Cricothyroid joint anatomy as a predicting factor for success of cricoid-thyroid approximation in transwomen

Objectives/Hypothesis Cricoid‐thyroid approximation (CTA) performed to elevate the vocal pitch in transwomen fails in about one‐third of the patients. The purpose of this study was to test the feasibility of predicting the likelihood of success of CTA by preoperative determination of the crico‐thyroid joint (CTJ) type using three‐dimensional (3‐D) images derived from high‐resolution computer tomography (HRCT). Study Design Prospective cohort study of 18 transwomen who underwent CTA at our institution. Methods All patients had a preoperative and a postoperative HRCT of the larynx, as well as pre‐ and postoperative measurements of the fundamental vocal pitch (F0). Results Three‐dimensional images showed type A CTJs in 11 patients and type B or C CTJs in seven patients (see below for the definition of these types). Cricoid‐thyroid approximation raised the F0 on average by 76 Hz in patients with type A CTJs and by 45 Hz in patients with type B/C CTJs. Moreover, CTA produced a vocal fold elongation of 17% in larynges with type A joint but only of 3% in larynges with type B/C joints. Conclusion Three‐dimensional images allow the differentiation of type A versus type B/C CTJs but not the distinction between type B and type C CTJs. Both vocal pitch elevation and vocal fold elongation following CTA are significantly greater in patients with type A CTJs than in patients with type B/C CTJs. Based on these preliminary results, we recommend identifying the CTJ type on 3‐D images and limiting CTA to patients with type A CTJs. Level of Evidence 4. Laryngoscope, 126:1380–1384, 2016