A Ruptured Blood Blister-Like Aneurysm Associated with Intraperitoneal Hemorrhage due to Segmental Arterial Mediolysis: A Case Report and Literature Review

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.

Advantages of Extradural Anterior Clinoidectomy and Extradural Approach with Dural Incision for Blood Blister Aneurysm or Pseudoaneurysm in the Internal Carotid Artery: Two Case Reports

Blood blister aneurysms (BBAs) or pseudoaneurysms (PAs) in the internal carotid artery (ICA) have fragile necks; therefore, conventional neck clipping is difficult. The standard treatment for BBAs or PAs is trapping with high or low flow bypass. However, there is no consensus on whether or not anterior clinoidectomy should be performed together. Two patients with ruptured ICA PA (anterior protrusion) or BBA (posterior protrusion) were presented to our hospital. Complete trapping was safely performed for both types of aneurysms via extradural anterior clinoidectomy and the extradural approach with dural incision. The advantages of the procedure are 1) safe proximal clipping, 2) early identification of the ICA C3 portion, 3) minimized frontal lobe retraction, 4) optic canal opening to allow mobility of the optic nerve, and 5) dural ring incision to allow mobility of the ICA.

Intraperitoneal hemorrhage due to segmental arterial mediolysis associated with cerebral vasospasm after subarachnoid hemorrhage

A man in his 50s with no significant past medical history developed subarachnoid hemorrhage due to ruptured left middle cerebral artery aneurysm. On the ninth hospital day, he had a ruptured visceral aneurysm with segmental arterial mediolysis, and we successfully treated with transarterial embolization using metallic coils.

Intra-abdominal hemorrhage due to segmental arterial mediolysis of an ovarian artery pseudoaneurysm and concomitant aneurysmal subarachnoid hemorrhage: illustrative case

BACKGROUND

Aneurysmal subarachnoid hemorrhage (SAH) is one of the most severe neurosurgical diseases in which systemic management is important from the acute phase to the chronic phase. The authors reported a case of aneurysmal SAH associated with intra-abdominal hemorrhage possibly caused by segmental arterial mediolysis (SAM).

OBSERVATIONS

A 60-year-old woman collapsed suddenly at home. On arrival at our hospital, she was comatose and her head computed tomography (CT) showed SAH, probably from an anterior cerebral artery aneurysm. Simultaneous body CT to screen for pneumonia associated with COVID-19 incidentally detected an intra-abdominal hematoma and the bleeding point. Emergent ventriculostomy was conducted first. Because abdominal angiography detected a ruptured pseudoaneurysm of an ovarian artery, emergency embolization was subsequently performed for hemostasis. However, she deteriorated again, and her pupils became fully dilated. The patient died on day 3 of hospitalization.

LESSONS

Patients with aneurysmal SAH rarely have intra-abdominal hemorrhage in the acute stage and may have a fatal outcome. Intra-abdominal hemorrhage should be suspected in the setting of unstable vital signs, and prompt treatment is necessary.

Single-Cell RNA Sequencing Reveals the Pathogenic Relevance of Intracranial Atherosclerosis in Blood Blister-Like Aneurysms

Background

Intracranial non-branching site blood blister-like aneurysms (BBA) are extremely rare and vicious. Their etiology remains elusive, and no molecular study has been carried out to reveal its pathogenic relevance to intracranial atherosclerosis. To investigate its transcriptomic landscape and underlying potential pathogenesis, we performed single-cell RNA sequencing with extensive pathological validation.

Methods

In total, 12,245 cells were recovered for single-cell RNA sequencing analysis from 1 BBA and 2 saccular intracranial aneurysms (IAs). Unbiased clustering using Seurat-based pipeline was used for cellular landscape profiling. Cellchat was used to understand intracellular communications. Furthermore, 10 BBAs and 30 IAs were retrospectively collected for pathological validations like scanning electron microscopy, H&E stain, Masson stain, Verhoeff Van Gielson stain, and immunofluorescence.

