Segment Of Vertebral Artery Research Articles

Endovascular revascularization of chronically occluded vertebral artery: single-center experience.

IntroductionChronic vertebral basilar artery occlusion is one of the most common causes of ischemic stroke, which accounts for roughly 20% of all cases. However, the evidence for the precise clinical effect in treatment of the initial segment of chronic vertebral basilar artery occlusion is not sufficient.AimTo evaluate the feasibility and efficacy of endovascular therapy in the initial segment of chronic vertebral basilar artery occlusion.Material and methodsThis is a retrospective study based on data obtained from Lishui Hospital of Zhejiang University. We identified patients who underwent treatment for initial segment occlusion of the vertebral basilar artery from September 2014 to September 2018.ResultsAmong a total of twenty-two subjects, 77.27% of them were men and the median age was 61 years old. The primary medical history of these patients included hypertension (15, 68.18%), hyperlipidemia (13, 59.09%), diabetes mellitus (11, 50.00%), and coronary artery disease (6, 27.27%). About 54.54% of the patients were current smokers. Successful recanalization was achieved in 86.36% of patients. Five cases of balloon dilatation were recanalized and fourteen cases were treated by balloon dilation combined with stent implantation. During the follow-up period, there were no recurrent cerebral ischemic events, including transient ischemic attack or stroke. Six (27.27%) arteries were found to exhibit angiographic re-stenosis.ConclusionsThe clinical effect of balloon dilatation or balloon dilatation combined with stenting in the treatment of chronic vertebral basilar artery occlusion in the beginning segment was feasible and safe.

Evaluation of hemodynamic characteristics in posterior circulation infarction patients with vertebral artery dominance by color doppler flow imaging and transcranial doppler sonography

Purpose The aim of this study was to investigate the hemodynamic characteristics of posterior circulation infarction (PCI) patients with the vertebral artery dominance (VAD) using Color Doppler flow imaging (CDFI) and Transcranial Doppler sonography (TCD) and to explore the pathogenesis of PCI caused by VAD. Materials and methods A total of 186 consecutive PCI patients were enrolled. All the patients underwent magnetic resonance (MR) examination and the clinical data were collected. According to the brain magnetic resonance angiography (MRA), the patients were divided into VAD and non-VAD groups. CDFI and TCD were performed to identify the hemodynamic parameters of the vertebral artery (VA) and basilar artery (BA). Results The male population was significantly more frequent in the VAD group (71.3%) as compared to the non-VAD group (53.1%). The significant difference in hemodynamic parameters was observed between VAD and non-VAD groups. Resistance index (RI) of extracranial and intracranial VA was different as well. There were also differences in the VA side-to-side diameter difference-value, peak velocity (Vp), mean velocity (Vm) and pulsatility index (PI) with varying degrees of BA curvature. Conclusions VA and BA hemodynamic changes caused by VAD may be an important risk factor in the process of occurrence of PCI. The combination of CDFI and TCD can help to detect the hemodynamic changes in the intracranial and extracranial segments of VA and BA. This can have important clinical value in understanding the pathogenesis of PCI.

Novel use of intraoperative cone-beam imaging with on-table angiography for excision of an occipitocervical tumour: A technical note and its feasibility

IntroductionIntraoperative imaging and stereotactic navigation in spinal surgery to guide instrumentation placement and tumour resection is well documented. However, image depiction is restricted to high attenuation structures such as osseous tissue and metal objects. Vascular anatomy like major arteries or vascular neoplasm cannot be depicted. We reported angiographically enhancing intraoperative cone-beam imaging (O-arm) to facilitate resection of a craniocervical junction neoplasm that distorted the course of vertebral artery, and discussed the feasibility of this technique. MethodsWe performed intraoperative angiography employing the O-arm for image acquisition, and applied the images in S7 Stealth Station to guide tumour resection in an occipitocervical osseous tumour in which the course of the vertebral artery was heavily distorted. ResultsIntraoperative findings matched the 3D navigation images demonstrating the V3 and upper V2 segments of the vertebral artery in close proximity to the tumour. Complete en bloc tumour removal was achieved without injury to the adjacent vertebral artery. No intra- or postoperative complications occurred. ConclusionIt is feasible intraoperatively to acquire angiographically enhancing cone-beam imaging of spinal tumour in close proximity to the V3 and upper V2 segments of vertebral artery. It appears to facilitate safe tumour resection by mapping critical vascular structures in the surgical field that is initially occult to direct vision. Such novel use of technique warrants further validation.

