Coma is an alteration of consciousness in which a person appears to be asleep, cannot be aroused, and shows no awareness of the environment . Coma is therefore the most profound degree to which the two components of consciousness, arousal and awareness, can be diminished. Less profound states of impaired consciousness (stupor, lethargy, obtundation) preserve one or more of these components to some degree.
Coma represents an acute, life threatening emergency, requiring prompt intervention for preservation of life and brain function. Although discussed separately, the assessment and management are performed jointly in practice (table 1).
This topic will discuss the evaluation of children presenting in stupor or coma. Initial treatment and prognosis are discussed separately. (See "Treatment and prognosis of coma in children".)
States of impaired consciousness — There is a spectrum of impaired consciousness between full arousal and complete unresponsiveness.
- Coma, a state of "unarousable unresponsiveness," is the most profound degree to which arousal and consciousness are impaired .
- Lethargy, obtundation, and stupor refer to states in which arousal is somewhat less impaired. These patients have some difficulty maintaining attention during an examination, tend to fall asleep when not stimulated, and respond poorly (if at all) to questions and commands. These terms are imprecise. In clinical situations, it is more useful to describe the patient's responses to specific stimuli.
- Delirium is a disturbance of consciousness with reduced ability to focus, sustain, or shift attention. Patients show both hyperactivity and diminished sleep. Confusion, excitement, hallucinations, and irritability are common. Delirium is caused by a subset of conditions that can lead to coma, including medical conditions, substance intoxications, and medication side effects. (See "Acute toxic-metabolic encephalopathy in children".)