I hope that they did an MRI on this person. There are many things that can cause vertigo. He should get checked (follo-up) with a neurologist. My vertigo they thought was an inner ear situation. For me an epidode is when the couch goes UP to the ceiling and down the other side. OR the car, which means I cannot drive when I am experiencing these episodes. (opposed to a circle spinning)
Keep us posted. High blood pressure, low blood pressure, inner ear...something in the brain....SO many things can cause dizziness. A small TIA could be to blame. Again FOLLOWING UP is really important. Never would I rely on the ER to diagnose me. But that is just my experience.
Your friend has my thoughts and prayers..