Recent Advances in Neuroanesthesiology

Introduction

Perioperative neuroscience is a very dynamic field due to ongoing research, clinical innovations, and technological developments. In this chapter, we review some of the major recurring themes, innovative findings, and prevalent topics associated with advances in the field of neuroanesthesiology.

Endovascular Treatment of Stroke and Perioperative Stroke

Ischemic stroke is one of the leading causes of morbidity and mortality worldwide. Treatment of ischemic stroke may involve administration of intravenous thrombolytic drugs such as tissue plasminogen activator (tPA). Endovascular treatment can supplement intravenous thrombolytic treatment for acute ischemic stroke or provide an alternative therapy for thrombolysis. Initially, data from randomized controlled trials suggested that endovascular treatment was not superior to intravascular tPA administration for the treatment of ischemic stroke. However, subsequent large randomized trials have demonstrated improved rates of recanalization and outcomes with endovascular treatment without increased rates of complications.

The anesthetic care of patients undergoing endovascular treatment of stroke has been highly debated. Several anesthetic techniques have been described for patients undergoing endovascular treatment of stroke including general and local anesthesia with or without sedation. Data have suggested that clinical outcomes may be worse in patients who have received general anesthesia compared to those who underwent local anesthesia. This association may be due to effects of anesthetic drugs on the injured brain, a deeper anesthetic state with general anesthesia, greater risk for systemic hypotension with general anesthesia, or a selection bias on the part of general anesthesia. For the last of these, patients with greater stroke severity may require general anesthesia due to factors such an altered consciousness, severe neurologic deficits, respiratory dysfunction, or inability to protect their airway. Thus, greater stroke severity, and not specifically general anesthesia, may be a more important factor determining the outcome.

Perioperative stroke can be a devastating complication in surgical patients and is associated with an increased risk of death compared to patients who did not have a perioperative stroke. The Peri-Operative Ischemic Evaluation trial demonstrated an increased risk of stroke and death after noncardiac surgery with the use of perioperative metoprolol compared with placebo. In 57,218 patients having noncardiac surgery, Mashour et al. found the rate of perioperative stroke to be 0.09% and that preoperative metoprolol use was associated with a 4.2-fold increased odds for perioperative stroke [P < 0.001; 95% confidence interval (CI), 2.2–81]. Patients who were taking preoperative metoprolol had a significantly higher incidence of stroke compared to those taking atenolol (P = 0.016). Intraoperative metoprolol administration was associated with a 3.3-fold increase in perioperative stroke (P = 0.003; 95% CI, 1.4–7.8). This differential perioperative stroke risk associated with specific β-blockers was confirmed by other data. Further studies are necessary to determine the safety of β-blockers in the perioperative period.