Assessment of functionality of vocal cords using ultrasound before and after thyroid surgery: An observational study

The preservation of recurrent laryngeal nerve (RLN) is an essential part of thyroid surgery. The various methods to test the normal functionality of vocal cords (VCs) include direct visualisation under the fiber bronchoscope, indirect laryngoscopy, laryngeal muscles electromyography, computed tomography (CT), and magnetic resonance imaging (MRI). We aimed to assess the usefulness of ultrasound (USG) in the examination of VC morphology and movement.

After Institutional Ethical Committee (IEC) clearance, 65 American Society of Anesthesiologists physical status I/II patients between the age group 18 and 60 years scheduled for thyroid surgery were enrolled in this observational study. All patients underwent USG examination before, immediately after and 2 days after thyroidectomy. The vocal fold (VF) displacement velocity (VFDV) was recorded and analysed. If any VF disorder was detected, the patients underwent two additional examinations: 2 and 3 months after thyroidectomy. All the findings were correlated with those of video rhinolaryngoscope (VRL).

The visualisation rate of the VCs with USG was 96.9% whereas with VRL was 100%. Two patients had preoperative VC palsy that was picked up by USG and confirmed by VRL. The sensitivity and specificity of USG as a tool to detect paralysis were 100% CI = (0.34, 1.00) and 93.44% CI = (0.84, 0.97), respectively.

USG examination can prove to be a good, noninvasive, cheap alternative to VRL in examination for functionality of VCs perioperatively.