The video of Branson's nonsensical speech has gone viral on the Internet, viewed by millions around the world. Many who saw the footage wondered if she had a stroke.
Branson's doctor said she suffered a complex migraine with symptoms including numbness in her face. It's a type of migraine that can mimic symptoms of a stroke.
"A complex migraine is a migraine which is almost like a mini stroke. It causes neurological symptoms," said Dr. George Rappard with the Hollywood Presbyterian Medical Center.
Rappard specializes in vascular operations in the brain.
"What's important is that sometimes, that can actually cause a stroke. In fact, people with these types of migraines have more likelihood of going on and having a stoke that is loss of brain function or brain damage," Rappard explained.
Branson has had migraines since childhood. On the night of the Grammy Awards, she was treated by paramedics and went home.
Rappard says if you have similar symptoms, you should get immediate help.
"So if you decide to wait and see what it turns into, and if you're wrong and it really is a stroke, you're going to suffer from very significant brain damage," Rappard warned.
The doctor added that women who experience migraines, use birth control medication and smoke are 10 times more likely to have a stroke.