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).

Association between cervicocerebral artery dissection and tortuosity - a review on quantitative and qualitative assessment.

Cervicocerebral artery dissection stands out as a significant contributor to ischemic stroke in young adults. Several studies have shown that arterial tortuosity is associated with dissection. We searched Pubmed and Embase to identify studies on the association between arterial tortuosity and cervicocerebral artery dissection, and to perform a review on the epidemiology of cervicocerebral artery tortuosity and dissection, pathophysiology, measurement of vessels tortuosity, strength of association between tortuosity and dissection, clinical manifestation and management strategies. The prevalence of tortuosity in dissected cervical arteries was reported to be around 22%-65% while it is only around 8%-22% in non-dissected arteries. In tortuous cervical arteries elastin and tunica media degradation, increased wall stiffness, changes in hemodynamics as well as arterial wall inflammation might be associated with dissection. Arterial tortuosity index and vertebrobasilar artery deviation is used to measure the level of vessel tortuosity. Studies have shown an independent association between these two measurements and cervicocerebral artery dissection. Different anatomical variants of tortuosity such as loops, coils and kinks may have a different level of association with cervicocerebral artery dissection. Symptomatic patients with extracranial cervical artery dissection are often treated with anticoagulant or antiplatelet agents, while patients with intracranial arterial dissection were often treated with antiplatelets only due to concerns of developing subarachnoid hemorrhage. Patients with recurrent ischemia, compromised cerebral blood flow or contraindications for antithrombotic agents are usually treated with open surgery or endovascular technique. Those with subarachnoid hemorrhage and intracranial artery dissection are often managed with surgical intervention due to high risk of re-hemorrhage.

Duplication of right vertebral artery in Klippel-Feil anomaly.

The duplicated origin of the vertebral artery (VA) is an uncommon anatomical variant, which is generally identified incidentally during angiography and can be misdiagnosed as dissection in the setting of posterior circulation stroke. Here, we describe a case of the right V1 VA duplication with embryological aspects in a patient with Klippel-Feil anomaly, which was diagnosed during preoperative evaluation. Surgeons must be aware to avoid vascular injury from a duplicated VA before head-neck and spinal surgery.

[Anatomical Variations to the Vertebral Artery and Posterior Inferior Cerebellar Artery are Associated with the Partial Persistence of Primitive Lateral Basirovertebral Anastomosis].

The angioarchitecture of the hindbrain is homologous to that of the spinal cord, and its vascular system can be analyzed at the longitudinal and axial structures. During embryonic development, there are two main longitudinal arteries: the longitudinal neural artery and the primitive lateral basilovertebral anastomosis. Commonly observed variations are formed by the fenestration and duplication of either the vertebrobasilar artery, or cerebellar artery, which can be observed when the primitive lateral basilovertebral anastomosis partially persists. Understanding the pattern and development of blood supply to the hindbrain provides useful information of various anomalies in the vertebrobasilar junction and cerebellar arteries.

[Persistent Primitive Arteries].

Primitive anastomotic arteries temporarily exist between the future internal carotid and vertebrobasilar arteries during the early embryonic period(between 28 and 32 days of life). The primitive trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries serve as major blood channels to the developing vertebrobasilar circulation at this stage. These arteries are replaced by the posterior communicating and vertebral arteries, and the primitive anastomotic arteries rapidly regress following the development of the definitive vertebrobasilar circulation. Occasionally, these primitive anastomoses persist and are incidentally discovered after birth. Physicians who treat cerebrovascular diseases should be familiar with the anatomy and functions of these vessels. In this review, we discuss the embryonic basis of the carotid-vertebrobasilar anastomoses and the clinical significance of their persistent forms in adults.

Bilateral Variation of the Vertebral Artery: Report of a Case and its Clinical Implication / Variación Bilateral de la Arteria Vertebral; Reporte de un Caso y su Implicancia Clínica

SUMMARY: There are many reports on anatomical variations of the vertebral arteries, which may be related to origin, trajectory, caliber, and side. Bilateral variations are less frequent, however, and less common are bilateral variants that differ from each other. The aim of this work was to report the presence of a bilateral variation of the vertebral artery and its functional and clinical implications. Dissection of a female cadaver, fixed in 10 % buffered formaldehyde, which had not undergone any previous surgeries in the study area and had anatomical variations in both vertebral arteries. In each one, follow-up was done from its origin to its end, determining its trajectory, diameters, branching, and anatomical relations. A left vertebral artery was found, starting in the aortic arch and making a sinuous trajectory of 4 curvatures to enter the transverse foramen of C4. The right vertebral artery began as the first branch of the subclavian artery. Its initial trajectory was rectilinear, followed by a right concave curve, a 360° loop that included a second ascending curve, and ended straight before entering the transverse foramen of C6. The coexistence of bilateral variations in the vertebral arteries is possible. This atypical situation can potentially generate vascular and neurological pathologies, but with different symptoms and causes. Knowing these variations and deliberately searching for them will enable the specialist to make a suitable differential diagnosis.

