HSC Section 6 Nov2016 Green Book

Vojko Djukic, et al

Stroboscopy in Detection of Laryngeal Dysplasia

samples from normophonic speakers. The authors strongly ad- vised that caution should be used when determining the abnor- mality of mucosal wave variations during clinical visualization procedures. One concern in our study is that in 45.5% of the pa- tients with histopathologically determined CIS, nonvibrating segments were absent, which is a significant number. Treatment involves removing the lesion with epithelium, basal membrane, and lamina propria and, depending on the type of cordectomy, deeper underlying structures. Vocal fold scaring was examined on animal models. Rousseau et al 18,19 described the development of a vocal fold scar 6 months after surgical injury in canine and rabbit models. As early as 2 months after the surgical removal of the epithelium and lamina propria, no significant difference in collagen density was noted, but at 6 months after injury, collagen density was significantly increased in the surgically injured animals compared with those with normal vocal folds. By 6 months, the procollagen and elastin levels had achieved the densities observed in normal vocal folds, although the elastin fibers remain fragmented and disorganized. The basal layer of the mucosal epithelium continues to experience remodeling in the later stages of wound healing, whereas the intercellular epithelial space undergoes remodeling earlier during the acute stage of wound healing. 20 Kishimoto et al 21 investigated the maturation process of vo- cal fold scarring after cordectomy in 10 patients (eight with early laryngeal carcinoma and two with laryngeal dysplasia) us- ing videostroboscopy. The patients were treated with cordec- tomy types I–III. Improvements in amplitude of mucosal wave were visible 6 months after the procedure and continued to improve up to 14 months after the procedure. Twelve months after the initial treatment was a reasonable time to assess the treatment results in our study. Indeed, there were improvements in phase symmetry, periodicity, amplitude of vocal fold vibra- tions, and the regularity of mucosal wave. The number of pa- tients with nonvibratory segment decreased. At the end of the follow-up period, there were 23 (20.53%) patients with detected nonvibrating segment. Four patients who developed invasive carcinoma were among these patients. In other patients, this result could be explained by the vocal fold scarring process, particularly because in these patients, type II and type III cor- dectomies were performed as a treatment of choice. This is yet another limiting factor for stroboscopy use because it cannot reliably distinguish the vocal fold process resulting from the ex- istence of a nonvibrating segment. Many voice disorders are marked by either aperiodicity or fluctuating frequency and, therefore, cannot be visualized with stroboscopy. 22 There are a growing number of articles that emphasize the importance of different and more effective methods in evaluating irregular vocal fold vibrations and the propagation and existence of the mucosal wave, such as electro- glottography, high-speed digital imaging, videokymography, or digital kymography. Mucosal wave propagates in both vertical and horizontal directions, and quantifying the vertical displace- ment is crucial for understanding the effect of pathologies on the mucosal wave. Stroboscopy, videokymography, and high- speed digital imaging only provide a two-dimensional image Phase Symmetry Periodicity Amplitude Mucosal Wave Nonvibratory Segment t 5.31 7.65 1.39 2.36 6.69 5.288 10.39 OR (95% CI) 1.22 (0.76 to 1.68) 1.88 (1.39 to 2.37) 0.80 ( 0.34 to 1.94) 1.24 (0.19 to 2.28) 2.03 (1.43 to 2.63) 1.68 (1.05 to 2.30) 2.950 (2.39 to 3.51) Sig. 0.006* 0.791 0.076 0.265 0.474 0.636 0.000* Abbreviations: CI, confidence interval; OR, odds ratio. * P < 0.05. Cordectomy Type Glottic Occlusion

TABLE 6. Multivariate Regression Analysis of Correlation of Dysplasia With Stroboscopic Signs and Type of Treatment

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