Details of Propst's case continue to baffle doctors. What they do know is that a devastating "electrical storm" in her brain caused her declarative memory to be wiped clean. Facts, events, dates, acquaintances and even her identity were wiped away. As Propst describes it, "If I was a computer, it would be like my hard drive was erased."
David Ewing of Centennial Neurology in Greeley, Colo., Propst's doctor, said that it is remarkable that Propst has adjusted so well to her new life, which, in a way, began slightly more than 10 years ago. The seizure, he says, effectively disconnected the area of her brain in which her memories were stored.
"The area is still there, still intact," he said. "But it was like someone threw a breaker switch. ... She had a single general event, after which she woke up and all of her memories were wiped out."
Since the event, however, Propst has rebuilt her life. Her persistence in rejoining the work force has led to stable employment as a custodian at a state facility. She enjoys strong relationships with her family. And she has written a book, "Absent Memories: Moving Forward When You Can't Look Back," which documents her experiences.
"Every single person I met said, 'You need to write a book about this,'" Propst said. "I thought, 'What the heck, what do I have to lose?'"
While Propst's experience is rare, there have been numerous documented cases in which an injury has led to long-term amnesia.
Traumatic events in the brain can have other unusual effects as well. For 52-year-old Canadian Rosemarie Dore, a stroke on the left side of her brain in 2006 led to a very unusual side effect -- she began to speak with a different accent.
Specifically, Dore, who lives on the Western side of Lake Ontario, adopted a distinctively eastern Canadian accent. She has never been to that region, and she does not know anyone from that part of the country.
"[There was a] nurse that was from Newfoundland," Dore told ABC News. "She comes down the hall, and she come into the room and she says, 'Who's the Newfie here?'" referring to Newfoundland.
"I said, 'There's nobody here like that.'"
"And she said, 'I think I'm talking to her.'"
Though rare, foreign accent syndrome is not entirely undocumented in medical literature. Researchers who have studied the syndrome estimate there are only as many as 60 legitimate recorded cases.
One of the first known patients was reported after World War II by Norwegian neurologist Georg Herman Monrad-Krohn. He described a Norwegian woman who was hit on the head by a bomb fragment during the war and began to speak with a German-like accent. Because of her speech, she became the target of anti-German sentiment.
More recent cases include a Florida woman speaking with a British accent, a Japanese woman sounding to other Japanese as if she were Korean and a South Carolina man developing a French-like accent.
"I have only seen a couple of people with [foreign accent syndrome] ... and I've seen a lot of stroke patients in my time," said Dr. Julius Fridriksson, an associate professor of neuroscience at the University of South Carolina who worked with the South Carolina patient. "These folks have brain damage that alters the way the neurological system works."
While it may be true that musical taste resides in the ear of the beholder, it is somewhat less common that a song can send a listener into an epileptic seizure.