Altered Mental Status in Older Emergency Department Patients

Background

There are two main components to the category of altered mental status. The first consists of the level of consciousness, or arousal. The second consists of the content of consciousness, or cognition [7]. The distinction between these two components is important, because impairments of the content of consciousness are not necessarily accompanied by impairments in level of consciousness. This may help lead the physician to the appropriate diagnosis.

Determinations of the level of consciousness,

Epidemiology

Numerous studies have evaluated the epidemiology of cognitive impairment in older ED patients. Although the overall proportions of cognitively impaired patients in the studies vary somewhat, it is clear that cognitive impairment is common in this population. Approximately 10% to 20% of community dwelling persons have cognitive impairment [10], [11], as do 48% of nursing home residents [12]. This increases with age, reaching a prevalence of nearly 50% in those over age 85 years [11]. Cognitively

Delirium

Delirium is an acute, fluctuating change in cognition, accompanied by impaired attention and consciousness [9], [13]. Delirium represents the most serious cause of altered mental status seen in older ED patients [14]. Approximately 10% of ED patients over age 65 years present with delirium [4], [5], [6], [14], [15], [16]. Most often, however, these patients are not diagnosed by the emergency physician [6], [14], [15], [16].

Tests for cognitive impairment

Cognitive impairment from dementia or delirium is common, yet frequently it is not diagnosed by emergency physicians. Given the complexity of evaluating older patients who have even simple complaints, emergency physicians must maintain a high index of suspicion for cognitive impairment in older ED patients. When cognitive impairment is relevant to the reason a patient is in the ED, an evaluation of their mental status is warranted. The standard mental status screen since 1975 has been the Mini

Stupor and coma

As noted, the impairment in consciousness in patients who have delirium does not reach the level of stupor or coma [9]. Delirium, however, if untreated, may progress to stupor, coma, and eventually death. Most cases of coma (85%) are caused by systemic disease rather than by primary CNS abnormalities, and the etiologies are similar to those of delirium [43]. Consequently there is substantial overlap between the discussion of delirium and that of stupor or coma. Although comatose patients

Dementia

Dementia is characterized by the gradual and progressive development of multiple cognitive deficits, especially memory [13]. It is rare for an emergency physician to be confronted with the need to diagnose dementia. Most patients who have a gradual cognitive decline without acute change can be referred for evaluation as an outpatient. Chronic cognitive impairment, however, may affect the patient's ED care in many ways, from limiting the reliability of the medical history to reducing his or her

General approach

Based on all of this information, a general approach to evaluating mental status in older ED patients can be developed. This approach should be used to evaluate mental status in all older ED patients, because the recognition of delirium is difficult [6], [14], [15], [16] and the consequences of missed delirium are serious [14]. To be used this widely, however, the approach must be rapid, simple, and easy to incorporate into the routine history and examination, without substantially increasing

Summary

Mental status abnormalities are common in older emergency department patients and may be present in up to 40% of ED patients. These abnormalities may be chronic, from dementia, or acute, from delirium. Making the diagnosis of delirium in the ED is challenging and requires a systematic approach to patients who have an altered mental status. Gerson and colleagues found that 60% of geriatric ED patients had some degree of cognitive impairment. The challenge is to identify those geriatric patients