Inflammation promotes progression of thrombi in intracranial thrombotic aneurysms.

Advances in the understanding of the pathogenesis of arteriosclerosis, abdominal aorta aneurysms and dissections, and carotid artery plaques have focused on chronic inflammation. In this study, we report that inflammatory changes of thrombi contribute to the enlargement and growth of giant intracranial thrombotic aneurysms. Surgical and postmortem samples were collected from 12 cases of large or giant intracranial thrombotic aneurysms diagnosed via pathological investigations. Degeneration of the aneurysmal wall and the infiltration of inflammatory cells in the thrombi were assessed. The number of blood cells and immunohistochemical stain-positive cells was enumerated, and the inflammation and neovascularization in the thrombi were assessed. In all cases, the appearance of inflammatory cells (CD68+ cells, CD206+ cells, lymphocytes, and neutrophils) was apparent in the thrombi. The number of CD34+ cells was moderately correlated with the number of CD68+ cells, and CD34+ cells significantly and strongly correlated with the number of CD206+ cells. Based on the number of neutrophils per CD68+ cells, we classified the cases into 2 groups: a macrophage inflammation-dominant group and a neutrophilic inflammation-dominant group. The neutrophilic inflammation-dominant group had significantly more cases with previous treatments and neurological symptoms due to mass effect than the macrophage inflammation-dominant group. Chronic inflammation due to macrophages in thrombi is a fundamental mechanism in the enlargement of an intracranial thrombotic aneurysm, and neutrophilic inflammation can accelerate this process. Microvascularization in thrombi is linked to inflammation and might promote thickening of the intima and repeated intimal microbleeds.

Neurofibromatosis Type 1 with Giant Thrombotic Aneurysm of the Internal Carotid Artery Presenting with Rapid Progression of Visual Disturbance: A Case Report and Literature Review.

Background Patients with neurofibromatosis type 1 (NF1) have various vascular diseases due to the vascular fragility, but no reports of case of giant thrombotic aneurysm was found. We treated a rare case of giant thrombotic aneurysm of the internal carotid artery (ICA) in a patient with NF1. Case Presentation A 60-year-old man had suffered deteriorating visual loss and homonymous hemianopia. Contrast-enhanced computed tomography showed a giant thrombosed aneurysm on the anterior wall of the ICA located in the optic chiasma. We planned and completed the external carotid artery-middle cerebral artery high-flow bypass using radial artery graft. The visual fields test was performed 14 days after surgery. Homonymous hemianopia persisted but no exacerbation of visual field impairment was observed. No complications were found at 14 days after surgery and the postoperative course was uneventful. Conclusion We consider that external carotid artery-middle cerebral artery bypass surgery using radial artery grafts is a safe and effective treatment method for giant thrombotic aneurysm associated with NF1.

A complete thrombotic large aneurysm at the nonbranching segment of the distal anterior cerebral artery mimicking a cavernous malformation: illustrative case.

BACKGROUND: Thrombotic aneurysms at the nonbranching segment of the distal anterior cerebral artery (ACA) are extremely rare and difficult to differentiate from cavernous malformations by radiographic features alone. OBSERVATIONS: Computed tomography and magnetic resonance imaging of a 30-year-old female patient with a chronic headache complaint revealed a 22-mm frontal lobe mass. The mass showed heterogeneous mixed intensity and hemosiderin deposits on magnetic resonance images. It was not visualized by conventional angiography, indicating that the mass and ACA/other vessels were not connected. The patient was preoperatively diagnosed with a cavernous malformation. However, during resection, the mass surface was white and smooth, different from a cavernous malformation. Although the mass was adherent to the pericallosal artery branch, no luminal continuity was observed. After detachment, the mass was completely resected. Pathological and immunohistochemical findings indicated a vessel wall and interior thrombus. The patient was rediagnosed with a thrombotic aneurysm at the distal ACA nonbranching segment and discharged 10 days postsurgery without neurological deficits. LESSONS: Because radiographic findings of thrombotic aneurysm and cavernous malformation are similar, mass lesions in contact with major arteries should be differentiated as thrombotic aneurysms, even when the artery lumen appears disconnected from the mass.

Microsurgical Clipping of Giant P3 Segment Posterior Cerebral Artery Aneurysm: 2-Dimensional Operative Video.

Posterior cerebral artery (PCA) aneurysms comprise <2% of all intracranial aneurysms and are usually located on the P1 and P2 segments. Aneurysms of the P3 segment of the PCA are even rarer, and despite their proximity to the cerebral aqueduct, presentation with hydrocephalus is exceptional. This video demonstrates the case of a 28-year-old female patient who presented acute hydrocephalus due to a partially thrombosed, giant P3 segment PCA aneurysm. The patient was operated on in the semisitting position, and a right frontal ventricular drain was placed for brain relaxation. A U-shaped skin incision was made, and a left-sided, 6 cm × 6 cm parietooccipital craniotomy crossing the midline was performed. An interhemispheric approach was used to reach the aneurysm. The aneurysm was trapped via temporary clipping of the inflow and outflow arteries, thrombectomized, and then clipped using a right-angled fenestrated aneurysm clip. Postoperative computed tomography and magnetic resonance imaging revealed resolution of the hydrocephalus, and cerebral angiography confirmed total exclusion of the aneurysm from the circulation and occlusion of the P4 segment of the PCA, which was considered embolic. The patient made an excellent recovery, and she was discharged on postoperative day 3 (Video 1). This case demonstrates the efficacy of microsurgical clipping for a giant thrombotic P3 segment PCA aneurysm that caused a mass effect. Surgery excluded the aneurysm from the circulation and decompressed the cerebral aqueduct, obviating the need for a permanent ventriculoperitoneal shunt.