Superior laryngeal nerve block as an adjuvant to General Anesthesia during endoscopic laryngeal surgeries

Background: Direct rigid endoscopic laryngosurgery is a short procedure usually performed under general anesthesia. This is a double blinded randomized placebo-controlled trial, which was designed to evaluate the effect of bilateral block of the internal branch of superior laryngeal nerve (SLN) as an adjuvant to general anesthesia during endoscopic laryngeal surgery when smaller dose of muscle relaxant is used. Method: Seventy-six patients required endoscopic laryngosurgery in whom general anesthesia was preceded by bilateral superior laryngeal nerve block either with 2% lidocaine (L-group) or with saline (C-group). Results: The reaction to endotracheal tube insertion was better in L-group as less frequent cough occurred in L-group (one patient) compared to (8 patients) C-group (P value <0.05). The maximum pressor response was observed immediately after intubation, at which the increase in MAP from baseline in C-group (24.4%) was significantly higher than in L-group (6.4%) (P < 0.05) and the increase in HR from baseline in C-group (29.5%) was significantly higher than in L-group (14.8%) (P < 0.05). The MAP and HR remain significantly higher in C-group than that of the L-group all through the intraoperative period. The incidence of severe cough was significantly higher in C-group just before extubation (bucking), 5 min and 30 min postextubation. Incidence and severity of postoperative sore throat was significantly higher in C-group in the first 4 h postoperatively. Conclusion: During endoscopic laryngeal surgeries, using bilateral block of the internal branch of superior laryngeal nerve as an adjuvant to general anesthesia was associated with better intubation conditions, better intraoperative hemodynamic response to intubation and surgical procedure and better recovery profile in the form of improved postoperative cough and sore throat