Prevention and treatment of peripheral neuropathy after bariatric surgery.

OPINION STATEMENT: Given the ever-increasing problem of obesity, it is not surprising that the number of patients who undergo bariatric surgery continues to rise. For patients who have gastric banding, the amount of food they can consume is limited, and nausea and vomiting may further limit nutritional intake early on. More extensive procedures, such as the Roux-en-Y or biliopancreatic diversion with or without a duodenal switch, not only restrict intake but also limit absorption in the small intestine. As a result, deficiencies in vitamins, minerals, and trace elements may develop, leading to a variety of neurologic complications. The peripheral neuropathies best described with a clear-cut cause are an acute, frequently painful neuropathy or polyradiculoneuropathy associated with thiamine deficiency, and an isolated neuropathy or myeloneuropathy associated with deficiencies of either vitamin B12 or copper. Thiamine deficiency tends to occur in the first weeks or months after surgery, vitamin B12 deficiency may develop at any time from a few years to many years after surgery, and copper deficiency tends to be a fairly late complication, developing several years to many years following surgery. Patients who have undergone bariatric surgery may also have an increased risk of developing focal neuropathies, though these are less clearly related to specific nutritional deficiencies.Ideally, one would like to prevent these neuropathies, but there is no consensus of opinion as to what vitamins and micronutrients need to be taken following bariatric surgery. In addition, many patients who take supplements early on fail to maintain the regimen even though some of the neuropathies can occur fairly late. Supplements frequently recommended include a multivitamin, iron, vitamin D, folic acid, calcium citrate, and vitamin B12. Although thiamine is typically included in a multivitamin, the amount is fairly small, so I recommend adding 100 mg daily for at least the first year. Some have suggested zinc supplementation, but this is potentially problematic because exogenous zinc may interfere with copper absorption. Obtaining blood work every 6 months after surgery will help to identify and treat nutritional deficiencies early.For those patients who have had a bariatric procedure and then develop a neuropathy, evaluating levels of thiamine, copper, vitamin B12, methylmalonic acid, and homocystine is indicated. In addition, since one deficiency is frequently associated with others, obtaining levels of vitamin A, C, D, K, and E, as well as iron, zinc, selenium, and magnesium is worthwhile. Checking total protein, albumin, and cholesterol also gives a sense of general nutritional status. Occasionally, no clear-cut deficiency of a vitamin, mineral, or trace element can be identified in patients with various peripheral nervous system manifestations. Nevertheless, these patients may have at least some recovery with improving nutritional intake and vitamin supplementation, suggesting that we still do not fully understand how nutritional status affects the peripheral nervous system.