How do stupor, coma, persistent vegetative state, minimally conscious state, and akinetic mutism differ?
What historical features and examination findings are useful in the diagnosis of acute stupor and coma?
How is acute coma in hospitalized patients managed?
What prognostic information should be given to surrogate decision makers for patients with severe alterations of consciousness?
Alterations of consciousness are frequently encountered by hospitalists in the practice of general medicine. Coma is an unconscious brain state produced by several acute or chronic brain insults. The acute onset of coma is a medical emergency and requires immediate assessment and specific therapy. Coma is distinct from vegetative state, minimally conscious state, and akinetic mutism, conditions that are sometimes confused with it. The timing and probability of recovery from coma and the vegetative state differ considerably, depending on the nature of the underlying brain injury. We review diagnosis and prognosis in disorders of consciousness, address ethical challenges arising in the care of these patients, and provide a guide to discussions with surrogate decision makers for the comatose or severely brain-injured patient.
Lethargy, Obtundation, and Stupor
Lethargy refers to a minor decrease in alertness and energy, whereas obtundation refers to a moderate decline in responsiveness. Stupor is applied to patients with marked impairment of arousal who nevertheless sometimes respond purposefully to vigorous physical stimuli, such as prodding, sticking with a pin, or calling out loudly. Stupor resembles deep sleep.
Coma is a brain state characterized by the total absence of patterned behavioral arousal. Comatose patients are completely unresponsive. Like stuporous patients, they appear to be in deep sleep, lying motionless with eyes closed, but without eye opening or purposeful movements induced by vigorous stimulation. Coma is produced by a variety of acute or chronic brain insults. It may be distinguished from syncope, concussion, or other forms of transient unconsciousness by its time course. The term coma implies duration of at least 1 hour. Although some comatose patients recover rapidly, especially when coma is due to a concurrent systemic illness, a more gradual recovery is often seen for patients with brain injuries sufficient to produce even a day of coma. In such patients, recovery will be marked by the patient's entering into a vegetative state or minimally conscious state, as defined below.
Although coma patients lack purposeful responses to internal or external stimuli, noxious stimuli may cause them to grimace or make stereotyped withdrawal movements of the limbs generated by spinal reflexes. These movements are not directed toward the external stimuli and are not organized actions consistent with purposeful avoidance. In very deep coma, even these primitive reflex responses may disappear.
In coma, normal brain arousal mechanisms that control the level of neuronal activity in the brain and the normal sleep–wake cycle are disrupted. Coma requires disruption of either bilateral hemispheric functioning or the brainstem reticular activating system (...