Trigeminocardiac Reflex: Case Report and Literature Review of Intraoperative Asystole in Response to Manipulation of the Temporalis Muscle

BACKGROUND: The trigeminocardiac reflex is a sudden onset of bradycardia, hypotension, apnea, or gastric hypermotility in response to stimulation of the trigeminal nerve. CASE DESCRIPTION: A 60-year-old female underwent a left orbitozygomatic craniotomy to debulk a large skull base epidermoid cyst compressing the brainstem and cranial nerves. Intraoperatively, retraction of the temporalis muscle consistently produced asystole. Cessation of retraction resulted in prompt return of sinus rhythm. CONCLUSIONS: Our report describes an unusual and extreme example of the trigeminocardiac reflex and explores possible etiologies. This is the third reported surgical case in which manipulation of the temporalis muscle alone was sufficient to elicit bradycardia and asystole, and the first such case within the context of neurosurgery. We emphasize the importance of surgical teams to be cognizant of such extreme examples of this reflex.