The physiopathogenetic basis for the angiographic diagnosis of bacterial infections of the brain and its coverings in children. I. Leptomeningitis.

This is a descriptive analysis of the angiographic characteristics of leptomeningeal infections in 36 children and a correlation of these angiographic observations with anatomopathologic changes. Vascular, meningeal and parenchymal changes are described and discussed. In the normal situation, tracer protein particles injected into the subarachnoid space perfuse easily through the extracellular spaces but stop at the outer continuous arachnoidal layer. The parenchymal layer, pia-arachnoid, on the other hand, consists of a uni or pluricellular layer which is regularly crossed by tracer particles. Though the internal carotid, vertebral and basilar arteries have some anatomical characteristics: thinner tunica media and adventitia, the absence of vasa vasorum and the presence of a fluid cushion (CSF) in which they are bathed. The most striking angiographic observation in leptomeningitis is the transmural extravasation of the contrast meding 'halo' formation. Long after the cerebral circulation time, one may identify contrast media 'pooling' within the cisterns and sulci.