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Development and Maintenance of the Blood–Brain Barrier

Introduction The blood–brain barrier (BBB) serves to limit the exposure of the brain parenchyma to foreign substances. Early experiments illustrate the “barrier” function present in the neurovasculature, as tracers such as peroxidase injected systemically are confined to vessel lumens or in a small number of pinocytic vesicles and do not reach the brain parenchyma . Endothelial cells, pericytes, astrocytes, neurons, and microglia comprise the “neurovascular unit…

Endothelium

Introduction The vascular endothelium is a simple monolayer of cells that line the capillary lumen and is optimally placed at the interface of the blood circulation and vessel wall. Once considered to be merely a “cellophane wrapper” of the vessel wall, it is now well known that the endothelium is an active endocrine organ responsible for regulating vascular tone, blood coagulation and thrombosis, nutrient delivery, cellular…

Cerebral Vascular Muscle

Acknowledgments Work summarized in this chapter was supported by research grants from the National Institute of Health (HL-62984 and HL-113863), the Department of Veteran’s Affair’s (BX001399), the Fondation Leducq (Transatlantic Network of Excellence), and the National Health and Medical Research Council of Australia (1053786). Introduction Cerebral blood flow (CBF) is controlled predominantly by the level of arterial pressure (perfusion pressure) and the diameter of resistance vessels…

Cerebral Vasa Vasorum

Introduction Vasa vasorum (VV) are defined literally as vessels of vessels, and are predominantly observed in large vessels with an important role under pathological conditions. Research on noncerebral VV has been established for over a century, including cardiac, pulmonary, aortic, and portal vein VV. Intracranial vessels were misrepresented to be devoid of VV, and increasing evidence for their existence widens the field of cerebral VV research.…

Anatomy of Cerebral Veins and Dural Sinuses

Introduction Venous infarction of brain comprises only 1% of all strokes . Many predisposing conditions such as dehydration, coagulopathies, pregnancy, trauma, surgical interventions, inherited collagen disorders, and autoimmune vascular diseases may result in cerebral vein thrombosis. Fortunately not all of veins lead to severe complications. However, in case of clinical manifestations developed, diagnosis must be done immediately in order to investigate and treat possible reasons. This…

Cerebrospinal Fluid: Formation, Absorption, Markers, and Relationship to Blood–Brain Barrier

Introduction Cerebrospinal fluid (CSF) reflects pathology in the brain, and is essential in diagnosis of many neurological diseases, including those due to inflammation, infection, and immunological processes. CSF indicates pathological processes because of the continuity of the brain interstitial fluid (ISF) with the CSF across the ependymal lining of the ventricles. CSF and ISF are actively secreted by energy-requiring mechanisms: mainly epithelial cells make CSF in…

The Glymphatic System and Brain Interstitial Fluid Homeostasis

Introduction The maintenance of the interstitial compartment is a basic element of an organ’s function that is of utmost importance in the brain, given neural cells’ exquisite sensitivity to changes in their extracellular environment. In peripheral tissues, interstitial fluid (ISF) is formed from the filtration of plasma across the permeable capillary endothelium. Although a portion of the ISF is reabsorbed into postcapillary venules, much of the…

Cerebral Microcirculation

Introduction Research on microcirculation has led to an unprecedented progress with help of amazing developments in imaging technology. It is now possible to image capillaries with high resolution down to the depths of cortex, measure O 2 saturation and tension in them, track fast erythrocyte movements, and study Ca 2+ signaling, vascular diameter changes, and neurovascular coupling in wild-type as well transgenic animals expressing a large…

Cerebrovascular Anatomy and Hemodynamics

Introduction The adult human brain represents about 2% of total body weight, but receives nearly 15% of total resting cardiac output. Under normal conditions, the brain is highly perfused and is extremely sensitive to any change or interruption in its blood supply. If the brain’s circulation is completely obstructed, loss of consciousness occurs within seconds and irreversible pathological changes occur within minutes. For example, in cardiac…

