Bradycardia and even asystole may occur suddenly during posterior fossa surgery and requires immediate evaluation and treatment in order to prevent potential ischemia and major neurologic complications. Trigeminocardiac reflex (TCR) commonly manifests as bradycardia and hypotension in response to mechanical stimulation of any of the branches of the trigeminal nerve. This chapter presents a case study of a 53-year-old female with a history of progressive headaches and a syncopal episode was found to have a right-sided tentorial mass consistent with a falcine meningioma. The tentorial nerves arise from the intracranial portions of ophthalmic branch (V1) and course into the dura of the parieto-occipital region and the posterior third of the falx, where there is a converging and bilaterally overlapping innervation at its midpoint. When stimulation of the falx results in the TCR, cessation of the surgical manipulation in that area is the first step in correcting the hemodynamic instability.