Chapter 48 - Delirium and Dementia

Abstract

Emergency physicians are frequently presented with patients exhibiting neurobehavioral abnormalities. These can be a harbin­ ger of a serious medical condition, and critical decisions must be made expeditiously about diagnostic evaluation, therapeutic intervention, and disposition. The first critical action is to recog­ nize the presence of the neurobehavioral abnormality. The second is to distinguish delirium from dementia or some other neuropsy­ chiatric condition. In the past, terms such as acute confusional state, sundowning, and organic brain syndrome have been used to describe a host of abnormal cognitive states that can be observed in the emer­ gency setting. These terms have loosely defined a group of neurobehavioral disorders that are caused by a physiologic dis­ turbance. Organic brain syndrome is a nebulous term that the Diagnostic and Statistical Manual of Mental Disorders (fourth edition, text revision) eschews because the “organic” connotation implies that so­called functional mental disorders are without a biologic basis. Several key features best distinguish delirium from dementia: the time course of disease evolution, the presence of autonomic system involvement, the level of consciousness, and the presence of an underlying disease processes. Delirium is characterized by a fluctuating level of neurobehavioral disturbance typically pro­ gressing during minutes to hours to days. Delirium is a direct consequence of an acute systemic or central nervous system (CNS) stressor. Dementia, on the other hand, tends to follow a more gradual course, with evolution during months to years. Although patients with dementia exhibit confusion, disturbance in level of consciousness usually is not a feature, and manifestations of auto­ nomic nervous system abnormalities are minimal or absent. The evaluation of patients who present to the emergency department (ED) with a disturbance of neurobehavioral state is best conducted in accordance with the following basic guidelines: 1. The first step is to determine whether this state represents delirium or dementia. The clinical findings may be subtle, and establishment of the diagnosis can be challenging, especially because delirium may be superimposed on dementia and dementia remains an independent risk factor for delirium. Early symptoms and signs may go unrecognized unless an adequate history is obtained from the patient, family members, and caregivers. A careful examination must include memory and cognitive assessment with a mental status screening examination. 2. Supportive care must be provided. This care may range in extent from aggressive airway and cardiovascular support to pharmacologic or physical restraint to simply placing the patient in a quiet room with appropriate environmental support. 3. A diligent search must be initiated for the underlying precipitating stressors in patients presenting with delirium.