Histological Study of the Normal Vertebral Artery : Etiology of Dissecting Aneurysms

概要

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Histological evaluation of dissecting aneurysms of the cerebral arteries has suggested that defects in the internal elastic lamina (IEL) induce dissection of the arterial wall. Dissecting aneurysms occur most frequently in the vertebral artery (VA). The present study examined sections of the normal VA to elucidate the mechanisms of arterial dissection. Bilateral VAs (20 vessels) were obtained from 10 patients who died of causes other than intracranial lesions. The VAs were detached from the VA union to the site 10 mm proximal from the point penetrating the dura mater. The VAs were cut at 5-mm intervals, and each segment was observed using modified Masson's trichrome staining for elastic fibers. The thickness of the media and adventitia significantly thinned after the origin of the posterior inferior cerebellar artery (PICA). TEL defects were observed at 35 sites in 11 vessels from six subjects. There was a high incidence of TEL defects in the extradural portion and near the origin of the PICA, areas frequently involved in arterial dissection. There was a high incidence of intimal thinning at areas of TEL defects (19 of 35), and thinning was particularly marked distal to the origin of the PICA. Tn the absence of intimal thickening, the vascular strength at the site of TEL defects may be reduced, which would promote the occurrence and progression of arterial dissection.
日本脳神経外科学会の論文
2004-12-15