[Abnormal adductor movement of the vocal cords in spasmodic dysphonia]

Adductor movement of the vocal cords in initial/ke/phonation was recorded using a laryngeal fiberscope, CCD camera, and videocassette recorder. Three patients with adductor spasmodic dysphonia (SD), a 53 year old male and 48 and 52 year old females, and 7 normal volunteers participated in this study. During the examination, the subject sat on a chair holding a microphone about 20 cm away from his or her lips. A laryngeal fiberscope was inserted through either side of the nostril. The tip of the fiberscope was positioned just caudal to the tip of the epiglottis to get a complete view of both sides of the vocal cords. The examiner told the subject to make the speech sound/ke/repeatedly, and to insert a sufficient inspiratory period between each phonation. The vocal cord images were recorded at 30 frames per second and printed successively from several frames ahead of the beginning of adductor movement to the frame of initial adjustment of the membranous part of the vocal cords following a time code indicator. The tips of both sides of the vocal processes and anterior commissure were marked, then, scanned and transported to a personal computer. An imaginary line connecting the vocal process and anterior commissure was drawn on the screen of the computer, which was done on both sides of the vocal cords. Then, an angle made by the two lines was measured in degrees and stored. The time and speed of adductor movement varied among subjects. Normal subjects, however, never failed to finish making the explosive sound in /ke/ before initial vocal cord adjustment.(ABSTRACT TRUNCATED AT 250 WORDS)