The Electroencephalogram of the Newborn

Newborn EEG interpretation is considered a particularly challenging area. An understanding of the appearance of the normal newborn EEG was achieved considerably later than for EEGs of childhood and adulthood. In fact, before the 1960s, it was not generally accepted that there was scientific or clinical value to be found in the analysis of the EEGs of newborns. The relatively slower progress in the field of…

EEG Patterns in Stupor and Coma

The term coma refers to a state in which a person is unaware of self and surroundings, even if stimulated from the outside. Between consciousness and deep coma, there is a continuum of possible levels of responsiveness and awareness. Encephalopathy is a broad term that may be used to indicate a decrease in awareness; a patient who develops confusion and decreased awareness can be said to…

Normal Variants in the Electroencephalogram

This section deals with a group of waveforms that may mimic abnormal waves but have now been recognized as normal variants. By definition, a normal variant is not associated with disease, be it epilepsy or another abnormal state. A few of the waveforms discussed in this chapter are of uncertain clinical significance: they are known to occur frequently in normal individuals but may be seen more…

The EEG in Epilepsy

There are many indications for EEG testing, but the most common reason that an EEG is obtained is to assist in the diagnosis of seizures and epilepsy. Although the history is still the cornerstone of the diagnostic process, in some cases, the results of the EEG can make an equal or even greater contribution to the diagnosis of seizures, especially when some elements of the history…

The Abnormal EEG

An EEG is considered abnormal if it has findings known to be associated with a pathologic or disease state. As discussed in Chapter 8 , “The Structure and Philosophy of the EEG Report,” this distinction is designed to prevent the interpreter from calling an EEG abnormal simply because it includes a finding that “looks unusual” or is uncommon, because uncommon findings may not be abnormal. When…

The Structure and Philosophy of the EEG Report

The essential purpose of recording and interpreting an EEG is to communicate information to the clinicians that will help guide the patient’s care. When patients are referred for EEG testing, the referring physician often does not have the opportunity to review the EEG personally but usually relies completely on the report of the EEG to learn the findings and clinical implications of the test. Physical and…

Filters in the Electroencephalogram

The use of filters in recording and displaying EEG data is an indispensable tool in producing interpretable EEG tracings. Without filters, many segments of EEG would be essentially unreadable. As we shall see in this chapter, the use of filters can affect the EEG signal in ways that range from the subtle to the dramatic. The main benefit of filters is that they can appear to…

Electroencephalographic Artifacts

An artifact is a waveform in the EEG that is not of cerebral origin. Those new to the world of EEG interpretation are often surprised to learn that at least half the challenge of EEG reading consists of identifying artifacts correctly so as not to mistake them for true EEG (cerebral) activity. This is quite different from other types of interpretation in clinical electrophysiology such as…

Electroencephalographic Electrodes, Channels, and Montages and How They Are Chosen

In electroencephalography, the term montage refers to the order and choice of channels displayed on the EEG page. Several decisions go into the design of a good display montage: which electrodes to use, how the electrodes should be paired to comprise each channel, and the ordering of the channels in a way that will render the tracing easy to interpret visually. Decisions of secondary importance include…

Electroencephalographic Localization

It is easy to underestimate the importance of learning the skills of precise EEG localization compared with the bigger picture of EEG interpretation. On the face of it, the purpose of localization is to identify the location in the brain at which a recorded EEG event has occurred. Indeed, if this were the only benefit of learning accurate localization, it would still be a key skill…

Introduction to Commonly Used Terms in Electroencephalography

In this chapter, we review the basic terms used in electroencephalography and strategies for communicating EEG findings to others. The creation of a concise description of an EEG tracing is a key part of the art and science of EEG interpretation. The ideal EEG description allows its reader, on the basis of the report alone, to visualize the appearance of the EEG even in the absence…