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.
The main symptom of a coma is unconsciousness. A patient in a coma will have no conscious response to external stimuli and may appear to be in a deep sleep.
The patient in a coma may exhibit spontaneous body movements. Patients may shake or jerk abnormally, and the eyes may move. If the coma is severe, even basic body functions such as breathing may be affected.
- Coma may result from significant traumatic injury to the head, such as from a car accident or fall.
Bleeding (Hemorrhage) into the brain or skull
Types of brain/skull hemorrhage include:
- Intracerebral hemorrhage: bleeding within the brain tissue
- Epidural hemorrhage: bleeding inside the skull, but outside the dura, (the covering of the brain)
- Subdural hemorrhage: bleeding inside the skull, and inside the dura, but not in the brain tissue itself
- Subarachnoid hemorrhage: bleeding in the space immediately adjacent to the brain tissue
Causes of brain/skull hemorrhage include:
- High blood pressure (hypertension)
- Cerebral aneurysm: a weak spot in a blood vessel of the brain
- Arteriovenous malformation (AVM): an abnormal cluster of blood vessels
Swelling of the brain (cerebral edema)
Causes of swelling of the brain
- Chemical imbalances
- Traumatic injuries
- Problems with the flow of cerebrospinal fluid (CSF)
Lack of oxygen to the brain
The most common causes for lack of oxygen to the brain include:
- Heart arrhythmias
- Lung disease, including pneumonia,emphysema, or asthma.
- Anemia (low red blood cell count)
- External poisons are those that are ingested or inhaled
- Internal poisons are by-products of the body's normal metabolism that for some reason cannot be excreted properly
Although the brain is protected by tough bone (skull) and padding (membranes), it can still be injured. Head injuries that are severe enough to affect brain function are termed traumatic brain injuries (TBIs). Damage can range from mild to severe as the brain can affect everything you do.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.