Histopathologic analysis of intraarterial polyvinyl alcohol microemboli in rat cerebral cortex.

Polyvinyl alcohol (PVA) foam particles have been used with success in both experimental and clinical embolization of vascular lesions. Cellular response to PVA has been well documented outside, but not within, the central nervous system. This study was directed specifically at the cellular response to PVA in rat brain vasculature. By using small numbers of microparticles, an effort was made to define the response to PVA alone, rather than associated occlusions or infarctions. It was determined that PVA elicited no significant inflammatory response in the embolized vessels nor in the surrounding tissue. The isolated fragments did not appear to alter the blood-brain barrier. The PVA microemboli were extremely adherent to vascular endothelium, lodging in vessels of larger diameter and in relatively high-flow locations without actually wedging within the vessel lumen. On the basis of this analysis, it was determined that PVA foam has properties suitable for an intracerebral vascular embolic agent.