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positioning_of_the_laryngeal_endoscope_on_videokymography [2014/04/04 13:24] (current)
bziolko created
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 +Mara Behlau (1,2), Glaucya Madazio(1,2), Paulo Pontes (2,3) (Brazil)
 +**Positioning of the laryngeal endoscope on videokymography**
 +1. Centro de Estudos da Voz – CEV, São Paulo, Brazil\\
 +2. Universidade Federal de São Paulo – UNIFESP, São Paulo, Brazil\\
 +3. Instituto da Laringe – INLAR, São Paulo, Brazil\\
 +Videokymography is a sophisticated high-speed imaging technique to investigate vocal fold vibration. The system has been considered useful, particularly in the analysis of irregular signals, making it possible to observe left-right asymmetries, open quotient, propagation of mucosal waves, and movement of the upper and lower margins. Some caution should be taken because videokymographic images are obtained from different points of the vocal folds; so that telescope should remain on the selected line. Furthermore, at videokymography, telescope rotation can produce an asymmetric illusory image. On the other hand, the regular laryngeal examination via endoscopy  does not require fixed position of the instrument to produce a better laryngeal image and facilitate an accurate diagnosis. The goal of the present study was to verify the correspondence of the videokymographic images with larynx exposition angle variation. Three Brazilian adult female subjects, with normal voices, no vocal complains and no laryngeal disorders, were evaluated. Videokymographic images were obtained with the laryngeal endoscope 90o positioned on the measuring line, perpendicular to the glottal axis - zero degree, during a sustained “ae” vowel, using habitual frequency and intensity. The procedure was repeated twice and adjusted by rotating the camera in fifteen degrees from the perpendicular line to the right and to the left. The results showed clear differences depending on the position of the endoscope, suggesting the standardization of laryngeal exposition to interpret videokymographic images correctly. As an example, regarding the opening and closing (at the opening phase) a symmetric image became asymmetrical with rotation and another asymmetric sample became symmetric with rotation; both subjects had symmetrical larynges during regular videostroboscopic examination. Visual perception depends on the angle of visualization and it is a perceptual analysis with all related limitations on technique and experience of the evaluator.
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