Segmental arterial mediolysis
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Segmental arterial mediolysis (SAM) is a rare disorder of the arteries characterized by the development of aneurysms, blood clots, narrowing of the arteries (stenoses), and blood collections (hematomas) in the affected distribution.[1][2]
SAM most commonly affects the arteries supplying the intestines and abdominal organs.[citation needed]
Varies depending on the location of the affected blood vessels.
- Acute abdominal pain (most common)[4]
- Flank pain
- Nausea
- Vomiting
- Diarrhea
- Bloody stools
- Back pain
- Headache
- Stroke
The most severe signs occur if an aneurysm ruptures potentially resulting in:[4]
- Shock
- Loss of consciousness
- Bleeding into the abdominal cavity
- Bleeding into the brain
Mechanism
- The middle layer of an artery, called the media, made of smooth muscle is damaged.[3]
- Mediolysis occurs when the smooth muscle cells in the area of damage are destroyed.[3]
- Small gaps are formed in the wall of the artery which then fill with blood.[3]
- Gaps create weakness in the wall of the artery, allowing increasing pressure from blood to expand the gaps resulting in an aneurysm.[3]
- Aneurysms have potential for rupture.[3]
Diagnosis
Often Segmental Arterial Mediolysis is diagnosed after clinical presentation with symptoms as above followed by CT angiogram or MRI demonstrating aneurysm(s).[4] The gold standard method for confirming the diagnosis is surgical resection of the affected area of blood vessel followed by histologic investigation under a microscope.[3] Segmental Arterial Mediolysis must be differentiated from fibromuscular dysplasia, atherosclerosis, and other systemic vasculidites including polyarteritis nodosa, Takayasu's arteritis, Behcet's disease, cystic medial necrosis, and cystic adventitial artery disease.[4]