Intracranial artery to artery spontaneous revascularization in a child.

Introduction: Intracranial artery-to-artery antegrade revascularization is a poorly recognized entity, more so when it involves main stem arteries. The etiology, appearance, and significance of this condition are not described in the literature.

Case Presentation: We describe a case of spontaneous revascularization of a chronically occluded middle cerebral arterial branch by collaterals from the proximal segment reconstituting distal flow, mimicking a brain arteriovenous malformation in a 9-year old boy. We discuss the nature of these channels, presumed to be related to artery to artery collaterals that are either dilated adventitial vasa vasorum, or, more likely, leptomeningeal collaterals that are hypertrophied in response to cerebral demand. We review the literature regarding intracerebral vasa vasorum and leptomeningeal collaterals including their imaging.

Conclusion: Recognizing the tortuous channels associated with this type of vascular abnormality as normal vessels reconsituting distal flow may prevent unnecessary and potentially dangerous treatments.