V3 Segment Research Articles

A case of occipital artery originating from the vertebral artery.

Anomalies of the vertebral artery (VA) and its branches are rare but critical in neurovascular procedures. In a 38-year-old female, digital subtraction angiography revealed an anomalous origin of the occipital artery (OA) from the V3 segment of the left VA, with a tortuous course supplying the neck and scalp. Below the OA's origin, the suboccipital artery of Salmon arose, bifurcating into two branches. Additionally, an extradural posterior inferior cerebellar artery originated from the same segment, entering the skull via the foramen magnum and dividing into medial and lateral trunks. This unique coexistence of vascular variants highlights the need for detailed preoperative vascular outlining to minimize intraoperative risks.

Anatomical analysis of vertebral arteries in vertebrobasilar dolichoectasia: A multi-center study

BackgroundVertebrobasilar dolichoectasia (VBD) is a rare disease with significant morbidity. Its propensity for posterior circulation and relationship with aneurysms is poorly understood. Here, we aimed to describe the anatomical characteristics of the vertebral arteries (VA) in patients with VBD. MethodsWe conducted a multi-center retrospective cohort analysis on patients diagnosed with VBD between January 2009 and December 2022. Anatomical variables were measured after manual segmentation on CTA. Length of the VAs, basilar artery (BA), sectional diameters, and tortuosity index were measured and compared with a control group. Results124 patients were included: 38 patients with VBD and 86 controls. VBD patients had longer VAs (right VA 262.5 vs. 228.7 mm, p<0.01; left VA 253.4 vs. 222.1 mm, p<0.01), longer BAs (41.9 vs. 30.0 mm, p<0.01), and larger cross-sectional diameters of right V3 (5.1 vs. 4.6 mm, p<0.05) and V4 segments (4.5 vs.2.9 mm, p<0.05) and left V1-V4 segments (V1 6.1 vs. 4.2, V2 7.2 vs.4.8 mm, V3 6.4 vs.5.0 mm, V4 6.5 vs. 3.0 mm, p<0.01). Patients with VBD and fusiform aneurysms had longer VAs and BA than patients without aneurysms (p<0.01). The VAs tortuosity index was higher in VBD than controls (60.69 vs. 44.18, p<0.01). No cases of vertebral stenosis were detected. ConclusionsOur study offers an anatomical study of VBD. While the natural history is poorly understood, the higher tortuosity index with associated wall shear stress, provides a possible mechanism for disease progression. Further studies are needed to better understand the

Ruptured coronary sinus aneurysm in pregnancy combined with cardiogenic shock and elevated V1 and aVR ST segments: Case report.

Sinus of Valsalva aneurysm (SOVA), a rare cardiac malformation, is usually congenital and rarely acquired and most commonly occurring in the right coronary sinus. The clinical presentation of patients with SOVA varies. It is usually asymptomatic when it has not ruptured, and when it compresses neighboring structures or ruptures, it can lead to heart failure or shock, at which point urgent surgical intervention is usually required. Rupture of the sinus of Valsalva aneurysm (RSOVA) during pregnancy is really hard to come by, especially if the clinical presentations resemble that of an acute myocardial infarction. This report describes a pregnant woman with severe chest pain and hypotension with aVR and V1 ST-segment elevation due to RSOVA. Effects of RSOVA on the fetus, disease survival, and prognosis. RSOVA. Open SOVA repair. The patient's blood pressure returned to normal range and clinical symptoms disappeared after the surgery. After 3 months of follow-up, the patient was hemodynamically stable without chest discomfort, and an echocardiogram showed a normal aortic sinus. Progressive aneurysm dilatation or rupture has a poor prognosis. A thorough history and physical examination are fundamental, with echocardiography being the initial diagnostic tool of choice, and other ancillary tests (e.g., computed tomography) being used to complement and confirm the diagnosis. Surgery remains the current treatment of choice for patients with RSOVA, while the continuation of pregnancy in pregnant patients with RSOVA remains a case-by-case measure.

A Prevalence Anatomic-Imaging Study of the Posterior Inferior Cerebellar Artery's Origin.

