[Protective measures against cerebral ischemia following subarachnoid hemorrhage: Part 1]

Oxidative Stress-Mediated Blood-Brain Barrier (BBB) Disruption in Neurological Diseases

The blood-brain barrier (BBB), as a crucial gate of brain-blood molecular exchange, is involved in the pathogenesis of multiple neurological diseases. Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) and the scavenger system. Since oxidative stress plays a significant role in the production and maintenance of the BBB, the cerebrovascular system is especially vulnerable to it. The pathways that initiate BBB dysfunction include, but are not limited to, mitochondrial dysfunction, excitotoxicity, iron metabolism, cytokines, pyroptosis, and necroptosis, all converging on the generation of ROS. Interestingly, ROS also provide common triggers that directly regulate BBB damage, parameters including tight junction (TJ) modifications, transporters, matrix metalloproteinase (MMP) activation, inflammatory responses, and autophagy. We will discuss the role of oxidative stress-mediated BBB disruption in neurological diseases, such as hemorrhagic stroke, ischemic stroke (IS), Alzheimer’s disease (AD), Parkinson’s disease (PD), traumatic brain injury (TBI), amyotrophic lateral sclerosis (ALS), and cerebral small vessel disease (CSVD). This review will also discuss the latest clinical evidence of potential biomarkers and antioxidant drugs towards oxidative stress in neurological diseases. A deeper understanding of how oxidative stress damages BBB may open up more therapeutic options for the treatment of neurological diseases.

Principles of neuroanesthesia in aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage is associated with high mortality. Understanding of the underlying pathophysiology is important as early intervention can improve outcome. Increasing age, altered sensorium and poor Hunt and Hess grade are independent predictors of adverse outcome. Early operative interventions imposes an onus on anesthesiologists to provide brain relaxation. Coiling and clipping are the two treatment options with increasing trends toward coiling. Intraoperatively, tight control of blood pressure and adequate brain relaxation is desirable, so that accidental aneurysm rupture can be averted. Patients with poor grades tolerate higher blood pressures, but are prone to ischemia whereas patients with lower grades tolerate lower blood pressure, but are prone to aneurysm rupture if blood pressure increases. Patients with Hunt and Hess Grade I or II with uneventful intraoperative course are extubated in operation theater, whereas, higher grades are kept electively ventilated. Postoperative management includes attention toward fluid status and early management of vasospasm.