IStock Photo 9748780 © Jodi Jacobson

What are the odds that a man who has never been to Ireland and has no Irish relatives, will wake up from brain surgery and suddenly break into “Danny Boy,” in a perfect Irish brogue? Or that a Czech speed car racer, with very little command of English, will emerge from an accident spouting English like a BBC news reader? How about the English woman stricken with a stroke who wakes up talking like a Jamaican—or the Southern gentleman, also hit by a stroke, who suddenly talks like he hails from Paris—not a rural town in South Carolina, population 2,000 plus?

And now Croatian doctors are reporting that a 13-year-old girl, who recently suffered a brain injury, awoke from her a coma unable to speak her native tongue, but fluent in German, a language she had just began to study.

For over a hundred years, researchers have been trying to unlock the mystery of what has been dubbed “Foreign Accent Syndrome.” Since the syndrome was first described in 1907 by a French physician, approximately 60 cases have been reported worldwide. Based on that estimate, and using an average annual world population of 3,483,864,825 (about 3.5 billion) over the 103 year period, the odds any person would be stricken with FAS in a year are about 1 in 5,981,000,000 (using 4-digit rounding). A person in the US is three times more likely to be killed by a waterspout in a year.

It is impossible to assign the exact odds, in part because there is still disagreement about which cases qualify. Does speaking an unfamiliar language fall into the FAS category, or should it be limited to those who have merely acquired an unfamiliar accent? As researchers expand their understanding of these rare neurological cases, they are also expanding the number of potential causes. Most commonly patients with FAS have suffered an injury to the brain which produced a lesion or bleeding. In 2008, a study was published in the journal Cortex, by Belgium and British researchers, asserting that FAS cases involving accents can also be a result of developmental motor speech impairment. Another intriguing study, published in Neurocase, presents the istory of a French patient who had lost the ability to speak his mother tongue as a result of a brain injury, but was able to speak German, a language he had learned as a child, but not mastered - leading to fascinating questions on how the brain organizes multiple languages, and how those languages are accessed.

According to Dujomir Marasovic, the director of the hospital where the Croatian teen is now recovering, it is too early to settle on an explanation for her baffling condition. If it does turn out to be categorized as FAS, the duration is uncertain. The condition can be transitory, as it was for 30-year-old Chris Gregory of Yorkshire, who, after spending three days on life support following surgery in 2007 for a ruptured vessel in his brain, greeted his fiancé with “It’s da broid!” Within thirty minutes Gregory had returned to normal, leaving him with no memory of regaling nurses with his song, and no ability to reproduce an Irish brogue. The condition lasted several days for Czech race driver, Matej Krus, who knew only a few phrases in English when a fellow driver ran over his head in 2007; regaining consciousness he conversed with paramedics in fluent English, compete with top-drawer accent.

For Berley Stabler, who suffered a mild stroke in 2004, the French accent which replaced his Southern drawl persisted for eleven months before it began to fade. Neurologists have discovered that many people with FAS have lesions in a region of the brain’s left hemisphere called the Broca area, and in Stabler’s case, doctors were able to monitor a small, discreet lesion. Imaging studies showed abnormal blood floor to the damaged area, which doctors believed caused his altered speech. Although he sounded like a Frenchman to many, to some ears he sounded German, Greek or even Iraqi. The discrepancy underlies what many researchers believe: that the initial brain injury leads to irregular accentuation on syllables and a change in the timing of speech, rather than to the assumption of an actual discrete accent. As Stabler’s lesion healed, the blood flow to the area returned to normal and Stabler began to sound more like his old self.

But FAS remains largely a mystery—with no firm explanation for an outburst of “Danny Boy” or the temporary command of a foreign language. Nor is it clearly understood why the condition can persist for years in a person—leaving them feeling alienated, like strangers in their own body or a foreigner among their own kind. The American Speech-language-Hearing Association has identified one of the early cases of Foreign Accent Syndrome as Astrid L., a 35 year-old Norwegian who suffered a severe head injury during an air attack by Germans in 1941; she emerged from the injury with a strong German accent and was widely shunned by her countrymen.

And then there is the case of Cindy Lou Romberg who has never ventured far beyond the borders of her home of Port Angeles, Washington. After falling out of a moving car and hitting her head on the pavement, she now speaks in an accent which alternately sounds Russian, German or Swedish. A group of phoneticians who studied the speech of FAS patients and published their findings in the Journal of Neurolinguistics, similarly found that the speech of affected patients did not consistently resemble any single accent, but rather fluctuated among a number of languages, even different language families.

Someday there may be a more precise name for Foreign Accent Syndrome, and a clearer understanding of how something so ingrained in a person as their speech patterns can change in an instant. As to how a person can attain instant fluency in a language they have had limited exposure to—that’s another part of the mystery, waiting to be solved.