Anatomic basis of the anterior surgery on the cervical spine: relationships between uncus-artery-root complex and vertebral artery injury

The transversoclasiotome: a novel instrument for examining the vertebral artery

Opening the foramen transversarium of the cervical vertebrae is necessary for accessing the vertebral vessels. There are no specialist tools for cutting the anterior lamina of the transverse processes, and alternatives lead to questionable results. A novel tool, the transversoclasiotome, is described and tested. The literature and patent databases were systematically reviewed. A blueprint of the transversoclasiotome was created, and the prototype was tested through autopsy on ten fresh-frozen cadavers within our Body Donation Program. The transversoclasiotome consists of two delicate branches mounted as a scissor, one a cutting jaw and the other a knocker with a rounded tip, both angled 30° to the principal axis. The jaws shut, facing each other in parallel. The cutting jaw corresponds to a slit on the knocker profile without protruding beyond it even when entirely closed. It acts by cutting and wedging. The testing autopsies demonstrated its suitability for its purpose, with an adequate response to the pressure exerted on the bone lamina. The section cut cleanly, without sliding off while closing on the bone. The vertebral vessels were not injured either during instrument insertion or cutting. Their morphological features are described. The transversoclasiotome has been proven appropriate for sectioning the anterior lamina of transverse processes of the cervical vertebrae. It meets the needs of clinical anatomy in teaching and training clinicians or surgeons, forensic clinical anatomy during medico-legal investigation, and research.

Vertebral Artery Injury in the Cervical Spine: Anatomy, Diagnosis, and Management

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Although rare, injury to the vertebral artery (VA) can occur after blunt trauma or iatrogenically during surgery. Clinicians should be aware of the anatomic variants of the VA, the presence of which may increase the risk of iatrogenic VA injury (VAI).

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If VAI is suspected following blunt trauma, rapid identification via advanced imaging modalities, such as computed tomography angiography, can help clarify the site of injury and guide management.

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VAI can be classified according to the Denver grading scale for blunt cerebrovascular injury, ranging from grade I to grade V, which includes intimal narrowing, pseudoaneurysm formation, complete occlusion, and arterial transection.

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Treatment modalities remain controversial and include anticoagulation, endovascular interventions, surgical tamponade, ligation, and microvascular repair. The choice of treatment is influenced by the setting of the injury (iatrogenic injury in the operating room versus blunt trauma in the field) and the laterality of the dominant VA with respect to brain perfusion.

Analysis of the morphometric change in the uncinate process of the cervical spondylosis patients: A study of radiological anatomy

Purpose

Although there are many researches that focus on the relationship between the vertebral artery and uncinate process (UP), there were no publications concerning difference in the dimensions of the UP between the normal spine and degenerative spine, especially in Chinese patient. The purpose of this study is to determine the anatomic parameters that can be used as a guide for the procedure in intervertebral foramen decompression and for analysis of the morphometric change in the UP of the cervical spondylosis patients.

Methods

Forty patients from January 2016 to January 2019 were enrolled in this study. Three-dimensional computed tomography scans of the cervical spine were performed. The patients were subdivided into two groups which were nondegenerative cervical spine group (20 cases) and degenerative cervical spine group (20 cases). Six parameters concerning the height, width and angle of the UP were measured.

Results

In nondegenerative group, the average pedicle width was 3.63 mm–5.91 mm from C3 to C7. The average width of safe UP resection will be 3.06 mm at C3, 3.12 mm at C4, 3.28 mm at C5, 2.74 mm at C6 and 2.01 mm at C7. The average safe depth will be 6.04 mm at C3, 6.52 mm at C4, 7.61 mm at C5, 6.07 mm at C6 and 5.09 mm at C7. There are statistic difference between degenerative group and nondegenerative group, especially in the parameter minimum height of UP, maximum height of UP, medial border's distance of UP and later border's distance of UP.

