Extensive Cerebrovascular and Visceral Artery Dissection and Pseudoaneurysm with Underlying Segmental Arterial Mediolysis

Differentiating between segmental arterial mediolysis and other arterial vasculopathies to establish an early diagnosis - a systematic literature review and proposal of new diagnostic criteria

Segmental arterial mediolysis (SAM) is a rare vascular disease, characterized by acute but transient vulnerability of the wall of medium-sized arteries. The most characteristic feature of SAM is its biphasic course: an injurious phase marked by acute weakness of the arterial wall leading to acute dissection and/or hemorrhage, followed by a reparative phase in which granulation tissue and fibrosis restore the injured arterial wall. Residual stenosis, aneurysms, and/or arterial wall irregularities may remain visible on future imaging studies. Differentiating between SAM and other arterial vasculopathies is difficult due to its similarities with many other vascular diseases, such as vasculitis, fibromuscular dysplasia, inherited connective tissue disorders, and isolated visceral artery dissection. In this systematic review, we provide an overview on SAM, with an emphasis on the differential diagnosis and diagnostic work-up. We propose new diagnostic criteria to help establish a prompt diagnosis of SAM, illustrated by case examples from our multidisciplinary vascular clinic.

Endovascular treatment of an isolated iliac artery aneurysm associated with segmental arterial mediolysis

Segmental arterial mediolysis is a noninflammatory nonatherosclerotic vasculopathy of uncertain etiology characterized by dissection and/or aneurysm formation. It affects medium-to-large arteries, primarily the celiac, superior mesenteric, and renal arteries. Iliac involvement is rare, and its specific treatment has not been described. We detail a patient who presented with intrabdominal hemorrhage from a ruptured right colic artery aneurysm. He underwent transcatheter arterial embolization followed by right hemicolectomy. Histopathology confirmed the diagnosis of segmental arterial mediolysis. Endovascular treatment of a 3-cm iliac artery aneurysm was performed 18 months later. There was successful exclusion of the aneurysm demonstrated on computed tomography angiography at 10 years.

Mesenteric Artery Dissection and Wall-Thickening, Case Study and General Review

Mesenteric artery dissection (D) and wall-thickening (WT) are rare vasculopathies that can lead to serious complications. This is a single center analysis of all patients evaluated for mesenteric arterial (celiac, superior (SMA) and/or inferior mesenteric (IMA)) D and/or WT from January 1, 2000, to January 31, 2020 at our hospital. Among the 101 included patients, the average age was 55.6 ± 13.6 years, mostly affecting men (62%). There were 20 celiac artery D, 8 WT, 15 D with WT, 15 SMA D, 7 WT, 8 D with WT, one IMA D, two WT, and 25 with multiple arterial involvement. Primary etiologies included segmental arterial mediolysis (SAM) (n = 17), isolated D (n = 17), localized vasculitis of the gastrointestinal tract (LVGT) (n = 16), fibromuscular dysplasia (FMD) (n = 13), extension of thoracoabdominal aortic D (n = 12), and trauma (n = 12). Most (71%) patients presented with abdominal pain. Hypertension (55%), hyperlipidemia (33%) and tobacco use (31%) were prevalent. Management included conservative (22%), medical (47%), endovascular (19%), and/or open repair (12%) with high in-hospital survival (98%) and symptom relief (73%). Our paper complements the scarce literature addressing the diagnosis and management of rare mesenteric vasculopathies. Most patients improved with conservative management, reserving endovascular or surgical interventions for symptomatic patients with more complicated presentations.

A case of subarachnoid hemorrhage caused by multiple cerebral aneurysms due to segmental arterial mediolysis

Background:

Segmental arterial mediolysis (SAM) is a condition in which an aneurysm is formed by causing lysis of the media and remodeling of blood vessels. Short-term recurrence has been reported in abdominal aortic aneurysms. Cerebral aneurysms have been suggested to form in a short period not only in the abdominal cavity but also in the intracranial arteries in SAM.

