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| Author(s): |
Saramira Cardoso Bohadana
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2002-01-30 |
| Examining board members: |
Luiz Ubirajara Sennes;
Ricardo Ferreira Bento;
João Batista Ferreira;
Roberto Campos Meirelles;
Domingos Hiroshi Tsuji
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| Advisor: | Luiz Ubirajara Sennes |
| Abstract | |
The cricothyroid approximation simulates the cricothyroid muscle contraction by approximating the cricoid and thyroid cartilages. By this surgery, the vocal folds are lengthened. Consequently, the fundamental frequency of the voice is increased. The main indications for this procedure are patients presenting voice hoarseness due to superior laryngeal nerve palsy or to rheumatoid and endocrinological diseases in women. Thirty fresh cadavers larynges were used for the purpose of studying the effects of the cricothyroid approximation on the vocal folds vibration in both genders. Ideally, this experiment would allow exclusion of the diverse phonation compensatory factors that can possible compromise the accuracy of an in vivo" study. The surgical procedure was performed in the excised larynges. Initially, the arytenoids cartilages were approximated by suturing both together, closing the glottis. Humidified compressed air was injected inside of the tracheal tube, causing vocal folds vibration. The cricothyroid approximation was performed by sutures placed in the cricoid and thyroid cartilages. Calipers were used to measure the length of the membranous portion of the vocal folds. Pre and post cricothyroid approximation. Vocal folds vibration was recorded by a portable camera specific for videokymographic studies. After digitalizing the recorded images, each one of them was carefully evaluated. The fundamental voice frequency, the vocal folds vibratory amplitude, and the vibratory cycle with its phases (opened, closed, opening and closing phases) were measured pre and post operatively. Indexes related to the duration of the different phases of the vibratory cycle, such as open quotient, closed quotient and speed quotient were then calculated and analyzed. Multivariate statistical analysis and profile analysis were used for correlation and understanding of the results. There was a statistically significant lengthen of the vocal folds after cricothyroid approximation, more noticeable in female laryngeal specimens. The fundamental voice frequency was increased, but no relation with the increased length of the vocal cords could be observed. The vibratory amplitude was significantly reduced, as was the vibratory cycle duration. The latter was directly correlated with the increase of fundamental voice frequency. The male laryngeal specimens presented a significant higher reduction of the opening phase of the vibratory cycle. In this study, the cricothyroid approximation caused lengthening of the vocal folds. The vibratory cycle and its phases were also altered, presenting a reduced duration. An inverse correlation between these variables and the increase of the vibratory frequency was noted. Although the female laryngeal specimens had shown a longer length when compared with the male, and the male specimens had a higher decrease of the opening phase of the vibratory cycle, there was no statistically significant difference in the cricothyroid approximation effect on the vocal frequency according to gender. (AU) | |