Gastrointestinal Issues Which Impede Successful Weight Restoration in Anorexia Nervosa and ARFID
By Philip S. Mehler, MD, FACP, FAED, CEDS
A second gastrointestinal issue which develops in patients with AN and ARFID and can impede refeeding is known as the superior mesenteric artery (SMA) syndrome. This develops as a direct result of the weight loss which accompanies AN and ARFID. SMA syndrome causes compression of the third portion of the duodenum. The compression occurs with weight loss because normally there is a fat pad which cushions the SMA and presents its lateral movement in the abdominal cavity. When there is significant weight loss, there is atrophy of the fat pad; this in turn allows for medial migration of the SMA, which in turn now constricts the lumen of the duodenum and blocks the passage of food through the small intestine on its normal path to the large intestine. As food then backs up from this point of obstruction, the patient experiences crampy upper abdominal pains, bloating, nausea and even vomiting of undigested food within approximately fifteen minutes of initiating their eating.
SMA syndrome should be suspected when a patient with anorexia nervosa, of moderately severe weight loss or greater, complains of the aforementioned symptoms during the early stages of their refeeding program. One can presumptively make the diagnosis in the proper clinical setting, but it might be best to definitively prove its presence by obtaining a CT scan of the abdomen with oral and intravenous contrast, and specifically requesting that the radiologist carefully look at the angle size between the SMA and the aorta. Normally, the SMA forms an approximately 45°angle (range 38°-65°) as it branches off the aorta. When the angle decreases to less than 25°, due to loss of the fat pad and the third portion of the duodenum is compressed, SMA syndrome symptoms ensue.
Treatment for SMA syndrome is a temporary change in the patients diet toward softer and more liquid calories. Surgical intervention is rarely, if ever, indicated. The treatment also includes close collaboration with a registered dietician to amend the dietary plan. Specifically, this involves dividing the dairy caloric prescription into smaller more frequent meals in addition to the softer foods or it may involve changing to an entirely oral liquid diet. Passage of a nasogastric (NG) tube may at times be necessary, or even less commonly, insertion of a nasojejunal (NJ) tube past the point of obstruction. Generally with just 5-10 pounds of weight gain, the fat pad is reconstituted and the SMA is again pushed back to its more lateral normal position, removing the compression on the duodenum.
Suggested reading: Mandarry MT, et al. A comprehensive review of SMA syndrome. Eur Surg 2010; 1[42:22]9-236.
About the author:
As President of Eating Recovery Center, Dr. Philip Mehler is the designated head of medical services across Eating Recovery Center’s full National treatment spectrum. Dr. Mehler began his career at Denver Health more than 30 years ago and was formerly its Chief of Internal Medicine. He was Denver Health’s Chief Medical Officer (CMO) for 10 years until he was promoted to its Medical Director, a position he held until his retirement in 2014. He is also the Glassman Professor of Medicine at the University of Colorado School of Medicine, and has conducted research into the optimal medical treatment of the most severe cases of Anorexia Nervosa and Bulimia. He founded ACUTE at Denver Health, the country’s center of excellence for those with the most extreme forms of Anorexia nervosa, and continues to serve as its Executive Medical Director. Dr. Mehler has authored 425 scientific publications, including 3 textbooks, Medical Complications of Eating Disorders, published by Johns Hopkins University Press and is now in its third edition. His newest book was just released in November 2017. Dr. Mehler was the recipient of the Academy of Eating Disorders 2012 Outstanding Clinician Award, has been recognized among the “Best Doctors in America” for the past 22 years in a row, and was voted the “Top Internal Medicine physician in Denver” multiple times by 5280 Magazine. Dr. Mehler is a member and fellow of the Eating Disorders Research Society and the Academy of Eating Disorders, as well as a member of the editorial board of the International Journal of Eating Disorders. He has lectured extensively on a national and international level as the world’s leading medical expert on the topic of the medical complications of eating disorders.