Obesity Surgery Linked to Atypical Encephalopathy

March 12, 2007 — Bariatric surgery appears to increase the risk for atypical Wernicke encephalopathy, a serious neurologic condition caused by thiamine deficiency that is typically associated with alcoholism.

In the first study to characterize the syndrome in this patient group, researchers at Wake Forest University School of Medicine in Winston-Salem, North Carolina, conducted a systematic literature review in an attempt to describe the clinical features, risk factors, radiographic findings, and prognosis of Wernicke encephalopathy.

"What we found in our paper, which is clinically useful, is that this syndrome is most commonly reported in young women who present with vomiting 1 to 3 months — although it can range from 2 weeks to 18 months — following obesity surgery," principal investigator Sonal Singh, MD, told Medscape.

The paper is published in the March 13 issue of Neurology.

Is Incidence Rising?

Growing rates of obesity in the United States and other developed countries, coupled with the increasing popularity of obesity surgery, could result in an increased incidence of this syndrome.

"I think this is definitely an emerging problem that neurologists are going to be confronted with more frequently. Most neurologists have some awareness of this syndrome, but many may not be fully aware of the heterogeneity of it following obesity surgery," said Dr. Singh.

Dr. Singh added that he became interested in studying the syndrome in this particular patient group because he observed an increased number of cases in clinical practice.

The scientific literature for all reported cases of the syndrome occurring after obesity surgery was reviewed, and investigators found a total of 32 reported cases, 27 of which were in women.

Wernicke encephalopathy was reported after vertical banded gastroplasty, Roux-en-Y gastric bypass, elective gastric partitioning, and gastric plication.

Patients ranged in aged from 23 to 55 years. Of the total group, 12 were aged 21 to 30 years, 14 were aged 31 to 40 years, 5 were aged 41 to 50 years, and 1 patient was older than 50 years.

Diagnostic Challenges

Because of its atypical presentation, diagnosing Wernicke encephalopathy in bariatric surgery patients poses a number of challenges, said Dr. Singh.

For instance, in addition to the typical triad of symptoms — confusion, ataxia, and nystagmus — that characterize Wernicke encephalopathy, many patients also presented with myriad atypical symptoms, including hearing loss, convulsions, peripheral neuropathy, and Korsakoff psychosis.

In addition, said Dr. Singh, the study showed magnetic resonance screening findings were not helpful in all cases.

"MRI [magnetic resonance imaging] is usually used to confirm a diagnosis of Wernicke [encephalopathy] in alcoholics, but in this patient group we found that in many cases MRI results were normal," said Dr. Singh.

Furthermore, he said, blood levels of thiamine were also inconsistent. "Blood levels [of thiamine] were low in a few cases but normal in others," he said. This finding, added Dr. Singh, suggests there are other, as-yet-unidentified, multiple nutritional factors at play.

"Gastric bypass may interfere with thiamine absorption but also with other vitamin absorptions. We are postulating that it may not only be thiamine deficiency but that it could be a mechanism of some other unexplained vitamin deficiency or some inflammatory injury to the brain that is causing these atypical features. This is something that needs to be explored in further studies," he said.

There was also wide variability with respect to timing of onset, which ranged from 2 weeks to 18 months. "We really don't have a plausible explanation for this variation — 1 to 3 months makes sense, but the fact that it can occur so long after surgery is something we can't explain and requires further study," he said.

High Index of Suspicion

Currently, said Dr. Singh, there is no standardized pre- or postoperative protocol aimed at preventing Wernicke encephalopathy; it is left up to the individual providers to determine treatment.

Although some research suggests preoperative thiamine supplementation provides effective prophylaxis, more research is required to confirm that this is the case.

The good news is that if caught in the early stages, the syndrome is very responsive to thiamine treatment given intravenously or by injection. The study showed that 13 of the 32 patients made a full recovery; others had some residual neurological deficits.

In the meantime, said Dr. Singh, clinicians should have a high index of suspicion for Wernicke encephalopathy in patients who present with any type of neurological symptoms after bariatric surgery.

"It is important that doctors and patients are aware that the outcome is wholly dependent on early diagnosis. Patients should be advised to immediately report any neurological symptoms," he said.

In the meantime, a prospective long-term study to determine the incidence of the syndrome is needed to help guide preventive, as well as treatment, protocols.

Neurology. 2007;68:807–811.

Source: http://www.medscape.com/viewarticle/553480?src=mp