There are well known cases of terry Wallis of USA and one of Belgium and one lady in India, All of them around twenty years and there may be many for more long period but could not become a news due to nothing special with them so they could not become a news. However it depends on standard of care provided to them.However I hope that this issue is near to some new phase. You can read at this site about Jawad Pasha and Muhammad Hussain Kakar. You can now also see some news about increasing know how through scan. So I hope that there will be some better for these patients in near future.