Early Localization of the Third Segment of the Vertebral Artery: The Atlanto-Mastoid Line

An In-Depth Analysis of the Artery of Salmon: Anatomy and Neurosurgical Implications

BACKGROUND

Michel Salmon was a prominent person in the field of plastic surgery during the early 20th century. His pioneering work contributed significantly to our understanding of human anatomy, particularly with the identification of the artery of Salmon (AOS). The objective of this study is to thoroughly investigate the AOS by conducting a comprehensive literature review, providing insights into its anatomy and surgical implications.

METHODS

This review was undertaken after a thorough examination of literature encompassing papers about the AOS. Right up until January 2024, databases like PubMed, ScienceDirect, and Web of Science were explored. The search was conducted using specific terms such as "Artery of Salmon," "suboccipital artery," and "vertebral artery anatomy." An in-depth assessment was conducted to examine the anatomy, and surgical significance of the AOS.

RESULTS

The AOS is a branch of the V3 segment of the vertebral artery that supplies the suboccipital muscles. The ability, to identify it, is critical for distinguishing the origins of intraoperative hemorrhage. Through careful surgical intervention, the artery was able to devascularize tumors and vascular lesions. We also touched on the technical issues of its possible application in bypass operations for aneurysms of the posterior inferior cerebellar artery or vertebral artery.

CONCLUSIONS

The AOS is sometimes vital in neurosurgery, facilitating precise interventions and serving as a conduit in suboccipital bypass surgeries. Understanding its variations is essential for neurosurgeons, showcasing ongoing advancements in patient care.

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

OBJECTIVE

The 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 METHODS

The 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.

RESULTS

In 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.

CONCLUSION

We 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.

Vascular reconstruction related to the extracranial vertebral artery: the presentation of the concept and the basis for the establishment of the bypass system

The intracranial vertebrobasilar artery system has a unique hemodynamic pattern (vessel trunk converged bilateral flow with three groups of perforators directly arising from it), is embedded within intense osseous constraints, and is located far from conventional donor vessels. Two major traditional modalities of posterior circulation revascularization encompass the superficial temporal artery to the superior cerebellar artery and the occipital artery to the posteroinferior cerebellar artery anastomosis, which are extracranial-intracranial low-flow bypass with donor arteries belonging to the anterior circulation and mainly supply focal perforators and distal vascular territories. As our understanding of flow hemodynamics has improved, the extracranial vertebral artery-related bypass has further evolved to improve the cerebral revascularization system. In this article, we propose the concept of "vascular reconstruction related to the extracranial vertebral artery" and review the design philosophy of the available innovative modalities in the respective segments. V1 transposition overcomes the issue of high rates of in-stent restenosis and provides a durable complementary alternative to endovascular treatment. V2 bypass serves as an extracranial communication pathway between the anterior and posterior circulation, providing the advantages of high-flow, short interposition grafts, orthograde flow in the vertebrobasilar system, and avoiding complex skull base manipulation. V3 bypass is characterized by profound and simultaneous vascular reconstruction of the posterior circulation, which is achieved by intracranial-intracranial or multiple bypasses in conjunction with skull base techniques. These posterior circulation vessels not only play a pivotal role in the bypass modalities designed for vertebrobasilar lesions but can also be implemented to revascularize the anterior circulation, thereby becoming a systematic methodology.

Course of the V3 segment of the vertebral artery relative to the suboccipital triangle as an anatomical marker for a safe far lateral approach: A retrospective clinical study

Background:

The third segment of the vertebral artery (V3) is vulnerable during far lateral and retrosigmoid approaches. Although the suboccipital triangle (SOT) is a useful anatomical landmark, the relationship between V3 and the muscles forming the triangle is not well-described. We aimed to demonstrate the relationship between the V3, surrounding muscles, and SOT in clinical cases.

Methods:

Operative videos of patients with the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms treated with occipital artery-PICA bypass through the far lateral approach were examined. Videos from January 2015 to October 2021 were retrospectively reviewed to determine anatomy of the V3 and the SOT.

Results:

Fourteen patients were included in this study. The ipsilateral V3 was identified without injury in all patients using the bipolar cutting technique. The lateral 68.2% of the horizontal V3 segment, including the V3 bulge, was covered by the inferomedial part of the superior oblique muscle (SO). The medial 23.9% was covered by the inferolateral part of the rectus capitis posterior major muscle. The inferomedial part of the horizontal V3 segment is located within the SOT.

Conclusion:

Most of the V3, including the V3 bulge, were located beneath the SO and the inferomedial part of V3 located within the SOT. Elevation of the SO should be performed carefully using the bipolar cutting technique to avoid injury to the V3. To the best of our knowledge, this is the first description of the V3 relative to the SOT in the clinical setting.