Conclusion

In this retrospective study, our results suggest that for the Chinese patients who suffered from cervical spondylosis could be performed intervertebral foraminotomy decompression by resecting part of the UP. The safe range within the spinal canal was up to 6.73 mm of width between inferior vertebral endplate and superior vertebral endplate in the intervertebral space and up to 5.09 mm of depth from medial border of the UP to the lateral side atC3 to C7 without interfering the spinal nerve root and vertebral artery.

The translational potential of this article

Our study found the safe margin to perform intervertebral foramen decompression to the UP for the cervical spondylosis patients. This may help to improve safeness of the surgical procedure and provide data for future robotic surgery.

Microanatomical considerations for safe uncinate removal during anterior cervical discectomy and fusion: 10-year experience

Cervical radiculopathy from uncovertebral joint (UVJ) hypertrophy and nerve root compression often occurs anterior and lateral within the cervical intervertebral foramen, presenting a challenge for complete decompression through anterior cervical approaches owing to the intimate association with the vertebral artery and associated venous plexus. Complete uncinatectomy during anterior cervical discectomy and fusion (ACDF) is a controversial topic, many surgeons relying on indirect nerve root decompression from restoration of disc space height. However, in cases of severe UVJ hypertrophy, indirect decompression does not adequately address the underlying pathophysiology of anterolateral foraminal stenosis. Previous reports in the literature have described techniques involving extensive dissection of the cervical transverse process and lateral uncinate process (UP) in order to identify the vertebral artery for safe removal of the UP. Recent anatomical investigations have detailed the microanatomical organization of the fibroligamentous complex surrounding the UP and neurovascular structures. The use of the natural planes formed from the encapsulation of these connective tissue layers provides a safe passage for lateral UP dissection during anterior cervical approaches. This can be performed from within the disc space during ACDF to avoid extensive lateral dissection. In this article, we present our 10-year experience using an anatomy-based microsurgical technique for safe and complete removal of the UP during ACDF for cervical radiculopathy caused by UVJ hypertrophy.

Total uncinectomy of the cervical spine with an osteotome: technical note and intraoperative video

Total uncinate process resection or uncinectomy is often required in the setting of severe foraminal stenosis or cervical kyphosis correction. The proximity of the uncus to the vertebral artery, nerve root, and spinal cord makes this a challenging undertaking. Use of a high-speed burr or ultrasonic bone dissector can be associated with direct injury to the vertebral artery and thermal injury to the surrounding structures. The use of an osteotome is a safe and efficient method of uncinectomy. Here the authors describe their technique, which is illustrated with an intraoperative video.

Covered Stent to Salvage Iatrogenic Vertebral Artery Injury with Uncontrolled Bleeding in the Operating Room Setting

BACKGROUND

Iatrogenic vertebral artery injury is an uncommon but well recognized complication during cervical spine surgery. Intraoperative surgical repair is extremely challenging, and options for endovascular repair are limited because of the lack of proper equipment in the operating room setting.

CASE DESCRIPTION

A 53-year-old woman who presented with myelopathy underwent anterior cervical diskectomy and fusion of C3-7. A significant laceration injury of the left vertebral artery was encountered during surgery, which was salvaged by intraoperative endovascular repair with a covered stent under portable fluoroscopy guidance. The salvage and repair led to the rest of the surgery being finished as planned preoperatively without any consequences.

CONCLUSIONS

Vertebral artery injury is an uncommon but severe complication of cervical spine surgery. For uncontrolled bleeding, intraoperative endovascular repair with portable fluoroscopy is warranted and possible. A covered stent can seal the laceration and stop the bleeding completely which enables completion of the surgery.

The Effect of Uncinate Process Resection on Subsidence Following Anterior Cervical Discectomy and Fusion

Objective

Subsidence is a frequent complication of anterior cervical discectomy and fusion. Postoperative segmental micro-motion, thought to be a causative factor of subsidence, has been speculated to increase with uncinate process resection area (UPR). To evaluate the effect of UPR on micro-motion, we designed a method to measure UPR area based on pre- and postoperative computed tomography images and analyzed the relationship between UPR and subsidence as a proxy of micro-motion.

