ER worker here. It really depends on the details. If she was C-STAT positive with last known normal within three hours, you assume stroke, activate the stroke team, and everything moves very quickly. This is where every minute counts, because you can do clot busting to recover brain function.
The fact that she was discharged without an overnight admit suggests to me that the MRI did not show a stroke, or perhaps she was outside the treatment window when she went to the hospital.