Case Description:

A 36-year-old pregnant woman at 35 weeks’ gestation developed sudden headache and disorientation. Head magnetic resonance imaging showed a small amount of subarachnoid hemorrhage in the right ambient cistern. A fusiform cerebral aneurysm was found in the periphery of the right superior cerebellar artery, and small saccular aneurysms were found in the periphery of the right posterior cerebral artery and left posterior inferior cerebral artery. After delivery of the fetus, endovascular embolization of the ruptured aneurysm was performed. However, 10-week postoperatively, she developed sudden headache. Hemorrhage was found in the fourth ventricle, and enlargement of the left posterior inferior cerebellar artery (PICA) peripheral aneurysm and disappearance of the right posterior cerebral artery peripheral aneurysm were confirmed. A ruptured aneurysm in the peripheral left PICA was removed after trapping. Intraoperatively, an unruptured thrombosed aneurysm that was not visualized by imaging was also removed. Histopathological examination showed no calcification or inflammation, rupture of the internal elastic lamina, and lack of segmentation, and SAM was diagnosed.

Conclusion:

In atypical dissecting aneurysms, SAM should be considered as a differential diagnosis. Systemic examination and short-term follow-up are also necessary.

A Single Center 8 Year Experience of Segmental Arterial Mediolysis Management

OBJECTIVE

Segmental Arterial Mediolysis (SAM) is a rare, poorly understood vasculopathy that involves vacuolization of the arterial wall, most commonly of the visceral arteries. There are no established therapeutic or monitoring guidelines for SAM, and intervention typically depends on patient presentation. The purpose of this study is to review the management and outcomes of patients with this rare vascular disease METHODS: Single center retrospective review of patients diagnosed with SAM between 2011 and 2019. Included were patients with radiological diagnosis of SAM. Demographic factors, past medical history, presenting symptoms, affected vessels, management, and lesion characteristics over time were collected. Demographic and periprocedural factors, and medical management strategies were compared for those who required operative intervention versus those managed non-operatively.

RESULTS

Thirty patients were included, 21 (70%) were male, mean age was 53.5 years (range: 35.7-72.2). Twenty-seven patients were managed non-operatively, 3 patients required surgical intervention. Patients who underwent operative intervention were more likely to present with pain >30 days (P < 0.05), and hemorrhage (P < 0.01). Abdominal pain was the most common presenting symptom (n = 24, 80%). Arterial dissection was the most common radiological finding at time of presentation (n = 20, 67%). The celiac artery and its branches were most often involved (n=22, 73%) followed by the superior mesenteric artery and its branches (n = 15, 50%). Non-operative management most often consisted of anti-hypertensive therapy (n = 13, 43%), antiplatelet agents (n = 17, 57%%), and lipid-lowering agents (n = 13, 43%), with 7 patients receiving all three. Six patients demonstrated confirmed resolution of lesions during surveillance imaging, with average time to resolution of 325.5 days.

CONCLUSIONS

Patients who underwent intervention for SAM presented with either mesenteric ischemia or pseudoaneurysm rupture. In patients that present without those conditions, medical management consisting of anti-hypertensives, antiplatelet agents, and lipid-lowering therapy was effective. Non operative management resulted in symptom resolution in all patients and surveillance imaging showed resolution of radiographic abnormalities in 6 patients out of 27 at less than one year.

Mimics of vasculitis

While prompt diagnosis of vasculitis is important, recognition of vasculitis mimics is equally essential. As in the case of vasculitis, an approach to mimics based on the anatomic size of vessels can be useful. Infections can mimic vasculitis of any vessel size, including the formation of aneurysms and induction of ANCAs. Genetic disorders and vasculopathies are important considerations in large and medium vessel vasculitis. Cholesterol emboli, thrombotic conditions and calciphylaxis typically affect the medium and small vessels and, like vasculitis, can cause cutaneous, renal and CNS manifestations. Reversible cerebral vasoconstriction syndrome is important to distinguish from primary angiitis of the CNS. As an incorrect diagnosis of vasculitis can result in harmful consequences, it is imperative that the evaluation of suspected vasculitis includes consideration of mimics. We discuss the above mimics and outline a systematic and practical approach for differentiating vasculitis from its mimics.

Natural history and management outcomes of segmental arterial mediolysis

BACKGROUND

Segmental arterial mediolysis (SAM) is a poorly understood, nonatherosclerotic, noninflammatory disease resulting from arterial medial degeneration. Patients may present with aneurysm, dissection, stenosis, or bleeding from visceral or renal arteries. Treatment algorithms are poorly characterized.

