Relation of the vertebral artery segment from C1 to C2 vertebrae: An anatomical study

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

STUDY DESIGN

A descriptive, quantitative cross-sectional study of the atlantic part (V3) of the vertebral artery (VA).

PURPOSE

This study aimed to bridge the research gap in the morphometry of the V3 segment of the VA in the South Indian population.

OVERVIEW OF LITERATURE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

An anatomical investigation of the suboccipital- and inferior suboccipital triangles

The suboccipital triangle (ST) is a clinically relevant landmark in the posterior aspect of the neck and is used to locate and mobilize the horizontal segment of the third part of the vertebral artery before it enters the cranium. Unfortunately, this space is not always a viable option for vertebral artery exposition, and consequently a novel triangle, the inferior suboccipital triangle (IST) has been defined. This alternative triangle will allow surgeons to locate the artery more proximally, where its course is more predictable. The purpose of this study was to better define the anatomy of both triangles by measuring their borders and calculating their areas. Ethical clearance was obtained from the University of Pretoria (reference number: 222/2021) and both triangles were subsequently dissected out on both the left and right sides of 33 formalin-fixed human adult cadavers. The borders of each triangle were measured using a digital calliper and the areas were calculated using Herons Formula. The average area of the ST is 969.82±153.15 mm2, while the average area of the IST is 307.48±41.31 mm2. No statistically significant differences in the findings were observed between the sides of the body, ancestry, or sex of the cadavers. Measurement and analysis of these triangles provided important anatomical information and speak to their clinical relevance as surgical landmarks with which to locate the vertebral artery. Of particular importance here is the IST, which allows for mobilisation of this artery more proximally, should the ST be occluded.

Surgical Anatomy of Vertebral Artery in Relation to Atlantoaxial Instrumentation: A Cadaveric Study

BACKGROUND

With the advent of pedicle screws and advanced instrumentation techniques, internal fixation and stabilization of upper cervical vertebrae are possible in fractures of an axis. However, the proximity of vertebral arteries (VAs) poses a unique challenge to surgeons during these procedures and can result in profound physical impairment to patients. Cadaveric studies contributing to fine anatomical details necessitate conducting such studies.

METHODS

After receiving due ethical permission, this descriptive cross-sectional study was carried out on 10 cadavers in the department of Anatomy, All India Institute of Medical Science (AIIMS) Rishikesh. Twenty VAs were dissected along their course, and measurements of parameters related to the axis and atlas vertebra were noted.

RESULTS

The length of the pre-osseous segment related to the axis (VAX-1) on the right and left sides were from 3.8 to 14.5 mm (7.48±3.88 mm) and 4.46 to 10.5mm (6.94±2.01mm) respectively. The length of the osseous segment related to the axis (VAX-2) on the right side and left sides were from 6.82 to 31 mm (17.9±7.84mm) and 7.35 to 20 mm (15.6±4.53). The osseous segment of the VA related to the axis (VAX-2) shows genu (bend), which extends to a variable distance towards the midline. The mean distance of VA genu from the midline of the axis vertebral body on the right and left sides was 15.6mm and 17.5 mm, respectively. The percentage of superior articular facet (SAF) surface area of the axis occupied by the VA was 25-50% in nine and 50-75% in 11 cadavers, reflecting incomplete occupancy.

CONCLUSION

The study suggests that for instrumentation of the axis vertebra in the midline, the minimum distance between the genu of both sides of VA segments, related to an osseous segment of the axis (VAX-2) and medial extent of the VA groove of the atlas, should be considered as a safe zone to minimize inadvertent VA injury. During atlantoaxial fixation through a posterior approach in interarticular, pars, and pedicle screws, the surgical anatomy of the VA in relation to the osseous segment of the VA within the transverse process of the axis should be kept in mind to avoid inadvertent VA injury.

Neural Basis of Etiopathogenesis and Treatment of Cervicogenic Orofacial Pain

(1) Background and Objectives: The aim of this narrative review was to analyze the neuroanatomical and neurophysiological basis of cervicogenic pain in cervico-cranial pain syndromes, focusing particularly on cervico-orofacial syndromes as a background for the proper diagnosis and non-surgical treatment. Relevant literature on the topic from past 120 years has been surveyed. (2) Material and Methods: We surveyed all original papers, reviews, or short communications published in the English, Spanish, Czech or Slovak languages from 1900 to 2020 in major journals. (3) Results: The cervicogenic headache originates from the spinal trigeminal nucleus where axons from the C₁–C₃ cervical spinal nerves and three branches of the trigeminal nerve converge (trigeminocervical convergence) at the interneurons that mediate cranio-cervical nociceptive interactions. The role of the temporomandibular joint in the broad clinical picture is also important. Despite abundant available experimental and clinical data, cervicogenic orofacial pain may be challenging to diagnose and treat. Crucial non-surgical therapeutic approach is the orthopedic manual therapy focused on correction of body posture, proper alignment of cervical vertebra and restoration of normal function of temporomandibular joint and occlusion. In addition, two novel concepts for the functional synthesis of cervico-cranial interactions are the tricentric concept of mouth sensorimotor control and the concept of a cervicogenic origin of bruxism. (4) Conclusions: Understanding the basis of neuroanatomical and neurophysiological neuromuscular relations enables an effective therapeutic approach based principally on orthopedic manual and dental occlusal treatment.

