The segmentation of the vertebral artery: An ambiguous anatomical concept

The course of the vertebral artery from its subclavian artery origin up to its termination at the vertebrobasilar junction is divided into four segments (V1–V4). This segmentation, based on schemes that have evolved since the late nineteenth century, should be a consistent and reproducible anatomical concept. However, the current literature offers conflicting definitions of that scheme, not infrequently within a single article or monograph. The principal inconsistency found in modern publications concerns the termination of the V2 segment, which is either set at the C2 or C1 transverse foramen depending on the scheme considered. Consequently, the portion of the vertebral artery extending between C2 and C1—a frequent site of pathological involvement—either belongs to the V2 or V3 segment. This discrepancy can affect the validity of studies evaluating the diagnosis and management of vertebral artery disorders. A V3 segment extending from the transverse foramen of C2 to the posterior atlanto-occipital membrane and subdivided into vertical, horizontal, and oblique subsegments—a pattern suggested by Barbieri in 1867 and adopted in some modern publications—would provide a simple, precise, and reliable solution without significantly altering the widely accepted division of the vertebral artery into four segments (V1–V4).

Kraniovertebral Bileşke Kemiklerinin Morfometrik Özellikleri

Introduction: The craniovertebral junction comprises the occipital bone, atlas, axis and supporting ligaments. Surgical interventions for treatment of instability, require knowledge of morphometric properties of this area. Therefore, the aim of the present study was to evaluate adult dried human skulls to analyze morphometric features of the bones that joined the craniovertebral junction. Materials and Methods: Morphometric analysis was performed on dry bones which found in the excavations. 9 occipital bone, 18 atlas and 16 axis were measured. Differences between measurements were determined using t-tests and were considered significant at p<0.05. Results: The distance between both tips of the transverse processes (p<0.001), the distance between both outermost edges of the transverse foramen (p=0.011), the distance between both innermost edges of the transverse foramen (p=0.013), the maximum transverse diamater of the vertebral canal (p=0.014), the maximum anteroposterior diameter of the vertebral canal (p=0.014) and the width of the inferior articular facet (left p<0.001 and right p=0.005) were found significantly shorter in females atlases. The width of the dens axis (p<0.001), the height of the corpus axis (p=0.034), the distance from lateral most edge of the transvers process to midline (left p=0.049), the length of the inferior articular facet (left p=0.004, right p=0.005), the width of the superior articular facet (right p=0.007) were found significantly shorter in females axises. Conclusion: Morphometric analysis is very important in the development and improvement of surgical techniques. In this context, the results of our study can contribute to developments in this area. Keywords: Atlas, axis, occipital bone, craniovertebral junction

Bilateral typeIIpersistent proatlantal intersegmental artery: a rare variant of persistent carotid-vertebrobasilar anastomoses

The persistent proatlantal intersegmental artery is a rare variant of persistent carotid-vertebrobasilar anastomoses, especially their bilateral presence is rarer. We report a case of bilateral typeII persistent proatlantal intersegmental artery. The absence of bilateral vertebral arteries was incidentally noted on neck ultrasound examination. Subsequent time-of-flight MR angiography confirmed this. The bilateral typeIIpersistent proatlantal intersegmental artery arose from the cervical external carotid artery, penetrated the C1 transverse foramen, entered the skull via the foramen magnum, and joined the lower portion of the basilar artery.

Morphometric Analysis of V2 Segment of Vertebral Artery in Patients with Symptomatic Neck Pain in South Indian Population – A CT Angiography Based Study

Objectives: The morphometric changes in the vertebral artery are essential for various interventions. Inadequate details about it can lead to risk of vertebral artery injury and other complications. This study explains the normal anatomical course of V2 segment of vertebral artery which is more prone for iatrogenic injury. Materials and Method: 25 adult patients with symptomatic neck pain were involved in the study. Various measurements were made from seventh cervical vertebra (C7) to the third cervical vertebra (C3) that included Distance from midline to VA, Distance from medial margin of Longus Colli to VA, Perpendicular distance from anterior margin of transverse process to center of VA, Horizontal distance from anterior tubercle to VA, sagittal and coronal diameter of the transverse foramen and vertebral artery. Result: Distance from midline, Distance from medial margin of Longus Colli, Perpendicular distance from anterior margin of transverse process to center of VA and Horizontal distance from anterior tubercle were increased towards right compared to left side. The sagittal and coronal diameter of the transverse foramen and vertebral artery decreased from C6 to C3 vertebra. Vertebral artery dominance was seen on left side in all cases. Conclusion: Preoperative assessment by computed tomography angiography helps to know the course of the vertebral artery, understand its patterns and assess various abnormalities thereby aids in preventing complications in future surgeries.

Paravertebral foramen screw fixation for posterior cervical spine surgery: clinical case series