Background and Objectives: Typically, the vertebral arteries (VAs) enter the posterior fossa through dural rings and further unite, forming the basilar artery. The posterior inferior cerebellar artery (PICA) is usually a branch of the V4 segment of the VA (intradural origin). It may also leave the V3 suboccipital segment of the VA (extradural origin). The transdural origin of the PICA within the VA's dural ring has been consistently overlooked. A study was designed to determine the topographical patterns of the PICA's origin. Materials and Methods: Determinations were performed in a retrospective sample of 225 computed tomography angiograms. Four types of PICA origin were documented: type 0, absent PICA; type 1, the extradural origin of the PICA from the V3 segment of the VA; type 2, the transdural origin of the PICA within the dural ring; and type 3, the intradural origin of the PICA from the V4 segment of the VA. The bilateral symmetry of types was also investigated. Results: Out of 450 VAs, type 0 (absent PICA) was found in 36%, type 1 (extradural) in 0.44%, type 2 (transdural) in 5.56%, and typical type 3 in just 58%. In types 1 and 2, the PICA entered the posterior fossa through the dural ring and the marginal sinus. In the overall group (N = 225), the type combinations 1_1, 1_2 and 1_3 were not found. Bilaterally absent PICAs occurred in 18.67%. The bilateral combinations 0_1/0_2/0_3/2_2/2_3/3_3 were found, respectively, in 0.89%/3.11%/30.67%/1.78%/4.44%/40.44%. Four of the seventy-eight PICAs opposite to an absent one, three intradural and one transdural, were true bihemispheric PICAs. Conclusions: The PICAs with extradural or transdural origins are facultative contents of the dural ring and are at risk during neurosurgical approaches in the foramen magnum. Rare bihemispheric PICAs could originate either intradurally or within the dural ring.

Basilar artery occlusion management: An international survey of gender influence on management.

The superiority of endovascular thrombectomy (EVT) over medical management was not established in two early basilar artery occlusion (BAO) randomized controlled trials. Despite this, many clinicians recommended EVT for acute BAO under certain circumstances. This paper aims to compare physicians' diagnostic and management strategies of BAO according to gender. From January to March 2022 an international survey was conducted regarding management strategies in acute BAO. We compared responses between clinicians by identifying gender. Questions were designed to examine clinical and imaging parameters influencing management of patients with BAO. Among the 1245 respondents from 73 countries, 311 (25.0%) identified as female. This figure was 13.6% amongst interventionists. Geographically, female respondents were lowest in Asia (14.5%) and North America (23.9%). The proportion of respondents identifying as female was consistent regardless of their years of experience. Female respondents were more likely to choose time of onset as time of first estimated stroke like symptom (48.0% vs. 38.5%, p < .01), were less likely to favor thrombectomy in the V4 segment of vertebrobasilar artery occlusions (31.5% vs. 43.3%, p < .01), and were less likely to find it acceptable to enroll all patients who met trial criteria in the standard medical treatment arm of a clinical trial (41.2% vs. 47.0%, p = .01). Male respondents were more likely to agree that thrombolysis would not alter their decision on proceeding with EVT (93.7% vs. 88.3%, p < .01). Female clinicians appear to be significantly underrepresented in stroke medicine. This is most pronounced amongst interventionists and in Asia. Although male and female opinions were closely aligned on many aspects of BAO management, differences in opinion were observed in a number of significant areas which influence decision making.

Exploring the atlantic part of the vertebral artery in the South Indian population and its implications in spine surgery.

A descriptive, quantitative cross-sectional study of the atlantic part (V3) of the vertebral artery (VA). This study aimed to bridge the research gap in the morphometry of the V3 segment of the VA in the South Indian population. The microsurgical anatomy of this segment of the VA has been explored in various populations, and a thorough understanding of the anatomy and course of the VA, particularly the V3 segment, is essential to prevent iatrogenic complications. Several computed tomography studies but a few cadaveric studies have explored the V3 segment of the VA in the South Indian population. This study examined 40 VAs from 20 embalmed cadavers that were obtained from the voluntary donation program, and Institutional Ethical Clearance was obtained before the study. The length, diameter, and angle of the vertical, horizontal, and exit parts of the V3 segment of the VA were documented after its exposure. The mean lengths of the right and left VAs on each part were nearly similar, except for the mean length of the horizontal part (right: 38.937 mm, left: 40.237 mm) and total length of the V3 segment (right: 66.870 mm, left: 70.350 mm). These morphometric parameters are essential to spine surgeons who intend to operate on a small part (vertical, horizontal, or exit part) of the V3 segment of the VA. The mean values of the parameters obtained in this study give average measurements or safe limits to surgeons for safe surgical procedures such as the occipital condyle screw technique and C1 laminectomy.

