Apr. 22, 2010 -- A Croatian teenager awoke from a coma last week to find she could no longer speak in her native Croatian -- but was fluent in German, a language she had just started studying in school, the U.K. press reports.

Following a mysterious 24-hour coma, the thirteen-year-old girl from the southern town of Knin has been able to understand Croatian, according to the U.K. press. She can only respond in German and requires a translator to communicate with her family, the stories said.

Dujomir Marasovic, director of Firule Hospital in Split where the girl is being treated, declined to provide further details about the girl's case, saying he wishes to protect her privacy.

Though doctors say it's unlikely that the girl's German actually improved because of the coma, instances of lost language and bizarre changes in speech are more common than one may think.

ABC News asked neurologists and language experts to weigh in on these kinds of remarkable language phenomena.

Not a Native Speaker

One such rare but well-documented speech condition is known as Foreign Accent Syndrome. Those with this disorder will often be unable to speak after suffering a stroke or other brain trauma and when their voices return, they will sound as if they have a foreign accent.

Their new accent may sound French, Chinese, Slavic, or any number of nationalities -- but their new sound is not truly an accent.

This condition is "actually a speech impairment that makes them sound 'foreign,'" says Toronto-based speech-language pathologist Regina Jokel, though often the "origin" of the accent is in the ear of the listener.

It's not a newly-acquired accent, but a disturbance in the patient's ability to form words, says Dr. Gregory O'Shanick, president and medical director of the Center for Neurorehabilitation Services in Virginia.

The case of the Croatian teen is a bit more puzzling, however, because she has reportedly swapped languages. Though her condition remains unexplained, experts say her injury may have something to do with damage to the language production centers of the brain.

Waking Up German

"These kinds of events are infrequent so being able to really study them in a consistent way is difficult," says O'Shanick, but there are "situations where people learning a second language will be better able to speak that language post-injury."

This shift has to do with the different places in the brain where language knowledge is stored, he says.

While information to let one speak in one's native tongue is stored on the left side of the brain, the ability to speak a second language predominantly comes from the right side, O'Shanick says.

As long as a second (or third, or fourth) language is mastered in early childhood, it will be stored in the same place as the first, Jokel adds, but languages learned later in life will be stored elsewhere.

So when trauma results in better recall of the second language, it may be that they had an injury to the left side of the brain, O'Schanick says.

In a similar case reported in the U.K., a Czech race car driver regained consciousness after a crash and was speaking only in English -- with a British accent, no less -- to the paramedics. This effect was temporary however, and he regained the use of his native Czech soon after.

"When a trauma to the brain occurs -- due to a car accident or a stroke, tumor, or other causes -- some parts of the network may be spared while some others temporarily or irreversibly damaged," Jokel says.

"It is not very common, but certainly not unusual for a multilingual person to lose, completely or partially, one language but retain another."

As for the Croatian case, many doctors have their doubts.

"In earlier times this would have been referred to as a miracle," Dr. Mijo Milas, a psychiatric expert involved in the teen's case told the U.K. press. "We prefer to think that there must be a logical explanation -- it's just that we haven't found it yet."