The word coma is based on a Greek word, meaning “state of sleep.” When the brain is injured, or the blood flow from the rest of the body is cut off, conscious action is impaired – we call this a coma.
When a person is in a coma, they are alive and will sometimes breathe on their own, but they won’t respond to stimuli. The brain of a comatose person is active but only at a base level. Someone that is comatose can’t be woken up or perform any voluntary action; it’s sort of being asleep. The brain’s oxygen supply can be cut off for any number of reasons. If the brain bounces around your skull, you get a concussion which causes swelling and cutting off blood flow; blood vessels could tear that will lead to cutting off blood flow. Or an artery supply in the brain can be blocked which could also cause to cut off blood flow. Each will cause a coma.
People with diabetes can fall into a coma as well if blood sugar becomes too high or too low. There are also medically induced comas though these aren’t really a coma. Regular ones are biological, but medical coma is basically long-term anesthesia. Doctors use drugs to keep people under, keeping the brain from swelling or the immune system from responding.
Every coma is different, depending on the part of the brain being starved. Some comatose patients will twitch while others will not breathe on their own.
The Glasgow coma scale assigns a ranking from 3 to 15. 3 being a deep coma, and 15 being awake and responsive. If left alone, comatose patients would suffer brain damage and assume they can breathe, would eventually die of starvation without the ability to feed themselves. Doctors would normally put a comatose patient on IV nutrients and use ventilators to keep to keep them breathing. In the long term, the machines keep the patient alive while nurses move them around to avoid bed sores or muscle atrophy.
On average, coma only lasts 2 to 4 weeks. But the longer the coma and the deeper it is, the less chance of the patient emerging or surviving. Because there is some brain activity, television would have us believe that patients could understand the outside world around them, but we can’t confirm that’s true for all coma patients. We can’t interact directly to ask them, but we can scan their brains.
A study in 2010 at New England Journal of Medicine looked at 54 patients in vegetative or minimally conscious states who are asked to imagine hitting a tennis ball. And the appropriate quote areas of their brain associated with hitting the tennis ball lit up that was in the 9% of them though. One patient was actually able to use that technique to answer yes or no questions. Although vegetative states aren’t a coma, we can say that they are somewhat similar. Coma is a little deeper; they require hospitalization while a patient in a vegetative state can open their eyes, moan, they can be startled, cry, smile, make facial expressions, but they won’t interact or have purposeful movement.
When Israeli Prime Minister Ariel Sharon fell into a vegetative state after a stroke, functional MRI scans were taken to assess his brain activity while his son spoke to him, and also while he was being shown pictures of his family. The scans revealed that Sharon had “Robust brain activity.” fMRI’s don’t tell us what’s happening in the brain; just where blood is flowing, but it does count for something else.
An early 2015 paper published in Neuro rehabilitation and neural repair found that comatose patients who heard the voices of their families four times a day for six weeks recovered consciousness significantly faster and had an improved recovery. Unfortunately, there’s no treatment to wake someone from a coma. Some wake and some don’t. Diabetic comas can be ended relatively quickly with treatment, but brain impacts or clots can take a lot longer.
Coma is not all just one thing, people on the Glasgow scale at 3 to 5 are in the deepest of coma with minimal activity and often never recover. But people from 11 to 15 can be nearly awake and conscious.
In the end, the length of the coma depends on the severity of the brain injury, and after regaining consciousness, doctors will have to assess lasting impact on the brain starvation. Parts of the brain could be damaged beyond repair, causing permanent physical and mental disability, but after all, all coma patients will need physical and psychological therapy to restore their functions fully.