I have this same symptom. It can come up from a non- pre-syncopal episode, too. Like if I was recently stressed or had a busy week. I sound like I have had a seizure. With can’t speak at all, or it’s slow and slurred or it’s gibberish. I have had these episodes checked out by a neurologist and cardiologist to see if if it’s the heart not pumping blood up to my brain or if it’s my brain having seizures and short circuiting. Nothing came of the results from MRI’s, CT scans, tilt table, and seizure brain wave tests. I just chalk it up to one of my funky quirks I have now and am glad it’s not something dangerously wrong.
