The cricothyroid muscle does not influence vocal fold position in laryngeal paralysis

The status of the cricothyroid muscle, which is innervated by the superior laryngeal nerve, is believed to influence the vocal fold position in laryngeal paralysis. It is believed that isolated lesions of the recurrent laryngeal nerve generally result in the paralyzed vocal fold assuming a paramedian position but that with lesions of both the superior and recurrent laryngeal nerves, a more lateral (intermediate or cadaveric) vocal fold position can be expected. Twenty-six consecutive patients with unilateral vocal fold paralysis underwent transnasal fiberoptic laryngoscopy (TFL) and laryngeal electromyography (LEMG). By TFL, the vocal fold positions were paramedian in 8 patients, intermediate in 7, and lateral in 11. By LEMG, 13 patients had isolated recurrent laryngeal nerve lesions and 13 patients had combined (superior and recurrent laryngeal nerve) lesions. There was no correlation between the vocal fold position and the status of the cricothyroid muscle, i.e., the status of the cricothyroid muscle by LEMG did not predict the vocal fold position nor did the vocal fold position by TFL predict the site of lesion. In addition, we investigated the possibility that the degree of thyroarytenoid muscle recruitment (tone) might correlate with vocal fold position, but no relation was found. We conclude that 1. the cricothyroid muscle does not predictably influence the position of the vocal fold in unilateral paralysis; 2. thyroarytenoid muscle recruitment (tone) does not appear to influence vocal fold position; and 3. still unidentified and unknown factors may be responsible for determining vocal fold position in laryngeal paralysis.