In 1988, when food rationing was a daily reality in communist Poland, railway worker Jan Grzebski fell into a coma after being hit by a train. Doctors gave him only two or three years to live but in June this year - 19 years after the accident - Grzebski awoke to find the communists had fallen from power. 'When I went into a coma, there was only tea and vinegar in the shops,' Grzebski told newspapers. While waking from a coma after decades remains a rare phenomenon, patients such as Grzebski continue to stun the medical establishment and thrill their relatives. A coma is usually caused by an injury to either side of the brain or to the upper brain stem. People may become comatose as a result of a range of conditions, including intoxication, brain injury, central nervous system diseases and acute neurological injuries such as stroke. The Brain Injury Association of America defines a coma as 'a state of unconsciousness from which the individual cannot be awakened, in which the individual responds minimally or not at all to stimuli and initiates no voluntary activities'. When people enter a coma they do not have sleep-wake cycles. They do not respond to pain or light but may move spontaneously. Most comas last for only a few days to a few weeks. Some patients will gradually regain consciousness and some will die, but others can remain in a vegetative state for years. While doctors can't predict which coma patients will wake and when, a patient's chances of recovery often depend on the original cause of the coma. Some patients may make a complete recovery while others may be left with physical, intellectual or psychological impairment. Some reports suggest adults who remain in a coma for more than four weeks are unlikely to regain their previous level of functioning. The dramatic story of a coma patient coming back from the brink of death might be a popular storyline for television soap operas but a 2005 University of Pennsylvania study published in the British Medical Journal found the portrayal of comas on the small screen could give relatives of real-life patients false hope. The study found only 8 per cent of fictional comatose patients died in soap operas compared to about half in real life. While television characters usually recover quickly and are left with no side-effects, data shows real patients are nowhere near as fortunate. Movies often depict relatives talking to comatose patients and wondering whether they can 'hear' them. Grzebski vaguely recalls his wife and children trying to communicate with him. They didn't manage to prepare him, though, for the shock of having 11 'instant' grandchildren. And being suddenly thrust into the new millennium took some getting used to. 'Now ... there are so many goods in the shops, it makes my head spin,' Grzebski said.