The arteriovenous malformation associated with major arterial occlusion and moyamoya vessels: a cerebral blood flow study

Abstract

We report 2 patients with arteriovenous malformation (AVM) associated with complete occlusion of the unilateral middle cerebral artery and moyamoya vessels. Xenon CT CBF study demonstrated diffusely decreased CMF in unilateral or bilateral hemispheres with multiple areas of decreased vascular reserve. A significant reduction of AVM size was seen in one patient who received radiosurgery with marked CBF improvement.

Figure 1

Case l. A) T2 weighted axial images, showing an AVM with a prominent draining vein (arrows) in the right basal ganglia and frontoparietal region. B, C) Right carotid angiogram. Anteroposterior projections in early and late arterial phases (B) and lateral projections of early arterial and venous phases (C). There is complete occlusion of the middle cerebral artery and prominent moyamoya vessels are seen (thin arrow). The AVM is supplied by the leptomeningeal collaterals from the ACA branches (thick arrows) and moyamoya vessels. Superficial and deep draining veins are seen (arrowheads). D) Xenon CT CBF study showing very high flow in the AVM but diffusely decreased flow in the area posterior to the AVM (arrow). E) T2 weighted axial image at 2 years after gamma-knife radiosurgery showing a small residual nidus with disappearance of a large draining vein. F) Xenon CT without acetazlamide challenge showing significant improvement of CBF in the right hemisphere compared with figure 1D. G) Xenon CT with acetazolamide challenge showing marked augmentation of left hemispheric flow but poor augmentation in the right hemisphere. There are areas of focal flow decrease adjacent to the residual AVM indicating decreased vascular reserve (arrowheads).

Figure 1

Case l. A) T2 weighted axial images, showing an AVM with a prominent draining vein (arrows) in the right basal ganglia and frontoparietal region. B, C) Right carotid angiogram. Anteroposterior projections in early and late arterial phases (B) and lateral projections of early arterial and venous phases (C). There is complete occlusion of the middle cerebral artery and prominent moyamoya vessels are seen (thin arrow). The AVM is supplied by the leptomeningeal collaterals from the ACA branches (thick arrows) and moyamoya vessels. Superficial and deep draining veins are seen (arrowheads). D) Xenon CT CBF study showing very high flow in the AVM but diffusely decreased flow in the area posterior to the AVM (arrow). E) T2 weighted axial image at 2 years after gamma-knife radiosurgery showing a small residual nidus with disappearance of a large draining vein. F) Xenon CT without acetazlamide challenge showing significant improvement of CBF in the right hemisphere compared with figure 1D. G) Xenon CT with acetazolamide challenge showing marked augmentation of left hemispheric flow but poor augmentation in the right hemisphere. There are areas of focal flow decrease adjacent to the residual AVM indicating decreased vascular reserve (arrowheads).

Figure 2

Case 2. A) T2 weighted axial images showing a large AVM in the left temporal lobe especially in the parahippocampal gyrus. A large draining vein is seen (arrow). B, C) Left carotid angiogram, anteroposterior and lateral projections of early arterial (B) and late arterial (C) phases demonstrating complete occlusion of a major trunk of the MCA with prominent moyamoya vessels (arrow). The large AVM in the medial temporal lobe is supplied by the leptomeningeal collaterals from the ACA (arrowheads) and by moyamoya vessels.

Figure 3

Case 2. A) Xenon CT without acetazolamide showing markedly increased CBF in the AVM nidus and multiple areas of significantly decreased flow in both hemispheres (arrows). B) Xenon CT with acetazolamide challenge test reveals flow augmentation in the left frontal lobe indicating preserved vascular reserve (small arrows). However, bilateral temporo-occipital regions show significantly decreased CBF indicating decreased vascular reserve (large arrows). An area of decreased CBF was also seen in the left parietal region indicating a steal phenomenon.