He had no Spanish knowledge but started speaking it perfectly after surgery. What is this rare, mysterious syndrome?

Unusual medical cases often reveal how complex and unpredictable the human brain can be, especially during moments of physical stress such as surgery. While anaesthesia is designed to temporarily shut down pain and awareness, its effects on brain function are not always straightforward. One such case has gained attention after a man in the United States woke up from a routine operation speaking fluent Spanish, despite having almost no working knowledge of the language. Doctors say the episode may be linked to an extremely rare neurological condition known as Foreign Language Syndrome.

The case involves Stephen Chase, a Utah resident, whose experience has been reported by LADbible and Kennedy News and Media. Chase was just 19 years old when he underwent surgery on his right knee following a football injury. When he regained consciousness, nurses were surprised to find him responding to routine post-operative questions in Spanish rather than English.

At the time, Chase had no meaningful command of Spanish. His exposure was limited to a basic high school course, and he had never been fluent or confident in speaking the language. Despite this, he appeared to communicate clearly and comfortably in Spanish for a short period after waking up, while being unaware that he was doing so.

Confusion and limited memory of the episode

Chase experienced unexpected episodes of speaking fluent Spanish after several surgeries, despite never having spoken the language at that level before. Each episode lasted around 20–60 minutes, during which he was confused when asked to speak English. Initially thought to be a side effect of anesthesia, the repeated occurrences after multiple procedures—including sports injury surgeries and a septoplasty—led him to inform medical staff in advance to prepare for the unusual reaction.

Exposure rather than upbringing

Although Chase does not consider himself bilingual, he believes early exposure may have played a role. He grew up around Spanish-speaking communities and spent time in households where the language was frequently spoken, even though he did not actively understand it at the time.

Years after his first surgery, Chase spent two years in Chile for church-related work, which improved his conversational Spanish. However, he has noted that the level of fluency displayed immediately after surgery felt different from his learned language skills, appearing more instinctive and effortless.

What doctors say about Foreign Language Syndrome

According to the US National Library of Medicine, Foreign Language Syndrome is a rare neurological condition in which a person temporarily and involuntarily switches from their native language to another language they have previously encountered. This is different from Foreign Accent Syndrome, where speech remains in the same language but sounds altered.

Medical research suggests FLS may occur after events such as head injuries, strokes, brain tumours, psychological stress, or exposure to general anaesthesia. Some researchers believe the condition may be linked to how anaesthetic drugs affect cognitive control and language pathways as the brain regains consciousness.