Existen múltiples reportes sobre variaciones anatómicas de las arterias vertebrales, las que se pueden relacionar con origen, trayecto, calibre y lateralidad. Sin embargo, las variaciones bilaterales son menos frecuentes, y menos común es que las variantes bilaterales sean diferentes entre ellas. El objetivo de este trabajo fue reportar la presencia de una variación bilateral de la arteria vertebral y su implicancia funcional y clínica. Disección en un cadáver de sexo femenino, fijado en formaldehido tamponado al 10 %, el cual no presentaba intervenciones quirúrgicas previas en la región de estudio y que tenía variaciones anatómicas en ambas arterias vertebrales. En cada una se realizó seguimiento desde su origen hasta su terminación, pudiendo determinar su trayecto, diámetros, ramificaciones y relaciones anatómicas. Se encontró una arteria vertebral izquierda originada en el arco aórtico, que realizaba un trayecto sinuoso de 4 curvaturas e ingresaba al foramen transverso de C4. La arteria vertebral derecha se originaba como primera rama de la arteria subclavia. Su trayecto inicial era rectilíneo seguido por una curva de concavidad derecha, un loop (giro) de 360° que incluía una segunda curva ascendente y terminaba en dirección recta antes de ingresar al foramen transverso de C6. La coexistencia de variaciones bilaterales en las arterias vertebrales es posible. Esta situación atípica, potencialmente puede generar en la persona patologías neurológicas de origen vascular, pero con sintomatología y causas diferentes. Conocer estas variaciones y realizar una búsqueda intencionada de ellas permitirá el especialista realizar un adecuado diagnóstico diferencial.

Multidetector computed tomography evaluation of origin, V2 segment variations and morphology of vertebral artery.

BACKGROUND: The current study aimed to determine the origin of vertebral artery (VA) on both sides and the levels of entry into respective foramen transversarium (FT), to evaluate possible effects of sex on the entry levels, and to investigate the frequency of VA dominance and VA hypoplasia based on the VA V2 segment. MATERIALS AND METHODS: For this study, archived images of patients undergoing multidetector computed tomography (MDCT) examination of the chest and headneck for various reasons at Gaziantep University Medical Faculty Hospital were reviewed retrospectively. Three-dimensional reconstructions were performed for a total of 644 VA images from 322 patients using Horos software, and VA origin, the level of entry to FT and transverse diameters of both VA and FT were measured at the point of entry. RESULTS: It was found that, among males, the VA originated from the truncus brachiocephalicus on the right side in only 1 patient and from the aortic arch in 2 patients on the left side. Left VA emerging from the aortic arch was observed in 2 females. The right VA was found to enter the FT at C3 in 1 male, at C4 in 6 patients (5 males, 1 female), at C5 in 19 patients (3 males, 16 females), and at C6 in 300 patients (141 males, 159 females). The left artery entered the FT at C5 in 23 patients (9 males, 14 females) and at C6 in 298 patients (141 males, 157 females). Looking at the relationship between variations of VA origin and the levels of entry to the FT, it was observed that only one of the left VAs originating from the arcus aorta entered the FT at C6 and at C5 in all others. On the right side, there was only one VA originating from the truncus brachiocephalicus, which entered the FT at C3. Of the remaining 248 VAs originating from the subclavian artery, 5 VAs entered the FT at C4, 14 VAs at C5 and 229 VAs at C6. The measurements of VA diameters showed right VA hypoplasia in 14 patients and left VA hypoplasia in 17 patients. Also, the right VA dominance was found in 110 patients and the left VA dominance in 128 patients. A moderate, positive correlation was observed between VA and FT diameters in both sides. A regression analysis showed that a 1 mm change in the right VA diameter was associated with a 75% change in the FT diameter and a 1 mm change in the left VA diameter caused a 72% change in the FT diameter. CONCLUSIONS: An understanding of VA variations and FT morphometry is crucial for informed clinical practice. This will clearly affect the success rates of physicians in the diagnosis and treatment of pathologies involving cervical region. The presence of any VA variation in a patient should be investigated on computed tomography or magnetic resonance imaging images prior to surgery.