Results

Single-cell transcriptome profiled 14 total subclusters in 6 major groups, namely, 6 monocyte/macrophage clusters, 2 T&NK clusters, 3 vascular smooth muscle cell (VSMC) clusters, 1 dendritic cell, 1 B cell, and 1 endothelial cell cluster. The only mural cell identified in BBAs was VSMC-2 cluster, while mural cells in IAs comprise most clusters of VSMCs and endothelial cells. Upregulated genes in BBA-derived VSMCs are related to arterial mineralization and atherosclerosis, such as PTX3, SPP1, LOX, etc., whereas vasodilation and physiological regulatory genes such as MGP, ACTA2, and MYL9 were conversely enriched in conventional IA-derived VSMCs. Immune cells in the BBA were predominantly macrophages, with a low fraction of T&NK cells, while conventional IAs had a higher percentage of T&NK. Gene enrichment analysis suggested that macrophages in BBA were highly enriched in lipid metabolism as well as atherosclerosis. Ligand–receptor interaction suggested that secretory phosphoprotein 1 (also known as osteopontin) played a major role in mediating the intracellular communication between VSMC and macrophages, especially in BBA. Pathological experiments corroborate with the bioinformatic findings and further characterized BBAs as a thin-walled thrombotic aneurysm with severe atherosclerotic lesions, where ApoE+ macrophages and OPN+ mural cells are intimately involved in the inflammation process.

Conclusions

The preexisting intracranial atherosclerosis might predispose the parent artery to the pathogenic occurrence of BBAs. These data shed light on the pathophysiology of intracranial aneurysms and might assist in the further resolution of the complexity in aneurysm pathogenesis.

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 case presenting as fatal subarachnoid hemorrhage due to segmental arterial mediolysis associated with Crohn's disease

BACKGROUND

Segmental arterial mediolysis (SAM) is a rare arterial pathology and can cause rupture or dissection of the intracranial arterial wall. The etiology is unveiled, but vasospastic stimuli such as migraine are considered as a possible cause of SAM. We present the first case of subarachnoid hemorrhage (SAH) due to SAM associated with Crohn's disease and migraine, and discuss the possible contribution of Crohn's disease to the development of SAM besides migraine.

CASE DESCRIPTION

A 33-year-old man with Crohn's disease, which had been treated with adalimumab, repeatedly underwent 3-tesla magnetic resonance (MR) imaging and angiography for severe headache due to migraine and the subsequent development of fatigue in the left arm and both legs. At 7 months after the last MR imaging studies showing no abnormalities, he had a sudden onset of severe SAH, which was caused by rupture or dissection of the terminal portion in the right internal carotid artery. As his brain-stem reflexes were absent, the patient was conservatively treated and died 6 days after the ictus. By postmortem histopathological examination, SAM was diagnosed as the cause of SAH. Vasa vasorum was also observed around the rupture point.

CONCLUSIONS

Our case suggests that: 1) the formation of vasa vasorum may be an antecedent pathology for vessel rupture of the fragile arterial wall affected by SAM, and 2) vasospastic nature of both Crohn's disease and migraine may contribute to the development of intracranial SAM.

Idiopathic Middle Meningeal Arteriovenous Fistula Associated with Segmental Arterial Mediolysis: A Case Report

Objective

Middle meningeal arteriovenous fistula (MMAVF) is typically post-traumatic or iatrogenic in origin, but it can have an idiopathic origin in rare cases. Here, we report a case of idiopathic MMAVF complicated by segmental arterial mediolysis (SAM).

Case Presentation

The patient was a 63-year-old woman admitted to our hospital with symptoms of right pulsating tinnitus for the past 2 months. She had no significant medical history. MRI and DSA revealed a right MMAVF. Selective embolization using coils was performed. Seven years later, when she underwent laparotomy for intestinal perforation, multiple aneurysms were found in the abdominal cavity. Left hemicolectomy was performed, and an aneurysm of the gastroepiploic artery was resected. Based on a pathological examination of the aneurysm, the patient was diagnosed with SAM. Coil embolization was performed to prevent rupture.

Conclusion

This case report shows that MMAVF may be associated with SAM. Fistula embolization with coils is an effective treatment of MMAVF associated with SAM. Therefore, it is important to check for systemic diseases, such as SAM when idiopathic MMAVF is detected.

Comparison of clinical and histopathological characteristics of short-term progressive and non-progressive blood blister-like aneurysms

BACKGROUND

Many blood blister aneurysms (BBAs) have been documented with a rapid progression history in repeated angiography. The underlying mechanism and clinical significance remained elusive. This current study aims to clarify the clinical and histopathological differences between short-term progressive BBA and non-progressive BBAs.

