Neuroimaging in brain swelling.

Modern neuroimaging techniques have added to the understanding of brain edema and its earlier diagnosis. It is now possible to quickly know whether a lesion is focal with associated pressure effects or whether the symptoms are due to a diffuse process whose treatment may be different. The various herniation syndromes can be appreciated on the CT without risk to the patient. The neuropathologic proof of earlier pathophysiologic theories of three types of edema (vasogenic, cytotoxic, and interstitial) caused by various diseases need no longer wait for the autopsy specimen; it is strongly suggested by modern neuroimaging techniques. Some disease entities (meningitis, trauma, ischemic infarction) are characterized by several types of edema, depending on when the patient is examined. Swelling of the brain is an important topic to study not only because it is common, but also because it may be fatal. Neuroimaging in brain swelling has led to new knowledge regarding this important subject. This review is primarily that of the computerized tomogram in diagnosing both focal and diffuse swelling of the brain and some basic understanding pathophysiologically that would allow one to explain the image obtained. Because edema is primarily water, it seems likely that magnetic resonance imaging will shed even further light on this intriguing subject.