Vertebral-carotid bypass for common carotid artery occlusion

One of the treatment options for long segment common carotid artery (CCA) occlusion is bypass surgery with different combinations of donors and receipts. Using vertebral artery (VA) as the donor for CCA occlusion was uncommonly reported. The reported cases were using jump graft to connect V3 segment of VA to either CCA or ICA. We describe our patient using V2 segment as the donor for VA-CCA bypass as treatment for CCA occlusion. Our patient was a 51 years old gentleman with Marfan syndrome and had multiple operations that included total arch replacement. He presented with sudden onset of spontaneous right frontal subarachnoid haemorrhage and repeated episodes of TIA with left upper limb numbness. CTA showed occluded right CCA and anastomosis between branches from subclavian artery and occipital artery. CT perfusion showed hypoperfusion of right hemisphere. To avoid damaging the anastomosis at subclavian artery and occipital artery, we decided for V2-RAG (radial artery graft)-CCA bypass. It was done by exposing the V2 segment at C4/5 level, performing end-to-side anastomoses at V2-RAG and RAG-CCA junctions where the RAG was underneath the internal jugular vein. Patient had no new deficits after surgery and no more TIAs. CTA performed one week after surgery showed patent RAG. In conclusion, using V2 for VA-CCA bypass is technically feasible and may have theoretical advantages over using V3. V2-CCA bypass is an option for CCA occlusion in very selected patients.

Bow Hunter's Syndrome: Complete Microsurgical Decompression of Vertebral Artery by Far Lateral Retrocondylar Approach: 3-Dimensional Operative Video.

This 50-yr-old man had a 15-yr history of presyncopal episodes that were precipitated by turning his head to the right, and had worsened recently. Cerebral angiogram demonstrated complete cessation of anterograde flow in left vertebral artery (VA) at the level of the C1 sulcus arteriosus while turning head to right, indicating dynamic compression at the C1 level. Patient underwent left extreme lateral retrocondylar approach, partial C1 laminectomy and opening of the C1 foramen with complete microsurgical decompression of the VA. After skin incision, meticulous muscle dissection was performed and superior and inferior oblique muscles were disconnected from the tubercle of C1. The VA was exposed, and three areas of constriction were visible, first at the atlanto-occipital membrane laterally; second, located more medially as the artery curved around the occipital condyle to enter the posterior fossa; and third, located anterior to C2 nerve root. The artery was dissected from all the surrounding tissues, preserving the C2 nerve root, and the Cl foramen was opened completely. The Cl lamina was also partially resected and grooved to allow free placement of the VA. The VA was also decompressed near the C2 foramen. Postoperative computed tomography angiogram of the head and neck showed complete decompression of VA. The patient had no episodes of presyncope or dizziness while turning head to right and his mRs was 0 at 8 mo follow up. This 3D video shows the technical nuances of decompression of V3 segment of VA in bow hunters's syndrome. Informed consent was obtained from the patient prior to the surgery that included videotaping of the procedure and its distribution for educational purposes. All relevant patient identifiers have also been removed from the video and accompanying radiology slides.

