Effect of vasa vasorum in cerebrovascular compensation: 2 case reports.

Intracranial vasa vasorum (VV) are rare and develop predominantly in the proximal segments of the internal carotid artery (ICA) and vertebral artery (VA). The typical appearance of intracranial VV has not yet been reported in clinical practice. Although VV in the ICA have been found to re-institute the collateral flow, bypassing the obstructive segment, far less attention has been paid to the manner in which VV can connect the two ends of the obstructive segment through the plaque. In this study, we present two cases and discuss the positive effects of VV. In our first case, a patient with basilar artery (BA) occlusion and multiple infarcts in the posterior circulation territory received endovascular treatment. Digital subtraction angiography (DSA) showed the existence of VV, which originated from the proximal BA lumen, penetrated through the vessel wall, bypassed the obstructive segment, re-penetrated through the vessel wall, and reconnected to the distal BA lumen. Balloon angioplasty was performed, specifically avoiding the path of the VV, then the VV had disappeared in follow-up angiography. In our second case, a patient who had been diagnosed with occlusion in the initial segment of the left ICA two years ago suffered a stroke. DSA revealed that the VV collaterals penetrated directly through the plaque of obstructive site and reconnected to the distal vessel lumen, which caused low hemodynamic compensation. Angioplasty was performed directly following the VV path, then follow-up angiography showed the VV had disappeared. Arterial occlusion, including in the intracranial and extracranial artery, could trigger the occurrence of VV, which can improve downstream perfusion. VV also could play a role of signal light in endovascular treatment.