After Knee Surgery, a 17-Year-Old Speaks a New Language

In an unusual medical case from the Netherlands, a 17-year-old boy awoke from knee surgery speaking a foreign language.

The teenager had undergone a successful operation to repair a football-related injury. However, when he regained consciousness, he spoke exclusively in English—claiming to be in the United States—despite having only studied the language in school, according to Live Science.

Doctors noted that the boy, whose native language was Dutch, could neither speak nor comprehend spoken Dutch after the surgery. He failed to recognize his parents and showed no signs of prior psychiatric illness, though several relatives on his mother’s side had experienced depression.

The medical staff first became aware of the situation when a nurse overheard the patient speaking English. Initially, she dismissed it as temporary post-surgical confusion. But hours later, when he remained unable to utter a single word in Dutch, the hospital summoned a psychiatrist.

During the psychiatric evaluation, the teenager appeared calm and alert, though he continued speaking English with a noticeable Dutch accent. He struggled to produce short responses in Dutch when prompted.

A thorough neurological examination revealed no abnormalities, leading doctors to diagnose him with foreign language syndrome (FLS)—a rare condition marked by an abrupt, involuntary switch to a second language over one’s native tongue.

Eighteen hours post-surgery, the boy began to understand Dutch again, though he still couldn’t speak it fluently. The following day, a visit from friends triggered a sudden return to his native language. Deeming further tests unnecessary, doctors discharged him three days after the operation.

• 
  Man speaks Danish after stroke, forgetting native language

This case stands out as exceptional. Foreign language syndrome is extraordinarily rare, with only about nine similar instances documented in medical literature.

Most reported cases involve men transitioning from their native language to one learned later in life, making this the first known instance of FLS in a teenager, according to the case report authors.

A related condition, foreign accent syndrome—where individuals adopt a new accent, often following brain injury—offers some comparison, though it differs from FLS.

The origins of FLS remain poorly understood, but its emergence after anesthesia has been noted. Experts suggest that anesthetics’ impact on cognitive function might trigger postoperative confusion, raising questions about whether FLS warrants classification as a distinct disorder.