A case of multiple Vertebrobasilar artery fenestration misdiagnosed as vertebral artery dissection

BackgroundFenestration of vertebra-basilar artery is an uncommon congenital vascular anomaly, which is identified by incidental findings on imaging in patients presented without related symptoms or in patients with intracerebral hemorrhage secondary to concomitant artery aneurysm or arteriovenous malformations. Yet, cases of fenestration being misdiagnosed as cerebral artery dissection have never been reported.Case presentationWe present a patient of 66-year-old female with acute onset of dizziness after chiropractic manipulation of the neck. Neck computed tomography angiography (CTA) showed ‘double lumen’ sign and ‘intimal flap’ of the V1 segment of the vertebral artery, which led to the initial diagnosis of vertebral artery dissection (VAD). However, vertebral artery fenestration at V1 segment was eventually identified by multi-directional digital subtraction angiography (DSA). Interestingly, concomitant vertebral fenestration at V3 segment, basilar fenestration and basilar artery tip aneurysm was also revealed by DSA.ConclusionThe triple fenestration at vertebrobasilar artery with basilar tip artery aneurysm is extremely rare, and the fenestration at the V1 segment of vertebral artery was easily misdiagnosed as VAD due to the similar imaging morphology.

Abstract TP400: The Differences of Vessel Wall Features Between the Anterior and Posterior Brain Arteries Detected by High Resolution Magnetic Resonance Imaging in Patients With Acute Ischemic Stroke

Backgrounds: The purpose of this study was to investigate vessel wall features visualization by high resolution magnetic resonance imaging (HRMRI) in a series of ischemic stroke patients and to identify differences between lesions in the anterior and posterior circulation. Methods: We consecutively recruited Chinese patients with acute ischemic stroke or transient ischemic attack from 2016 to 2018. All patients were scanned at 3T magnetic resonance imaging. We evaluated pre-and post-contrast cross-sectional views of M1 and M2 segments of middle cerebral arteries (MCAs), basilar arteries (BA) and V4 segments of vertebral arteries (VAs). Results: A total of 74 patients (males 52.3%; median age 62 years old) were included in this study, among which, 234 lesions were identified on HRMRI, including 117 MCA lesions, 26 BA lesions, and 91 VA lesions. The sensitivity and specificity of MRA for diagnosing stenosis in anterior circulation were 89.3% (95% CI, 81.8%- 94.2%) and 50.0 (95% CI, 9.2%- 90.8%). The sensitivity and specificity of MRA for diagnosing stenosis in posterior circulation were 73.2% (95% CI, 63.9%- 80.9%) and 40.0 (95% CI, 7.3%- 83.0%). VA had a significantly higher contrast enhancement index (43.71± 7.74, p <0.016) than MCA (23.32± 2.46) or BA (22.69± 5.31) . Anterior circulation plaques had higher degree of stenosis (anterior versus posterior: 68.5% vs. 62.9%, p =0.036), more eccentric distribution (anterior versus posterior: 70.1% versus 53.8%, p =0.015) and higher rate of intraplaque hemorrhage (anterior versus posterior: 17.1% versus 7.7%, p =0.046). The plaques in posterior circulation had a thicker lesion wall (posterior versus anterior 16.58± 8.25 mm 2 vs. 9.10± 4.07 mm 2 , p <0.001) and higher enhancement index (posterior versus anterior 39.04± 8.50 vs. 23.32± 2.46, p <0.001) than the plaques in anterior circulation. Conclusions: The lesions in posterior circulations could be obscure on MRA. The area stenosis, intraplaque hemorrhage and enhancement index differed between circulations.