Methods

We retrospectively collected clinical and radiological data from January 2011 to June 2016. A total of 38 patients (53 segments) were included. All procedures included bilateral UPR and anterior plate fixation. UPR area was evaluated with reformatted coronal computer tomography images. To reduce level-related bias, we converted UPR area to the proportion of UPR to the pre-operative UP area (pUPR).

Results

Subsidence occurred in 18 segments (34%) and positively correlated with right-side pUPR, left-side pUPR, and the sum of bilateral pUPR (sum pUPR) (R=0.310, 301, 364; p=0.024, 0.029, 0.007, respectively). Multiple linear regression analysis revealed that subsidence could be estimated with the following formula: subsidence=1.522+2.7×sum pUPR (R²=0.133, p=0.007). Receiver-operating characteristic analysis determined that sum pUPR≥0.38 could serve as a threshold for significantly increased risk of subsidence (p=0.005, area under curve=0.737, sensitivity=94%, specificity=51%). This threshold was confirmed by logistic regression analysis for subsidence (p=0.009, odds ratio=8.471).

Conclusion

The UPR measurement method confirmed that UPR was correlated with subsidence. Particularly when the sum of pUPR is ≥38%, the possibility of subsidence increased.

Microanatomy of the brachial plexus roots and its clinical significance

PURPOSE

To provide the anatomical basis of brachial plexus roots for the diagnosis and treatment of brachial plexus root avulsion injury.

METHODS

The morphological features of brachial plexus roots were observed and measured on 15 cervicothoracic spine of adult cadavers. The relationship of brachial plexus nerve roots and the surrounding tissues also were observed, as well as the blood supply of anterior and posterior roots of the brachial plexus.

RESULTS

Origination of the nerve roots in the dorsal-ventral direction from the midline was fine-tuned at each level along the spinal cord. The minimum distance of the origin of the nerve root to midline was 2.2 mm at C ₅, while the maximum was 3.1 mm at T ₁. Inversely, the distance between the origin of the posterior root and the midline of the spinal cord gradually decreased, the maximum being 4.2 mm at C ₅ and minimum 2.7 mm at T ₁. Meanwhile, there was complicated fibrous connection among posterior roots of the brachial plexus. The C _5-6 nerve roots interlaced with tendons of the scalenus anterior and scalenus medius and fused with the transverse-radicular ligaments in the intervertebral foramina. However, these ligaments were not seen in C _7-8, and T ₁. The blood supply of the anterior and posterior roots of the brachial plexus was from the segmental branches of the vertebral artery, deep cervical artery and ascending cervical artery, with a mean outer diameter of 0.61 mm.

CONCLUSIONS

The systematic and comprehensive anatomic data of the brachial plexus roots provides the anatomical basis to diagnose and treat the brachial plexus root avulsion injury.

Morphometric evaluation of the uncinate process and its importance in surgical approaches to the cervical spine: a cadaveric study

INTRODUCTION

The uncinate process (UP) has an important role because of its relationship with the vertebral artery and spinal roots. Degenerative diseases cause osteophyte formation on the UP, leading to radiculopathy, myelopathy and vertebral vascular insufficiency, which may require surgical management. This study aimed to evaluate the morphometry of this region to shed light on the anatomy of the UP.

METHODS

Morphometric data was obtained from 13 male formaldehyde-fixed cadavers. Direct measurements were obtained using a metal caliper. Computed tomography (CT) morphometry was performed with the cadavers in the supine position.

RESULTS

Direct cadaveric measurements showed that the height of the UP increased from C3 (5.8 ± 1.0 mm) to C7 (6.6 ± 0.5 mm). On CT, the corresponding measurements were 5.9 ± 1.2 mm at C3 and 6.9 ± 0.6 mm at C7. The distance between the left and right apex of the UP from C3 to C7 also increased on both direct cadaveric and CT measurements (C3: 20.8 ± 1.0 mm and C7: 28.1 ± 2.4 mm vs. C3: 23.7 ± 3.4 mm and C7: 29.0 ± 3.0 mm, respectively). On CT, the distance between the UP and superior articular process at the C3 to C7 levels were 9.8 ± 1.7 mm, 7.9 ± 1.8 mm, 7.9 ± 1.6 mm, 7.8 ± 1.3 mm and 8.2 ± 1.7 mm, respectively.

