Laryngoscopic techniques to assess vocal cord mobility following thyroid surgery

Assessment of vocal cord mobility using Macintosh laryngoscope is frequently performed after extubation following thyroid surgery to rule out laryngeal nerve palsy. This study compared patient comfort and assessment accuracy of post-operative vocal fold mobility with Macintosh laryngoscope and fibreoptic endoscope.

One hundred four physically fit patients undergoing thyroid surgery were included for the study. Tele-laryngoscopy was done to rule out pre-existing vocal cord palsy. Direct laryngoscopy (DL) was performed to each patient after extubation, followed by nasal fibreoptic endoscopy (NFE) to assess the vocal cord mobility. Tele-laryngoscopic assessment was repeated after 1 week to compare the DL and NFE findings. Patient reactivity score (PRS) and haemodynamic parameters were recorded with each technique.

Macintosh laryngoscope could pick up 4 (50% sensitivity and 88% specificity) and fibreoptic endoscope 7 (87.9% sensitivity and 98.9% specificity) out of the 8 vocal cord palsies identified by tele-laryngoscopy. Patients had significant discomfort during DL (PRS median 3) when compared with NFE and tele-laryngoscopy (PRS median 2), P<0.05. Grade 1 view of larynx in 92.1% patients during intubation worsened to grade 2 (76.3%) and grade 3 (15.8%) during extubation with DL, and a significant rise in mean arterial pressure and heart rate was observed from the baseline value till 5 min and when compared with NFE (P<0.05).

NFE provides accurate assessment of vocal fold mobility with reasonable patient comfort in the immediate post-operative period. Macintosh laryngoscope fails to give optimum visualization and predisposes the patient to significant discomfort and stress.