Absence of pontine perforators in vertebrobasilar dolichoectasia on ultra-high resolution cone-beam computed tomography

Abstract

BackgroundVertebrobasilar dolichoectasia (VBDE) is a rare type of non-saccular intracranial aneurysm, with poor natural history and limited effective treatment options. Visualizing neurovascular microanatomy in patients with VBDE has not been previously reported, but may yield insight into the pathology, and provide important information for treatment planning.ObjectiveTo carry out a retrospective analysis of ultra-high resolution cone-beam computed tomography (UHR-CBCT) in patients with fusiform basilar aneurysms, visualizing neurovascular microanatomy of the posterior circulation with a special focus on the pontine perforators.MethodsUHR-CBCT was performed in seven patients (mean age 59 years; two female) with a VBDE, and in 14 control patients with unrelated conditions.ResultsThe mean maximum diameter of the fusiform vessel segment was 28 mm (range 19–36 mm), and the mean length of the segment was 39 mm (range 15–50 mm). In all patients with VBDE, UHR-CBCT demonstrated an absence of perforating arteries in the fusiform arterial segment and a mean of 3.7 perforators arising from the unaffected vessel segment. The network of interconnected superficial circumferential pontine arteries (brainstem vasocorona) were draping around the aneurysm sac. In controls, a mean of 3.6, 2.5, and 1.2 perforators were demonstrated arising from the distal, mid-, and proximal basilar artery, respectively.ConclusionsThe absence of pontine perforators in the fusiform vessel segment of VBDE is counterbalanced by recruitment of collateral flow from pontine perforators arising from the unaffected segment of the basilar artery, as well as collaterals arising from the anterior inferior cerebellar artery/posterior inferior cerebellar artery and superior cerebellar artery. These alternative routes supply the superficial brainstem arteries (brainstem vasocorona) and sustain brainstem viability. Our findings might have implications for further treatment planning.

Principles, techniques and applications of high resolution cone beam CT angiography in the neuroangio suite

“…Another role of HR-CBCT in the work-up of brain aneurysms is to evaluate the detailed features of a target aneurysm before treatment, such as: small lobulations in the aneurysm fundus, better understanding of complex neck aneurysms (figure 5), or, as importantly, the presence of small perforators arising from the aneurysm itself (figure 6) or from the parent vessel close to the aneurysm neck—specifically of paramount importance in cases of parent vessel sacrifice such as in dissecting vertebral artery aneurysms (figure 7). 15 16…”

Cone-beam CT angiography to assess the microvascular anatomy of intracranial arterial dissections

“…However, IAD with mural haematoma may present as 'flame-shaped' occlusion, while intraluminal clot presents as a 'cup-shaped' occlusion 5 and, in our opinion, the CBCT-A might be used to identify these distinctive characteristics. Moreover, CBCT-A allows to visualize the neurovascular microanatomy 8 and might assess the relation between IAD and perforating arteries, as seen in patient 2 and 3.…”

“…This imaging modality has been used to provide meaningful radiological information with regard to the neurovascular anatomy and morphology as well as implanted devices. Dobrocky et al 8 used the CBCT-A to demonstrate the absence of pontine perforators in the fusiform vessel segment of vertebra-basilar dolichoectasia. Two studies used the CBCT-A to evaluate the flow diverter braid expansion and conformability to the vessel wall, during treatment of brain aneurysms with flow diverters, 6,13 in order to avoid common complications of its deployment.…”

“…5 Here we present a case series of patients with IADs studied with intraprocedural cone-beam computed tomography angiography (CBCT-A), a useful tool to visualize microvascular structures and increasingly used in endovascular procedures. [6][7][8][9]…”

Prospects and Dilemmas of Endovascular Treatment for Vertebrobasilar Dolichoectasia

“…In VBD, pontine perforators in the fusiform vessel segment of the BA may be occluded and absent, and these pontine perforators must obtain blood flow from the unaffected segment of the BA, as well as from the proximal segments of the anterior inferior cerebellar artery/posterior inferior cerebellar artery and superior cerebellar artery ( 65 , 66 ). Therefore, during EVT for VBD, these major vessels of the BA and VA should be preserved to avoid brainstem infarction.…”