CONCLUSION

Direct cadaveric and CT measurements of the UP are useful for preoperative evaluation of the cervical spine and may lead to better surgical outcomes.

An unusual course of the vertebral artery posterior to the nerve root in the inter-transverse space: a cadaveric study

Background

The V2 segment of the vertebral artery is very vulnerable to injury during cervical spine surgery. The incidence of vertebral artery injury during anterior cervical spine procedures is reported to be 0.22–2.77 %. This is partially due to its variable course while running in the transverse foramens of the cervical vertebrae.

Case presentation

The course of the vertebral artery in the dissected cadaver of a 79 year old female is presented. Dissection of the left vertebral artery showed that the 5^th nerve root passes in front of the vertebral artery in the 4^th intertransverse space. Further exploration showed that although vertebral artery at first passed at the back of the nerve root it curved downwards again and after passing underneath the 5^th nerve root entered the 4^th vertebral body. After making a loop in the left half of the vertebrae, vertebral artery ran anterior to the nerve root and after entering the 4^th transverse foramen showed up in the 3^rd intertransverse space. The shortest distance of the vertebral artery to the midline at the 4^th vertebrae level was 4.78 mm.

Conclusions

To our knowledge this case is the first report of a nerve root lying anterior to the vertebral artery in the intertransverse space of the cervical spine. Additionally vertebral artery has never been reported to be so close to the midline. This report signifies the importance of obtaining MRI or contrast enhanced CT scan prior to any cervical spine surgery in the vicinity of the vertebral artery including corpectomies and also careful approach to the intertransverse space during the operation.

Vertebral artery injuries in cervical spine surgery

Background:

Vertebral artery injuries during cervical spine surgery are rare, but potentially fatal. When performing cervical spine surgery, it is imperative that the surgeon has a systematic approach for avoiding, and if necessary, dealing with a vertebral artery injury.

Methods:

This is a review paper.

Results:

Upper posterior cervical spine surgeries put the vertebral artery at the highest risk, as opposed to anterior subaxial cervical spine procedures, which put the artery at the least risk. A thorough understanding of the complex anatomy of the vertebral artery is mandatory prior to performing cervical spine surgery, and since the vertebral artery can have a variable course, especially in the upper cervical spine, the surgeon must minimize the possibility of an arterial injury by preoperatively assessing the artery with a computed tomography (CT) scan or magnetic resonance imaging (MRI). Intraoperatively, the surgeon must be aware of when the vertebral artery is most at risk, and take precautions to avoid an injury. In the event of an arterial injury, the surgeon must have a plan of action to (1) Achieve control of the hemorrhage. (2) Prevent acute central nervous system ischemia. (3) Prevent postoperative complications such as embolism and pseudoaneurysm

Conclusion:

Prior to performing cervical spine surgery, one must understand the four A's of vertebral artery injuries: Anatomy, Assessment, Avoidance, and Action.

Quantitative evaluation of the anatomical parameters for subaxial cervical spondylectomy: an anatomical study

OBJECT

The object of this investigation was to conduct a morphometric study in cadavers to determine anatomical structures, their relationships, and their morphometry for subaxial cervical spondylectomy.

METHODS

Forty sides of 20 cadavers were used for this study. Dissections were performed in 2 stages (anteriorly and posteriorly). Twenty-one morphometric measurements were performed for both sides of the C3-6 vertebrae. Data were analyzed statistically.

RESULTS

Morphometry of the laminas, tuberculum posterius, pedicle, corpus, foramen transversarium, and processus costalis were measured.

CONCLUSIONS

Detailed quantitative anatomical knowledge for operations requiring wide dissection and resection, such as cervical spondylectomy, lowers the morbidity rate.

