The Stroboscopic Evaluation Of Advanced Symptomatic Unilateral Vocal Fold Paralysis

Objective:(1) To modify a new stroboscopic rating form used for assessment of unilateral vocal fold paralysis (UVCP). (2) To explore stroboscopic characteristics of advanced symptomatic UVCP with this rating form. (3) To explore the feasibility of videostrobokymography (VSK) for assessment of vibration of vocal cord in UVCP.Methods:(1) Based on the clinical characteristics of UVCP, and making reference to multiple stroboscopic rating methods designed by several scholars,15 parameters were selected to evaluate stroboscopic characteristics in assessment of UVCP. Inter-rater agreement and intra-rater reliability of all the parameters in the rating form were calculated. (2) 38 inpatients with advanced symptomatic UVCP (UVCP group) in Changhai hospital and 38 age and gender-matched normal persons (control group) during an 8-months period were reviewed. and Two groups all had videostroboscopy. With the stroboscopic rating form,76 videos were rated by three raters. The difference of multiple parameters was compared between two groups. (3) Three lines at the anterior third, the mid area and the posterior third of the vocal fold length were selected on corresponding kymograms. Values of open quotient (OQ) were obtained by using PC-based technique, together with kymograms to study the characteristics of VSK in UVCP. The difference of the OQ was compared between two groups.Results:(1) 76 videos were reviewed by seven raters. The range of the intraclass correlations for the parameters on the stroboscopic rating form was 0.49 to 1.0, with four parameters exhibiting lower interclass coefficients (paralyzed arytenoid position during inspiration, mucosal wave, periodicity, phase symmetry). The range of intra-rater reliability was 0.81 to 0.98. (2) The extremely hoarse voices of 12 patients in UVCP group failed to trigger the stroboscope. Because of different causes such as etiology, five parameters including amplitude, mucosal wave, vocal fold position, phase symmetry and phase closure were not sent for statistical analysis. There were significant differences between UVCP group and control group in supraglottic activity, vocal fold edge straightness, arytenoids position, vocal folds bulk asymmetry, vocal fold atrophy, glottic closure, vertical level of vocal folds and regularity (P<0.05). It indicated those parameters can be used in assessment of UVCP. No Statistically significant differences were observed in vocal fold smoothness and non-vibrating portion between two groups (P>0.05). So those two parameters were not suitable for assessment of UVCP. (3) In control group, Phase symmetry on the posterior third of the vocal fold length was slightly asymmetry in 8 cases in corresponding kymograms, and mucosal waves were fundamental symmetry. Slightly posterior gaps were observed on the posterior third of the vocal fold length in 2 cases. Phase symmetry were symmetry on the anterior third, the mid area of vocal cord length in this 8 cases. Phase symmetry were symmetry on the anterior third, the mid area of vocal cord length and other 30 cases. Because the extremely hoarse voices of 12 patients in UVCP group failed to trigger the stroboscope, so the corresponding kymogorams were ambiguous, and their values of OQ were not available. Phase symmetry was asymmetry in 26 cases of UVCP group in corresponding kymograms. It included 12 cases which mucosal waves were observed in paralysed vocal cord, and glottic closures were observed on the anterior third of the vocal fold length in the 4 cases of those 12 cases, but not on the mid area and the posterior third. The mucosal waves were attenuated.In other 8 cases and 14 cases which mucosal waves were not observed in paralysed vocal cord, glottic closures were not observed on the anterior third, the mid area and the posterior third of the vocal fold length. In 26 cases of UVCP group, the mean and standard deviation of OQ on the anterior third, the mid area and the posterior third of the vocal fold length were 0.94±0.14,1.0±0.0,1.0±0.0, respectively. The mean and standard deviation of OQ on the anterior third, the mid area and the posterior third of the vocal fold length in 26 cases of control group were 0.55±0.10,0.64±0.13 and 0.60±0.17, respectively. There were significant differences in values of OQ between two groups (P<0.01).The values of OQ on the anterior third, the mid area and the posterior third of the vocal fold length in UVCP group which can trigger the stroboscope were bigger than what in control group.Conclusions:(1) A new modified stroboscopic rating form was presented; Many parameters on the stroboscopic rating form exhibited high inter-rater agreement, and intra-rater reliability of seven raters was high.13 parameters such as glottic closure, vocal fold edge straightness, supraglottic activity and regularity, had great significance in assessment of UVCP. Vocal fold smoothness and non-vibrating portion had no significance in assessment of UVCP. So this stroboscopic rating form was suitable for assessment of UVCP. (2) There were many stroboscopic characteristics of advanced symptomatic UVCP, and it was important for diagnosis of UVCP. Meanwhile, this study provided objective and systematic data of UVCP patients for comparing with postoperative data. (3) The opening and closing conditions of vibration of one point on vocal cord,the phase symmetry and musocal wave in VCP patients are all observed by VSK. It is an effective tool for the assessment of vibratory patterns of vocal folds. (4) There was some limitation for videostroboscopy in assessment of advanced symptomatic UVCP.