What happens during COMA !

Coma is a medical condition in which a person can't respond to any external stimuli. A person is considered in coma only if he/she remains unconscious for more than 6 hours. It can occur due to some head injury or internal bleeding in brain. When a person is in Coma, it appears as if he/she is in deep sleep, but can't get up even if you shake him/her up. In medical terms coma is persistent vegetative state or a state of deep unconsciousness. What happens to a person during Coma differs from person as it depends on the level of coma. Level of coma can be measured using Glasgow Coma Scale.

Glasgow Coma Scale (GCS)

It is a scale used by medical practitioners around the world to measure the intensity of Coma. Its readings differ from 3 to 15. A patient with level 3 Coma is most severe and chances of recovery are usually very rare, while a person at level 15 is considered fully awake and conscious. There are three criteria on which the condition of a patient is measured. These criteria are eye movement, verbal ability and motor function (ability to move the body). Eye movement is rated on scale of 1 to 4, verbal ability is rated on scale of 1 to 5, and motor function is rated on scale of 1 to 6. Thus sum of all these criteria gives the final result. So the minimum result is 3 while the maximum result is 15. Usually the medical practitioners write intensity of coma in following way : GCS7 = E3 V2 M2 . Such description of  Glasgow Coma Scale gives whole information above patients consciousness level.

What causes coma ?

Coma can occur due to following reason.

• Head injury: It might be due to some accident and impact on head. Internal bleeding in brain can also cause coma. Sometimes due to sudden impact during an accident, brain moves inside the skull and causes coma.
• Stroke: Stroke can stop the blood supply to some important parts of brain which may lead the patient into coma.
• Blood loss: Blood loss due to an injury can cause coma as brain stops functioning due to lack of blood. If this condition remains same for longer duration then some parts of brain may get damaged permanently and severity of coma may increase.
• Swelling in Brain: Swelling in brain can cause come. Swelling may occur due to lack of oxygen or electrolyte imbalance.
• Blood Sugar: Both  hyperglycemia (very high blood sugar) and hypoglycemia (very low blood sugar) can cause coma. But this condition is reversible in most cases by correction of blood sugar level.
• After Surgeries: It is found that some patients enter the state of coma after some surgeries. It is not necessary to be a brain surgery. However such cases are very rare.
• Drowning or Choking: These conditions stops the oxygen supply to brain for longer duration and sometimes found responsible for coma.
• Repeated seizures: Single seizure can't put a person into coma but repeated seizures can.

What happens during COMA

Different people have different experiences during coma.

• Pupils of a person in coma are usually dilated. It means pupils don't expand or contract due to light.
• In most of the cases the patient don't remember anything that happened during coma, as if he/she was in a deep sleep.
• Some patients report that they were able to hear all voices around them but can't react as they are not able to move their body, not even eyes. Such condition is very bad as person is trapped in his own body.
• In some cases the patient is able to control eyes and eyelids but not other parts of body. Such patients sleep and wake up like other patients but can't move any other part except their eyes.
• Some patients face memory loss after recovery from coma as some vital part of brain responsible for memory was damaged. Once a patient who recovered from coma was not able to recognize his wife, to whom he was married for 20 years.
• Once a patient came out of coma after 8 years and spent a day catching up with family and fell back into coma the very next day and never recovered.
• Mel Blanc, a loony toons voice actor fell into coma and didn't respond until a neurosurgeon addressed him as "Bugs Bunny", to which he responded "Myeeeh...Whats up doc".
• Hours before Thomas Edison died, he recovered from coma and looked upwards and said "It is very beautiful over there". I am struggling to find whether has was talking about ceiling or heaven.

Experts on the subject of coma have different views about it. But the best explained is that our brain is a large bunch of neurons, all of which are never used and only some part or some circuit is used. If some import part of brain is damaged then we fell into coma and in the mean time our brain tries to make some alternate circuit by using the remaining neurons. Damaged neurons can't be regenerated by our body but circuits can be reconstructed with the remaining neurons. If it succeeds then the patient recovers from coma gradually.

How long do a person remains in coma ?
There is no time limit as it depends on cause of coma and severity of come. On an average it takes 2 to 4 weeks to recover from a coma but as the duration increases the chances or revival gets less. Some patients recover from coma in a few days while some can spend their complete remaining life in that state. Terry Wallis woke up from a coma after 19 years, which is the longest duration for a patient waking up from coma. However Elaine Esposito was in coma for 37 years and 111 days but she never recovered and died in coma.
The longer the person takes, the chances of some body disability increases. Due to this reason some therapies are recommended to recovered patients to recover from disability.

When it comes to brain then nothing is impossible. We humans still have a lot to learn about functioning of brain. May be some day in future we will be able to scan the brain circuits and make a person recover at a faster rate.