The impact of an anomalous third segment of the vertebral artery on bypass surgery: a case report and literature review.

The horizontal part of the third segment (V3) of the vertebral artery (VA) is a critical anastomotic site for bypass procedures involving either donor or recipient vessels. It is rare for the V3 segment to deviate from its typical course of passing through the atlanto-transverse foramen. V3 anomaly encountered in occipital artery (OA)-V3 bypass surgery has not been previously reported. Here, we present a case involving a patient undergoing bypass surgery due to recurrent post-stent occlusion at the first segment (V1) of the left VA. During the operation, it was noted that the V3 horizontal segment could not be identified within the left VA groove, leading to initial suspicion of left V3 disuse atrophy attributed to prolonged chronic ischaemia. Consequently, there was a need to modify the operative method and to transition from an OA-V3 bypass to an OA-posterior inferior cerebellar artery bypass. Post-operative computed tomography angiography confirmed that indeed, the left V3 did not traverse through the transverse foramen of the atlas and instead entered the dural membrane between the first cervical vertebra (C1) and the second cervical vertebra (C2).

Complementary advantages of microsurgical treatment for vertebral artery dolicoarteriopathies: Mitigating symptoms of restless leg syndrome in refractory vertebrobasilar insufficiency

Objective: This retrospective study examines the impact of microsurgical treatment on vertebral artery (VA) dolicoarteriopathies and associated restless leg syndrome (RLS) in patients with refractory vertebrobasilar insufficiency (VBI). Patients and Methods: We analyzed 78 patients with grade 2 and 3 kinks, and found out that the targeted microsurgical interventions, primarily designed to address VBI, improved secondary RLS symptoms in 12 patients. Procedures included arteriolysis and, depending on severity, grafting. Statistical analysis was conducted using Stata 16 (StataCorp LP, Texas, USA). Results: In twelve patients aged 55 to 72 years with refractory VBI and drug-resistant RLS, micro-neurosurgical correction of V1 segment dolicoarteriopathy, abnormal elongation and kinks in the artery, demonstrated promising outcomes. Postoperatively, 83.33% (10 patients) reported complete resolution of RLS symptoms, and 16.66% (2 patients) experienced partial symptom relief (p&amp;lt;0.05). Overall, 86.8% of various VBI-related symptoms were significantly improved or resolved (p&amp;lt;0.05). The microsurgical technique, avoiding traditional flow-arresting procedures, proved to be highly effective in this preliminary study with no mortality and minimal temporary complications, underscoring its potential treatment avenue for such complex neurovascular conditions. Conclusion: This study illuminates the relationship between VBI and RLS, proposing a potential vascular etiology for RLS, and highlights the need for a broader diagnostic approach for patients with refractory VBI.

A Comparative Study of AI-Based Automated and Manual Postprocessing of Head and Neck CT Angiography: An Independent External Validation with Multi-Vendor and Multi-Center Data.

To externally validate the performance of automated postprocessing (AP) on head and neck CT Angiography (CTA) and compare it with manual postprocessing (MP). This retrospective study included head and neck CTA-exams of patients from three tertiary hospitals acquired on CT scanners from five manufacturers. AP was performed by CerebralDoc. The image quality was assessed using Likert scales, and the qualitative and quantitative diagnostic performance of arterial stenosis and aneurysm, postprocessing time, and scanning radiation dose were also evaluated. A total of 250 patients were included. Among these, 55 patients exhibited significant stenosis (≥ 50%), and 33 patients had aneurysms, diagnosed using original CTA datasets and corresponding multiplanar reconstructions as the reference. While the scores of the V4 segment and the edge of the M1 segment on volume rendering (VR), as well as the C4 segment on maximum intensity projection (MIP), were significantly lower with AP compared to MP across vendors (all P < 0.05), most scores in AP demonstrated image quality that was either superior to or comparable with that of MP. Furthermore, the diagnostic performance of AP was either superior to or comparable with that of MP. Moreover, AP also exhibited advantages in terms of postprocessing time and radiation dose when compared to MP (P < 0.001). The AP of CerebralDoc presents clear advantages over MP and holds significant clinical value. However, further optimization is required in the image quality of the V4 and M1 segments on VR as well as the C4 segment on MIP.

Vertebral artery hypoplasia and hemodynamic impairment in transient global amnesia: a case control study.

