A coma is a medical condition of unconsciousness. More than the unconsciousness of sleep, it is ongoing and often unintentional, although comas can be medically induced in special cases. A wide variety of issues can cause comas, from diabetes to traumatic brain injuries. Here’s a look at the common causes of comas.
Traumatic Brain Injury
Comas are perhaps most frequently associated with extreme blows to the brain. Of course not every head wound is going to cause a coma, but even concussions (a much shorter period of unconsciousness resulting from an injury, generally associated with memory loss not only of the injurious event, but often several hours prior) can cause serious brain damage. In any case, when the head is injured from blunt force trauma, the damage often occurs on the opposite side of the brain, in a sort of backlash movement.
For example, if your forehead bangs into the dashboard, more serious trauma may be present at the back of the brain where it is thrown against the skull. The damage to the skull and surrounding tissue can cause the brain to bleed and swell. Because the brain is encased by the bone of the skull, it only has a finite amount of room to extend into. Eventually, it can put so much pressure on the brain stem that brainstem reflexes (blinking, pupil dilation, breathing patterns, etc.) are damaged in addition to the original point of damage. Bleeding in tandem with this swollen tissue can actually make the brain shift slightly from its normal position, also increasing compression on the injured area and brainstem.
Direct Causes
Certain viral and bacterial infections can actually move into the nervous system, causing encephalitis (inflammation of the brain or spinal cord) or meningitis (inflammation of the meninges, or tissue surrounding the brain and spinal cord). Similarly to traumatic injuries, extreme cases can cause enough swelling to result in a comatose state.
Hypoxia, a lack of oxygen, can also result in a coma. Common causes of hypoxia are drowning, choking, or suffocating. It can even occur as a result of a heart attack or stroke. Essentially, something interferes with the body’s ability to intake oxygen, the blood can’t send oxygen around the body, and the different parts of the body -- including the brain -- slowly become so deprived of oxygen that they lose the ability to function.
Underlying Conditions
Other medical conditions can become severe enough to cause comas as well. Epilepsy, a condition in which an individual experiences chronic seizures, can, in the long term, become frequent enough that the brain doesn’t have time to recover and eventually causes the patient to become comatose. Diabetics are also at risk of lapsing into a coma. Extremely unbalanced blood sugar levels -- whether too high or too low -- can cause a coma.
Exposure to certain types of toxins, such as lead or carbon dioxide (as a result of an extreme asthma attack in which the body cannot get rid of the excess carbon dioxide) can accumulate in the body because of prolonged or high levels of exposure, leading to coma and/or brain damage. Likewise, overuse of drugs and alcohol can cause an overdose resulting in prolonged unconsciousness or brain damage, particularly if treatment is not sought immediately.
