Brain Embolism PDF

Preface

In medicine, as in other areas of life, interest and emphasis on various topics go through periods of ups and downs. Brain embolism was defined by most physicians during the middle years of the twentieth century as embolism to the brain arising from clots, bacteria, and other substances that came from the heart. During the last three decades, technology has been introduced that can show brain infarction during life and can detect embolic particles passing through arteries that supply the brain. These more recent brain and vascular studies showed that the great majority of brain ischemic events are caused by embolism. However, not all of the embolic particles arise from the heart. Many come from the aorta, from systemic veins, and from the cervico-cranial arteries. This knowledge has led to a return to the original definition of embolism, that is, blockage of an artery by material originating from a distant site.

The process of brain embolism is complex. There are a variety of donor sites and sources of embolic material. The particles that embolize also vary greatly. Emboli travel to many different recipient sites. Whether or not the emboli cause brain infarction is also complex and depends on other factors, including the vascular endothelium at the recipient site and the blood together with its constituents. No prior monographs have covered the complex topic of brain embolism in depth, stimulating us to try and fill this gap in the literature. Drs. Willis Hurst, Marc Chimowitz, and Caplan authored a monograph nearly a decade ago entitled Clinical Neurocardiology that contained a single chapter on brain embolism. The time has come for an updated review of this important topic.

To ensure a thorough review of the topic, we recruited experts in areas of knowledge that we believed would enhance the monograph. Dr. Warren Manning, a cardiologist, contributed chapters related to cardiac origin and therapy for cardiac lesions that can lead to brain embolism. We also enlisted the help of experts in neck and transcranial ultrasound technology (Professor Michael Hennerici and his colleagues at the University of Heidelberg in Germany, and Dr. Carlos Molina (Barcelona, Spain) and Dr. Alexei Alexandrov (Houston, Texas, U.S.A.). Dr. Gregory del Zoppo added his considerable expertise about blood and endothelial factors that contribute to thromboembolism.

The first part of the book begins with a historical review of the subject. Knowing where a topic has been is key to recognizing where it now is and where it is most likely headed in the future. This is followed by an overview that introduces the three main dramatists personae in the theatre of brain embolism—donor sites, embolic substances, and recipient sites. Pathological, clinical, and diagnostic aspects related to the recipient sites of brain emboli are explored in detail, followed by detailed analyses of the donor source of emboli—the heart, aorta, and cervico-cranial brain supply arteries. Next, the pathophysiology of embolism and the role of the blood, vascular endothelium, and neurovascular unit are explored. The nature of embolic substances is discussed, including their usual sources and clinical features. The monograph also reviews therapeutics and analyzes the effectiveness and risks of the various treatments employed. Finally, we look to the future.