Stroboscopy in detection of laryngeal dysplasia effectiveness and limitations

Abstract

Vocal fold pathology changes the appearance and vibratory patterns observed during stroboscopic examination, but a strict correlation between the vibratory pattern and the dysplasia type does not exist. The aims of this study were to determine the role of stroboscopy in vocal fold dysplasia assessment and to determine whether stroboscopy is the deciding factor when performing laryngomicroscopy with biopsy in suspicious lesions. This prospective controlled study involved 112 patients with laryngeal dysplasia treated over a 2-year period at a tertiary medical center. Patient data and clinical, stroboscopy, laryngomicroscopy, and histopathologic reports were reviewed. During the stroboscopy, glottic occlusion, phase symmetry, periodicity, amplitude, mucosal wave, and nonvibratory segments were followed. Laryngomicroscopy with different types of endoscopic cordectomies (types I-III) was performed as a therapeutic measure, with a 12-month follow-up period. Nonvibrating segments were present in 15.1% of the patients with mild dysplasia and in 38.5% of the patients with moderate dysplasia. In 45.5% of the patients with severe dysplasia (carcinoma in situ), nonvibrating segments were absent. The amplitude of vocal fold vibrations in patients with mild dysplasia (P=0.03) was a significant factor indicative of recurrent disease, but none of the stroboscopic signs was significant for the disease progression. Severe dysplasia can be related to both nonvibrating and vibrating vocal fold segments. Stroboscopy cannot be used reliably for classifying laryngeal dysplasia and may indicate the need to perform laryngomicroscopy with biopsy in suspicious vocal fold lesions. The warning factors for recurrence and progression of dysplasia are treatment modality, abnormal amplitude of vibration, and nonvibrating segment.

Keywords: Laryngeal dysplasia; Nonvibrating segment; Stroboscopy.