Anatomic correlation between intimal pathology and cerebral vasospasm following subarachnoid hemorrhage

ABSTRACT

Subarachnoid hemorrhage [SAH] resulting from a ruptured intracranial aneurysm can induce cerebral vasospasm with subsequent reduction in cerebral blood flow [CBF]. The present study examines the pathological alterations in the wall of human cerebral arteries at autopsy, especially with regard to intimal pathology, following aneurysmal SAH. Arterial segments from the circle of Willis were fixed in 10% formalin, embedded in paraffin, sectioned at 4[micro] and stained with hematoxylin-eosin or toluidine blue. Similar numbers of sectioned vessels were also examined in control material. The areas of intima, lumen and the length of internal elastic lamina were compared with those from control sections. Pathological changes such as myonecrosis and fibrosis in muscular layers associated with a possible loss of compliance and elasticity of the vessel wall were also noted. The average luminal area decreased to 56.8% +/- 12.5% compared to comparable controls [p<0.005]. The tunica intima was the most abnormal component of the arterial wall with cellular proliferation which was made up predominantly of collagen fibers and loose fibroblasts. These pathological findings are mainly due to myonecrotic changes and intimal proliferation with the resultant luminal constriction and CBF impairment which might explain the high incidence of cerebral infarction in cases of SAH