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.

Subarachnoid hemorrhage (SAH) is a complex disease with high morbidity and mortality. Management of patients with SAH requires a multisystem approach. This chapter presents a case study of a 45-year-old female who had presented to an outside hospital with a 1-month history of progressive right-sided facial and body numbness that had worsened acutely over the week prior to her admission. The patient underwent definitive correction of the aneurysm the following day. Aneurysmal SAH is a neurologic emergency, resulting from blood extravasation into the subarachnoid space normally filled with cerebrospinal fluid (CSF), that requires complex treatment and monitoring. Patients present for elective clipping of an unruptured aneurysm or emergent surgery following SAH. Thorough assessment of the patient, effective organ support and correction of pathophysiology are vital prior to leaving the intensive care unit (ICU) for what may be a challenging case in the operating room.