Combined unusual origin and course of the right vertebral artery and right inferior thyroid artery: a case report.

PURPOSE: An unusual unilateral origin and course of the prevertebral part of the right vertebral artery and anomalous course of the right inferior thyroid artery was observed during dissection of the neck of a cadaver. METHODS: An accidental finding in the cadaver within the anatomical dissection was assessed. RESULTS: The right vertebral artery originated a nonstandard from brachiocephalic trunk and travelled in the anterior cervical region, along the longus colli muscle in front of the transverse processes from C7 to C4, and it entered the transverse foramen of C3. During its course, the position of the right inferior thyroid artery varied: it turned medially and passed posterior to the vertebral vessels and later curved inferomedially to its termination. Additionally, the left vertebral artery of the same cadaver arose directly from the subclavian artery and entered the transverse foramen at C6, and the left inferior thyroid artery passed anterior to the vertebral artery. CONCLUSION: Variation in the vertebral artery and inferior thyroid artery alone have been reported, but a combined variation is rare. The anatomical information from this study will be useful during dissection, angiography, endovascular surgery, thyroidectomy and non-invasive procedures in the cervical region.

Arterial abnormalities and associated variations of the vertebrobasilar system on the brain base: apropos of a rare case / Anomalías arteriales y variaciones asociadas del sistema vertebrobasilar en la base del cerebro: un caso raro

SUMMARY: The presented case characterizes an association of primitive and definitive arteries with variations on the cadaveric brain base of a very old man. This case is found by the retrospective review of the data archive obtained during many years of cooperation of the author and co-authors. Fenestration of the (ectatic) basilar artery, partial and total duplication of some cerebellar arteries was associated with other variations of the vertebrobasilar and carotid systems. Although this is a case autopsied because of the myocardial infarction, the peculiarity of the case lies in the absence of the aneurysm based on the fenestration or dissection of one of the cerebral arteries.

RESUMEN: El caso presentado caracteriza una asociación de arterias primitivas y definitivas con variaciones sobre la base cerebral cadavérica de un anciano. Este caso se encuentra mediante la revisión retrospectiva de datos obtenidos durante muchos años de un trabajo de cooperación del autor y coautores. La fenestración de la arteria basilar (ectásica), la duplicación parcial y total de algunas arterias cerebelosas se asoció con otras variaciones de los sistemas vertebrobasilar y carotídeo. Si bien se trata de un caso de autopsia a causa de un infarto del miocardio, la peculiaridad del caso radica en la ausencia del aneurisma en base a la fenestración o disección de una de las arterias cerebrales.

Aberrant right subclavian artery with right type 1 proatlantal artery and segmental dysplasia of the right internal carotid artery: a case report.

PURPOSE: We present a case of an aberrant right subclavian artery (ARSA) with extremely rare vascular anomalies. CASE REPORT: A 69-year-old woman was suspected to have right internal carotid artery (ICA) stenosis. Computed tomography angiography demonstrated an ARSA and hypoplasia of the right ICA. The proximal segment of the right vertebral artery (VA) was aplasia, and a right type 1 proatlantal artery (PA) arose from the right common carotid artery. Cerebral angiography demonstrated segmental dysplasia of the right ICA. The ascending intrapetrous segment and the ascending foramen lacerum-horizontal intracavernous segment of the right ICA demonstrated hypoplasia. The collateral pathways promoted reconstitution of each of the distal segments. Left internal carotid angiography demonstrated anterior communicating artery aneurysm and sufficient cross flow to the contralateral middle cerebral artery via the AcomA. DISCUSSION: A type 1 PA with an ARSA may result in the regression of the right dorsal aorta with persistence of the first cervical intersegmental artery. Although there are few findings of a relationship between an ARSA and intracranial artery anomalies, a developmental error of the right dorsal aorta may cause such complex vascular anomalies. CONCLUSION: Knowledge of anatomical variations in patients with ARSA is useful when performing angiography or endovascular therapy, as well as during clinical follow-up.

Total arch replacement with the frozen elephant trunk technique for a right-sided aortic arch with a Kommerell diverticulum and aberrant right vertebral artery.

