When a 17-year-old boy in the Netherlands woke up from routine knee surgery, hospital staff initially noticed something unusual but not alarming. Instead of speaking Dutch, his native language, he was communicating only in English, a language he normally used only during school lessons. At first, nurses assumed the behaviour would pass. It did not.The case, later documented by doctors, has since been identified as an instance of foreign language syndrome, an exceptionally rare condition that remains poorly understood.
What doctors observed after the operation
The teenager had been admitted for knee surgery after injuring himself while playing football. The procedure itself was successful, and there were no immediate surgical complications. However, on waking from general anaesthesia, the patient spoke exclusively in English and repeatedly insisted that he was in the United States.He did not recognise his parents and could neither speak nor understand spoken Dutch. According to the medical report, he had no prior psychiatric history and no relevant family medical history, apart from instances of depression on his mother’s side.A nurse initially believed the symptoms were consistent with emergence delirium, a known state of confusion that can occur during recovery from anaesthesia. When several hours passed and the patient still could not produce a single word of Dutch, medical staff requested a psychiatric consultation.The psychiatric team found the teenager calm, attentive and cooperative. He answered questions appropriately, although entirely in English spoken with a Dutch accent. Over time, he began giving brief responses in Dutch, but found speaking it difficult.
Diagnosis and recovery
Doctors diagnosed the teenager with foreign language syndrome (FLS), a condition in which patients suddenly and involuntarily switch to speaking a second language instead of their native one. Unlike foreign accent syndrome, where speech sounds altered but remains in the same language, FLS involves a full transition to another language.A neurologist carried out a complete neurological examination and found no abnormalities. Eighteen hours after surgery, the patient could again understand Dutch, though he was still unable to speak it.The following day, friends visited him in hospital. Shortly after their arrival, the teenager suddenly regained both his ability to speak and understand Dutch without difficulty. Because the recovery was spontaneous and complete, doctors decided not to carry out neuropsychological testing, electroencephalograms (EEGs) or brain scans. He was discharged three days after surgery.
Why the case stands out
Foreign language syndrome is extremely rare. According to the authors of the case report, only around nine cases have been described in medical literature. Most involved male patients who were not raised bilingually and who switched to a language learned later in life.The authors noted that FLS is rarely reported in children and believe this may be the first formally documented case in an adolescent. In eight similar cases they reviewed, patients switched entirely to a different language rather than adopting a foreign-sounding accent.The precise cause of FLS remains unknown. Other cases have also occurred after general anaesthesia, leading researchers to question whether the condition is distinct or a variation of emergence delirium related to the effects of anaesthetic drugs on cognition and their clearance from the central nervous system.What is clear, the authors emphasised, is that the condition appears temporary, with patients typically making a full recovery without long-term impairment.