The role of carotid stenosis ultrasound scale in the prediction of ischemic stroke

IntroductionTo improve the accuracy of ultrasound techniques for the assessment of carotid stenosis, we designed a novel carotid artery stenosis ultrasound scale (CASUS), and evaluated its accuracy, reliability, and its value in predicting the occurrence of cardiovascular and cerebrovascular diseases in a prospective study.MethodsA total of 750 patients with first-time ischemic stroke and hospitalized within 24 h were enrolled in the study. Using color Doppler ultrasound (CDUS), the degree of stenosis and blood flow (BF) in bilateral internal carotid arteries (ICA) and the V1-V3 segment of vertebral arteries (VA) was assessed. Cubic simulation curves for BF and global blood flow (GBF) over the stenosis score (SS), total stenosis score (TSS), and radiological imaging- total stenosis score (RI-TSS) were fitted and compared. The receiver operating characteristic (ROC) curves using TSS, RI-TSS, or GBF to predict various ischemic stroke endpoints were also analyzed and compared.ResultsThere was a linear relationship between SS and BF both ICA and VA (R2 were 0.734 and 0.783, respectively, both P < 0.05). Both TSS and RI-TSS with GBF showed an inverse “S” curve relationship (R2 was 0.839 and 0.843, all P < 0.05). The AUC values of TSS-based and RI-TSS-based predictions of each endpoint were all greater than 0.7 (all P < 0.05), but the differences of the AUC values between TSS, RI-TSS, and GBF were not statistically significant (all P > 0.05).ConclusionsThe novel CASUS can better reflect the level of cerebral reperfusion in patients with ischemic stroke and can better predict the occurrence of cardiovascular and cerebrovascular diseases.

The applied anatomy and clinical significance of the proximal, V1 segment of vertebral artery.

The aim of the study was to probe the morphological features of the proximal segment (V1) of vertebral artery (VA) in a sample of Chinese cadavers. The origin, course and outer diameter at origin of the pre-vertebral part of the VAs were evaluated in 119 adult cadavers. It was found that 94.12% of the VAs originated from the subclavian arteries, bilaterally. The variant origins were present in 5.88% of the cadavers and all originated directly from the arch of the aorta. All the variations were observed on the left side of male cadavers. The average outer diameters at origin of the normal and variation groups were 4.35 ± 1.00 mm and 4.82 ± ± 1.42 mm, respectively, p = 0.035. In the normal group, but not in the variation group, the average diameter in the males was significantly larger than that in the females (4.50 ± 0.99 mm, 3.92 ± 0.92 mm, respectively, p = 0.000). In addition, only 5 cadavers in the normal group had hypoplastic VAs (4.20%, 4 males, 3 right-sided). Vertebral artery dominance (VAD) was present in 91 (69 males) out of 112 cadavers and more common on the left (n = 48). In addition, 3 cadavers satisfied conditions for coexistence of VAD and vertebral artery hypoplasia. All 7 cadavers in the variation group exhibited VAD, which was more common on the right side (n = 5). The morphologic variations and frequencies described above have implications for the early prevention, abnormal anatomy detection, accurate diagnosis, safe surgery and endovascular treatment of cardiovascular and neurological disease.

The vertebral artery convergence to the cervical spine in elders

In the older population, tortuosity of the vertebral artery (VA), uncovertebral joint (UVJ) osteoarthritis, and abnormal vertebral alignment may alter the normal anatomy. We aimed to determine the anatomical variations and relationships between the cervical segment of the VA and the cervical spine with regard to ageing. In this retrospective cross-sectional study, the computed tomography angiography scans of 110 subjects were reviewed. Any variations in the VA, UVJ degeneration were identified. The distance between the VA and uncinate process (UP) was measured electronically. The distance between the VA and UP were compared according to the age group (group A < 45, group B = 45-65, and group C > 65 years-old). With regard to the transverse foramen, 7.2% of the cases had entering abnormalities of the VA, while in one case (0.83%), the right VA had an exiting abnormality (exiting from the C2 instead of the C1). UVJ degeneration was found to be significantly higher in the older age group (p < 0.05). Furthermore, at the C4-C7 levels, the distances between the VA and UP were significantly smaller in the older age group (p < 0.01). The VA-UP distance has been shown to decrease due to increasing UVJ osteoarthritis in the elderly. The convergence of the VA toward the spine occurs at the most mobile segment of the cervical spine, and this anatomical alteration may predispose temporary and/or permanent vertebral artery occlusion clinically, and be dangerous during cervical spine surgery.

