If someone is having an ischemic stroke, is it possible it will get worse if they go to er by ambulance?

Yes: There is always a possibility of getting worse.

Gets worse any way: Time is brain. The quicker someone gets to a hospital where stroke care is available, the better the result. If private transportation would be significantly quicker in doing this, then do it. But paramedics have medications on board and are in direct communication with the receiving hospital's doctors, so that they can monitor and respond to patient needs en route.

No: If someone is having an ischemic stroke, ambulance is the best way to go to the er. Driving yourself is not advisable. Paramedics can institute appropriate measures "in the field" such as starting an iv, directing you to a primary stroke center, administering oxygen, checking serum glucose level, etc.

Go quickly: Ambulance can allert er stroke coming so team ready. Can support very sick person so they get to er safely.

How in the world??: 1} Might that happen? If someone is having a stroke, then can extend / spread / worsen their stroke--EMS providers and/or the ride in have nothing to do with.