Patients Should be Alert for Obesity Surgery Complication, Researchers Say

March 12, 2007

WINSTON-SALEM, N.C. – It is important for obesity surgery patients to take their prescribed vitamin supplements and to be alert for symptoms such as vomiting, confusion, lack of coordination and visual changes – signs of a serious neurological condition that can develop after the surgery.

“There are more than 170,000 obesity surgeries performed annually in the United States and this neurologic condition, known as Wernicke encephalopathy, is increasingly being reported after the operation,” said Sonal Singh, M.D., lead author and an instructor in internal medicine at Wake Forest University School of Medicine.

Wernicke encephalopathy is caused by a deficiency of thiamine and is often associated with severe alcoholism or chronic malnutrition. In obesity surgery patients, it can develop when patients stop taking their vitamin supplements, or when frequent vomiting prevents the vitamins from being absorbed. Vomiting can also occur after the surgery either as a complication of the procedure or if patients eat more than their stomachs can hold – the surgery reduces the organ to the size of an egg.

Because little information is available on Wernicke encephalopathy after bariatric surgery, the researchers conducted a review of medical literature to learn when it occurs, risk factors and symptoms. Their report is published in the March 13th issue of Neurology, a journal of the American Academy of Neurology.

The researchers identified 32 cases of Wernicke encephalopathy after obesity surgery, 27 involving women. Singh said it isn’t clear if the condition is more common in women, or if there were more cases in women because 75 percent of obesity surgery patients are female.

The syndrome can occur after all types of bariatric surgery, including gastric bypass, the most common type, as well as after surgery to “band” the stomach and a procedure known as gastric partitioning that divides the stomach into two parts.

Most cases of Wernicke encephalopathy occurred from four to 12 weeks after the surgery, although one case occurred 18 months later. Most patients (25) had vomiting as a risk factor. Many of the patients also had three symptoms commonly associated with the syndrome: confusion, lack of coordination and rapid, rhythmic eye movement. Several patients had other uncommon symptoms including weakness, seizures, deafness and numbness of the arms and legs.

“Patients and doctors should be most alert for symptoms in the first few weeks after surgery,” said Singh. “Vomiting is a predisposing factor in most patients.”

Most patients were treated with intravenous thiamine and made a complete recovery. However, some patients continued to have memory problems, lack of coordination and visual changes.

In 2005, an estimated 170,000 obesity surgeries were performed in the United States, up from 120,000 in 2004. In 1992, only 16,000 of the operations were performed.

Singh said the frequency of the surgery makes it important to conduct studies to learn about the prevalence of the problem and how it can be prevented. For example, some physicians have advocated that patients receive thiamine injections.

Singh’s co-researcher was Abhay Kumar, M.D., from the University of Iowa.


Media Contacts: Karen Richardson,, or Shannon Koontz,, 336-716-4587.

Wake Forest University Baptist Medical Center is an academic health system comprised of North Carolina Baptist Hospital and Wake Forest University Health Sciences, which operates the university’s School of Medicine. U.S. News & World Report ranks Wake Forest University School of Medicine 18th in family medicine, 20th in geriatrics, 25th in primary care and 41st in research among the nation's medical schools. It ranks 35th in research funding by the National Institutes of Health. Almost 150 members of the medical school faculty are listed in Best Doctors in America.

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