Both vegetative and comatose patients retain some brain stem function, meaning that they maintain some ability to breathe on their own, and exhibit other reflexes, like pupil dilation in response to bright lights, according to the Finger Lakes Donor Recovery Network.

She went under general anesthetic and never came out. Dubbed the “sleeping beauty,” Esposito stayed in a coma for 37 years and 111 days before succumbing in 1978 — the longest-ever coma, according to Guinness World Records.

However, while neurostorming may be an initial positive sign, the effects of storming after brain injury can be devastating if left untreated. For example, prolonged fever and high blood pressure can result in secondary brain injuries that will severely prolong recovery.

Over time, the person may start to gradually regain consciousness and become more aware. Some people will wake up after a few weeks, while others may go into a vegetative state or minimally conscious state (see recovering from a coma, below).

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 lying in comma neither responds to environmental stimuli nor has self-consciousness. He/she is supported by machines to carry out the vital life processes and he/she is brain-dead. Such patients are never come back to normal life. They are considered living or non-living.

Comas can last from several days to several weeks. In more severe cases a coma may last for over five weeks, while some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die.

Nourishing the unconscious person requires bypassing the normal chewing and swallowing process, and at times avoiding the gastrointestinal tract altogether. A nasogastric tube bypasses mouth and esophagus to deliver liquid nutrition directly to the stomach.