The best treatment for a right-sided aortic arch (RAA) and Kommerell diverticulum (KD) has not been determined due to the rarity of these conditions. The current trend in the treatment of this disease is to increase the endovascular approach without a sternotomy. We describe a rare condition with an association of an RAA with a KD of an aberrant left subclavian artery and an anomalous right vertebral artery originating from the aortic arch (AVA). The left vertebral artery was missing. Also, there was an incomplete circle of Willis due to the absence of the left and right posterior communication arteries. Therefore, the AVA was the only artery to supply the vertebral-basilar system. In our case, a simple thoracic endovascular aortic repair was not suitable because of the sharply curved arch and short landing zone. Also, a debranching thoracic endovascular aortic repair was not appropriate because that approach would not permit reconstruction of the AVA. The patient successfully underwent a total arch replacement with the frozen elephant trunk technique. This procedure could be an effective option for patients with RAAs with KDs associated with another arch vessel anomaly.

Isolated atlas-duplication as a manifestation of persistent proatlas: a case report.

PURPOSE: Atlas-duplication is an exceedingly rare dysplasia of the craniocervical junction. To the best of our knowledge, only two cases of atlas-duplication have been reported and these were associated with complete anterior rachischisis and os odontoideum. We aimed to report a case of isolated atlas-duplication of incidental finding and without attributable symptoms which makes it unique. METHODS: Following a normal coronarography for a suspected myocardial infarction, a 60-year-old-man with no significant medical history developed a transient ischemic attack that justified brain computed-tomography angiography. RESULTS: There was no evidence for cerebral ischemic lesion, intracranial occlusion or significant artery disease. Bone analysis revealed eight cervical vertebral segments with an additional vertebral level located between the occiput and the atlas. This vertebra presented all the morphological characteristics of an atlas vertebra except for hypoplasia of the left transverse process. An incomplete anterior rachischisis was associated, and there was no other abnormality of craniocervical junction. The clinical examination revealed no neck pain, no limitation of joint amplitude and no neurological deficit. Apart from preventive treatment of ischemic stroke, no orthopedic or surgical treatment was undertaken. After 1.5 years of radiological monitoring, the patient remains symptom-free. CONCLUSIONS: Atlas-duplication is an exceedingly rare dysplasia of the craniocervical junction that may be found isolated and incidentally. If this variation does not necessarily warrant specific treatment, brain CT angiography is recommended to detect anatomical variations of the vertebral arteries.

Anterior artery release, distraction and fusion (ARDF) for radiculopathy caused by a vertebral artery loop.

BACKGROUND: Anomalous vertebral artery (VA) with loop formation is a rare cause of cervical nerve root compression. Various techniques with anterior and posterior approaches have been described for surgical treatment once conservative treatments fail. We herein present a case treated with the new technique of anterior release, distraction and fusion (ARDF) and further provide an updated review of surgically managed VA loops in the subaxial spine. CASE DESCRIPTION: A 76-year-old female complained of a 6-year history of pulsating, shooting pain in her right arm to the thumb. After obtaining repeated MRI, the VA loop compressing the right-sided C6-nerve root was detected. A neurovascular decompression through ARDF which led to an indirect loop straightening was performed. The patient immediately improved after surgery and remained pain-free 1 year postoperative. CONCLUSION: Neural irritation due to VA loop formation is a rare cause of cervical radiculopathy. While various surgical strategies have been described, we believe that anterior and anterolateral approaches are the safest to yield neurovascular decompression. We described and documented ARDF (anterior VA release, intervertebral distraction and fusion) on a patient case. LEVEL OF EVIDENCE: II (Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding).

Can Intracranial Vertebral Artery Hypoplasia be an Etiopathogenetic Factor for Barré-Licou Syndrome Other than Arcuate Foramen? A Retrospective Clinical Study and Review of Literature.