Intraoperative Computed Tomography Scanner-Guided Craniovertebral Junction Surgery in a Patient with an Occipitalized C1

Craniovertebral junction surgery is associated with unique difficulties. Type 2 odontoid fractures (Anderson and D Alonzo) have a great potential for nonunion and malunion. These fracture patients may require a circumferential decompression and fixation. The addition of intraoperative CT with neuronavigation greatly aids in craniovertebral junction surgery. We operated on a 59-year-old-male with a type 2 fracture with posterior subluxation of C1 anterior arch and a cranially displaced odontoid peg. First, a transoral odontoidectomy was performed followed by a craniocervical fixation. Occipital plates and C3-C4 lateral mass screws were used as C1 was discovered to be occipitalized intraoperatively and atlantoaxial facet joints could not be reduced as discovered by intraoperative CT resconstruction. Intraoperative CT scan was crucial to this circumferential decompression and fixation, allowed us to resect the odontoid peg safely and completely and to confirm adequate screw trajectory making this complex surgery easier for us and safer for the patient. The patient was discharged 4 months after admission with stable neurology. Intraoperative CT was fundamental to correct decision making.

Changes in Vertebral Artery Blood Flow in Different Head Positions and Post-Cervical Manipulative Therapy

OBJECTIVE

The objective of this study was to investigate the hemodynamics of blood flow through the V3 region of the vertebral artery contralateral to the side manipulated during different rotary head positions and post-cervical spinal manipulation.

METHODS

This quasi-experimental study was performed on 25 healthy, asymptomatic participants, both male and female, between 20 and 30 years of age. Each participant presented with a C0/C1 or C1/C2 cervical facet restriction (as determined by motion palpation). Participation was voluntary, and participants had no symptoms of vertebrobasilar artery insufficiency or contraindications to cervical spinal manipulation. Doppler ultrasound was used to measure vertebral artery blood flow (V3 region) hemodynamics, contralateral side of manipulation, as close to C1/C2 region as possible in 4 positions of cervical rotation (neutral, 45°, maximum, and post-manipulation neutral). Doppler ultrasound parameters included peak systolic flow velocity, end diastolic flow velocity, mean flow velocity, vessel diameter, and flow rate. The nonparametric Friedman test was used for analysis across each head and neck position, and post manipulation.

RESULTS

No clinical or statistically significant results (P > .05) were found for any of the hemodynamic parameters in any of the head positions.

CONCLUSIONS

Hemodynamic measurements of the V3 region of the vertebral artery do not show significant changes in the measured head positions or following manipulation of the upper cervical spine in patients without pre-existing risk factors.

Prevalence of foramen arcuale and its clinical significance: a meta-analysis of 55,985 subjects

OBJECTIVE

The foramen arcuale (FA) is a bony bridge located over the vertebral artery on the posterior arch of the atlas. The presence of an FA can pose a risk during neurosurgery by providing a false impression of a broader posterior arch. The aim of this study was to provide the most comprehensive investigation on the prevalence of the FA and its clinically important anatomical features.

METHODS

Major electronic databases were searched to identify all studies that reported relevant data on the FA and the data were pooled into a meta-analysis.

RESULTS

A total of 127 studies (involving 55,985 subjects) were included. The overall pooled prevalence of a complete FA was 9.1% (95% CI 8.2%–10.1%) versus an incomplete FA, which was 13.6% (95% CI 11.2%–16.2%). The complete FA was found to be most prevalent in North Americans (11.3%) and Europeans (11.2%), and least prevalent among Asians (7.5%). In males (10.4%) the complete FA was more common than in females (7.3%) but an incomplete FA was more commonly seen in females (18.5%) than in males (16.7%). In the presence of a complete FA, a contralateral FA (complete or incomplete) was found in 53.1% of cases.

CONCLUSIONS

Surgeons should consider the risk for the presence of an FA prior to procedures on the atlas in each patient according to sex and ethnic group. We suggest preoperative screening with computerized tomography as the gold standard for detecting the presence of an FA.

The Impact of Engorged Vein within Traumatic Posterior Neck Muscle Identified in Preoperative Computed Tomography Angiography to Estimated Blood Loss during Posterior Upper Cervical Spine Surgery

Objective

Injuries of upper cervical spine are potentially fatal. Thus, appropriate diagnosis and treatment is essential. In our institute, preoperative computed tomography angiography (CTA) has been performed for evaluation of injuries of bony and vascular structure. The authors confirmed the engorged venous plexus within injured posterior neck muscle. We have this research to clarify the relationship between the engorged venous plexus and engorged vein.

Methods

A retrospective review identified 23 adult patients who underwent 23 posterior cervical spine surgeries for treatment of upper cervical injury between 2013 and 2015. Preoperative CTA was used to identify of venous engorgement within posterior neck muscle. The male to female ratio was 18:5 and the mean age was 53.5 years (range, 25-78 years). Presence of venous engorgement and estimated blood loss (EBL) were analyzed retrospectively.

Results

The EBL of group with venous engorgement was 454.55 mL. The EBL of group without venous engorgement was 291.67 mL. The EBL of group with venous engorgement was larger than control group in significant.

Conclusion

The presence of engorged venous plexus is important factor of intraoperative bleeding. Preoperative CTA for identifying of presence of engorged venous plexus and fine operative techniques is important to decrease of blood loss during posterior cervical spine surgery.