Parameters for lateral extent of dissection during anterior cervical decompression and fusion

The purpose of this anatomic study was to determine the extent of lateral dissection that can be performed during anterior cervical decompression and fusion to maximize decompression without compromising the vertebral arteries. Although vertebral artery injury is rare, it is sometimes catastrophic and leads to significant morbidity and mortality. Previous studies have attempted to establish standards for surgical anatomy during anterior cervical decompression and fusion; however, none have accounted for significant degenerative changes that occur with increased age.The uncus-to-uncus distance, representing part of the vertebral endplate, of 500 cervical spine specimens was measured at each vertebral level from C3 to C7. The corresponding femoral head diameter (a correlate of body mass index) was also measured. These values were used to determine whether a specific uncus-to-uncus distance exists per vertebral level regardless of age, and whether the uncus-to-uncus distance becomes more specific when correlated with body mass index. According to the data, uncus-to-uncus distance increases between each vertebral level, and each level has a range of approximately 6 mm. The range does not decrease when compared with femoral head diameter. Although a statistically significant, positive correlation existed between uncus-to-uncus distance and femoral head diameter, the correlation coefficient was not large enough to suggest that uncus-to-uncus distance varies greatly from femoral head diameter. Although anatomical markers such as the distance between the uncinate processes can aid surgeons in safe decompression of the cervical vertebrae, vertebral artery injury is best avoided by thorough pre- and intraoperative radiological and anatomical analysis.

A safe approach to explore/identify the V2 segment of the vertebral artery during anterior approaches to cervical spine and/or arterial repairs: anatomical study

Object

The purpose of this study was to find a landmark according to which the surgeon can dissect the cervical spine safely, with the lowest possibility of damaging the vertebral artery (VA) during anterior approaches to the cervical spine or the VA.

Methods

The “safe zone” for each level of the cervical spine was described as an area where the surgeon can start from the midline in that zone and dissect the soft tissue laterally to end up on the transverse process and cross the VA while still on the transverse process. In other words, safe zone signifies the narrowest width of the transverse process at each level. In such an approach, the VA is protected from the inadvertent deep penetration of the instruments by the transverse process. The surgical safe zone for each level was the common area among at least 95% of the safe zones for that level. For the purpose of defining the upper and lower borders of the safe zone for each level, the line passing from the upper vertebral border perpendicular to the midline (upper vertebral border line) was used as a reference.

Cervical spines of 64 formalin-fixed cadavers were dissected. The soft tissue in front of the transverse process and intertransverse space was removed. Digital pictures of the specimens were taken before and after removal of the transverse processes, and the distance to the upper and lower border of the safe zone from the upper vertebral border line was measured on the digital pictures with Image J software. The VA diameter and distance from the midline at each level were also measured. To compare the means, the authors used t-test and ANOVA.

Results

The surgical safe zone lies between 1 mm above and 1 mm below the upper vertebral border at the fourth vertebra, 2 mm above and 1 mm below the upper vertebral border at the fifth vertebra, and 1 mm above and 2 mm below the upper vertebral border of the sixth vertebra. The VA was observed to be tortuous in 13% of the intertransverse spaces. There is a positive association between disc degeneration and tortuosity of the VA at each level (p < 0.001). The artery becomes closer to the midline (p < 0.001) and moves posteriorly during its ascent.

Conclusions

Dissection of the soft tissue off the bone along the surgical safe zone and removal of the transverse process afterward can be a practical and safe approach to avoid artery lacerations. The findings in the present study can be used in anterior approaches to the cervical spine, especially when the tortuosity of the artery mandates exposure of the VA prior to uncinate process resection, tumor excision, or VA repair.

Anterolateral approach to the cervical spine: major anatomical structures and landmarks. Technical note

OBJECT

The authors undertook a study to explore the topographic anatomical features seen during the anterolateral approach to cervical spine, anatomical variations, and certain landmarks related to the surgical procedure.

METHODS

The study was conducted in 30 fresh cadavers.