AIM: To investigate the co-occurrence of the arcuate foramen (AF) variation of atlas and intracranial vertebral artery (V4) hypoplasia and, therefore, to understand the pathophysiology of Barré-Licou syndrome (BLS). The AF localizes on the vertebral artery (VA) sulcus posterior to the atlas and has incomplete and complete types. Complete-type AF can exert pressure on the VA that passes through it, resulting in vertebrobasilar insufficiency finding, a BLS component. By the surgical decompression of VA at the AF level, complaints could be decreased in some cases. However, a reliable theory regarding BLS has not yet been established; therefore, the cases that do not respond to AF decompression have not been fully elucidated. We assumed that V4 hypoplasia that accompanies AF might be the main factor in the pathophysiology of BLS. MATERIAL AND METHODS: Cervical computed tomography and magnetic resonance angiography images of 139 patients aged 14?88 years with head and neck pain and dizziness were retrospectively evaluated. RESULTS: Of the patients, 19.4% exhibited complete AF and 32.4% exhibited VA hypoplasia (VAH); 10% of the patients with VAH had accompanying contralateral complete AF variation. There was no significant relationship between complete AF and contralateral and ipsilateral VAHs (right side: p=0.527 and p=0.433, respectively; left side: p=1.000 and p=0.740, respectively). CONCLUSION: Our findings indicate that V4 hypoplasia is not the main factor of BLS pathophysiology. Furthermore, the rarity of the relationship suggests why some cases do not respond to decompressive surgery.

Endovascular treatment of vertebro-vertebral arteriovenous fistula in neurofibromatosis type I: A report of two cases and literature review with a focus on endovascular treatment.

Vertebro-Vertebral arteriovenous fistula (VV-AVF) associated with neurofibromatosis Type I (NF-1) is rare. We presented two female NF-1 patients with a diagnosis of VV-AVF treated with endovascular approach. The fistula was completely obliterated with balloon assisted embolization and covered stent separately and VA patency was preserved in both cases. Reviewing the literature with a focus on endovascular treatment, endovascular occlusion of VV-AVF in NF-1 patients is safe and effective. To preserve the parent VA patency and obliterate the fistula simultaneously is challenging generally, but feasible in some cases.

Variations of the extracranial segment of vertebral artery as a bleeding risk factor.

BACKGROUND: Standart interventional procedures such as screw instrumentation, aortic arch endovascular surgery and cervical nerve blockade may be of fatal risk due to anatomic reason of variations in the proximal part of the vertebral artery (VA). The aim of this study is to study the VA variations of the extracranial segments to evaluate the frequency of the incident to demonstrate the importance of clinical condition strategy. METHODS: The prevalence of variations and morphometric measurements of the VA in three-dimensional computed tomographic angiography (3D-CTA) scans were studied. Total 400 VA was investigated for the aortic arch origin of the VA, diameter of the VA, its level of entry into the transverse foramen, the dominance sides, and related basilar artery course. RESULTS: 3D-CTA radiographs of 200 Anatolian patients (120 men and 80 women with age range 17-90 years). In most cases (approximately 94%), both sides of VA were the first branch of subclavian artery. While all the right VAs was branched from the subclavian artery, 6% of the left VAs were branched from the aortic arch. 2/3 of them originated from the proximal of the subclavian artery and 1/3 from the distal. The VA which were originating from the proximal of the classical anatomic pattern tended to enter the transverse foramen more distally than C6 level. VAs with a different level of entry than C6 are left-sided and aortic arch originated (out of 8 cases 3 had a level of entry at C5 and 2 at C4). The outer diameter ranges of the prevertebral part of the VA of subclavian origin and left VA of aortic arch origin were 3.2-3.6 mm and 3.2-3.6 mm, respectively. While the diameters of the right and left VAs were almost the same in approximately 20% cases, the left VA was dominant in up to 60% of cases. A significant relationship was found between the side of the dominant VA and in the course of the basilar artery. CONCLUSIONS: The relationship between the dominant side of VA and the course of the basilar artery of its own vessel has never been reported elsewhere. Such anatomical variations, routine preoperative 3D-CTA evaluation is mandatory to prevent the VA injury when C5-C2 instrumentation, anterior cervical decompression, cervical nerve blockade and aortic arch surgery are planned.

Non-Dolichoectatic Vertebral Artery Compression of the Medulla: A Comprehensive Literature Review.

OBJECTIVE: Vertebral artery compression of the medulla is a rare vascular finding that causes a variety of clinical presentations, from asymptomatic to neurological disability. This article presents the largest literature review to date on medullary compression of the vertebral arteries. METHODS: An English literature search was performed using the PubMed database and the keywords vertebral artery tortuosity, vertebral artery compression, and medullary compression. RESULTS: A comprehensive literature search yielded 68 patients (57% male) with medullary compression by an intracranial vertebral artery (ICVA). The left side of the medulla was compressed in 44, the right side in 19, and bilateral in 7. The most common clinical symptom was weakness - 26 patients (36%) - 6 had quadriparesis and 6 had hemiparesis. 21 patients reported imbalance; 12 various sensory symptoms; 4 patients were asymptomatic. CONCLUSIONS: Understanding the anatomy of the vasculature can help mitigate future debilitating stroke symptoms. Concrete guidelines for revascularization surgery in symptomatic patients may also be effective. Future studies are needed to further clarify the prevalence, natural history, vascular etiology, and treatment of this condition, including asymptomatic patients and the likelihood that they will develop further neurological signs and disability.