The aetiology of transient global amnesia (TGA) is still a matter of debate. Besides ischemia of the mesial temporal lobe including the hippocampus, migraine-like mechanisms, epileptic seizures affecting mnestic structures, or venous congestion in the (para) hippocampal area due to jugular vein insufficiency have been discussed. We assessed the diameters of the intracranial arteries of TGA patients compared to controls to identify differences that support the hypothesis of reduced hippocampal perfusion as a pivotal factor in the pathophysiology of TGA. We reviewed magnetic resonance imaging time of flight angiographies (TOF-MRA) that were acquired during in-patient treatment of 206 patients with acute TGA. The diameters of the vertebral artery (VA) in the V4 segment, the proximal basilar artery, and the internal carotid arteries were measured manually. We compared the findings with TOF-MRA images of an age and sex matched control group of neurological patients without known cerebrovascular pathology. In TGA patients the diameter of the right VA was significantly (p < 0.01) smaller compared to controls (2.09 mm vs. 2.35 mm). There were no significant differences in the diameters of the other vessels. Only the fetal variant of the posterior cerebral artery was slightly more common in TGA. The smaller diameter (hypoplasia) of the right VA supports the hypothesis of a contribution of hemodynamic factors to the pathophysiology of TGA. The fact that hypoplasia represents a congenital condition might be the explanation why previous studies failed to find an increased rate of the classical (acquired) vascular risk factors.

Direct V3 Vertebral Artery Access for Embolization of Partially Thrombosed Fusiform Basilar Trunk Aneurysm: Technical Case Instruction.

Fusiform vertebrobasilar aneurysms carry significant morbidity. Endovascular strategies are preferred; however, unsafe or unfeasible access can call for innovative strategies. An octogenarian patient with an enlarging fusiform proximal basilar artery aneurysm causing a sixth nerve palsy was found to have multiple anatomic features that precluded a transradial or transfemoral endovascular approach. She was thus treated with direct microsurgical access of the V3 segment of the vertebral artery for subsequent coil embolization and flow diversion. This case introduces a novel combined microsurgical and endovascular strategy for treating a complex partially thrombosed fusiform basilar artery aneurysm. This approach should be reserved only for patients where conventional endovascular access is dangerous or unfeasible.

Transarterial Embolization of Intracranial Dural Arteriovenous Fistulas Cognard Type V With Direct Drainage Into the Perimedullary Veins: Case Report and Literature Review.

Cognard type V fistula (CVF) is a rare type of dural arteriovenous fistula characterized by spinal perimedullary venous drainage. Owing to the lack of pathognomonic findings, misdiagnosis is common. Patients often undergo multiple spinal angiograms negative for spinal vascular malformations. Digital subtraction angiography is the gold standard diagnostic tool. The preferred treatment option is endovascular management with embolization through a transarterial, transvenous, or combined approach. Other options include open surgery, stereotactic radiosurgery, or a combination of both. The patient from case # 1 presented with progressive weakness and hypoesthesia in the bilateral lower extremities, with urinary and bowel incontinence. The DSA identified a CVF fed by the meningohypophyseal trunk and a draining perimedullary vein. Embolization with 0.1 ccs of Onyx-18 was performed with complete fistula occlusion. The patient from case # 2 developed bilateral lower extremity weakness, diffuse numbness, and urinary incontinence. The DSA showed a CVF fed by tributaries from the ascending pharyngeal artery and posterior meningeal artery branches of the V3 segment, draining into a perimedullary vein. Embolization with 0.3 cc of Onyx-18 was performed with 100% occlusion of the fistula. A 1-year follow-up angiogram confirmed complete fistula occlusion. Both patients consented to the procedure. Even if a patient only presents symptoms of myelopathy, CVF should be considered. Herein, we present 2 cases of CVF with direct drainage into the perimedullary veins which presented exclusively with myelopathy syndrome and describe treatment with trasarterial embolization with Onyx.

Dolichoectatic Posterior Inferior Cerebellar Artery Aneurysm Treated With Excision and Posterior Inferior Cerebellar Artery Double Reimplantation Bypass: 2-Dimensional Operative Video.