OBJECTIVE The goal of this study was to clarify the clinical utility of paravertebral foramen screws (PVFSs) and to determine intraoperative indicators for appropriate screw placement during posterior cervical fusion surgery to improve its safety. METHODS The authors included data from 46 patients (29 men and 17 women, mean age 61.7 years) who underwent posterior cervical spine surgery with 94 PVFSs. Of the 94 PVFSs, 77 were used in C6, 9 in C3, 5 in C4, and 3 in C5. According to the cervical lateral radiographic view, the authors divided the 94 PVFSs into 3 groups as follows: a longer group, in which the tip of PVFS was located anteriorly from the line of the posterior wall of the vertebral body (> +0 mm); an intermediate group, in which the screw tip was located up to 2 mm posteriorly to the posterior wall of the vertebral body (–2 to 0 mm); and a shorter group, in which the screw tip was located more than 2 mm posteriorly (< –2 mm). The accuracy of screw placement was assessed using CT imaging in the axial plane, and the proportion of screws penetrating a vertebral foramen or a transverse foramen was compared between the 3 groups. Screw loosening was defined as a lucent zone around the screw evaluated on cervical radiography at 1 year after surgery. Complications related to PVFS insertion and revision surgery related to PVFS were evaluated. RESULTS The authors classified 25 PVFSs into the longer group, 43 into the intermediate group, and 26 into the shorter group. The proportion of screws penetrating a vertebral foramen was largest in the shorter group, and the proportion penetrating a transverse foramen was largest in the longer group. Screw loosening was confirmed for 3 of 94 PVFSs. One PVFS inserted in C6 unilaterally within a long construct from C2 to C7 showed loosening, but it did not cause clinical symptoms. Revision surgery was required for 2 PVFSs inserted in C3 bilaterally as the lower instrumented vertebra in occiput–cervical fusion because they pulled out. There was no neurovascular complication related to PVFS insertion. CONCLUSIONS PVFSs are useful for posterior cervical fusion surgery as alternative anchor screws, and the line of the posterior wall of the cervical body on lateral fluoroscopic images is a potential intraoperative reference to indicate an appropriate trajectory for PVFSs.

A comparative shape analysis of the cervical spine between individuals with cervicogenic headaches and asymptomatic controls

As some researchers theorized that cervicogenic headache (CEH) might be related to bony and discal features of the cervical spine, this retrospective study examined the shapes of the cervical vertebrae and intervertebral discs (IVDs) of individuals with CEH and compared them to asymptomatic controls. Scans of 40 subjects in their late 20’s–mid 30’s affected with CEH and 40 asymptomatic controls were obtained (overall = 19,040 measurements, age-sex matched, 20 males and 20 females in each group). The following cervical spine variables were measured: Supine lordosis, vertebral body-heights, A-P lengths, mediolateral widths and sagittal-wedging; IVDs heights and sagittal-wedging; pedicle heights, widths and transverse angles; laminar widths and transverse angles; articular facet angles, spinal canal, and transverse foramen lengths, widths, and areas. Both groups had similar shape variation along the cervical in all the measured parameters. There were no significant left–right differences in all measured parameters and no significant differences between the CEH and control groups concerning sex and age. Cervical IVDs were lordotic in shape, whereas their adjacent vertebral bodies were kyphotic in shape except for C2. In conclusion, the shape of the cervical spine and IVDs in subjects in their late 20’s–mid 30’s affected with CEH is identical to asymptomatic controls.

High-Entry Vertebral Artery Variant during Anterior Cervical Discectomy and Fusion

Anterior surgical approaches to the cervical spine have allowed for treatment of common and complex pathologies with excellent outcomes. During the approach, complications can result from injury to the surrounding structures. The transverse processes usually protect the vertebral artery (VA) as it enters at C6 and courses cranially through the transverse foramina to C2 (referred to as the V2 segment). This is a case report of a patient who presented with myeloradiculopathy attributed to a C4-C5 disc herniation, severe canal stenosis, and marked bilateral neural foraminal stenosis. Preoperative imaging showed the right VA entering the C4 transverse foramen. This anatomic variant on a routine MRI led to further imaging and precautions when performing an uneventful anterior cervical discectomy and fusion (ACDF) at C4-C5. A high VA entry point into the transverse foramen above C6 could increase the risk of iatrogenic vascular injury in anterior approaches to the cervical spine. Rarely reported, the currently presented case describes a patient with a C4 right VA entry variant and highlights the importance of proper surgical planning.

Mild trauma causing cervical fracture through transverse foramen leading to a vertebral arteriovenous fistula

Vertebral arteriovenous fistula (vAVF) is an uncommon vascular disease defined as abnormal connections between the vertebral artery or its branches extracranially with nearby venous structures. This case report outlines the case of a man in his late 70s presenting with C1–C3 fractures after a mild trauma falling down a small staircase. CT angiogram (CTA) gave suspicion of vertebral artery dissection and pseudoaneurysm; however, digital subtraction angiography revealed a fracture-induced vAVF successfully treated endovascularly with coils. In conclusion, cervical fractures involving the transverse foramen regardless of trauma mechanism should result in a CTA. Endovascular treatment with ipsilateral vertebral artery closure is preferred due to its feasibility and safety.

Evaluation of tortuous vertebral arteries before cervical spine surgery: illustrative case

BACKGROUND Cervical spine surgery sometimes necessitates complex ventral/dorsal approaches or osteotomies that place the vertebral artery (VA) at risk of inadvertent injury. Tortuosity of the VA poses increased risk of vessel injury during anterior decompression or placement of posterior instrumentation. OBSERVATIONS In this report, the authors describe a patient with degenerative cervical spondylotic myelopathy and focal kyphotic deformity requiring corrective surgery via a combined ventral/dorsal approach. Computed tomography (CT) and CT angiography (CTA) of the spine identified a left medially enlarged C4 transverse foramen and tortuous VA V2 segment forming a potentially dangerous medial loop into the vertebral body, respectively. The patient’s presentation and management are described. LESSONS The course of the VA is variable, and a tortuous VA with significant medial or lateral displacement may be dangerous during ventral and dorsal approaches to the cervical spine. CTA of the cervical spine is warranted in cases in which atlantoaxial fixation is needed or suspicious transverse foramen morphology is identified to understand the course of the VA and identify anatomical variations that would put the VA at risk during cervical spine surgery.