Sex and level differences in the diameters of extradural segment of vertebral artery: computed tomography angiographic study.

We investigated diameters of prevertebral - V1, and atlantic - V3 parts of extradural segment of vertebral artery (VA). Variable results from the literaturę about VA diameters reflect variety of diagnostic and imaging methods, various sample sizes, different levels of measurements, and lack of possible specific ethnic, regional or genetic data. Additionally, the data are often without distinctions of left-right or of sex. For this computed tomography (CT) angiographic study 91 adult people (182 VAs) of both sexes (47 males and 44 females) and of age between 33 and 75 years were selected. Diameters were measured at fixed predefined points of VA, marked as inferior (A) point (at V1 part in region of VA origin), as middle (B) point (the end of V1 part), and superior (C) point, at V3 part - 5 mm before VA penetrated the dura. Inferior (A) and middle (B) points actually represent locations at beginning (A) and at terminal (B) regions of V1 part of VA, and superior point C represents terminal part of V3. In total sample ipsilateral (both left [L] and right [R] sided) diameters on investigated levels of VA showed progressive and highly significant decreases. The mean values were on the right side at point A - 3.63 mm, at B point - 3.31 mm, and at C point - 3.08 mm. On the left side, mean values were at point A - 3.76 mm, at B point - 3.50 mm, and at point C - 3.21 mm. Pattern of increasing sex differences in diameters of VA, was ranging from no differences (point A), trough significant (point B), to highly significant differences (point C). For inferior point (A) we did not find significant differences in VA diameters between males (R 3.78 mm; L 3.89 mm) and females (R 3.50 mm; L 3.62 mm), in middle (B) point sex differences were significant (males: R 3.44 mm, L 3.66 mm; females: R 3.18 mm, L 3.33 mm) and in most superior point (C) differences were highly significant (males: R 3.278 mm, L 3.39 mm; females: R 2.88 mm, L 3.01 mm). However, we did not find significant intrasex (in males or in females) left-right differences in mean values of VA diameters for all three investigated levels. Our findings, as the first data about diameters of VA systematically obtained by CT angiography in the population of western Balkans and wider, suggest that in design of future studies of VA diameters is necessary to analyse separately the data for sex, as well as to use defined standard levels.

Surgicoanatomical aspect in vascular variations of the V3 segment of vertebral artery as a risk factor for C1 instrumentation

ObjectAwareness of vascular anomalies in V3 segment of vertebral artery (VA) is crucial to avoid iatrogenic injuries during surgical procedure. This study aimed to analyze the incidence of V3 segment vascular variations and demonstrate the importance of deciding the surgical strategy for C1 screw placement. MethodsPrevalence of vascular variations and morphometric measurements of the VA in the region of the craniocervical junction in 200 cases based on three-dimensional computed tomographic angiography (3D-CTA) scans were studied. ResultsThe VA has a variable course through C2 before it passes above its groove on the posterior arch of C1. Following the vascular variations of V3 segments of VA were persistent including first intersegmental artery (FIA), fenestration (FEN) of the VA, high-riding (HRVA and the posterior inferior cerebellar artery (PICA) branch originating from the C1/2 part of VA. HRVA was observed in 10.1% of patients, FIA in 1.8%, FEN in 1.3%, and PICA in 1.3%. One hundred and twenty-three (24.1%) patients were identified to have HRVA, 6% present on both sides. ConclusionThe VA with FIA and FEN were rare in this study as many as a 10% the VA present over the starting point for C1 lateral screw. With respect to the vascular anatomy of V3 and more frequent left-sided VA dominancy, standard screw insertion should be started from the right side. Routine preoperative 3D-CTA evaluation is mandatory to prevent the VA injury when C1-C2 instrumentation is planned.