Posterior inferior cerebellar artery (PICA) aneurysms account for 0.3% of all intracranial aneurysms, and they commonly present with a complex fusiform morphology that necessitates unique bypass strategies.1-5 An adolescent boy with a familial predisposition to aneurysmal subarachnoid hemorrhage was identified as harboring a fusiform aneurysm of the right distal PICA, characterized by 2 outflow branches. Our recommended treatment strategy involved a right far lateral craniotomy, followed by P1 PICA reanastomosis and P2 PICA reimplantation. Informed written consent was obtained. On exposure, the aneurysm was trapped, and the inflow and 2 outflow PICA branches were excised. Revascularization was established through a P1 PICA end-to-end reanastomosis using running continuous suturing techniques, followed by P2 PICA end-to-side reimplantation into a more distal portion of PICA. Subsequent indocyanine green videoangiography confirmed patency of the P2 PICA reimplantation; however, the initial P1 PICA reanastomosis was noted to be thrombosed. After several unsuccessful attempts to dissolve the thrombus, the decision was made to proceed with a P2 PICA side-to-side in situ reimplantation into the V4 segment of the vertebral artery. Indocyanine green videoangiography and postoperative digital subtraction angiography confirmed patency of the PICA double reimplantation bypass. The patient tolerated the procedure well and was discharged home at his neurological baseline. This video showcases the microsurgical treatment of a complex dolichoectatic, distal PICA aneurysm using a double reimplantation technique, in addition to highlighting bypass decision-making processes for managing complex PICA aneurysms.

Variability in Intracranial Vessel Diameters and Considerations for Neurovascular Models: A Systematic Review and Meta‐Analysis

BackgroundIn vitro experiments are critical for understanding the impact of medical devices and techniques on blood vessels and blood flow. However, their interpretation is often limited by anatomical models’ inability to capture the wide range of vessel sizes observed in real‐world practice. The current study aims to address this limitation by describing the distribution of vessel diameters in a real‐world population.MethodsThis systematic literature review using the PubMed database analyzed cerebral vessel diameters in patients from 2000 to 2022. The diameter measurements of various vessels within the neurovasculature were extracted. Random‐effects meta‐analyses were performed to synthesize vessel diameters across studies. Predicted distributions were generated from the meta‐analytical results.ResultsSeventy‐six studies were included in the analysis. The M1 segment, internal carotid artery (cervical and communicating segments), A1 segment, V2 segment, V4 segment, and basilar artery had sufficient data for generating predicted distributions of vessel diameters. Predicted mean diameters were as follows: M1 segment, 2.55 ± 0.42 mm (95th interpercentile range [IPR]: 1.71–3.38); internal carotid artery‐cervical segment, 4.74 ± 0.64 mm (95th IPR: 3.49–5.99); internal carotid artery‐communicating segment, 3.40 ± 0.64 mm (95th IPR: 2.15–4.66); A1 segment, 1.89 ± 0.34 mm (95th IPR: 1.23–2.55); V2 segment, 3.36 ± 0.67 mm (95th IPR: 2.05–4.67); V4 segment, 2.42 ± 0.74 mm (95th IPR: 0.98–3.86); and basilar artery, 2.96 ± 0.52 mm (95th IPR: 1.94–3.97).ConclusionCerebral vessel diameter measurements can vary substantially due to patient‐specific factors and imaging techniques. This literature review highlights the diverse range of vessel sizes observed in different patient populations, emphasizing the need for anatomical models that accurately represent clinical observations.

Secondary Benefits of Microsurgical Intervention on the Vertebral Artery (V1 Segment) for Refractory Vertebrobasilar Insufficiency: Alleviation of Parkinsonism-Like Symptoms

ObjectiveTo investigate the outcomes of micro-neurosurgical interventions on V1 segment of vertebral artery (VA) in patients with refractory vertebrobasilar insufficiency (VBI) due to dolicoarteriopathy and external compressions and to assess the secondary benefits of Parkinsonism-like symptoms. MethodsRetrospective analysis encompassed 101 patients treated for VA dolicoarteriopathy or compression-related refractory VBI from 2016-2023. Of these, 16 patients exhibited drug-resistant Parkinsonism-like symptoms. The diagnostic evaluation included cerebral CT/MR angiography or DSA and brain CT or MR perfusion studies, corroborated by preoperative and 6- and 12-month postoperative MDS-UPDRS Part 3 assessments. Data was analyzed through Turkey's 'E-nabız' system, employing Stata16 for statistical scrutiny. ResultsA significant reduction in MDS-UPDRS scores was observed (preoperative: 26.75 ± 10.91; 6 months: 23.09 ± 9.24; 12 months: 22.5 ± 8.73; P<0.001). Postoperative follow-up denoted that 43.7% of patients ceased medication, and 50% reduced antiparkinsonian drugs. The micro-neurosurgical approach resulted in complete remission of VBI-related symptoms in 84.6% of patients, with the rest showing partial or marked improvement. At six months post-operation, perfusion studies revealed posterior border zone or cerebellar perfusion enhancements in 81% (13 out of 16) of patients, with full symptom resolution, while the remaining 19% (3 out of 16) showed partial perfusion and clinical improvements, particularly in regions supplied by the posterior cerebellar artery (PCA) or posterior inferior cerebellar artery (PICA). The absence of operative mortality and minimal transient morbidities underscored the procedure's safety. ConclusionMicroneurosurgery for VA anomalies in refractory VBI patients, particularly those with concomitant parkinsonian-like syndromes, has demonstrated potential in symptom remission and medication reduction.

