probable diagnosis for each clip. Intrarater and interrater reliability were evaluated using repeat clips incorporated in the presentations. MAIN OUTCOMES AND MEASURES We measured diagnostic accuracy for video-only, audio-only, and combined multimedia clips. These measures were established before data collection. Data analysis was accomplished with analysis of variance and Tukey honestly significant differences. RESULTS Of patients with SD, diagnostic accuracy was 10%, 73%, and 73% for video-only, audio- only, and combined, respectively (P <.001, df = 2). Of patients with vocal tremor, diagnostic accuracy was 93%, 73%, and 100% for video-only, audio- only, and combined, respectively ( P =.05, df = 2). Of the controls, diagnostic accuracy was 81%, 19%, and 62% for video-only, audio- only, and combined, respectively ( P <.001, df= 2). CONCLUSIONS AND RELEVANCE The diagnosis of SD during examination is based primarily on auditory cues. Viewing combined audio and video clips afforded no change in diagnostic accuracy compared with audio alone. Laryngoscopy serves an important role in the diagnosis of SD by excluding other pathologic causes and identifying vocal tremor.