Median arcuate ligament syndrome (MALS), also known as Celiac Artery Compression Syndrome (CACS), is an uncommon condition affecting the blood supply to the upper abdomen. It occurs when a fibrous band of tissue presses on the celiac artery, the main artery that feeds the stomach, liver, and spleen. Surgery is the primary approach for providing lasting relief from the symptoms associated with this compression. The goal is to eliminate the pressure, restoring proper blood flow and alleviating pain.
Understanding Median Arcuate Ligament Syndrome
MALS is rooted in an anatomical variation where the median arcuate ligament sits lower than its typical position. This ligament is a muscular arch connecting the tendinous edges of the diaphragm where they meet in front of the aorta. Normally, it sits above the celiac artery, the first major branch off the abdominal aorta.
When the ligament is positioned too low, it crosses directly over the celiac artery, creating a physical choke point. This compression is often dynamic, worsening when the patient exhales deeply as the diaphragm moves down. The resulting pressure narrows the artery, restricting blood flow to the digestive organs.
The mechanism of pain is thought to be twofold, involving both vascular and neurologic components. The narrowing of the celiac artery may cause abdominal angina, or pain due to insufficient blood supply, especially after a meal when digestive organs require more blood. A significant part of the syndrome also relates to the compression and irritation of the celiac plexus, a dense network of nerves surrounding the artery.
The most common symptom is severe, chronic pain in the upper abdomen, frequently worsening after eating. This post-prandial pain can be so intense that patients develop a fear of eating (sitophobia), leading to significant, unexplained weight loss. Patients may also experience nausea, vomiting, and a distinct whooshing sound, known as a bruit, heard over the abdomen due to turbulent blood flow through the narrowed artery.
Confirming the Diagnosis
Diagnosing MALS can be challenging, as its symptoms overlap with many common gastrointestinal disorders, making it a diagnosis of exclusion. Physicians must first rule out other potential causes of chronic abdominal pain.
Initial screening often involves a non-invasive duplex ultrasound of the abdomen. This test uses sound waves to measure the speed of blood flow through the celiac artery during deep inhalation and exhalation. A significant increase in blood flow velocity during expiration indicates dynamic compression by the median arcuate ligament.
To confirm the diagnosis and visualize the anatomy, a Computed Tomography Angiography (CTA) or Magnetic Resonance Angiography (MRA) is often performed. These imaging studies reveal the characteristic “hooked” or “J-shaped” narrowing of the celiac artery at its origin. Like the ultrasound, these scans are performed with breathing maneuvers to capture the dynamic nature of the compression.
In some cases, a celiac plexus block (an injection of anesthetic near the celiac nerves) is used as a diagnostic tool. Temporary relief of pain following this block suggests that the neurogenic component is a primary source of symptoms, which helps predict a favorable response to surgical decompression.
Performing the Ligament Release
The surgical procedure to correct MALS is called median arcuate ligament release, or celiac artery decompression. The objective is to cut the fibrous arch of the median arcuate ligament to completely free the celiac artery and surrounding nerves from external pressure.
Surgeons use two primary approaches: open surgery (laparotomy) or a minimally invasive technique, typically laparoscopic or robotic-assisted surgery. Minimally invasive methods use small incisions and specialized instruments, often resulting in a shorter hospital stay and quicker recovery. Regardless of the approach, the procedure requires meticulous dissection to avoid injury to the aorta and the celiac artery.
Once the ligament is divided, the surgeon performs a thorough neurolysis, which involves removing the dense network of nerve and ganglionic tissue surrounding the artery. This step addresses the pain caused by nerve compression and irritation, a major component of the syndrome. Intraoperative duplex ultrasound is often used to confirm that the blood flow velocity in the celiac artery has returned to a normal range after the release.
In rare instances, the celiac artery may remain significantly narrowed or damaged even after the ligament is fully released. In this scenario, a secondary procedure, such as vascular reconstruction, may be necessary to restore adequate blood flow. This might involve a patch angioplasty or a bypass graft from the aorta to the celiac artery.
Recovery and Long-Term Outlook
Following a minimally invasive MALS release, the typical hospital stay is brief, often lasting two to four days. Patients are monitored for pain control and progression to a soft or regular diet before discharge. The post-operative period focuses on managing the surgical site and allowing the body to heal.
Full recovery can take several weeks to a few months, with the return to normal activities occurring gradually. Patients are encouraged to walk soon after surgery to aid recovery and prevent complications. Nutritional support is important, especially for those who experienced significant pre-operative weight loss.
The long-term outlook for MALS surgery is encouraging, with a majority of carefully selected patients experiencing significant symptom improvement or complete resolution of pain. Studies show that between 60% and 85% of patients report initial relief following decompression. Long-term freedom from symptoms is estimated to be around two-thirds of patients at five years post-surgery.
The variability in success often relates to whether the pain was primarily due to arterial compression or nerve irritation. While surgical release addresses both, patients whose pain is overwhelmingly neurogenic tend to have a better outcome than those with complex vascular damage. Follow-up imaging, such as a duplex ultrasound, is performed to ensure the celiac artery remains patent and blood flow is adequate.