Bradycardia and hypotension associated with trigeminocardiac reflex during orthognathic surgery: two case reports

Abstract

Introduction and importance: The trigeminocardiac reflex (TCR) is an uncommon but significant complication that can arise during orthognathic surgery.

Case presentation: We present two cases of TCR-induced bradycardia and hypotension during such procedures. In the first case, bradycardia was noted following a controlled downward fracture of the maxilla. In the second case, both bradycardia and hypotension occurred while the left mandibular ramus was split with a separator.

Clinical discussion: In both instances, interruption of the surgical procedure led to normalization of heart rate and blood pressure, indicating that TCR was likely triggered by stimulation of the second and third branches of the trigeminal nerve. Moreover, to the best of our knowledge, this is the first reported case of TCR during Le Fort I osteotomy in Japan.

Conclusion: Given that TCR can potentially lead to cardiac arrest, surgeons must anticipate this reflex and communicate closely with the anesthesiologist to ensure prompt management.

Keywords: bradycardia; case report; hypotension; orthognathic surgery; trigeminal nerve stimulation; trigeminocardiac reflex.

Figure 1.

Electrocardiogram and anesthesia record. (A) Heart rate decreases to 46 beats/min in Case 1. (B) Recovery to approximately 60 beats/min in Case 1. (C) Blood pressure and heart rate are reduced to 54/25 mmHg and 52 beats/min, respectively, (blue arrow) in Case 2. ┸ ┰: ABP (Arterial Blood Pressure), ▼▲: BP, ◆: HR.

Figure 2.

Trigeminocardiac reflex pathway. TCR occurs when sensory branches of the trigeminal nerve transmit signals from the Gasserian ganglion to the sensory nucleus of the trigeminal nerve on the floor of the fourth ventricle (afferent pathway). These signals are then relayed to the vagus motor nucleus via short nerves and directed to the myocardium via the cardiac branches of the vagus nerve (efferent pathway). For example, traction of the posterior superior alveolar nerve or the greater palatine nerve during Le Fort I osteotomy and traction of the inferior alveolar nerve during SSRO can act as triggers. V1: ophthalmic nerve; V2: maxillary nerve; V3: mandibular nerve. 1. Gasserian ganglion; 2. Trigeminal nerve; 3. Sensory nucleus of the trigeminal nerve; 4. Short internuncial fibers; 5. Motor nucleus of the vagus nerve; 6. Cardiac branch of the vagus nerve.