213 Acute Flow Diversion for Ruptured Cerebral Aneurysms Arising From Vessels of Small Caliber Using FRED Jr: A Clinical Case Series

INTRODUCTION: Ruptured aneurysms arising from small caliber (&lt;2.5 mm) or distal vessels beyond the circle of Willis are considered challenging for all treatment modalities. Recently, the FRED Jr stent, designed for flow diversion in small arteries, was approved in the US for the treatment of non-ruptured aneurysms. METHODS: Clinical and radiological records of patients sustaining SAH treated with FRED Jr between June 2020 and October 2022 were reviewed. Treatment course including anti-platelet therapy, external ventricular drain (EVD) management, and vasospasm, as well as clinical outcomes were analyzed. Angiographic results were assessed according to the O’Kelly-Marotta (OKM) scale. RESULTS: Nine patients with at a median age of 62 (27-75) were included. The median Hunt Hess score was 2 (IQR 1) and modified Fischer score was 4 (IQR 1). Six aAneurysms’ morphologies included were saccular (6 case), 1 blister (1 case) and 2 were and dissecting (2 cases) type, located at the ACOM complex (3), A2/A3 (3), M2/M3 (1), V4 (1), and P2 (1) segments. All stents were deployed successfully with no intraprocedural complications. Post-operatively, no re-bleeding events were encountered. Vasospasm therapy was initiated in 6 cases, and no symptomatic EVD-related hematomas were observed. Post- operative ischemic events were encountered in 2 cases. Median 3-month mRS was 2 (IQR 1) for the7 surviving patients, and 3-months radiographic follow-up revealed OKM scale D in 4/7 cases. CONCLUSIONS: Flow diversion as a potential treatment strategy for acutely ruptured aneurysms arising from small caliber vessels is feasible using FRED Jr. Since As the complication profile reported in this series is comparable to historical microsurgical cohorts and effective protection was conferred by this treatment modality, our small cohort provides a glimpse into acute flow diversion for this subset of difficult-to-treat aneurysms.

Endoscopic decompression of a C1 osteophyte causing bow hunter's syndrome in a 22-year-old male.

The patient is a 22-year-old male with a history of C1 avulsion fracture causing vertebral artery compression with pseudoaneurysm and symptomatic stroke. Cerebral angiography demonstrated dynamic compression of the V3 segment of the vertebral artery due to a chronic C1 avulsion fracture. The authors utilized a full endoscopic approach with intraoperative angiography for proximal control and Doppler ultrasound to confirm adequate decompression. The surgery duration was 3 hours with blood loss < 5 ml. The patient was discharged on postoperative day 1 with no complication and has been asymptomatic since surgery. This is the first documented use of endoscopic decompression to treat this condition. The video can be found here: https://stream.cadmore.media/r10.3171/2024.1.FOCVID23234.

Delimitation of the risk area of the vertebral artery during the paramedian suboccipital approach

