Upper Displacement of the Anterior Commissure: Experimental Study of a New Phonosurgical Approach to Raising Vocal Pitch

Abstract

Objectives:

The present study assessed the effects of a unique pitch-raising surgical technique designated upper displacement of the anterior commissure (UDAC), comparing the results with those obtained through cricothyroid approximation (CTA).

Methods:

Vocal fold vibration was artificially evoked in 20 excised human larynges through tracheal injection of compressed air. Vocal fold length, fundamental frequency, and videokymography parameters were determined preoperatively, post-CTA, and post-UDAC. In UDAC, a bilateral incision was made between the middle and anterior thirds of the thyroid cartilage. The inferiormost portion of the anterior thyroid cartilage (anterior to the cartilaginous incision) was sutured to the superiormost portion of the posterior thyroid cartilage (posterior to the cartilaginous incision). The anterior commissure was thus moved upward and forward, ensuring increased vocal fold tension.

Results:

The mean vocal fold length was 16.88 mm preoperatively, 20.02 mm post-CTA, and 18.67 mm post-UDAC (p < .05). The mean fundamental frequency was 151.60 Hz preoperatively, 271.10 Hz post-CTA, and 239.30 Hz post-UDAC (p < .05). The post-CTA and post-UDAC vibration amplitudes were significantly lower than the preoperative values (p < .05).

Conclusions:

Vocal fold length and fundamental frequency increased significantly after UDAC (p < .05), although to a lesser degree than after CTA.