My dad had a stroke which left him without speech and use of his right side, but he came back fairly quickly.
I think they've ruled out stroke though in the case of Senator Johnson. They seem to be reporting it wasn't a stroke, but not really saying what it is, only he's in surgery.
My grandmother had a massive stroke. She was paralyzed after that. The doctors never brought up surgery. The main treatments for strokes are blood thinners, low fat/salt diets and therapy.
If they are doing surgery it sounds more serious like an aneurysm.
Prayers for the Johnson family.