Delirium

This chapter presents a study on clinical aspects of delirium and the cognitive and behavioral disorders associated with it. Delirium is a syndrome characterized by altered consciousness and multiple cognitive impairments, including deterioration in the capacity to direct and sustain attention. The domain of consciousness, which varies from alertness to stupor, is distinguished from cognitive domains such as memory and attention, which depend on consciousness. In his work Bonhoeffer describes several syndromes, delirium, stupor, clouded states, and twilight states, that he characterized as exogenous reaction types, which are differentiated from schizophrenia and mania. The term "delirium" encompasses all of these syndromes. The characteristic features were alteration of consciousness, cognitive impairment, and prominent noncognitive symptoms such as anxiety, depression, delusions, and hallucinations. Twilight and postictal states that occur after temporal lobe epilepsy are characterized by inaccessibility, marked slowing of cognition, and intermittently unpredictable and occasionally violent behavior. The unity of the syndrome of delirium is still debated depending on the primacy of etiology in the classification scheme. The chapter presents two sets of diagnostic criteria-one of the Diagnostic and Statistical Manual of the American Psychiatric Association and the other of International Classification of Disease (ICD), which are similar but not identical. The chapter also discusses the importance of mental state examination in delirium, including a number of essential parts.