Coma

1. Decreased alertness, awareness or consciousness, which may result from a variety of conditions including intoxication (drug, alcohol or toxins), metabolic abnormalities (hypoglycemia, hyperglycemia?, ketosis etc.), central nervous system diseases (stroke, [head trauma]?, seizure) and hypoxia. The metabolic abnormalities are the most common causes of coma. The difference between coma and stupor is that a patient with coma can not give a suitable response to both noxious and verbal stimuli, whereas a case with stupor can give a rough response (like screaming) to a noxious stimulus. A persistent coma is called vegetative state.

2. A coma is the tail of a comet produced by vapor boiled off the comet as it nears the sun.