Teaching Case

A 48 year old woman presented at the emergency room with abdominal pain and vomiting for four days. Routine blood tests revealed a slight increase in serum amylase, which prompted for an abdominal ultrasound.
Relevant previous medical history includes joint hyperlaxity and a heavy family history of deadly hemorrhagic events.

Abdominal ultrasound – focusing over the tender umbilical region, a fusiform superior mesenteric artery (SMA) aneurysm with 3.4cm in diameter was found. An eccentric luminal thrombus was noted. On Doppler imaging, one can appreciate the turbulent flow within the aneurysm (the yin-yang sign).
Abdominal CT – the presence of a mid-distal superior mesenteric artery fusiform aneurysm was confirmed. The aneurysm had an eccentric thrombus, with a crescent shape and was spontaneously hyperdense to luminal blood, indicating recent formation. There was also slight stranding of the fat surrounding the aneurysm, indicating fast growth and inflammation, which frequently precede rupture [1].
Incidentally, bilateral renal arteries (RA) fusiform aneurysms were found. Other interesting finding were multiple bilateral wedge shaped, renal parenchymal defects, which the authors believe to be secondary to aneurysm formed emboli [2, 8].

Background: Visceral arteries aneurysms (VAAs) are saccular or fusiform dilatations of the celiac trunk, mesenteric and RA and their branches, with a 1.5 fold increase of normal vessel size. With an estimated incidence of 0.1 to 2%, most occur in the splenic artery (60%), whereas SMA and RA aneurysms are rarer (10-15%)[3].
RA aneurysms and SMA aneurysms are commonly associated with atherosclerosis and hypertension but medial fibrodysplasia is also an important risk factor for RA aneurysms. Other possible causes include vasculitides, connective tissue disorders and trauma[4].
Our patient had no prior history of hypertension, no significative atherosclerotic disease, no features suggesting medial fibrodysplasia and no reported trauma. Besides the aneurysm there are no apparent arterial wall changes suggesting vasculitides. Considering the patient's age, aneurysms location, reported joint hyperlaxity and family history, a collagen disorder was highly suspected, namely Marphan or Ehlers-Danlos syndromes.
Vascular Ehlers-Danlos syndrome (vEDS) was genetically confirmed.
vEDS subtype has autosomal dominant inheritance, with an estimated prevalence of 1:25.000[5]. The 2017 International Classification of Ehlers-Danlos Syndromes, defines 13 disease variants, according to clinical and genetic features, our patient being classified as vEDS (COL3A1 - type III protocolagen gene)[9].
The resulting vessel wall fragility is prone to disease development, such as dissection, aneurysm and rupture. Another common complication is embolization of aneurysm formed thrombus, most frequently with splenic and kidney infarctions and stroke[5].
The preferred affected arteries are the abdominal visceral arteries, the iliac arteries and arteries in the head and neck, but others can also be involved.
About 80% of patients experience a vascular complication by age 40[6].
The treatment of VAAs is warranted when the calibre reaches 2cm for asymptomatic aneurysms and any size for the symptomatic ones[3]. Standard treatment comprises open surgery for vessel ligation, aneurysm repair or aneurismectomy with graft replacement. Main complications include transection by vascular clamps and post surgical rupture[3,7,10,11].
Despite no long term results, endovascular stenting or coiling is gaining acceptance, due to lower reported complications and faster recovery. Endovascular complications essentially relate to access site, dissection and tear[7,10,11].

Outcome: Due to acute symptoms, extent, location of the SMA aneurysm and vessel wall fragility, endovascular treatment with a covered stent was preferred over open surgery.
Unfortunately, stent occlusion occurred by day 3, but no bowel injury was documented, and the patient has fully recovered.

Take home message: Suspect vEDS when VAAs are found in young patients and no other explanation fits the clinical picture.

Written informed patient consent for publication has been obtained.