RESULTS

The common carotid artery bifurcation was mostly found at the level of C-4 (78%). The inferior belly of the omohyoid muscle was seen to cross the sternocleidomastoid muscle at the C5-6 disc level along the entire C-6 vertebral body. To reach the lower cervical region, the sacrifice of this muscle makes the procedure easier. The facial vein drained into the internal jugular vein mostly at the level of C3-4 (54%). The superior ganglion of the cervical sympathetic chain was located at the C-4 vertebra, but the location of the intermediate ganglion exhibited some variation. The vertebral artery entered the transverse foramen of C-6 in 27 cadavers (90%), the transverse foramen of C-7 in two cadavers (7%), and the transverse foramen of C-4 in one cadaver (3%). Because the inferior thyroid artery crossed the C6-7 interspace obliquely, the course of the inferior thyroid artery may complicate the procedure. The C-5 uncinate process was shortest and narrowest and had the greatest distance from the medial edge of the process to the anterior tubercle (p < 0.001).

CONCLUSIONS

Understanding the qualitative anatomy of this region not only improves the safety of anterior and anterolateral cervical spine surgery but also allows adequate decompression of neural elements and resolution of the other pathological processes of this region. In this fresh cadaveric study, our goal was to improve the approach and decrease the incidence of complications.

In vitro flexibility of the cervical spine after ventral uncoforaminotomy

Object

Degenerative spine disorders are, in the majority of cases, treated with ventral discectomy followed by fusion (also known as anterior cervical discectomy and fusion). Currently, nonfusion strategies are gaining broader acceptance. The introduction of cervical disc prosthetic devices was a natural consequence of this development. Jho proposed anterior uncoforaminotomy as an alternative motion-preserving procedure at the cervical spine. The clinical results in the literature are controversial, with one focus of disagreement being the impact of the procedure on stability. The aim of this study was to address the changes in spinal stability after uncoforaminotomy.

Methods

Six spinal motion segments derived from three fresh-frozen human cervical spine specimens (C2–7) were tested. The donors were two men whose ages at death were 59 and 80 years and one woman whose age was 80 years. Bone mineral density in C-3 ranged from 155 to 175 mg/cm3. The lower part of the segment was rigidly fixed in the spine tester, whereas the upper part was fixed in gimbals with integrated stepper motors. Pure moment loads of ± 2.5 Nm were applied in flexion/extension, axial rotation, and lateral bending. For each specimen a load-deformation curve, the range of motion (ROM), and the neutral zone (NZ) for negative and positive directions of motion were calculated. Median, maximum, and minimum values were calculated for the six segments and normalized to the intact segment. Tests were done on the intact segment, after unilateral uncoforaminotomy, and after bilateral uncoforaminotomy.

Results

In lateral bending a strong increase in ROM and NZ was detectable after unilateral uncoforaminotomy on the right side. Overall, the ROM during flexion/extension was less influenced after uncoforaminotomy. The ROM and NZ during axial rotation to the left increased strongly after right unilateral uncoforaminotomy. Changes after bilateral uncoforaminotomy were marked during axial rotation to both sides.

Conclusions

Following unilateral uncoforaminotomy, a significant alteration in mobility of the segment is found, especially during lateral bending and axial rotation. The resulting increase in mobility is less pronounced during flexion and least evident on extension. Further investigations of the natural course of disc degeneration and the impact on mobility after uncoforaminotomy are needed.

Treatment of an iatrogenic vertebral artery laceration with the Symbiot self expandable covered stent

Vertebral artery laceration is difficult to treat surgically. Endovascular treatment with balloon expandable covered stents often fails due to their rigidity and poor navigability. We present a case of iatrogenic vertebral artery laceration where endovascular treatment with a balloon expandable covered stent failed. Eventually a self expandable symbiot covered stent was deployed over the laceration, securing hemostasis and preserving the vessel patency. The newer self expandable covered stents seem promising in the treatment of vertebral artery injury.

