Case of man left with 90-minutes of memory after routine dental procedure baffles doctors

In a case that has no parallel in the annals of medicine, a man in the UK has been left with just 90-minutes of memory after a root-canal treatment at a dentist, researchers said.

The incident had left the 38-year-old man stuck in a never ending loop of waking up and thinking he had a routine dental appointment.

He was referred to Dr Gerald Burgess, a clinical psychologist from University of Leicester, a decade ago.

''One of our reasons for writing up this individual's case was that we had never seen anything like this before in our assessment clinics, and we do not know what to make of it, but felt an honest reporting of the facts as we assessed them was warranted, that perhaps there will be other cases, or people who know more than we do about what might have caused the patient's amnesia,'' said Burgess.

''Our experience was that none of our colleagues in neurology, psychiatry, and clinical neuropsychology could explain this case, or had seen anything like it themselves before,'' said Burgess, who collaborated with Bhanu Chadalavada, consultant psychiatrist at Northamptonshire Healthcare Foundation NHS Trust.

The man who went for a routine dental procedure lost the ability to create new memories. Since the one-hour root-canal treatment, during which he was administered a local anaesthetic, he cannot remember anything beyond 90 minutes.

Though he remains fully aware of his identity and retains his original personality, every day he thinks it is the day of his dental appointment. He manages to get along using an electronic diary and access to prompts.

The patient called ''WO'' by his physicians, woke up on the morning of 14 March, 2005, at his military post in Germany. He went to the gym where he played volleyball for 45 minutes, returned to his office, attended to a backlog of e-mails and underwent a routine root canal treatment.

Seating himself in the dentist's  chair, he donned a pair of tinted glasses, felt his mouth go numb as the dentist inserted local anesthetic.

Every day since, WO has been waking up thinking it was the morning of 14 March, 2005, believing he was still in Germany and that this was the day of his dentist appointment.

Starting from that moment in the dentist's chair a decade ago, he had not been able to remember almost anything for over 90 minutes. He forgets the present as if a switch had flipped, and he's back to 14 March, 2005, once more.

The case published in the journal Neurocase, remains a medical mystery.

In another bizarre medical episode, Englishwoman Sarah Colwill from Plymouth, Devon, suffered a stroke from which she recovered - but with a permanent Chinese accent, despite never having been to China. (See: Woman in UK suffers stroke, wakes up with strong Chinese accent).