Final answer:
Terri Schiavo entered a persistent vegetative state with no brain activity in her cerebral cortex after a cardiac arrest due to a bulimic episode, requiring a feeding tube and having no chance of recovery.
Step-by-step explanation:
The major event that happened while Christiane was in a coma, referring to the case of Terri Schiavo, was that Schiavo was in a persistent vegetative state due to severe and permanent cerebral atrophy. After suffering from cardiac arrest caused by a bulimic episode on February 25, 1990, Schiavo was resuscitated but had been without oxygen for a significant period, which led to no activity in her cerebral cortex. Terri Schiavo required a feeding tube to stay alive, and her condition was determined to be irreversible, with no chance of improvement or recovery.