Non-traumatic recurrent dissection and its spontaneous repair in the circle of Willis: report of two autopsy cases

Superficial temporal artery aneurysm with segmental arterial mediolysis: a case report

Segmental arterial mediolysis (SAM) is a rare non-arteriosclerotic and non-inflammatory vascular disease. Superficial temporal artery (STA) aneurysms are usually associated with trauma, surgery, and hair transplantation. Spontaneous aneurysms of the STA are uncommon, but an STA aneurysm caused by SAM is rare. We report a 70-year-old woman with a spontaneous aneurysm of the STA. The mass in the left parietal region was pulsatile and gradually enlarged in size without any history of head trauma. The mass was successfully removed by surgery and was proved histopathologically to be a true aneurysm with SAM.

Unraveling the Links between Chronic Inflammation, Autoimmunity, and Spontaneous Cervicocranial Arterial Dissection

Advances in imaging techniques have led to a rise in the diagnosis of spontaneous cervicocranial arterial dissection (SCCAD), which is now considered a common cause of stroke in young adults. However, our understanding of the pathophysiological mechanisms underlying SCCAD remains limited. Prior studies have proposed various factors contributing to arterial wall weakness or stress as potential causes for SCCAD. A combination of biopsies, case reports, and case-control studies suggests that inflammatory changes and autoimmunity may play roles in the cascade of events leading to SCCAD. In this review, we examine the close relationship between SCCAD, chronic inflammation, and autoimmune diseases, aiming to explore potential underlying pathophysiological mechanisms connecting these conditions. While some relevant hypotheses and studies exist, direct evidence on this topic is still relatively scarce. Further investigation of the underlying mechanisms in larger clinical cohorts is needed, and the exploration of animal models may provide novel insights.

Cerebrovascular Dissections—A Review Part I: Spontaneous Dissections

Spontaneous cerebrovascular dissections are subintimal or subadventitial cervical carotid and vertebral artery wall injuries and are the cause of as many as 2% of all ischemic strokes. Spontaneous dissections are the leading cause of stroke in patients younger than 45 years of age, accounting for almost one fourth of strokes in this population. A history of some degree of trivial trauma is present in nearly one fourth of cases. Subsequent mortality or neurological morbidity is usually the result of distal ischemia produced by emboli released from the injury site, although local mass effect produced by arterial dilation or aneurysm formation also can occur. The gold standard for diagnosis remains digital subtraction angiography. Computed tomography angiography, magnetic resonance angiography, and ultrasonography are complementary means o evaluation, particularly for injury screening or treatment follow-up. The annual rate of stroke after injury is approximately 1% or less per year. The currently accepted method of therapy remains antithrombotic medication, either in the form of anticoagulation or antiplatelet agents; however, no class I medical evidence exists to guide therapy. Other options for treatment include thrombolysis and endovascular therapy, although the efficacy and indications for these methods remain unclear.

Traumatic subarachnoid hemorrhage and the COL3A1 gene: emergence of a potential causal link

We describe two previously unreported associations in four cases. The first two cases demonstrate an association between segmental mediolytic arteriopathy and vascular Ehlers-Danlos syndrome. The second two cases illustrate an association between vascular Ehlers-Danlos syndrome and traumatic subarachnoid hemorrhage. In case 1, there was acute subarachnoid hemorrhage and mesenteric artery dissection. In case 2, there was an acute mesenteric artery dissection with intestinal infarction. In both cases 1 and 2, segmental mediolytic arteriopathy was found in the vertebral arteries. Cases 3 and 4 were sudden deaths from traumatic subarachnoid hemorrhage with intracranial vertebral artery rupture. Genetic testing in all four cases revealed point mutations in the type 3 procollagen gene (COL3A1), as observed in vascular Ehlers-Danlos syndrome. Based on the first two cases, we propose that segmental mediolytic arteriopathy may be a marker for this disease. We further suggest that vascular Ehlers-Danlos syndrome may be related to the pathogenesis of traumatic vertebral artery injury, in some cases. We recommend that cases of segmental mediolytic arteriopathy and traumatic subarachnoid hemorrhage undergo genetic testing for COL3A1 mutations.

Nontraumatic and noninfectious pseudoaneurysms on the circle of Willis: 2 case reports and review of the literature

BACKGROUND

Nontraumatic and noninfectious pseudoaneurysms with similar shape of true saccular aneurysm on the circle of Willis are rare.

CASE DESCRIPTIONS

Two patients with such pseudoaneurysms are reported, one is a 37-year-old man, the other is a 50-year-old woman. They presented with sudden headache; CT scan showed subarachnoid hemorrhage in both. Thorough medical history had been reviewed; physical and laboratory examination had been made but demonstrated no evidence of craniocerebral injury and intracranial or systematic infection. On the cerebroangiogram, they represented the same imageologic changes of true saccular aneurysm, but subsequent operation and pathologic examination revealed that they were pseudoaneurysms consisting of blood clot enclosed with a layer of connective tissue; degenerative changes may have contributed to their formation.

CONCLUSION

Careful attention should be given in classifying these saccular pseudoaneurysm from true saccular aneurysms because of their friable nature, tendency of rupture, and different pathologic findings.

Segmental arterial mediolysis with accompanying venous angiopathy: a clinical pathologic review, report of 3 new cases, and comments on the role of endothelin-1 in its pathogenesis

The authors review 20 cases of segmental arterial mediolysis (SAM) including 3 newly reported cases. SAM developed in areas of vascular distention in 2 of the latter cases: 1 in utero in the heart of a recipient of a twin transfusion syndrome and the other in the jejunum secondary to partial venous obstruction. In the third case, it occurred in a patient with Raynaud disease. Characterizing SAM are injurious and reparative lesions that occur in the media and/or at the adventitial medial junction. Four distinctive alterations are recognized: (1) mediolysis, (2) a tearing separation of the outer media from adventitia, (3) arterial gaps, and (4) a florid reparative response that replaces zones of mediolysis and fills areas of medial adventitial separation. The repair can transform SAM into lesions indistinguishable from common types of fibromuscular dysplasia (FMD.) A venous angiopathy involving large and medium-sized veins accompanies SAM. It features medial muscle vacuolar change with lysis leading to apparent separation of residual muscle bundles. Immunostaining shows endothelin-1 (ET-1) decorating adventitial capillaries in SAM and neighboring arteries, in capillaries of adjoining tissues, and outlining smooth muscle cell membranes in adjacent veins including those of the venous angiopathy. The significance of these changes is uncertain. Vasospasm is believed to cause SAM, but ET-1 is not the direct pressor agent responsible for this condition. The reason(s) for synthesis and release of ET-1 in SAM are still hypothetical, but local perturbations in vascular tone may be an important factor. ET-1 may be indirectly play a role in SAM by cross-talking and potentiating the activities of other vasoconstrictors such as norepinephrine and by orchestrating its reparative phase.

Trunkal intracranial aneurysms: dissecting and fusiform aneurysms

Aneurysms arising along the arterial trunk are uncommon and not well-characterized lesions in contrast to saccular aneurysms. According to pathological studies, most of spontaneous trunkal aneurysms are related to dissecting phenomena. On the basis of clinical presentation, dissecting aneurysms can be separated into acute or chronic lesions. Understanding of the underlying pathological mechanisms associated with these aneurysms is useful for planning appropriate treatment. This article reviews the etiopathogenesis, the angiographic aspects, and the endovascular treatment of dissecting aneurysms. Fusiform aneurysms and aneurysms in atherosclerotic disease also are discussed briefly.