Michelle Myers. Picture: Screengrab/YouTube

Michelle Myers, from Arizona in US, says she has gone to bed with extreme headaches in the past and woke up speaking with what sounds like a foreign accent.

At various points, Australian and Irish accents have inexplicably flowed from her mouth for about two weeks, then disappeared, the 45-year-old woman says.

But a British accent has lingered for two years.

Myers says she has been diagnosed with foreign accent syndrome (FAS). The disorder typically occurs after strokes or traumatic brain injuries damage the language center of a person's brain - to the degree that their native language sounds like it is tinged with a foreign accent, according to the Center for Communication Disorders at the University of Texas at Dallas.

In some instances, speakers warp the typical rhythm of their language and stress of certain syllables. Affected people may also cut out articles such as "the" and drop letters, turning an American "yeah" into a Scandinavian "yah," for instance.

Unlike many stroke or brain-injury victims, sufferers typically produce grammatically correct language, Sheila Blumstein, a Brown University linguist who has written extensively on FAS, told The Washington Post for a 2010 article about a Virginia woman who fell down a stairwell, rattled her brain and awoke speaking with a Russian-like accent.

The injury caused her brain to truncate pronunciations for "this" and "that," resulting in foreign-sounding "dis" and "dat."

Over the next century, only about 60 cases were documented in literature, the National Institutes of Health said in a 2011 study. Cases have spanned the world, from a Louisiana woman who suddenly spoke with a Cajun accent after a brain injury to a Japanese stroke patient who sounded Korean.

The most prominent case of foreign accent syndrome occurred in Oslo during World War II. Norwegian neurologist G.H. Monrad-Krohn, in bedrock research for the condition, studied a woman struck in the head by shrapnel during a bombing raid in 1941. The injury distorted the rhythm and melody of her speech, suggesting a foreign accent to those who heard her speak.

Myers, who said she also suffers from Ehlers-Danlos, a condition that makes skin elastic and joints flexible to the point of dislocation, is currently seeking treatment for her rare condition, with the hope of being cured.