| Common causes of unilateral vocal fold paralysis (UVFP) are iatrogenic, neoplastic, idiopathic, and traumatic. UVFP is characterized by varying degrees of hoarseness, poor coughing effort, and occasional aspiration, which impair the quality of life of the patients. Presently surgical procedures including vocal fold injection, thyroplasty, arytenoid adduction, and laryngeal reinnervation can be expected to restore vocal function of symptomatic UVFP. Although improved voice quality can be obtained by vocal fold injection, thyroplasty and arytenoid adduction, these static procedures cannot prevent the atrophy of denervated laryngeal muscles. Theoretically, laryngeal reinnervation is an ideal approach that can restore the connection of motoneurons with denervated laryngeal muscles. Neurorrhaphy of the ansa cervicalis to recurrent laryngeal nerve (RLN) is one of the most popular laryngeal reinnervation procedures. Nevertheless, only a few cases of ansa cervicalis-to-RLN anastomosis have been reported. Its long-time outcome was still elusive. The influence of denervation course on the outcome of this procedure has not been reported in the literature. The objectives of this study were shown as follows: 1. to evaluate the long-term efficacy of the main branch of the ansa cervicalis to RLN anatomosis and a subbranch of the ansa cervicalis to RLN anatomosis in treatment of UVFP; 2. to compare between the efficacy of the main branch of the ansa cervicalis to RLN anatomosis and a subbranch of the ansa cervicalis to RLN anatomosis; 3. to investigate the influence of denervation course on the outcome of the main branch of the ansa cervicalis to RLN anatomosis; 4. to evaluate the long-term efficacy of contralateral ansa cervicalis to RLN anatomosis in treatment of UVFP. In order to multidimensionally evaluate the procedures, The Chinese Putonghua version of RBH perceptual assessment system and a new stroboscopic rating form for UVFP were established. Abstracts of Part one to Part four were shown as follows:Part one: Objective: to establish the Chinese Putonghua version of RBH perceptual assessment system. Methods: a new Chinese Putonghua version of short passage for collecting voice samples was established. The similarity was tested between the proportions of vowel, consonant and tone in the short passage and the ones in Chinese language reported by the institute of Acoustics Chinese Academy of Sciences. Legibility was tested in the short passage. Forty normal voice samples and 160 pathological voice samples were collected including sustained vowels /a/ and connected speech samples. Jitter, shimmer, noise-to-harmonics ratio (N/H), dysphonia severity index (DSI), mean flow rate (MFR) and maximum phonation time (MPT) were tested in all the individuals in this study. All the 200 voice samples were rated by seven raters. Inter-rater reliability was calculated by intraclass correlation coefficient and intra-rater reliability was tested by Kappa coefficient. Validity of RBH perceptual assessment system was also tested. Results: The proportions of vowel, consonant and tone in the short passage were similar to the ones in Chinese language reported by the institute of Acoustics Chinese Academy of Sciences. Legibility of the short passage was well. The inter-rater reliability of roughness, breathiness and horseness were 0.86, 0.81 and 0.89. The intra-rater reliability of 7 raters was from 0.72 to 0.45. As the individuals were grouped according to the four levels of horseness, Jitter, shimmer, noise-to-harmonics ratio (N/H), dysphonia severity index (DSI), mean flow rate (MFR) and maximum phonation time (MPT) had significant differences between the adjacent two levels of horseness(p<0.05,respectively). As the individuals were grouped according to the four levels of roughness, the difference of Jitter, shimmer and N/H were significant between the adjacent two levels of roughness(p<0.05,respectively). As the individuals were grouped according to the four levels of breathiness, the difference of N/H, MFR and MPT were significant between the adjacent two levels of breathiness(p<0.05,respectively). Conclusion: The proportions of vowel, consonant and tone in the short passage were similar to the ones in Chinese language reported by the institute of Acoustics Chinese Academy of Sciences. Legibility of the short passage was well. The reliability and validity of Chinese Putonghua version of RBH perceptual assessment system were well.Part two: Objective: to establish a stroboscopic perceptual assessment form for UVCP. Methods: Based on the clinical characteristics of UVCP, and making reference to multiple stroboscopic rating methods designed by several scholars. 8 parameters including vocal fold amplitude, supraglottic activity, vocal fold position, vocal fold edge straightness, phase symmetry, regularity, glottal closure and phase closure were selected to evaluate stroboscopic characteristics in assessment of UVFP. Eleven raters rated the stroboscopic videos of 48 UVFP patients. Inter-rater reliability was calculated by intraclass correlation coefficient and intra-rater reliability was tested by Kappa coefficient. Validity of a stroboscopic perceptual assessment form was also tested. Results: Selecting raters with high intra-rater reliability can improve the reliability of the parameters in the stroboscopic form. After analysis of the highest intra-rater reliability of the 5 raters as a group, the inter-rater reliability of six parameters including vocal fold position, vocal fold straightness, phase symmetry, regularity, glottal closure and phase closure were from 0.55 to 0.80. Vocal fold amplitude and supraglottic activity were excluded from the stroboscopic form as their reliability were too low. The differences of the six parameters in the stroboscopic were significant between preoperative and postoperative stroboscopic videos(p < 0.001 ,respectively). The validity of the stroboscopic perceptual assessment form was well. Conclusion: The reliability and validity of the stroboscopic perceptual assessment form were well. The form was a valid tool for stroboscopic assessment of UVFP.Part three: Objective: 1. to evaluate the long-term efficacy of the main branch of the ansa cervicalis to RLN anatomosis and a subbranch of the ansa cervicalis to RLN anatomosis in treatment of UVFP; 2. to compare between the efficacy of the main branch of the ansa cervicalis to RLN anatomosis and a subbranch of the ansa cervicalis to RLN anatomosis; 3. to investigate the influence of denervation course on the outcome of the main branch of the ansa cervicalis to RLN anatomosis. Methods: From Mar. 1996 to Mar. 2008, a total of 309 UVFP patients who underwent ansa cervicalis main branch-to- RLN anastomosis were enrolled as main branch group. 