Multiple sinus pauses during suspension laryngoscopy with external laryngeal manipulation in hyperextended neck position in a patient with enlarged cervical lymph nodes: a case report

Abstract

Suspension laryngoscopy is a commonly performed procedure for effective laryngeal microsurgery (LMS). Although it is associated with few adverse events, cardiac complications such as severe arrhythmia induced by exaggerated vagal tone may arise during this procedure. Here, I present the case of a 52-year-old female patient who presented with a suspected thyroid follicular neoplasm and enlarged cervical lymph nodes. LMS was planned to remove a vocal fold polyp before the thyroid surgery. The patient was placed in a Boyce-Jackson position, and suspension laryngoscopy was performed. However, several sinus pauses were detected whenever external laryngeal manipulation (ELM) was performed to improve surgical field exposure, which was presumed to be attributed to vagal stimulation or reflex induced by numerous external and internal factors during laryngeal manipulation. The suspected mechanism was the direct stimulation of the vagus nerve termed the laryngo-cardiac reflex, or carotid sinus reflex, a type of baroreceptor reflex. When the first episode of sinus pause occurred, the effect-site target concentration of propofol was unadjusted after checking the bispectral index level indicating an adequate anesthetic depth, but ELM was discontinued. When the second episode occurred, ELM could not be stopped until good laryngeal visualization was achieved. Then, the patient received 0.2 mg of intravenous glycopyrrolate. Her heart rate returned within the normal range whenever ELM was not applied. When performing suspension laryngoscopy, the head and neck positioning, the procedure itself and laryngeal manipulation may act as external factors that could induce an exaggerated vagal response. Further, patients with head and neck tumors have various internal factors, such as tumor itself, cervical lymphadenopathy or post-irradiation fibrosis, which can affect the carotid sinus and deteriorate the vagal response. Therefore, careful preoperative evaluation is required to identify these internal factors in advance and take proper care to minimize the additional influence of external factors.