Abstract
There are several surgical techniques used for dilation of the glottis to treat the dyspnea and inspiratory stridor caused by a median fixation of both vocal cords. The method proposed by Ejnell et al. in 1984 is advantageous in that 1) it does not cause a destruction of the normal structure of the larynx; and 2) the surgical technique is easy. This method has recently come to be performed more frequently. Although Ejnell's technique is relatively simple, there has been no study on certain details of the procedure, such as in what position the needle that is inserted into the thyroid cartilage should be placed, or what direction the traction thread should take. Hence, a study on the optimal position of the needle, the best direction for traction on the thread, and a measurement of the degree of lateralization of the vocal cord was performed using cadaveric laryngeal specimens.
When the vocal cord was pulled perpendicularly to the thyroid cartilage wing, the mean glottal area was 106.2% of the same area before traction. When the vocal cord was pulled perpendicularly to the median line of the glottis, the mean glottal area was 112.7% of the same area before traction. The glottal area was therefore about 6% larger when the vocal cord was pulled perpendicularly to the median line of the glottis than when it was pulled perpendicularly to the thyroid cartilage wing (p<0.05; pailed t-test).
Based on an anatomic study of six cadaveric laryngeal regions, a formula was developed to predict at which points needles should be placed in Ejnell's technique for optimal results. Further clinical correlations will be carried out in patients to test the validity of this formula.
