A prospective study comparing the midline and lateral trans-laryngeal ultrasonography approaches in vocal cord assessment before and after thyroid and neck surgeries

A Prospective Study Evaluating the Feasibility and Accuracy of Post-operative Laryngeal Ultrasonography (LUSG) in Assessment of Vocal Cord Function After Esophagectomy

BACKGROUND

Vocal cord paresis (VCP) is a serious complication after esophagectomy. Conventional diagnosis of VCP relies on flexible laryngoscopy (FL), which is invasive. Laryngeal ultrasonography (LUSG) is non-invasive and convenient. It has provided accurate VC evaluation after thyroidectomy but it is unclear if it is just as accurate following esophagectomy. This prospective study evaluated the feasibility and accuracy of LUSG in VC assessment on day-1 after esophagectomy.

METHODS

Consecutive patients from a tertiary teaching hospital who underwent elective esophagectomy were prospectively recruited. All received pre-operative FL, and post-operative LUSG and FL on Day-1, each performed by a blinded, independent assessor. The primary outcomes were feasibility and accuracy of LUSG in the diagnosis of VCP on Day-1 post-esophagectomy. The accuracy of voice assessment (VA) was analyzed.

RESULTS

Twenty-six patients were eligible for analysis. The median age was 70 years (66-73). Majority were male (84.6%). Twenty-five (96.2%) received three-phase esophagectomy. Twenty-four (96%) had same-stage anastomosis at the neck. Three (11.5%) developed temporary and one (3.8%) developed permanent unilateral VCP. Overall VC visualization rate by LUSG was 100%; sensitivity, specificity, positive predictive value, negative predictive value (NPV) and accuracy of LUSG were 75.0%, 100%, 100%, 98.0%, 98.1% respectively, and superior to VA. Combining LUSG with VA findings could pick up all VCPs i.e. improved sensitivity and NPV to 100%.

CONCLUSION

LUSG is a highly feasible, accurate and non-invasive method to evaluate VC function early after esophagectomy. Post-operative FL may be avoided in patients with both normal LUSG and voice.

Using Intra-Operative Laryngeal Ultrasonography as a Real-Time Tool in Assessing Vocal Cord Function During Radiofrequency Ablation of the Thyroid Gland

BACKGROUND

Inadvertent injury of the recurrent laryngeal nerve can occur during radiofrequency ablation (RFA) of thyroid nodules. Methods to avoid permanent injury have not been described. Laryngeal ultrasonography (LUSG) can assess the function of vocal cords (VCs) in real time. The present study aimed to evaluate the feasibility and accuracy of LUSG in assessing real-time VC function during RFA of benign thyroid nodules.

METHODS

Consecutive patients undergoing RFA for benign thyroid nodules under local anesthesia were included. Spontaneous VC movements were checked with intra-operative LUSG (iLUSG) following each transverse ablation plane. In case of reduced VC movement, the ablation was stopped immediately. Post-ablation VC function was rechecked by LUSG on day-0 and flexible laryngoscopy (FL) on day-7. A concordance with day-0 LUSG or day-7 FL was a "true positive" or "true negative" depending on the presence or absence of VC palsy (VCP). Accuracy was calculated as the sum of all true positives and negatives divided by total nerves-at-risk.

RESULTS

Of 65 eligible patients, 56 (86.2%) were females. Twelve (18.5%) patients had bilateral lobe RFA, while 53 (81.5%) had unilateral RFA. The total number of nerves-at-risk was 77. Three unilateral VCPs (3.9%) were initially detected on iLUSG and confirmed by day-0 LUSG. All recovered fully within one week. The overall accuracy of iLUSG was 100%.

CONCLUSION

iLUSG is a highly accurate method that permits real-time feedback on the function of the VCs during RFA procedure. Real-time detection of VCP may prevent permanent injury. Methodological routine use of iLUSG is recommended during thyroid RFA.