Altered mental status natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Pratik Bahekar, MBBS [2]
Overview
Natural History, Complications and Prognosis
Delirium, stupor, and coma represent a broad spectrum of acute brain dysfunction and are associated with an impairment of consciousness. There are two interrelated domains of neurologic function that are related to consciousness:
- Content
- Level (also known as arousal) of consciousness.
The content of consciousness has many components such as orientation, perception, executive function, and memory, and is mediated at the cortical level. The level (or arousal) of consciousness signifies the patient’s wakeful state and reactivity to surrounding stimuli. This is mediated at the ascending reticular activating system located in the brainstem. Traditionally, terms such as lethargic, drowsy, or somnolent have been used to describe level or arousal of consciousness. Because these descriptors can have different meanings for different clinicians, using a structured arousal scale such as the Richmond Agitation Sedation Scale (RASS) may be a more reliable method to describe altered level of consciousness. This scale ranges from -5 (unresponsive to pain and voice) to +4 (extreme combativeness). As the patient’s level of consciousness becomes more disturbed, the concern for an underlying life threatening acute medical illness should similarly increase. Patients with acute brain dysfunction can not only fluctuate between different RASS scores, but can also transition between delirium, stupor, and coma.
Stupor and Coma: Definitions and their Epidemiology in the Emergency Department
Stupor and coma occurs in 5 to 9% of older ED patients and when present, are considered to be medical emergencies that require immediate evaluation. These two forms of acute brain dysfunction occur over a period of hours to days and represent the most severe disruptions in both the level and content of consciousness. Stupor (RASS −4) is a condition of deep sleep or similar behavioral unresponsiveness from which the patient can be aroused only with vigorous and continuous stimulation. Coma (RASS −5) is defined as a state of unresponsiveness in which the patient cannot be aroused with any stimuli.
Delirium: Definitions and its Epidemiology in the Emergency Department
Delirium is an acute disturbance of consciousness (i.e. attention) that is accompanied by an acute loss in cognition that is not better explained by a preexisting dementia. This form of acute brain dysfunction occurs in 8 to 10% of patients of older ED patients. Similar to stupor and coma, delirium occurs over a period of hours and days, and its course tends to wax and wane throughout the day. In contrast to stupor and coma, however, some elements of the level and content of consciousness are maintained in patients with delirium. The degree of impairment in the level of consciousness can be variable, ranging from moderate sleepiness (RASS −3) to extreme combativeness (RASS +4). Patients with delirium also have inattention which is considered a cardinal feature of delirium. The impairment of content of consciousness is similarly variable and leads to an acute loss in cognition. Examples of such impairments observed in delirious patients are disorganized thought, perceptual disturbances, and disorientation.