Doctor's Notes on Coma
A coma is a deep state of unconsciousness in which individuals do not consciously respond to stimuli in their environment. Causes of coma include head trauma/injury, bleeding (hemorrhage) into the brain or skull (such as from high blood pressure, aneurysm, or a tumor), swelling of the brain (cerebral edema) (such as from infections, traumatic injuries, and problems with the flow of cerebrospinal fluid), lack of oxygen to the brain (which may be due to heart arrhythmias, lung disease, anemia, or toxins), poisons, and endocrine disorders such as hypothyroidism or diabetes.
The main symptom of a coma is unconsciousness with no conscious response to external stimuli. The patient may appear to be in a deep sleep. Other symptoms of coma may include spontaneous body movements such as shaking or jerking abnormally, and the eyes may move. In severe cases basic body functions such as breathing may be affected.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.