What causes SMA syndrome?

SMA syndrome, or Superior Mesenteric Artery syndrome, occurs when the duodenum is compressed between the superior mesenteric artery (SMA) and the aorta. This anatomical relationship is crucial, as the SMA typically arises from the aorta and can create a narrowing or obstruction of the duodenum when there is a reduction in the angle between the SMA and the aorta. This often happens in situations where there is significant weight loss or a thin physique, leading to decreased fat around the duodenum, which normally helps to maintain the space and prevent compression.

The obstruction of the duodenum by adjacent structures can result in symptoms such as abdominal pain, nausea, and vomiting due to the resulting functional blockage. In this context, it is important to recognize that anatomical variations or pathological conditions that lead to this compression are the key factors in the development of SMA syndrome, rather than any infectious or toxic causes.