An anatomical investigation of the proximal vertebral arteries (V1, V2) in a select South African population.

INTRODUCTION: The most common type of vascular complication during cervical spine surgery is the vertebral artery (VA) injury. The presence of anatomical variation in the artery's morphology has been a significant factor for arterial injury during surgery. Therefore, physicians planning interventions in the craniospinal region need to be aware of the extents of variations. In addition to vascular injury, anatomical variations can predispose to some pathologies in the posterior circulation territory. To provide useful data to interventional radiologists, anatomists, and surgeons, we evaluated the anatomical features of the V1 and V2 segments of the VA in a South African population. MATERIALS AND METHODS: The study is an observational, retrospective chart review of 554 consecutive South African patients (Black, Indian and White) who had undergone computed tomography angiography (CTA) from January 2009 to September 2019. RESULTS: The VA exhibited morphological variation in its course. We report the incidence of variant origin of the left VA, all from the aortic arch. Variation in the level of entry into the transverse foramen ranged between C7 and C3. A left dominant pattern was observed; we also report on hypoplasia of the VA. In addition, we report incidence of VA tortuosity at V1, V2 to be 76.6% and 32.1%, respectively. CONCLUSIONS: The baseline data established in this study regarding the diameter, variant origin, and level of entry into the transverse foramen will assist neurosurgeons and interventional radiologists in interpreting, diagnosing, and planning and executing various vascular procedures and treatment of pathology in the vicinity of the VA.

Right vertebral artery entering the third transverse foramen diagnosed by magnetic resonance angiography: a report of two cases.

The vertebral artery (VA) usually enters the sixth transverse foramen (TF). The VA sometimes enters the fifth, and rarely enters the fourth or seventh TF. Reports describing a VA entering the third TF, identified by anatomical dissection or computed tomography angiography, are extremely rare. We herein report two cases in which magnetic resonance (MR) angiography showed the right VA entering the third TF. Coronal reformatted MR angiography source images were useful for identifying the level at which the VA entered the TF. Because the anomalous VA takes an anterior course, it poses a risk during anterior neck surgery. Thus, a correct diagnosis is important when interpreting cervical MR angiography.

Computed tomographic angiography to analyze dangerous vertebral artery anomalies at the craniovertebral junction in patients with basilar invagination.

OBJECTIVE: Failure to detect dangerous anatomic vertebral artery anomalies (AVAAs) and dangerous functional vertebral artery anomalies (FVAAs) at the craniovertebral junction (CVJ) in patients with basilar invagination (BI) can result in major complications such as intraoperative vertebral artery injury, brain infarctions, and even death. Iatrogenic vertebral artery injury is a rare but severe complication of cervical spine surgery. We aimed to evaluate dangerous vertebral artery anomalies at the CVJ in patients with BI using computed tomographic angiography (CTA). METHODS: CTA images of 61 BI patients were retrospectively analyzed to evaluate AVAAs and FVAAs at the CVJ. Dangerous AVAAs include a persistent first intersegmental artery (FIA), fenestration of the vertebral artery (FEN), and posterior inferior cerebellar artery with an extradural C1/2 origin (PICA-C1/2). Dangerous FVAAs include a dominant vertebral artery (DVA) and hypoplastic vertebral artery ending in the PICA (HVA-PICA) without joining the basilar artery. RESULTS: Overall, 31 female and 30 male patients (mean age, 42.3 years) were included. The incidences of FIA, FEN, and PICA-C1/2 were 29.5 % (18/61), 3.3 % (2/61), and 3.3 % (2/61), respectively, whereas the incidences of DVA and HVA-PICA were 36.1 % (22/61) and 1.65 % (1/61), respectively. CONCLUSION: Dangerous vertebral artery anomalies at the CVJ have a high incidence in patients with BI. Preoperative CTA is highly recommended in such patients to identify anomalous vertebral arteries and reduce the risk of intraoperative injury.