Morphological Evidence of Progressive Microvascular Impairment in Middle Cerebral Artery Occlusion-Reperfusion

Abstract

Approximately 80% of patients with focal cerebral ischemia, manifest as acute stroke, have either atherothrombotic or thromboembolic occlusions when examined within 6 h from symptom onset [4, 9]. Recent experience with the intra-arterial and intravenous infusions of fibrinolytic agents in patients with acute focal cerebral ischemia has demonstrated both the feasibility of effecting cerebral arterial reperfusion [3, 4, 13, 20, 21, 25, 27] and the clinical benefit of the procedure [13, 21]. However, residual CT scan abnormalities and neurological deficits have been observed in all studies. Particularly vulnerable is the territory of the lenticulostriate arteries where persistent occlusions exist following M₁ segment middle cerebral artery (MCA) occlusion and reperfusion [29]. This phenomenon is most commonly attributed to the absence of functional collaterals. The status and responses of the downstream microvascular bed to ischemia and reperfusion in this territory are unknown, but both ischemia and reperfusion may contribute to the radiographic and clinical defects detected in the lenticulostriatal territory. Furthermore, it is unknown if microvascular alterations following ischemia/reperfusion might be analogous to those developing in the microvascular beds of other organ systems following similar types of injury.

Supported in part by grant number 1 RO1 NS26945 from the National Institutes of Health. This is publication number 7506-MEM from Scripps Clinic & Research Foundation, La Jolla, California.