Anaesthesia for the posterior fossa provides a unique challenge for anaesthetists and neurosurgeons. Optimal patient positioning should facilitate surgical access without compromising patient safety. The important considerations are surgical access, securing and maintaining the airway, maintenance of adequate anaesthetic depth, haemodynamic stability and oxygenation. Care should be taken to limit the 'blackout state' during which the patient is not monitored or connected to the breathing circuits during patient transfer or positioning on the operating table. The hazards during positioning can be reduced by meticulous planning, careful positioning and vigilance to facilitate early detection of complications. The aim of maintenance of anaesthesia is to reduce the intracranial pressure (ICP) and to maintain haemodynamic stability. Anaesthesia can be maintained with either volatile agents or intravenous agents such as propofol. The choice of the anaesthetic agent is at the discretion of the individual anaesthetist.

Immediate emergence after neurosurgery is desirable to facilitate neurologic examination and early identification of complications. Awakening is determined by many factors including preoperative status, type of surgery, and intraoperative events. This chapter presents a case study of a 58-year-old female with a body mass index of 32 who complained about gradual hearing loss, increasing frequency of headaches and vertigo and subsequently was diagnosed with an acoustic neuroma. In order to facilitate early detection of neurologic complications, anesthesiologists usually aim for an early emergence following intracranial surgery. The most common causes of delayed postoperative emergence include residual drug effects, respiratory failure, metabolic derangements, and neurologic complications. Cerebral swelling can occur intraoperatively or preexist. In the context of posterior fossa surgery this is of particular concern. Multiple factors contribute to a delayed emergence from anesthesia and a systematic approach to rule out all possible causes is necessary.

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.