For seemingly no physical reason, you find yourself paralyzed and can't speak. It sounds like the plot of a horror movie you'd watch on Halloween night with the lights off, but such frightening symptoms can actually happen to people who have a rare condition called conversion disorder.
"Conversion disorder is a condition in which psychological stresses are expressed physically as neurologic symptoms," said John Speed, MBBS, a University of Utah Health physician and an expert on the mysterious affliction.
Everyone has stress, Speed said, and it can be expressed physically in different ways: tension headaches, tight necks, even diarrhea.
"I used to have friends in medical school who had to run to the bathroom before exams," Speed said. "These symptoms aren't just 'in your head.'"
Occasionally, stress becomes so severe that it can block messages that travel from the brain to different body parts such as the eyes, ears and limbs. Paralysis, numbness, deafness and blindness can result.
Famously, a group of about 20 teen girls in New York all came down with the same symptoms, including stuttering, seizures and verbal outbursts, between 2011 and 2012.
The good news? Conversion disorder can be cured.
"We have them unlearn the bad stuff and relearn the good stuff," said Speed, who has treated about 200-250 people with conversion disorder throughout his career.
The treatment is a combination of physical and psychological therapy, and patients usually need a few days up to a couple of weeks to recover.
In 2012, Dr. Speed was featured in this KSL piece, which examined the spooky history of conversion disorder.