Median Arcuate Ligament Syndrome (MALS) is an uncommon condition caused by an anatomical anomaly in the upper abdomen. The median arcuate ligament, a fibrous band of the diaphragm, is positioned lower than usual, pressing on the celiac artery and the surrounding celiac plexus nerves. This compression restricts blood flow to the stomach, liver, and other upper abdominal organs. The pain is attributed to either nerve irritation or reduced blood flow (ischemia) to the digestive organs, but the defining characteristic is severe abdominal pain.
The Defining Feature: Pain Triggered by Eating
The defining feature of MALS pain is its strong association with eating, often referred to as post-prandial pain. When a person eats, the digestive system requires a surge of blood flow for digestion and nutrient absorption. For individuals with MALS, the compressed celiac artery cannot meet this increased demand, resulting in temporary relative ischemia in the foregut organs.
This lack of adequate oxygen and nutrient delivery triggers the pain. The severity often correlates with the size and composition of the meal, as larger or higher-fat meals demand more blood flow. The painful response typically begins 15 to 60 minutes after the meal is consumed, coinciding with the peak of the digestive process. This severe discomfort can last for several hours, making the entire process of eating a source of dread.
Where the Pain is Felt
MALS pain is localized to the upper middle region of the abdomen, known anatomically as the epigastric area. This location is situated just below the breastbone and between the ribs, directly corresponding to the site of the compressed celiac artery. The pain felt here can be intense and persistent.
The pain is not always confined to this central upper abdominal spot and frequently exhibits radiation patterns. Patients commonly report that the pain extends horizontally to the sides or through to the back. In some cases, the pain may be felt high up, localized beneath the rib cage, reflecting the position of the diaphragm and the median arcuate ligament. This precise, high abdominal location helps distinguish MALS pain from discomfort originating in the lower abdomen or flanks.
Describing the Intensity and Quality of MALS Pain
The subjective quality of MALS pain is severe and often debilitating. Patients use a range of descriptors, most commonly reporting the sensation as deep, severe cramping, or a gnawing, aching pain. Other patients characterize the feeling as a sharp, piercing pain or a burning sensation that originates deep within the upper abdomen.
Unlike intermittent discomfort, this pain is constant, even though its severity may fluctuate. The intensity can escalate rapidly, making the experience distinct from the milder discomfort of common indigestion or a typical stomachache. This profound level of pain is thought to be caused by the limited blood flow and the direct irritation and compression of the celiac plexus nerves. The pain can be so overwhelming that it severely impacts daily life.
Other Modulating Factors and Associated Symptoms
Beyond the trigger of eating, the intensity of MALS pain is significantly influenced by physical positions and movements. Some patients find that changing their body posture can either relieve or intensify the pain. For instance, leaning forward, standing up straight, or specific phases of deep breathing may alter the degree of celiac artery compression.
The chronic, severe nature of the pain results in associated symptoms, most notably involuntary weight loss. This weight loss is a direct consequence of sitophobia, or the fear of eating, because consuming food reliably leads to intense pain. Additionally, many individuals with MALS experience other gastrointestinal symptoms, including persistent nausea, episodes of vomiting, and a feeling of early satiety or bloating.