METHODS AND MATERIALS

Eighty-one patients with BBAs were consecutively included for this single-center retrospective analysis. Clinical and radiological data on these patients were retrieved from 2017 to 2019. BBAs were defined as either progressive or non-progressive based on observed growth based on repeated imaging. Histopathological examinations of a saccular aneurysm, a progressive BBA, and a non-progressive BBA were conducted using representative aneurysm samples.

RESULTS

Among all enrolled patients, 26 of the them were identified with progressive BBAs, while the other 55 with non-progressive BBAs. Progressive BBAs were diagnosed significantly earlier in angiography (3.36 ± 0.61 vs. 6.53 ± 1.31 days, p < 0.05) and showed a higher presence rate of daughter sacs (61.5 vs. 38.2%, p < 0.05). Three different progression patterns were identified. BBAs that developed daughter sac enlargement are diagnosed significantly later than BBAs exhibiting other progression patterns. Patients with progressive and non-progressive BBAs exhibited similar overall clinical outcomes and incidence for complications. For patients with non-progressive BBAs, microsurgery appears to be inferior to endovascular treatment, while for patients with progressive BBAs, the short-term outcomes between microsurgery and endovascular treatment were identical. Histopathological analysis revealed that both subtypes shared a similar pseudoaneurysms structure, but non-progressive BBAs had more histologically destructed aneurysm wall with less remnant fibrillar collagen in adventitia.

CONCLUSIONS

Progressive and non-progressive BBAs may not be distinct pathological lesions but represent different stages during the BBA development. Early intervention, regardless of treatment methods, is recommended for salvageable patients with progressive BBAs, but microsurgery should be performed with caution for non-progressive BBAs due to increased surgical risk.

Current Knowledge of and Perspectives about the Pathogenesis of Blood Blister-like Aneurysms of the Internal Carotid Artery: A Review of the Literature

Blood blister-like aneurysms (BBAs) are rare and usually appear at nonbranching sites in the supraclinoid portion of the internal carotid artery (ICA). Because it is difficult to obtain histological specimens of the aneurysm wall and because experimental models are challenging to establish, the pathogenesis of BBAs remains uncertain. In this paper, we reviewed the diagnostic, radiological, and pathophysiological characteristics of patients with BBAs. We also summarized the existing evidence and potential mechanisms related to the causes of BBAs. Current evidence indicates that atherosclerosis and dissection are the main prerequisites for the formation of BBAs. Hemodynamics may play a role in the process of BBA formation due to the unique vascular anatomy of the supraclinoid ICA. Further research on histopathology and hemodynamics is warranted in this field.

A Case of Segmental Arterial Mediolysis: Hemoperitoneum with Hemorrhagic Shock due to Rupture of a Visceral Artery Aneurysm Following Subarachnoid Hemorrhage

Objective

Segmental arterial mediolysis (SAM) is a non-inflammatory and non-atherosclerotic vascular disease characterized by segmental medial defect/necrosis of muscular arteries as a result of mediolysis. SAM affects the visceral and intracranial arteries, and causes arterial dissection and aneurysm. We report a case of aneurysmal subarachnoid hemorrhage (SAH) followed by hemoperitoneum due to a ruptured visceral artery aneurysm.

Case Presentation

A 54-year-old man developed SAH from a ruptured anterior communicating artery aneurysm, which was clipped on the same day. Thereafter, he was treated to prevent cerebral vasospasm. Six days after onset, he developed acute anemia and his blood pressure decreased, suggesting hemorrhagic shock. Hemoperitoneum was detected on computed tomography and abdominal angiography was performed. Irregular and stenotic arterial findings, and an unusual aneurysm with contrast stasis were found in a branch vessel from the right gastroepiploic artery. SAM was diagnosed based on the clinical course and angiographic characteristics. Endovascular treatment consisted of embolization of the visceral artery aneurysm with liquid embolic material. after embolization, the vital signs stabilized and he recovered from shock. Acute treatment for SAH was continued. Although the patient did not develop vasospasm-related sequelae, he was transferred to the rehabilitation hospital 7 weeks after onset and his modified Rankin Scale score at 3 months after onset was 2.

Conclusion

Visceral artery aneurysm associated with SAM should be considered as the cause of hemoperitoneum with hemorrhagic shock during the acute phase of SAH.