METHODS

A retrospective review of all patients diagnosed with SAM was performed at our institution. Patients were identified by established criteria that include clinical presentation in combination with radiographic and serologic findings. Demographics, presenting symptoms, diagnostic evaluation, management, and outcomes were reviewed.

RESULTS

There were 117 patients diagnosed with SAM between 2000 and 2016; 67.5% (n = 79) were male. Mean age was 52.7 years (range, 23.4-90 years); 69.2% (n = 81) presented with acute abdominal pain, 22.2% (n = 26) with flank pain, and 19.7% (n = 23) with back pain; 15.4% (n = 18) had abdominal pain longer than 30 days; 13.7% (n = 16) had acute hypertension, and 5.1% (n = 6) were hypotensive; 10.3% (n = 12) were asymptomatic. There were 93 (79.5%) dissections and 61 (52.1%) aneurysms. Hemorrhage was seen in 10 (8.5%). The celiac axis was affected in 54.7% (n = 64), renal arteries in 49.6% (n = 5 8), superior mesenteric artery in 43.6% (n = 51), and inferior mesenteric artery in 2.6% (n = 3). After diagnosis of SAM, aspirin was prescribed in 60.7% (n = 71). Statins were prescribed in 29.9% (n = 35). Antihypertensive medications were prescribed in 65% (n = 76), including beta blockers in 42.7% (n = 50); 40.2% (n = 47) of patients were prescribed anticoagulation. Interventions were performed in 26 (22%) patients; 13 had endovascular intervention only, 9 open surgery only, and 4 open and endovascular interventions. Of the 17 patients undergoing endovascular intervention, 19 procedures were performed, most commonly embolization (78.9% [n = 15]), followed by stenting (10.5% [n = 2]). Of the 13 patients undergoing open surgery, 14 procedures were performed, including arterial bypass (50% [n = 7]) and splenectomy with aneurysm ligation (15.4% [n = 2]). Other surgery involved thrombectomy (21.4% [n = 3]) and angioplasty (14.3% [n = 2]). Only 11.5% (n = 3) experienced a perioperative complication, including one hematoma, one abscess, and one death secondary to ongoing hemorrhage. Follow-up imaging was performed in 96.6% (n = 112). Mean follow-up was 1258 days (range, 2-5017 days). Of these, 27.7% (n = 31) had regression, 43.8% (n = 49) stability, and 28.6% (n = 32) progression. Average time between initial diagnosis and progression was 666 days.

CONCLUSIONS

SAM is an uncommon disease that may require intervention; it is therefore important that the vascular surgery community be aware of this disease. Follow-up imaging is required to monitor for disease progression.

Segmental arterial mediolysis (SAM): Systematic review and analysis of 143 cases

Segmental arterial mediolysis (SAM) is a rare but serious nonatherosclerotic, noninflammatory vasculopathy of unknown etiology that often results in dissection, aneurysm, occlusion, or stenosis of, primarily, the abdominal arteries. Current literature lacks consensus on diagnostic criteria and management options for SAM. This review summarizes 143 cases and aims to advance appropriate recognition and management of SAM. Literature review of all relevant SAM case studies from 2005 to 2018 yielded 126 individual SAM cases from 66 reports. We identified 17 additional SAM cases from our center, bringing our analysis to 143 patients. Patients with SAM were most commonly men (68%) in their 60s. Hypertension (43%), tobacco use (12%), and hyperlipidemia (12%) were common comorbidities. Abdominal pain (80%) and intraabdominal bleeding (50%) were the most common presenting symptoms. Computed tomography was the most frequently used imaging method (78%), and histology was available in 44% of cases. The most commonly affected vessels were the superior mesenteric (53%), hepatic (45%), celiac (36%), renal (26%), and splenic (25%) arteries with aneurysm (76%), dissection (61%), and arterial rupture (46%). Treatments included coil embolization (28%), abdominal organ surgery (24%), open arterial repair (21%), and medical management (20%). Case-specific treatment modalities yielded symptom relief in the vast majority (91%) of patients, with a mortality rate of 7%.