Purpose: The primary objective of this study was to assess the value of translaryngeal ultrasound (TLUS) in assessing vocal fold (VF) function in patients after thyroid, parathyroid and neck lymph node surgery. Methods: A total of 219 patients that underwent 230 surgical procedures were enrolled in this prospective study. The study was conducted from October 2020 to October 2021. Patients’ VFs were analysed independently with TLUS and laryngoscopy before and after the surgery. Various TLUS variables, such as vocal folds displacement velocity (VFDV), arytenoids symmetry and angle between VFs, were measured. The questionnaire evaluating discomfort caused to patients by both methods was conducted. Results: Of the 230 surgeries in this study, 85% were from oncological indications. The incidence of RLN injury was 10.4%. The accuracy of TLUS compared to laryngoscopy was 98.3%, with sensitivity 98.1%, specificity 100%, PPV 100% and NPV 83.3%. Laryngoscopy was found to cause significantly more discomfort than TLUS. VF visibility was lower in men; smokers; and patients with higher BMI (32 vs. 28 kg/m2), multifocal cancer, higher left lobe volume and higher fT3 levels. Arytenoid symmetry VFDV was lower for “e” and “i” right side and “i” left side in injured/disabled VFs/RLN. Conclusions: TLUS can be an excellent and non-invasive method of VF evaluation in most patients. There are some technical aspects that can improve its accuracy. Sometimes, RLN injury after the surgery, especially among oncological patients, is unavoidable. Therefore, it is vital to diagnose dysphonia early with convenient methods, such as TLUS.

Transcutaneous laryngeal ultrasonography (TLUS) has become a cheap, convenient, and novel method in vocal fold (VF) assessment. The gold standard method of VF examination is laryngoscopy. It requires ear, nose, and throat specialist consultation and additional equipment. Moreover, laryngoscopy causes distress to patients, and during the COVID-19 pandemic it is a high-risk, aerosol-producing procedure. The aim of the paper was to review publications on the role of TLUS in VF evaluation. Considered aspects included VF visibility, factors affecting them, and different variables measured during TLUS examination. The visibility of VFs in TLUS ranged from 72.8 to 100%. Among men it was significantly lower (17-100%) in comparison to women (83-100%). All but 2 authors concluded that TLUS is a viable tool that can be an alternative to laryngoscopy in diagnosing VFs. Obesity, age, male gender, height, calcified thyroid, and incision close to the thyroid cartilage were independent factors for inaccessible vocal folds. VF displacement velocity (VFDV) is the most objective parameter measured by Doppler, and it is proportional to the velocity of the wave causing the vibrations of the VFs. After VF paralysis, this parameter is reduced. Valsalva manoeuvre, low-frequency transducer, and different transducer positions can improve images obtained on USG. TLUS in a majority of cases can adequately assess whether the function of the VFs is intact or paresis/paralysis has occurred. It is noninvasive and rapid, it adds no extra cost, and it can be a part of the preoperative examination of the thyroid gland. TLUS can usually be a convenient alternative to laryngoscopy.

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