Study of cerebral vascular structures in hypertensive intracerebral haemorrhage

The study was performed in order to assess the alterations of extra-parenchymal and intraparenchymal vascular structures in 82 hypertensive patients suspected of primary intraparenchymal hematoma, which died and were autopsied in order to confirm the diagnosis.

The studied material consisted of nervous tissue situated near and distant from the haemorrhagic lesion. The specimens of nervous tissue were processed by the classical histological technique and stained with the usual stainings and with immunohistochemical stains for basement membranes and endothelial cells.

Extra-parenchymal arteries showed classic lesions of atherosclerosis. Atheromatous lesions were of all types, even the extension towards the media being encountered a complication with thrombosis. At the level of the intraparenchymal blood vessels, the spectrum of the lesions due to arterial hypertension included all steps of vascular wall degeneration, from hypertrophy of smooth muscle layer to complete hyalinization of arterial wall, but with a focal irregular distribution, not related with the proximity of haemorrhagic focus. High arterial blood pressure also influenced the capillary walls which showed focal or circumferential thickening due to the densification of the type IV collagen material from the basement membrane structure. The CD34 immunostaining showed that endothelial cells kept their structural integrity.

The sequence of degenerative lesions of the cerebral vascular wall culminates with the hyalinization of excessive fibrillar material form arteriolar wall or from basement membranes. Hyalin material is weakening the wall resistance to the stress determined by the high values of blood pressure in hypertension, and, correlated with a minimal resistance of the surrounding cerebral parenchyma, can explain why the cerebral parenchyma is the only tissue in which blood pressure variations can determinate vascular rupture and cerebral haemorrhage. The more adequate term for describing the vascular wall changes seems to be sclerosis (arteriolar and even capillary) with hyalinosis.