Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland.
Department of Forensic Medicine, Medical University of Warsaw, Warsaw, Poland.
Folia Neuropathol. 2022;60(4):403-413. doi: 10.5114/fn.2022.122342.
Saccular intracranial aneurysm (sIA) rupture is a serious cerebrovascular event associated with inflammatory destructive processes leading to gradual weakening of the sIA wall. The aim of the present study was to identify the morphological and histological determinants for low wall strength in unruptured sIAs harvested from autopsy subjects.
A total of eight single unruptured sIAs were identified and excised with adjacent cerebral arteries during 8 of 184 postmortem examinations. The dome morphology was assessed for each sIA at a constant pressure of 100 mmHg. Then, after 5 preconditioning cycles which assured muscle fibre relaxation, sIA specimens were subjected to gradually increasing intraluminal pressure at a rate of 20 mmHg/s until rupture of the sIA or cerebral artery was achieved. Micro-structural degenerative changes and inflammatory cell infiltration within the sIA wall were quantitatively analysed after pressurization of the sIA specimens. The microscopic analysis of the slides stained with histological methods (HE, Mallory trichrome, Masson trichrome, orcein) and immunohistochemical methods (LCA, CD3, CD68) was performed.
The wall of the sIA ruptured in three specimens, while in the other cases, rupture occurred at the arterial wall. The mean maximal dome size was significantly larger in sIAs with low wall strength, that is, in sIAs that ruptured during pressurization, than in sIAs with high wall strength (6.46 mm vs. 2.43 mm, p = 0.034). Moreover, a significantly higher average percentage of wall hyalinization in sIAs that ruptured than in sIAs that did not rupture was observed (30% vs. 0%, p = 0.006). In contrast, the degree of inflammatory cell infiltration did not differ between the wall strength categories.
Our results support the observations that larger sIAs may be at a higher risk of rupture. Histological analysis revealed that hyalinization corresponds to the weakened regions of the wall of unruptured sIAs.
囊状颅内动脉瘤（sIA）破裂是一种严重的脑血管事件，与导致 sIA 壁逐渐弱化的炎症破坏过程有关。本研究旨在确定从尸检标本中采集的未破裂 sIA 中低壁强度的形态和组织学决定因素。
在 184 次尸检中的 8 次，总共确定并切除了 8 个单个未破裂的 sIA 以及相邻的脑动脉。在恒定的 100mmHg 压力下评估每个 sIA 的穹顶形态。然后，在 5 个预条件循环之后，保证肌肉纤维松弛，sIA 标本以 20mmHg/s 的速率逐渐增加管腔内压力，直到 sIA 或脑动脉破裂。在对 sIA 标本加压后，定量分析 sIA 壁内的微观结构退行性变化和炎症细胞浸润。用组织学方法（HE、Mallory 三色、Masson 三色、orcein）和免疫组织化学方法（LCA、CD3、CD68）对染色的幻灯片进行微观分析。
在三个标本中，sIA 壁破裂，而在其他情况下，破裂发生在动脉壁。在加压时破裂的低壁强度 sIA 的平均最大穹顶尺寸明显大于高壁强度 sIA（6.46mm 对 2.43mm，p=0.034）。此外，在加压时破裂的 sIA 中观察到的壁玻璃样变性的平均百分比明显高于未破裂的 sIA（30%对 0%，p=0.006）。相反，在壁强度类别之间，炎症细胞浸润的程度没有差异。
我们的结果支持这样的观察结果，即较大的 sIA 可能破裂的风险更高。组织学分析显示，玻璃样变性与未破裂 sIA 壁的弱化区域相对应。