Anatomical relationships between the V2 segment of the vertebral artery and the cervical nerve roots

OBJECT

During surgical procedures focused on the cervical nerve roots, the surgeon works in proximity to the V2 segment of the vertebral artery (VA). Depending on the specific surgical approach, it may be necessary to identify, expose, or mobilize the artery. In most cases, the artery may be left undisturbed. To reduce the risk of iatrogenic injury to the V2 segment during anterior and anterolateral approaches to the cervical spine, the authors analyzed the relationship between the V2 segment and the proximal segment of the C3-6 nerve roots.

METHODS

Six cadaveric cervical spines (12 sides) were fixed with formalin, injected with red and blue latex, and investigated intraoperatively using different magnifications (x 3-40). The VA rested on the anteromedial surface of the cervical nerve roots at the level of each intertransverse space. The exiting nerve roots intersected the VA at a distance ranging from 4.5 to 8.1 mm (mean 6.3 +/- 1.06 mm) from the dural sac. The distance was slightly shorter at cephalad levels, suggesting that the artery is more posteriorly and medially situated at those levels. Arterial pedicles anchored the VA to the cervical nerve roots at various levels. These arteries gave rise to purely radicular, ligamentous, and medullary branches without a predictable pattern. After reaching the nerve roots on their lower margin, the nonligamentous branches pierced the radicular dural sheath within the neural foramen at a distance of 2 to 4 mm from the VA.

CONCLUSIONS

Proximal-to-distal dissection of a cervical nerve root may proceed with relative safety for at least 4 mm. The V2 segment of the VA gives rise to at least one radicular arterial pedicle between C-4 and C-6. These trunks give rise to purely radicular, ligamentous, and medullary branches in an unpredictable pattern.

Tortuous course of the vertebral artery and anterior cervical decompression: a cadaveric and clinical case study

STUDY DESIGN

Both the cadaveric and clinical examples of anomalous vertebral artery courses are described. The incidence of this anomaly in the general population and recognition, complications, and treatment options for these patients when undergoing anterior cervical decompression are discussed.

OBJECTIVES

Cadaveric study: In this study vertebral artery's course through the cervical spine in the adult population was analyzed. The relation between an abnormal vertebral artery course and surgical landmarks are described. Clinical study: Complications and alternative treatment methods for decompression in patients with the anomaly are described.

SUMMARY OF BACKGROUND DATA

The incidence of anomalous vertebral artery course is low, but failure to recognize a medially located vertebral artery may result in a life-threatening iatrogenic injury during decompression. Neither the relation between the vertebral arteries and the surgical landmarks nor the guidelines for decompression in the face of a tortuous vertebral artery have been well described.

METHODS

Transverse foramens of the cervical spine were measured in 222 cadaveric spines. The measurements were taken describing the relation between transverse foramens and other surgical landmarks. Three patients with anomalies were identified in clinical practice. The complications and treatment options are identified in these patients.

RESULTS

In the cadaveric specimens, a 2.7% incidence of tortuous vertebral artery course was identified. In these abnormal specimens, the transverse foramen was located an average of 0.14 mm medial to the joint of Luschka. In one patient, the abnormal course of the vertebral artery was recognized after laceration of the artery during a routine corpectomy. Anomalies in the other two patients were recognized before surgery, and the patients underwent modified anterior decompression by combining a discectomy at the anomalous level with a corpectomy at other levels. Vertebral artery ectasia is identifiable on axial magnetic resonance or computed tomographic images.

CONCLUSIONS

Aberrant vertebral artery is rare. Preoperative recognition and appropriate modification of anterior decompression can yield excellent clinical results without risking significant complications.

The vertebral artery: surgical anatomy

Anterior cervical decompressive surgery is widely performed for spondylosis, herniated intervertebral disk, tumor, infection, and trauma in the subaxial cervical spine region. Laceration of the vertebral artery is the most challenging of surgical dilemmas during anterior cervical spine surgery, as gaining control of the massive hemorrhage from a ruptured vertebral artery is difficult and could possibly result in an uncertain neurologic morbidity. As such, the understanding the surgical anatomy of the vertebral artery is essential to prevent iatrogenic injuries.