(Ivanhoe Newswire) -- A deficiency in vitamin B1, or thiamine, may be a serious complication following gastric bypass surgery, according to a recent study.

During the study, a 35-year-old woman developed many difficulties after the surgery for obesity. Complications included nausea, anorexia, fatigue, hearing loss, forgetfulness, and ataxia -- an inability to coordinate muscle movements.

An MRI scan revealed abnormal signals in various parts of the woman's brain, indicating a deficiency in vitamin B1. If untreated, vitamin B1 deficiency can lead to Wernicke encephalopathy -- a severe neurological condition. This is because vitamin B1 is essential for carbohydrate metabolism and normal functioning of the nervous system.

Eleven days after her dose of vitamin B1 was increased, a follow-up MRI scan showed the abnormal signals decreased. Raul N. Mandler, M.D., a Fellow of the American Academy of Neurology and a neurologist at The George Washington University in Washington, says, "The neurological complications following gastric bypass surgery are diverse."

"Vitamin B1 deficiency and Wernicke encephalopathy should be carefully considered in surgically treated obese people," Dr. Mandler says.

SOURCE: Neurology, 2005;65:1987