The Inferior Nuchal Line as a Simple Landmark for Identifying the Vertebral Artery During the Retrosigmoid Approach

BACKGROUND

The V3 segment of the vertebral artery (V3-VA) is at risk during various approaches to the craniovertebral junction. Several landmarks have been defined to identify V3-VA, but these landmarks are not routinely exposed during a retrosigmoid (RS) approach, where musculocutaneous dissection inferiorly towards the foramen magnum can threaten this arterial segment.

OBJECTIVE

To find a landmark that will identify the V3-VA during the RS approach, and analyze the inferior nuchal line (INL) as this novel landmark.

METHODS

The anatomic relationships between the INL and the V3-VA were assessed in 7 cadaveric heads through RS exposure in the lateral position.

RESULTS

The INL is an L-shaped bony ridge with horizontal (medial) and vertical (lateral) arms, with the vertical arm being more conspicuous in all specimens (INLV). The mean depths of the V3-VA relative to the medial and lateral ends of the INLV were (mean ± standard deviation) 24.9 ± 7.1 mm, and 8.3 ± 3.2 mm, respectively. In all specimens, the V3-VA was located inferior and anterior to the INLV.

CONCLUSION

The INL provides an important landmark during RS approach that can protect the V3-VA from inadvertent injury or identify it for use in an interpositional bypass. The INLV identifies the region of the suboccipital triangle where the V3-VA is embedded. INLV is routinely seen during the RS approach, making it more relevant than other classic landmarks such as the transverse process of C1, C1 posterior arch, and the atlantomastoid line that are not exposed during the RS approach.

Safe and bloodless exposure of the third segment of the vertebral artery: a step-by-step overview based on over 50 personal cases

Craniovertebral junction surgery usually requires the exposure of the third segment of the vertebral artery (V3). However, the complexity of musculature, a relatively high incidence of anomalies in the course of the vertebral artery (VA), and the presence of a rich venous plexus in this region make the V3 exposure challenging with a high risk of serious complications while taking down the suboccipital muscles in a single layer. A muscle dissection in interfascial layers, however, overcomes the drawbacks inherent in a blind dissection of the V3 as each of the muscles represents substantial landmark aiding subsequent step of the procedure and thus helping identify underlying anatomical structure early and safely. Moreover, along with a bloodless VA dissection off its surrounding venous plexus, it permits a safe and comfortable V3 exposure during the surgically demanding procedures.

The subatlantic triangle: gateway to early localization of the atlantoaxial vertebral artery

OBJECTIVE Exposure of the vertebral artery (VA) between C-1 and C-2 vertebrae (atlantoaxial VA) may be necessary in a variety of pathologies of the craniovertebral junction. Current methods to expose this segment of the VA entail sharp dissection of muscles close to the internal jugular vein and the spinal accessory nerve. The present study assesses the technique of exposing the atlantoaxial VA through a newly defined muscular triangle at the craniovertebral junction. METHODS Five cadaveric heads were prepared for surgical simulation in prone position, turned 30°-45° toward the side of exposure. The atlantoaxial VA was exposed through the subatlantic triangle after reflecting the sternocleidomastoid and splenius capitis muscles inferiorly. The subatlantic triangle was formed by 3 groups of muscles: 1) the levator scapulae and splenius cervicis muscles inferiorly and laterally, 2) the longissimus capitis muscle inferiorly and medially, and 3) the inferior oblique capitis superiorly. The lengths of the VA exposed through the triangle before and after unroofing the C-2 transverse foramen were measured. RESULTS The subatlantic triangle consistently provided access to the whole length of atlantoaxial VA. The average length of the VA exposed via the subatlantic triangle was 19.5 mm. This average increased to 31.5 mm after the VA was released at the C-2 transverse foramen. CONCLUSIONS The subatlantic triangle provides a simple and straightforward pathway to expose the atlantoaxial VA. The proposed method may be useful during posterior approaches to the craniovertebral junction should early exposure and control of the atlantoaxial VA become necessary.

The V3 segment of the vertebral artery as a robust donor for intracranial-to-intracranial interpositional bypasses: technique and application in 5 patients

The V₃ segment of the vertebral artery (VA) has been studied in various clinical scenarios, such as in tumors of the craniovertebral junction and dissecting aneurysms. However, its use as a donor artery in cerebral revascularization procedures has not been extensively studied. In this report, the authors summarize their clinical experience in cerebral revascularization procedures using the V₃ segment as a donor. A brief anatomical description of the relevant techniques is also provided.