TORONTO - When people with obesity have surgery to help them lose weight, they can also lose something else - the ability to properly absorb certain nutrients, in particular vitamin B1. And that deficiency can potentially lead to permanent brain damage if left untreated, researchers say.
In a review of the medical literature, researchers at the Wake Forest University School of Medicine found 32 cases of bariatric surgery patients who developed symptoms of Wernicke encephalopathy, a condition marked by memory loss and confusion, an inability to co-ordinate movements and rapid eye movement.
Wernicke's is caused by a deficiency in vitamin B1, also called thiamine, and these classic symptoms are usually seen in alcoholics, said lead author Dr. Sonal Singh, an internal medicine specialist at Wake Forest University in Winston-Salem, N.C.
"But interesting to our study, we found that these people also had other symptoms, like hearing loss, convulsions and tingling and numbness of the arms and legs - symptoms that have not been previously described with Wernicke's," Singh said in an interview.
That made the researchers wonder if these bariatric surgery patients were suffering from more than just a B1 deficiency and may have been experiencing a deficit of other critical nutrients or had developed immunological problems.
Strangely, almost half of the patients with the neurological symptoms showed no brain lesions when given an MRI scan, said Singh, whose study is published Tuesday in the journal Neurology.
Of the 32 patients - who had one of four weight-loss surgeries, including gastric bypass and gastric banding - 13 made a full recovery. Eighteen others were left with various levels of dysfunction and one patient, a 33-year-old woman, died.
Most had experienced vomiting prior to onset of the neurological symptoms, said Singh, noting that patients ranged in age from 23 to 55, and 27 of the 32 were women. (In North America, close to 75 per cent of bariatric surgery patients are women, although the wide female-male ratio is starting to narrow.)
The vomiting could have been caused by any of several factors, including the anatomical changes created by the surgery; blockages caused by swelling around the surgical site; and ulcerations or other erosions of the stomach developed following the operation, the study suggests.
"When people who have had weight-loss surgery start experiencing any of these symptoms, they need to see a doctor right away," stressed Singh.
"Doctors should consider vitamin B1 deficiency and Wernicke encephalopathy when they see patients with these types of neurological complications after weight-loss surgery. If treated promptly, the outlook is usually good."
The average point at which patients began exhibiting Wernicke's symptoms was four to 12 weeks after surgery, although one patient developed problems two weeks after the operation and another 18 months later.
Dr. Nicolas Christou, director of the bariatric surgery program at the McGill University Health Centre, said Wernicke's is a rare complication that can occur with any type of operation, not just bariatric surgery.
"But the problem with bariatric surgery is it creates in the immediate post-operative period . . . some degree of a blockage at the outlet of the new stomach that is created, and that can cause a lot of vomiting," he said Monday from Montreal.
"And if then people aren't able to keep down their food, and more importantly their vitamin supplements, then it's quite possible that they can become vitamin deficient and develop this particular complication."
Christou, who was not involved in the study, said vomiting can go on for weeks after surgery before the problem - such as swelling - resolves on its own. Sometimes a blockage will occur that requires repair through gastroscopy, in which a tube with a scope is fed down the patient's throat into the stomach.
"In the case of persistent vomiting like that, you have to keep people hydrated and give them (intravenous) multivitamins," he said. "To prevent it you have to be vigilant and catch these people. Don't do the operation and say, 'Come back in a year.' "
Most properly "equipped and trained" bariatric surgery programs see patients two weeks after their operation, then again "at one month, three months and then every six months thereafter. Those are the critical periods."
The study could not determine how common Wernicke encephalopathy is among people who have surgery to help them lose weight, said Singh, adding that studies that follow patients' progress after surgery are needed to establish how often it occurs.
While some doctors prescribe thiamine supplementation after bariatric surgery as a matter of course, Singh believes national standards should be set for physicians to follow.
"This is an emerging risk which is going to become more important in the future as more people get surgery," he said.
