PMC8769423_01
Case 1. (a) Initial MRA. An abnormal hyperintense signal suggesting intramural thrombus is observed around the transposition part between the left V3 and V4 segments (arrow). The signal of the left VA is faint and interrupted at the V4 segment (double arrow). The top of the BA including the left SCA and the bilateral PCA is not depicted (arrowhead). Only the right SCA is preserved (double arrowheads). (b) Source image of initial MRA. The intimal flap and double lumen are demonstrated at the end of the V3 segment of the left VA (arrow). (c) Initial left vertebral angiogram. The left VA exhibits irregular long segment stenosis at the V3 segment (arrow), followed by irregular tapered occlusion (double arrow). (d) Initial right vertebral angiogram. A filling defect indicating a large clot (arrowhead) extends from the top of the BA to the left SCA and bilateral PCA. (e) Snapshot image of Penumbra ACE68. Penumbra ACE68 has already reached the occlusion site of the BA via the right VA. Afterward, thrombectomy by contact aspiration was performed. (f) Right vertebral angiogram after first pass of contact aspiration. Recanalization of the top of the BA is confirmed. (g and h) DWI obtained a day after the treatment. Small infarcts are observed in the territory of the left AICA and left PCA. (i) MRA obtained 6 months after the treatment. Left VA is spontaneously recanalized without any remaining findings of dissection. MRA: magnetic resonance angiography, VA: vertebral artery, BA: basilar artery, SCA: superior cerebellar artery, PCA: posterior cerebral artery, DWI: diffusion-weighted imaging, AICA: anteroinferior cerebellar artery.
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F1
Magnetic resonance angiography (MRA) revealed tandem occlusion of the left intracranial vertebral artery (VA) and basilar artery (BA) with intimal flap and double lumen at the left V3 segment (Fig. 1a and 1b). Digital subtraction angiography (DSA) immediately following MRI showed long irregular stenosis of the left V3 segment leading to the occluded V4 segment (Fig. 1c) and a thrombus in the top of the BA (Fig. 1d). The contralateral or right VA was intact and maintained antegrade blood flow to the BA (Fig. 1d). He underwent mechanical thrombectomy for an occluded distal BA by a direct aspiration first pass technique using Penumbra ACE68 (Penumbra, Inc., Alameda, CA, USA) via the non-dissected right VA (Fig. 1e). This resulted in recanalization with a modified thrombolysis in cerebral infarction (mTICI) score of 2b (Fig. 1f). DWI obtained a day after the treatment showed a small infarction in the territory of the left anteroinferior cerebellar artery (AICA) and left posterior cerebral artery (Fig. 1g and 1h). The left VA remained intact until the last MRA was obtained 6 months after the onset (Fig. 1i).
PMC8769423_02
Case 2. (a) Initial DWI. The spotty acute multiple infarcts in the territory of bilateral AICA and pons are demonstrated. (b) Initial MRA. The signal of the right VA is faint and interrupted at the V4 segment (arrow). The left VA and proximal BA are not depicted. The middle to distal parts of the BA are faintly shown (double arrow). (c) BPAS-MRI. The outer shape of the bilateral VA and BA is shown. The outer diameter of the distal end of the right V4 segment is larger than that of the mid V4 (arrow). The left V4 segment presents tubular dilatation (double arrow). These findings indicate the outward dilatation of the bilateral V4 segment. The discrepancy between the inner lumen on MRA and the outer shape on BPAS strongly suggests dissection of the bilateral VA. (d) Initial right vertebral angiogram (lateral view). The right VA exhibits a tapered occlusion at the V4 segment (arrow). The BA is inadequately reconstituted (double arrow) by collateral flow via the anterior spinal artery (arrowhead). (e) Right vertebral angiogram before stenting (oblique view). The right V4 segment is occluded over a long distance. (f) Initial left vertebral angiogram (lateral view). The left VA exhibits long, irregular, severe stenosis through the V4 segment (arrow), followed by pseudo-occlusion. The BA is faintly depicted (double arrow). (g) Right vertebral angiogram after stenting (oblique view). Distal and proximal markers of Enterprise 2 VRD deployed in the affected segment are depicted (arrows). (h) Right vertebral angiogram after the stenting (oblique view). Complete recanalization and good dilatation of the affected right V4 segment are confirmed. (i) DWI obtained two days after the treatment. The expansion of the left cerebellar infarction is observed. (j) MIP image of 3D-DSA obtained 12 months after stenting. No in-stent restenosis is demonstrated. DWI: diffusion-weighted imaging, AICA: anteroinferior cerebellar artery, MRA: magnetic resonance angiography, VA: vertebral artery, BA: basilar artery, BPAS: basi-parallel anatomical scanning, VRD: Vascular Reconstruction Device, 3D-DSA: three-dimensional digital subtraction angiography.
