Measurement of adult vocal fold length.

Laryngeal photographs from 165 Taiwanese subjects were taken during microlaryngoscopy. Photographs of the vocal fold during the open phase were chosen. For measuring the vocal fold length, both the photograph of a ruler and the larynx were taken under the operating microscope, thus forming a 'new scale'. Photographs of the vocal fold and the ruler were then processed at the same power of magnification. The length of the vocal folds was measured with the 'new scale'. In 100 patients receiving direct laryngoscopy under neuroleptic anaesthesia, the vocal fold length was 14.6 +/- 1.2 mm (n = 35) for males and 11.1 +/- 1.0 mm (n = 65) for females. In 65 patients under general anaesthesia, the vocal fold length was 15.3 +/- 1.6 mm (n = 23) for males and 13.5 +/- 1.3 mm (n = 42) for females. Statistical analysis revealed a significant difference between both groups and both sexes. Elongation of the vocal fold under general rather than neuroleptic anaesthesia may be important when performing functional surgery of the vocal fold.