What if the patient went into a seizure and while falling hit her C2 or C3 and injured them. What would be one of the outcomes?
Inability to breathe using chest muscles or diaphragm. Therefore, she would not be breathing. Could this cause cardiac arrest? Yes. Would C-spine stability help this patient? Most likely..
You are such an optimist, I like that.
But let me offer something more likely.
If the patient actually had cord or phrenic nerve damage with paralysis of the diaphragm, c-spine or not, the outcome is a vent dependant, perhaps quad who will lay in a nursing home until she dies from complications of a decubitus ulcer or pneumonia.