Postoperative Cognitive Dysfunction and Delirium

The brain is amazingly interesting and complex. As neuroscience progresses, we gain a broader understanding of specialized regional activity, chemistry and unique interconnections that makes us the fascinating and diverse organisms that we are. However, that same complexity makes assessment of brain function and injury causality difficult. A small embolic injury in the motor cortex results in substantial impact on one’s ability to move and function, while a much larger injury in silent areas of the cortex may go unnoticed. Furthermore, the brain is not static over the decades of life. In particular, the elderly are at increased risk of neurocognitive consequences of stress and injury due to reduced functional reserve. While the brain is amazingly complex on it’s own, it is not an isolated organ and our body’s broader response to stress or injury, including coagulation and inflammatory changes targeted toward a distant injury, may also impact the brain and the integrity of the connection between the brain and our body (the blood brain barrier). Finally, we add anesthesia and surgery into this complex mix of factors that can alter the ability to respond and function. This is particularly important, as anesthesia and surgery have progressed substantially in safety, such that older and sicker patients may now undergo increasingly complex procedures with low probability of morbidity and mortality. However, as previously noted the elderly are particularly susceptible to neurocognitive sequellae. The following chapter discusses our evolving understanding of postoperative cognitive dysfunction and delirium.