2018 年 12 巻 4 号 p. 161-168
Objective: To examine the involvement of segmental arterial mediolysis (SAM) in intracranial artery dissection.
Methods: In four autopsy cases of subarachnoid hemorrhage related to the rupture of the intracranial vertebral artery (IVA) with intraperitoneal hemorrhage, we calculated the extent of arterial dissection using elastica van Gieson staining from the tissue sections of the left/right IVAs and intraperitoneal arteries (IPAs), and examined the properties of the vascular smooth muscle and responses of mesenchymal cells using immunostaining with anti-α smooth muscle antibody (SMA) and anti-S100A4 antibodies.
Results: The length of the adventitia at the site of IVA rupture was ≤2.4 mm, and that of disruptions of the internal elastic lamina was 5.4–11 mm. The IVA/IPA rupture sites showed acute arterial dissection. In the blood vessels at the sites of dissection, defect/necrosis of the vascular smooth muscle, which are characteristic of SAM, were noted. In three cases, the topical infiltration of mesenchymal cells was observed in the adventitia at the dissected site of the ruptured IVA. In all cases, dissection of unruptured intracranial or -peritoneal arteries was also present. Its pathological properties vary from acute to old dissection.
Conclusion: Autopsy revealed SAM-related systemic multiple arterial dissection in all cases, suggesting the involvement of SAM in the development of intracranial artery dissection.