Trip to dentist left British man with 90-minute memory, study says

A British man lost the ability to create new memories after going to the dentist for a routine root canal, according to a recently published study.

After undergoing a root canal procedure in March, 2005, the 38-year-old man lost the ability to remember anything beyond 90 minutes, the University of Leicester said in a statement. Notes from his "astonishing" case were recently published in the journal Neurocase.

Since the surgery, the man wakes up each morning believing it is the same day of his 2005 dental appointment.

Gerald Burgess, the study's lead author and lecturer at the University of Leicester, said his team has "never seen anything like it before." The man was referred to Burgess as a patient almost 10 years ago, when Burgess was working as a clinical psychologist. Throughout the study the patient is referred to as "WO."

The year of the procedure, WO was a member of the U.K. military and was stationed in Germany with his wife and two children, the study said.

Burgess said WO was not injured during the root canal, and has no history of mental illness or mood disturbance.

On the day of the surgery, WO was injected with an anesthetic before the procedure started. When the surgery was completed, it became "apparent that WO was pale and faint, and could not get himself up," the study said.

Records from the day note that he was "vacant" and had "slow speech." He was eventually taken to the hospital as his condition did not improve.

Over the course of the next month, it was determined that WO had only a 10-minute memory span, which eventually improved to 90 minutes.

He was later assessed for any brain damage, but his CT, MRI and SPECT scans all came back normal, the study said.

Every day is the day of the appointment

Eventually WO and his family moved back to his childhood home in the U.K. According to the study, he recognizes his home, places in his hometown and the general geography of the town.

However, he still wakes up every day believing that it's the same day of the appointment.

"In general, each morning he is surprised to wake up in his mother's house. He wakes up believing that he should still be in the military, stationed abroad," the study said. "Every day he thinks it is the day of the dental appointment."

According to the study, WO can still recall events that happened in his life up to the day of the root canal. He can even remember receiving the anesthetic and the moment the dentist began drilling. But anything that has happened to him since he can only retain in his memory for about 90 minutes.

Now, WO relies on the help of his wife and an electronic diary to keep track of his daily activities.

While his wife reports "subtle differences" in his personality, including becoming more easily frustrated and intolerant, WO is aware of his own identity and that of his family, the study said. (He expects, however, everyone to still be the age they were in 2005).

He is aware that he has a memory problem, but requires his wife to answer questions about events that have happened since March, 2005.

Appeal to the public

Burgess speculates that WO's memory loss may be related to the protein formation that takes place in the structures and networks of the brain, called synapses. These networks are altered whenever a new experience is stored in our long-term memory in a process called "later-stage consolidation."

As an experience is being stored, new proteins are created to help form the new shape of these networks. If something gets in the way of the protein formation, the memory can be wiped out.

"We don't know if something about the surgery changed his ability to metabolize these proteins, or if there's some poison in the anesthetic – these are just all total speculations," Burgess told CTVNews.ca in a phone interview. In the study, it is stressed that it would be “unethical” at this time to blame the anesthetic or root canal for the memory loss.

Now, Burgess is appealing for anyone with knowledge of similar cases to contact him so he can further investigate. This is why he published the case notes, he said.

Eventually, Burgess would like to see his patient receive a diagnosis, and possibly be cured.

"I would love a cure for my patient," he said. "I suspect that that will only happen if there's a broader understanding of the problem by having other people's stories evident.

"But it may just be that he is just stuck with this for life."