Editors' Note: Teaching NeuroImages: Pseudopathologic Brain Parenchymal Enhancement due to Vascular Compression in Parotid Tumor

In “Teaching NeuroImages: Pseudopathologic Brain Parenchymal Enhancement due to Vascular Compression in Parotid Tumor,” Teixeira et al. present a CT angiogram (CTA) obtained through right antecubital vein injection that shows intracranial vascular reflux in the cortical veins and pseudopathologic enhancement of the right brain parenchyma in a patient with a right-sided parotid gland tumor who had transient left hemiparesis but had a normal digital subtraction angiogram (DSA) and a normal repeat CTA obtained through left-sided vein injection. The authors initially described the enhancement as being in the distribution of the right middle cerebral artery territory, but they subsequently agreed with Chen et al. that the involvement of the occipital lobe suggests the enhancement pattern is more consistent with the drainage territory of the right superficial cerebral veins. Chen et al. note the mechanism for this finding is unclear and question (1) whether the DSA showed any anomalies in the venous sinuses; and (2) whether the pseudopathologic enhancement could have been related to the fact that the initial injection was performed through a right-sided vein, suggesting there could be severe stenosis of the right brachiocephalic vein. On further review, Teixeira et al. reported the DSA showed a hypoplastic right anterior cerebral artery, occlusion of the right internal jugular vein, and critical stenosis of the right vertebral artery origin. They suspect the patient’s symptoms were the result of compression of the right internal carotid artery by the tumor in the setting of right vertebral artery stenosis, which led directly to either compensatory vasodilation or precipitated blood-brain barrier disruption. Although there was also occlusion of the right internal jugular vein, the patent right external jugular vein may have led to rapid spread of contrast into the right hemisphere and retrograde flow into the dilated capillary bed. They postulated that the CTA obtained through left-sided injection was normal because either the patent left internal jugular vein reduced the contrast velocity or vascular autoregulation was reestablished.

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