EFFECTS OF ROSUVASTATIN AND ATORVASTATIN ON BLOOD PRESSURE, CEREBRAL BLOOD FLOW, ENDOTHELIAL FUNCTION, ANGIOTENSIN II IN PATIENTS WITH ISCHEMIC STROKE-COMPLICATED HYPERTENSION

Objective: To study the dose-dependent effect of rosuvastatin (R) and atorvastatin (A) on blood pressure (BP) profile, cerebral blood flow (CBF), endothelial functional activity and level of angiotensin II (ATII) in patients (pts) with hyperlipidemia (HLP) and arterial hypertension (AH) after cerebral ischemic stroke (CIS). Design and method: 68 pts were randomized to 4 groups: 1)R10 mg, 2)R20 mg, 3)A10 mg, 4)A40 mg. The study lasted 12 weeks (wks). 24-hour ABPM was performed according to standard protocol, CBF was assesed by Doppler ultrasonography of extracranial carotid arteries (CA) and vertebral arteries (VA). We evaluated the blood levels of end-metabolites of NOx, endothelin-1 (ET-1), ATII. Results: 24-hour ABPM showed reduction of SBP variability of night time (by 16,1%, p < 0,05) on A10 mg, SBP time index at night (by 15,5%, p < 0,05) and DBP day/night difference (by 32,7%, p < 0,05) on A40 mg. Therapy R 20 mg observed increase SBP variability of daytime (by 13,9%, p < 0,05). After 12 wks there were some improvement of CBF: peak systolic velocity (Vps) to end diastolic velocity (Ved) ratio and pulsatility index (PI) decreased by 6% (p < 0,05) and 8.4% (p < 0.05), respectively, in pts on A10 mg end-diastolic velocity (Ved) increased by 10,5% (p < 0,05) in pts on A 40 mg. The R20 mg increase of Ved by 4,1% (p < 0.01), decrease of resistive index (RI) of CA by 3,1% (p < 0,05) and increase of Ved in V2/V3 segments of VA by 7,3% (p < 0,05). Assessment of CBF showed improvement of flow parameters after 12 wks of treatment only from «non-ischemic» sites. After 6 wks of treatment of A40 mg and R20 mg concentrations of NOx metabolites significantly increased by 7.7 and 8.1 % (p < 0.05), respectively, and after 12 months we observed maximal effect in all pts. Levels of ET-1 significantly decreased after 12 wks of A40 mg (by 4,8%, p < 0.05) and R10 mg (by 9,5%, p < 0,05). The levels of AT II were decreased after 12 wks therapy with A40 mg only (by 7.1%, p < 0.05). Conclusions: The different doses of R and A showed dose-depended antiatherogenic and pleiotropic effects in the post-CIS pts with HLP and hypertension.

Multiple Cerebrovascular Occlusion With Hypothyroidism: A Powerful Compensation

Cerebral vascular occlusion can often cause severe neurological deficits. This study aims to describe a case characterized by multiple large vessel occlusions with hypothyroidism and without clinical symptoms. The patient’s blood vessel condition, compensatory pathway and perfusion situation were understood through medical history inquiry, neurological physical examination, combined with blood lipid, blood glucose, electrocardiogram, transcranial Doppler (TCD), brain computed tomography (CT), cerebral angiography, cerebral perfusion imaging and other examinations. The main symptoms of the patient were dizziness and headache, with no symptoms of neurological function loss. Digital subtraction angiography (DSA) showed multiple large vessel occlusions in the head and neck: the initial part of the left internal carotid artery, the M1 segment of the left middle cerebral artery, the V2 segment of the right vertebral artery, and the V3 terminal segment of the left vertebral artery. According to CT perfusion (CTP) examination, the blood flow (BF) value of the left temporoparietal occipital lobe was lower than that of the contralateral side, the mean blood flow passage time value was increased, and the cerebral blood volume (BV) was slightly higher than that of the contralateral side. Cerebral vascular occlusion is affected by many factors, hypothyroidism can accelerate the process of atherosclerosis, and in severe cases multiple large vessel occlusions may occur. Powerful compensatory mechanisms can reduce the incidence of stroke. J Med Cases. 2019;10(6):158-163 doi: https://doi.org/10.14740/jmc3303