ObjectiveThe V3 segment of the vertebral artery (V3-VA) is at risk during diverse approaches to the craniovertebral junction. Our objective is to present a system of anatomic and topographic landmarks to identify the V3-VA during the paramedian suboccipital approach (PMSOA) with the help of minimal or basic tools. Material and methodsThe first was a retrospective analysis of the angiotomography (CTA) of 50 patients over 18-years old, and 9 anatomical dissections. A series of lines were defined between the different bony landmarks. Within this lines the risk area of the vertebral artery (RAsV3-VA) and the risk point of the vertebral artery (RPsV3-VA) were defined.The second stage was a prospective study, where the previously defined measurements were carried out by using neuronavigation in 10 patients (20 sides) operated with the PMSO approach in order to confirm the presence of the V3 segment in the RAsV3-VA and RPsV3-VA. ResultsIn the first stage, the V3 segment was found in the middle third of the X line in 96,6% of the cases. The distance between the inion and the UCP (percentile 5) was 20 mm and to the LCP (percentile 95) was 40 mm. In the range between the UCP and the LCP, in the middle third of the inion-mastoid line (RAsV3-VA), we found 90% of the V3-VA.The measurements taken during the second stage revealed that the artery was in the middle third of the X line in 97% of the cases. 85% of the patients presented the total of the V3s-VA on the RAsV3-VA and in 85% there was a direct relationship with the V3 segment and the RPV3s-VA. ConclusionWe propose an easy-to-implement system to delimit the risk area of the V3-VA during the PMSOA. We believe that these landmarks provide a practical, reliable, costless and useful tool that could decrease the risk of lesion of the V3-VA during this approach without the need of using.

Analysis of the clinical characteristics of V4 segment steal blood in the vertebral artery

Objective: To explore the clinical characteristics of unilateral vertebral artery V4 segment occlusive lesions (severe stenosis or occlusion), where the contralateral vertebral artery can be compensated through blood flow and reverse supply to the posterior inferior cerebellarartery (PICA). Methods: This study is a retrospective case series of 66 patients with V4 segment occlusive lesions of unilateral vertebral artery diagnosed and treated from June 2020 to October 2022. Patient data were retrospectively collected, and their hemodynamic characteristics and imaging data were analyzed. Results: Of the 66 cases, 11 patients (16.7%) with V4 segment occlusive disease showed the blood flow of the vertebral artery on the opposite side of the lesion on the digital subtraction angiography (DSA), which can be reverse stolen to the posterior inferior cerebellar artery of the diseased side through the confluence point of the vertebrobasilar artery through the distal end of the ipsilateral vertebral artery V4. Owing to the lack of literature on this pathway and based on the characteristics of previous definitions of subclavian artery steal and carotid artery steal, we referred to this pathway as the vertebral artery V4 segment steal. In 6 patients (9.1%), transcranial Doppler ultrasound (TCD) and transcranial color Doppler ultrasound (TCCD) showed that the blood flow signal was not detected at the proximal end of the V4 segment of the affected side, rather the blood flow direction was reversed at the distal end of the V4 segment, resulting in compensatory acceleration of the blood flow velocity of the V4 segment of the contralateral vertebral artery. Conclusion: "V4 segment steal of vertebral artery" is a very rare route of vertebral artery steal. When V4 segment of the vertebral artery is occluded, clinicians should pay attention to observe the blood supply of PICA and whether there is such a steal route, to better evaluate the blood flow compensation and prognosis of patients.

Abstract WP228: Vertebral Artery Configuration as a Risk Factor for Dissection in Children

Introduction: Arterial ischemic strokes are estimated to occur in 1.2 to 8 per 100,000 children per year with 15-22% occurring in the posterior circulation. Vertebral artery dissection(VAD) is a known cause of posterior circulation ischemic stroke in approx 7% of cases. Pediatric Bow Hunter syndrome, usually presents distinctively with VAD and stroke. It most commonly involves the V3 segment. In 2021, Braga et all proposed a new protocol for management for children with spontaneous VAD.They noted 2 different configurations of the vertebral artery. In this study we go on the explore these different configurations further and their role in spontaneous VAD. Aim &amp; Hypothesis: Two configurations of the vertebral artery at the V3 segment were observed. Type A and Type B depending on the angle of curvature of the V3 segment. Type A config. is more linear with &gt; 110 degree of angulation. Type B config. is angulated with 2 &lt; 110 degree angles. We aim to investigate these configurations in patients without dissection vs those with vertebral artery dissection. We hypothesized that Type B configuration would be more prevalent in patients with spontaneous VAD. Methods: Retrospective chart review conducted at UTSW medical center. MRA/IR angiograms reviewed of 49 patients; 19 with spontaneous VAD and 30 with no vertebral pathology. Results: 79% of the total dissected vessels(19/24) had configuration Type B and 20.83%(5/24) had configuration Type A. In the control group of 30 patients with no VAD, TypeB was present in 25.4%(13/51) and configuration A in 74.5% (38/51). Type B configuration had a statistically significant higher prevalence in V3 dissection group. (p=&lt;0.001) Conclusion: Type B configuration of the V3 segment would warrant further investigation in the right setting.