What does it mean that some people feel they are leaving their bodies, whereas others suddenly feel elated? Two different networks seem to play a role: the external, or sensory, network and the internal self-consciousness network.
The former is important for the perception of all sensory stimuli. To hear, we need not only ears and the auditory cortex but also this external network, which probably exists in each hemisphere of the brain—in the outermost layer of the prefrontal cortex as well as farther back, in the parietal-temporal lobes. Our internal consciousness network, on the other hand, has to do with our imagination—that is, our internal voice.
This network is located deep within the cingulate cortex and in the precuneus. For us to be conscious of our thoughts, this network must exchange information with the thalamus. The brain is so heavily damaged that neither of the networks functions correctly anymore. This malfunction can occur as a result of serious injury, a brain hemorrhage, cardiac arrest or a heart attack. At most, a coma lasts for a few days or weeks. This does not, however, mean that a person is conscious.
Most patients who awaken from a coma soon recuperate. But a minority will succumb to brain death; a brain that is dead is completely destroyed and cannot recover. But some patients who are not brain-dead will never recover either. For that we use the Glasgow Coma Scale. If we pinch their hand, they will move it away. But these signs of consciousness are not always evident, nor do we see them in every patient. A patient who awakens from a coma may also develop a so-called locked-in syndrome, being completely conscious but paralyzed and unable to communicate, except through eye blinks.
So the difference between unresponsiveness, minimal consciousness and locked-in would seem to be hard to determine. If there is no response to commands, sounds or pain stimuli, this does not necessarily mean that the patient is unconscious. Family members are often quicker than physicians to recognize whether a patient exhibits consciousness.
How do you determine whether they are conscious? If the motor cortex is activated, we know that the patient heard and understood and therefore is conscious.
With different brain scanners, I can find out where brain damage is located and which connections are still intact. This information tells family members what the chances of recovery are. If the results show that there is no hope whatsoever, we then discuss difficult topics with the family, such as end-of-life options. Occasionally we see much more brain activity than anticipated, and then we can initiate treatment aimed at rehabilitation.
He was a very important patient for us: as far as anyone could tell, he had been left completely unresponsive for 23 years after a car accident. But in the mids we placed him in a brain scanner and saw clear signs of consciousness. It is possible that he experienced emotions over all those years. He was the first of our patients who was given a different diagnosis after such a long time. We subsequently conducted a study in several Belgian rehab centers and found that 30 to 40 percent of unresponsive patients may exhibit signs of consciousness.
Yes, but his facilitator was the only person who seemed able to understand and translate his minimal hand signals.
She probably typed words of her own unconsciously. It is a complex case that the media has failed to report adequately. They were more interested in telling sensational, simplistic human-interest stories. A coma often lasts for a few days or weeks. Rarely, it can last for several years. If a person enters a coma, this is a medical emergency. Rapid action may be needed to preserve life and brain function. A person who is experiencing a coma cannot be awakened, and they do not react to the surrounding environment.
They do not respond to pain, light, or sound in the usual way, and they do not make voluntary actions. Although they do not wake up, their body follows normal sleep patterns.
Coma may occur for various reasons, such as intoxication, a disease or infection that affects the central nervous system CNS , a serious injury, and hypoxia, or oxygen deprivation. Sometimes, a doctor will induce a coma using medications, for example, to protect the patient from intense pain during a healing process, or to preserve higher brain function following another form of brain trauma. A coma does not usually last for more than a few weeks.
How long these will take to develop, and how long they will continue, depend on the underlying cause. Before entering a coma, a person with worsening hypoglycemia low blood sugar , or hypercapnia higher blood CO2 levels , for example, will first experience mild agitation. Without treatment, their ability to think clearly will gradually decrease. Finally, they will lose consciousness.
If a coma results from a severe injury to the brain or a subarachnoid hemorrhage, symptoms may appear suddenly. Anyone who is with the person should try to remember what occurred just before the coma started, because this information will help determine the underlying cause and give a better idea of what treatment to apply.
Alert is the most conscious state, and unconscious is the least. This helps the health professional assess whether this is likely to be an emergency. If the person is alert, there is no risk of coma. Patients with deep unconsciousness may be at risk of asphyxiation. They may need medical help to secure the airways and ensure they continue to breathe. This could be a tube that passes through the nose or mouth, into the lungs.
In , neuroscientists using fMRI scanning technology observed brain activity in a man who had been in a coma for 12 years after a road traffic accident. For example, when they asked the man to imagine he was playing tennis or walking round his house, his brain activity reflected that he was thinking of doing these things. Scientists now believe that 15 to 20 percent of people in a so-called vegetative state may be fully conscious.
Advances in technology mean that we are better able to understand what people are experiencing during a coma. A person who is visiting a friend or family member who is in a coma can speak to them as they normally would, for example, explaining what has been happening during the day.
It is unclear how much they can understand, but there is a chance the person may be able to hear and understand. They may like to listen to music. Research has also suggested that stimulating the senses of touch, smell, sound, and vision may help the person recover. Diabetes : If the blood sugar levels of a person with diabetes rise too much, this is known as hyperglycemia.
While in her mind she was in Alaska, in reality Wineland was in a California hospital in a medically-induced coma. Following a routine surgery, Wineland, who has cystic fibrosis , contracted a dangerous infection called blood sepsis.
In the years after her coma, Wineland has started a non-profit and video channel sharing her stories of surviving life as a sick person. But it goes through this weird filter thing… It turns into something else when it hits your consciousness.
Michael DeGeorgia, a neurologist from University Hospitals Case Medical Center, said patients can face post-traumatic stress disorder or other trauma from being left in the dream-like state during sedation. He clarified that a medically-induced coma is different from a coma caused by traumatic brain injury.
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