52 patients who underwent ansa cervicalis subbranch-to-RLN anastomosis were enrolled as subbranch group. According to the denervation course, the individuals in the main branch group were divided as three subgroups. 156 individuals whose denervation course was 6 to 12 months were grouped as group A. 108 individuals whose denervation course were 13 to 24months were grouped as group B. 45 individuals whose denervation course were more than 24 months were grouped as group C. Videostroboscopy, vocal function assessment, and electromyography were performed preoperatively and postoperatively. Results: 1. In the main branch group and subbranch group, videostroboscopic assessment showed that postoperative parameters including vocal fold position, vocal fold edge straightness, phase symmetry, regularity, glottal closure and phase closure had significant improvements compared by the preoperative corresponding ones(p<0.001, respectively). Laryngeal electromyography (LEMG) showed that there was a significant post-operative improvement in voluntary motor-unit recruitment during phonation (p<0.001, respectively). The RBH perceptual assessment showed that horseness, roughness, breathiness were also significantly decreased post-operatively (p<0.001, respectively). Post-operative values of jitter, shimmer, and NHR were significantly lower than the corresponding pre-operative values (p<0.001, respectively). The post-operative MPT value was significantly longer than the pre-operative one(p<0.001). 2. The postoperative values of jitter, shimmer, and N/H in main branch group were significantly lower than the corresponding postoperative values in subbranch group (p<0.05, respectively). The post-operative MPT value in main branch group was significantly longer than the post-operative one in subbranch group(p<0.001). 3. The postoperative values of jitter, shimmer, and N/H in group A had no significant differences than the corresponding postoperative values in group B(p>0.05, respectively). The postoperative values of jitter, shimmer, and N/H in group A and groupB were significantly lower than the corresponding postoperative values in group C (p<0.001, respectively). The post-operative MPT value in group A and group B was significantly longer than the post-operative one in group C (p<0.001). Conclusion: Laryngeal reinnervation with the main branch or subbranch of ansa cervicalis is a feasible and effective approach for treatment of UVFP. The efficacy of the ansa cervicalis main branch -to-RLN anastomosis was better than the ansa cervicalis subbranch -to-RLN anastomosis. The voice outcomes of UVFP patients with less than 2 years denervation course were better than the ones of UVFP patients with more than 2 years dernervation course. Part four: Objective: To evaluate the long-term efficacy of contralateral ansa cervicalis-to-RLN anastomosis for UVFP, when the ansa cervicalis on the side of the paralyzed vocal fold was absent or there was any question about its viability. Methods: Between Mar. 1996 and Mar. 2008, in total, 56 UVFP patients were enrolled into this study. All patients underwent contralateral ansa cervicalis-to-RLN anastomosis. Videostroboscopy, acoustic analysis, perceptual evaluation and MPT, and LEMG were performed pre- and post-operatively. Results: Analysis of videostroboscopic findings indicated that the glottic closure, vocal fold edge straightness, phase closure, vocal fold position, phase symmetry, and regularity were significantly improved (p < 0.001, post- vs. pre-operative). The RBH perceptual evaluation showed that horseness, roughness and breathiness were also significantly decreased post-operatively (p<0.001, respectively). Post-operative values of jitter, shimmer, and NHR were significantly lower than the corresponding pre-operative values (p<0.001, respectively). The post-operative MPT value was significantly longer than the pre-operative one (p < 0.001). LEMG showed that there was a significant post-operative improvement in voluntary motor-unit recruitment during phonation (p < 0.001). Conclusions: In cases with a lack of viable ansa cervicalis on the side of a paralyzed vocal fold, contralateral ansa cervicalis-to-RLN anastomosis is a feasible and effective approach in the treatment of UVFP and can restore physiological laryngeal phonatory function.In summary, this study showed that the proportions of vowel, consonant and tone in the short passage were similar to the ones in Chinese language reported by the institute of Acoustics Chinese Academy of Sciences. Legibility of the short passage was well. The reliability and validity of Chinese Putonghua version of RBH perceptual assessment system were well. The reliability and validity of the stroboscopic perceptual assessment form were well. The form was a valid tool for stroboscopic assessment of UVFP. Laryngeal reinnervation with the main branch or subbranch of ansa cervicalis is a feasible and effective approach for treatment of UVFP. The efficacy of the ansa cervicalis main branch -to-RLN anastomosis were better than the ansa cervicalis subbranch -to-RLN anastomosis. The voice outcomes of UVFP patients with less than 2 years denervation course were better than the ones of UVFP patients with more than 2 years dernervation course. In cases with a lack of viable ansa cervicalis on the side of a paralyzed vocal fold, contralateral ansa cervicalis-to-RLN anastomosis is a feasible and effective approach in the treatment of UVFP and can restore physiological laryngeal phonatory function.
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