Chapter 72 - Metabolic and Toxic Encephalopathies

Abstract

This chapter discusses metabolic and toxic encephalopathies. Metabolic encephalopathies are conditions of the central nervous system that are not because of structural abnormalities. Selected metabolic encephalopathies, however, can result in secondary structural damage to the central nervous system. Encephalopathies are often characterized clinically by the occurrence of symptoms of organic psychosis. Depending on the type and severity of ncephalopathy, these symptoms range from subtle personality changes, deterioration of memory, and cognitive functions to confusion and disturbances of consciousness. Neurological symptoms, including myoclonus, asterixis, weakness, and seizures, may also be present. Metabolic encephalopathies, include essentially any disorders associated with a nonpsychiatric cause of alteration in consciousness that does not have a macroscopic structural basis. Two common themes emerge with regard to presumptive causes of metabolic encephalopathies in systemic disease: impaired substrate delivery to the brain or release of circulating substances by the systemic disease, which cross the blood-brain barrier and causes diffuse neuronal and cellular dysfunction.