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F2
The spotty acute multiple infarcts in the territory of bilateral AICA and pons were confirmed on initial DWI (Fig. 2a). Bilateral intracranial VA occlusion with tubular enlargement of the external vessel calibre was shown on MRA and BPAS-MRI (Fig. 2b and 2c). DSA revealed long segment tapered occlusion of the right V4 segment (Fig. 2d and 2e) and long segment irregular pseudo-occlusion of the left V4 segment (Fig. 2f). BA was indicated by collateral flow via the anterior spinal artery (Fig. 2d). Based on the clinical course and the findings of imaging examination, the mechanism of cerebral ischaemia was considered as hypoperfusion resulting from the bilateral VA dissection. The occluded right VA was considered more suitable for recanalization by stenting rather than the left VA because the affected segment of the right VA was shorter than the left VA in length (Fig. 2d and 2f) and the assumed landing zone for the stent was clearer in the right VA (Fig. 2e). However, it happened so that the intact right V4 segment at the distal side of the occlusion was visible owing to collateral flow via the anterior spinal artery (Fig. 2e). Cerenovus) (Fig. 2g). Complete recanalization of the right VA was achieved, and antegrade blood flow to the BA was re-established (Fig. 2h). Although the expansion of left cerebellar infarction was observed on DWI obtained two days after the treatment (Fig. 2i), he reached functional independence with an mRS score of 2 by three months after the onset. The angiographic cure of the right VA dissection (Fig. 2j) and functional independence (mRS 2) was confirmed at the 12-month follow-up.
PMC8769423_03
Case 3. (a) Initial CTA. CTA shows a long, irregular stenosis of the left V3 segment (arrow), a contrast filling defect extending from the left V4 segment to the proximal BA (arrow heads), and occlusion of the right VA. The distal part of the BA is depicted with the collateral flow via the bilateral posterior communicating artery. (b) Initial left vertebral angiogram (lateral view). The intimal flap (arrow) followed by a long irregular stenosis (double arrow) is shown at the left V3 segment. The left VA is interrupted at the distal part of the V4 segment (arrowhead). (c) Superselective injection via the microcatheter (lateral view). A crescent-shaped filling defect suggesting embolic occlusion is demonstrated at the distal end of the V4 segment (arrowhead). (d) Mechanical thrombectomy for left V4 segment occlusion. Trevo XP 4 x 20 mm is deployed from the proximal BA to the distal left V4 segment (arrowhead). (e) Left vertebral angiogram after thrombectomy (lateral view). Although the left V4 segment is recanalized (arrowhead), blood flow to the BA is still restricted (double arrowhead) by severe stenosis of the left V3 segment resulting from dissection (arrows). (f) Left vertebral angiogram after the stenting (lateral view). Two Enterprise 2 VRDs were deployed at the dissected V3 segment in an overlapping manner. Markers of the distal stent (arrows) and proximal stent (arrowheads) are shown. (g) Left vertebral angiogram after the stenting (lateral view). Good dilatation of the left V3 segment (arrows) and complete restoration of blood flow to the BA (arrowhead) are confirmed. (h) CT immediately after the decompression craniectomy. The infarction and oedema in the right cerebellar hemisphere are observed. (i) FLAIR-MRI obtained 30 days after the treatment. The haemorrhagic infarction in the territory of the right PICA and AICA is revealed. (j) Left vertebral angiogram obtained 12 months after stenting (lateral view). The morphological normalization of the left V3 segment with no in-stent restenosis is demonstrated. CTA: computed tomography angiography, BA: basilar artery, VA: vertebral artery, VRD: Vascular Reconstruction Device, CT: computed tomography, FLAIR: fluid-attenuated inversion recovery, MRI: magnetic resonance imaging, AICA: anteroinferior cerebellar artery, PICA: posteroinfeior cerebellar artery.
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F3
Computed tomography angiography (CTA) showed a long, irregular stenosis of the left V3 segment, a contrast filling defect extending from the left V4 segment to the proximal BA, and occlusion of the right VA (Fig. 3a). DSA followed by endovascular treatment was started without MRI because of the patient's critical condition and necessity of urgent endovascular reperfusion. DSA revealed an intimal flap with long and irregular stenosis at the left V3 segment, which were definitive findings of arterial dissection (Fig. 3b). The interruption of blood flow at the left V4 segment was also observed (Fig. 3b). Additional superselective angiography strongly suggested an embolic occlusion of the left V4 segment (Fig. 3c). Because the contralateral (right) VA was occluded (Fig. 3a), mechanical thrombectomy for the occluded left V4 segment was performed via the dissected left V3 segment. The first pass using Trevo XP ProVue 4 x 20 mm (Stryker) achieved recanalization of the left V4 segment (Fig. 3d and 3e). Even after complete recanalization of the left V4 segment, blood flow to the BA was still restricted due to severe stenosis of the dissected V3 segment (Fig. 3e). In order to achieve patency of the left VA, two Enterprise 2 VRD were deployed to the affected left V3 segment in an overlapping manner (Fig. 3f) following the administration of a loading dose of DAPT (clopidogrel 300 mg and aspirin 200 mg). Good dilatation of the left V3 segment and restoration of antegrade blood flow were confirmed by the final DSA (Fig. 3g). The patient needed a decompression craniectomy two days after the treatment because of severe oedema in the right cerebellar hemisphere (Fig. 3h). Fluid-attenuated inversion recovery-MRI obtained 30 days after the treatment revealed haemorrhagic infarctions in the territory of the right posteroinfeior cerebellar artery and AICA that were not recanalized by the endovascular treatment (Fig. 3i). The morphological normalization of the left VA with no in-stent restenosis was confirmed by DSA obtained 12 months after the stenting (Fig. 3j).