Efficacy of transcutaneous laryngeal ultrasonography (TLUS) in the diagnosis of vocal cord function in an endocrine surgery referral center.

Chiara Offi; Giovanni Antonelli; Umberto Brancaccio; D’Ambrosio Edoardo; Esposito Maria Grazia; Claudia Misso; Romano Roberto Maria; Stefano Spiezia

doi:10.1530/endoabs.73.AEP633

Introduction

Thyroid diseases affect a large population worldwide and total thyroidectomy (TT) is the most common curative treatment [1]. Recurrent laryngeal nerve (RLN) lesions are the most dangerous complication [1]. The intraoperative neuromonitoring (NIM) is a useful tool in reducing the incidence of nerve injury, but a preoperative examinations of vocal cords function through flexible fiberoptic laryngoscopy (FFL) is recommended [1]. FFL is uncomfortable and expensive evaluation, so transcutaneous laryngeal ultrasonography (TLUS) has been proposed as alternative indirect examination of vocal cords function [2].

Materials and methods

We conducted a retro prospective on 100 consecutive patients with benign and malignant thyroid disease underwent to TT and preoperative and postoperative evaluation with FFL and TLUS. All TLUS was performed by one experienced investigator.

Results

Demographic data and results are showed in Tables 1 and 2, respectively.

Table 1. Patients¥ demographic and clinical information
	Population
Mean age ± s.d.	50.63 ± 12.15
Gender, % Male Female	24 (24%) 76 (76%)
Diagnosis, % Benign Malignant Indeterminate cytology	68% 4% 28%
Preoperative FFL, % Normal Vocal Impairment	100% 0%
Preoperative TLUS, % Normal Vocal cord impairment Correct correlation with FFL Incorrect correlation with FFL Normal visualization Lateral visualization	100% 0% 100% 0% 91% 9%
Postoperative FFL, % Normal Unilateral vocal cord hypomobility Unilateral vocal cord paralysis	80% 12% 8%
Postoperative TLUS, % Normal Unilateral vocal cord hypomobility Unilateral vocal cord paralysis Normal visualization Lateral visualization Correct correlation with FFL Incorrect correlation with FFL	80% 8% 8% 98% 2% 98% 2%
Postoperative diagnosis, % Benign Malignant	76% 24%

**Table 2.** Statistical data (PPV₊, predictive positive value; PNV, predictive negative value).
	CI of 95%
Sensitivity	0.833 (0.743–0.898)
Specificity	1.000 (0.954–1.000)
Prevalence	0.120 (0.066–0.204)
PPV+	1.000 (0.954–1.000)
PNV–	0.978 (0.919–0.996)

Discussion

In the literature, there are discordant data that give a sensitivity greater than 90% and others a 33%, while the specificity is always greater than 90% [1, 2]. Our study showed a sensitivity of 83.3%, a specificity of 100%, PPV+ of 100% and a PNV- of 96.7%. TLUS is safe in recognizing healthy patients but has some limitations in recognizing patients with chordal hypomobility, particularly in male patients with prominent and/or calcific thyroid cartilage.

References

1. Wong KP, et al. The importance of sonographic landmarks by transcutaneous laryngeal ultrasonography in post-thyroidectomy vocal cord assessment. Surgery 156(6):1590–1596.

2. Borel F, et al. Transcutaneous ultrasonography in early postoperative diagnosis of vocal cord palsy after total thyroidectomy. World J Surg 40(3):665–671.

Endocrine Abstracts

AEP633