In this cumulative dissertation we examined the influence of phonosurgical interventions and special vocal effects on glottal opening and closing function and phonation. In a first prospective observational multicentre trial we investigated the phonosurgical effect of posterior chordotomy and partial arytenoidectomy on glottal function. The residual glottal gap causes dysphonia. Yet the resulting improvement of breathing is much more important. 61 patients with bilateral vocal fold paralysis (BVFP) were screened of whom 36 were eligible. Subjects underwent standardized phoniatric and respiratory tests preoperatively and at one and six months postoperatively. The respiratory parameters improved significantly. Voice quality objectively worsened significantly; however, this was not perceived by the patients themselves. We conclude that endoscopic glottal enlargement is an effective method for relieving symptoms of dyspnoea due to BVFP. In a second prospective clinical pilot study we evaluated the efficacy of vocal fold augmentation with calcium hydroxylapatite (CaHA) in surgically pretreated larynges with glottal insufficiency. After several prior reconstructive attempts, CaHA was injected in 10 patients with residual glottal insufficiency ≤ 1.5 mm. Results were assessed after one day, one and three months. Evaluation of augmentation comprised intraoperative documentation, videolaryngostroboscopy (VLS), and voice function diagnostics. The study revealed that in pretreated vocal folds the exact placement of CaHA was not possible. Due to the insufficient augmentation, the voices did not improve. We conclude that the application of CaHA in the surgically pretreated scarred larynx is not reliable to improve phonation. In a third individual cohort study we investigated common vocal effects in professional nonclassical vocalists. Ten male singers (pop, rock, metal, musical theatre) repeatedly presented the usual nonclassical vocal effects in their repertoire. All performances were documented and analysed. VLS showed that the vocal apparatus of all singers was healthy. The vocal effects could be easily differentiated from each other; they were intraindividually consistently repeatable and also interindividually produced in a similar way. Partial glottal vibration was discovered in one singer when belting in the high register. We conclude that the long-lasting use of nonclassical effects does not necessarily cause negative impact on trained singers. The risk of long-term vocal fold damage depends on the individual constitution, duration, and extent of the hyperfunction. In summary, the investigated vocal effects and phonosurgical interventions had an important influence on glottal function and phonation, while in laryngeal diseases the treatment outcomes for respiration and voice might behave contrary to each other.