NEW DEVELOPMENTS IN MORPHOLOGICAL DIAGNOSIS OF ISCHEMIC STROKE IN THE VERTEBRO-BASILAR BASIN

Clinical manifestations of ischemic stroke in the VBB depend on many factors and their diagnosis is often difficult due to atypical clinical presentation and rare classic symptoms [1; 2; 8]. The pathomorphological comparison of changes in the brain in patients who died of ischemic vertebrobasilar and carotid stroke. In VBB stroke stenotic lesion precerebral and intracerebral vertebral artery segments are of most important etiopathogenetic importance. Maximum intensity of the pathological changes in ischemic stroke occurs at 2-3 days of onset of irreversible damage of structural elements of the nervous tissue in the area of the primary ischemic lesion.

NEW DEVELOPMENTS IN MORPHOLOGICAL DIAGNOSIS OF ISCHEMIC STROKE IN THE VERTEBRO-BASILAR BASIN

Clinical manifestations of ischemic stroke in the VBB depend on many factors and their diagnosis is often difficult due to atypical clinical presentation and rare classic symptoms [1; 2; 8]. The pathomorphological comparison of changes in the brain in patients who died of ischemic vertebrobasilar and carotid stroke. In VBB stroke stenotic lesion precerebral and intracerebral vertebral artery segments are of most important etiopathogenetic importance. Maximum intensity of the pathological changes in ischemic stroke occurs at 2-3 days of onset of irreversible damage of structural elements of the nervous tissue in the area of the primary ischemic lesion.

A Microanatomical Study of the Far Lateral Approach

The far-lateral approach (FLA) remains a challenge for neurosurgeons due to the complex anatomy of this region, especially in patients with anatomical variations. There is therefore an urgent need for better quantitative knowledge of the microsurgical anatomy of the FLA. The study was performed using the dried skulls and atlas vertebrae of 50 Chinese adults, in which significant clinical parameters were measured. We further used 12 cadaveric heads to simulate the FLA to explore the step-by-step anatomy entailed by this procedure, enabling us to obtain key images and related information. Limited to hypoglossal canal, the occipital condyle posterior was abraded by roughly 10 mm, which provided good exposure to the ventral front of the foramen magnum. When occipital artery exits the occipital groove, the mean diameter was 2.20 mm. The average occipital artery suboccipital segment length was 65.26 mm. The posterior spinal artery (PSA) and posterior inferior cerebellar artery (PICA) generally originated from the fourth vertebral artery segment intradurally, and the mean distances from the PSA and PICA to the dural entry point of the vertebral artery were 2.62 mm and 8.71 mm, respectively. The incidence of PSA and PICA arising from the third vertebral artery segment was 16.67% and 4.17%, respectively. Understanding the important anatomic structures of the CVJ region and developing improved knowledge of the microsurgical anatomy of the FLA offer an opportunity to ensure safe exposure and treatment of lesions in the ventral and ventrolateral regions of the CVJ.

Vertebral artery segment at the suboccipital dural penetration site: an anatomical study using magnetic resonance imaging.

The morphology of the vertebral artery (VA) segment at the suboccipital dural penetration site has little been explored with magnetic resonance imaging (MRI). Therefore, the aim of this study was to examine the structure using MRI. In total, 94 patients underwent thin-sliced, contrast MRI in the axial, coronal, and sagittal planes involving the atlas, axis, occipital bone, and V3 and V4 segments of the VA. The VA segment at the suboccipital dural penetration site was well-delineated in 93% on the axial images and in 95% on the coronal images. The axial images showed that 82% of the VA penetration sites were located in the middle third of the dural sac. Meanwhile, the coronal images revealed that the heights of both VA penetration sites were located at the same level in 87%. The axial VA penetration angle, which is formed by the VA and tangential line of the dural sac, was 66 ± 11.9° on the right side and 61 ± 14.1° on the left side. The coronal VA penetration angle, which is formed by the tangential line of the VA and dural sac, was 111 ± 24.6° on the right side and 112 ± 19.9° on the left side. The morphology of the VA segment is considerably variable at the suboccipital dural penetration site, while most penetration sites are located in the middle third of the dural sac on axial MRI. These should be assumed during surgeries around the suboccipital VA penetration site.

