In some cases a person can descend into a persistent vegetative state, where the brain has lost its higher functions including consciousness, self-awareness and personality but retains involuntary functions such as breathing and swallowing, heart rate and blood pressure. No amount of sensory stimulation can wake them up.
They may be breathing unusually. They may be holding their body in an unusual posture. Their pupils may be affected in a number of different ways. For example, one pupil is larger than the other or both pupils are constricted. Causes of coma The various causes of coma can be broadly divided into three main categories, which are: Intracranial — events occurring within the skull.
This can include infection such as meningitis , haemorrhage following a severe head injury, stroke, brain abscess, brain tumour, cerebral oedema swelling of the brain or the after-effects of an epileptic seizure Extracranial — any external event that reduces oxygen or blood flow to the brain cerebral hypoxia. Diagnosis of coma A coma is a medical emergency. A quick diagnosis can be life-saving. For example, a person with diabetes may have dangerously lowered their blood sugar levels by accidentally injecting too much insulin.
Immediate treatment is crucial in this type of life-threatening situation. Generally, the order in which medical personnel diagnose and treat for coma is: The airway, breathing, blood pressure and pulse of the person are checked. Their temperature is taken. A high temperature may indicate fever and infection, while a low temperature suggests hypothermia.
The body is examined for injuries in case the person may have sustained a serious head injury. The doctor checks for signs of brain damage such as complete limpness of the whole body or unusual breathing patterns.
In the longer term, healthcare staff will give supportive treatment on a hospital ward. A person in a coma may become restless, requiring care to prevent them from hurting themselves or attempting to pull on tubes or dressings. In these instances, medicine may be given to calm the patient. Side rails on the bed should be kept up to prevent the patient from falling. While not empirically validated, families have reported benefits from arousal regimes, such as those implemented by Dr Ted Freeman eg Coma Arousal Therapy.
The therapy involves family members taking the patient through a regimen of controlled auditory, visual and physical stimulation for up to six hours a day, every day. Comas can last from days to weeks while some severe cases have lasted several years. Recovery depends, to a considerable extent, on the original cause of the coma and on the severity of any brain damage.
Some patients e. They may need physiotherapy, occupational therapy, psychological assessment and support during a period of rehabilitation and may need care for the rest of their lives. Patients can gradually come out of the coma, some progress to a vegetative state aka unresponsive wakefulness syndrome and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness see Minimally Conscious State.
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. If they become too low, this is hypoglycemia. If hyperglycemia or hypoglycemia continue for too long, a coma can result.
Hypoxia, or lack of oxygen : If the supply of oxygen to the brain is reduced or cut off, for example, during a heart attack , stroke, or near drowning, a coma may result. Infections : Severe inflammation of the brain, spinal cord, or tissues surrounding the brain can result in coma.
People can remain in this state for a long time, and it can be difficult for family members to accept when there are seemingly conscious behaviours e. There are two scales commonly used to measure the depth and duration of a coma.
The most common is the Glasgow Coma Scale GCS which scores actions and reactions in three specific areas including eye, verbal and motor response. The scores in each area are summed to give an overall score, ranging from 3 deep coma to 15 fully awake.
The Rancho Los Amigos Scale is another measure of coma, it has a single scale and assesses global functioning. During a coma the medical team provides treatment to prevent any further complications.
A respirator may be used to assist breathing, and surgery may be required to stop any bleeding or swelling in the brain. There is constant monitoring of vital signs, such as blood pressure and pulse and levels of any prescribed medications.
Other therapies may be used to prevent problems upon awakening from coma.
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