Neuroform Atlas stent in treatment of iatrogenic dissections of extracranial internal carotid and vertebral arteries: a single-centre experience.

To present our experience in the treatment of iatrogenic dissections of extracranial internal carotid and vertebral arteries with the Neuroform Atlas stent. Between January 2017 and February 2018 we treated iatrogenic dissections of three internal carotid arteries and three vertebral arteries. These iatrogenic dissections occurred during the endovascular treatment of ruptured and unruptured intracranial aneurysms. The indication for stenting was haemodynamically significant, flow-limiting dissection with threatening flow arrest. In all six cases, the dissections were treated by placement of Neuroform Atlas stents in the dissected segments of internal carotid or vertebral arteries. Deployment of the stent was followed by the usual dual antiplatelet regimen. Single or multiple Neuroform Atlas stents were deployed without any technical difficulties, and blood flow was restored immediately after placement of the stents in all six cases. Midterm follow-up (6-8 months) showed complete reconstruction of the shape and lumen of all treated arteries, with negligible intimal hyperplasia. Our results indicate that a favourable outcome can be achieved by treating iatrogenic dissections of extracranial internal carotid and vertebral arteries with the Neuroform Atlas stent.

Abstract WMP40: Accuracy of Extracranial Vertebral Artery Hemodynamic Parameters in the Evaluation of Intracranial Vertebral Artery Steno-Occlusive Disease

Objectives: To explore the accuracy of the hemodynamic parameters of the extracranial segment of vertebral artery (EVA) for evaluating the intracranial segment steno-occlusive disease. Methods: A total of 275 consecutive patients who were diagnosed as posterior circulation ischemic stroke with unilateral intracranial VA (IVA) stenosis or occlusion in our hospital from January 2015 to December 2017 were enrolled. All patients were examined by neck vascular ultrasound, CT angiography (CTA) and / or digital subtraction angiography (DSA) within one week. According to the results of DSA or CTA,the patients were divided into mild,moderate,severe stenosis and occlusion groups. The peak systolic velocity (PSV), end diastolic velocity (EDV), resistance index (RI value) of the EVA (V2 segment) were recorded and analyzed. The area under the receiver operating characteristic curve (AUC) of the PSV, EDV, RI values were calculated. The sensitivity, specificity, and accuracy of the above hemodynamic parameters were compared. Results: With the severity of the IVA stenosis, the PSV and EDV of the V2 segment were gradually decreased, and the RI value was gradually increased ( P &lt;0.001). The AUC of the PSV, EDV, and RI values were gradually decreased when compared the occlusion before PICA(posterior inferior cerebellar artery),occlusion after PICA and severe stenosis. When EDV≤0 cm/s or RI value≥1.00, the accuracy of IVA occlusion before PICA was the highest (97.8%), with a specificity 98.7% and a sensitivity 91.9%. When EDV≤10cm/s, the accuracy of occlusion after PICA was 89.1%, with a sensitivity 91.2%, a specificity 87.9%. The accuracy of PSV≤39cm/s and RI value≥0.76 was less than that of EDV (86.2% , 84.7%).The accuracy for IVA severe stenosis were less than 85%. Conclusion: The ultrasonic hemodynamic parameters of the EVA can accurately diagnose the occlusion of the IVA and distinguish the occlusion site, but the diagnostic accuracy of the severe stenosis is relatively low.