Variance of cervical vertebral artery measured by CT angiography and its influence on C7 pedicle anatomy

A Novel Evaluation for Vertebral Artery Course Using 3D Magnetic Resonance Imaging with Computed Tomography -like Bone Contrast and Magnetic Resonance Angiography: A Proof of Concept Study

OBJECTIVE

Vertebral artery (VA) injury poses a significant risk in cervical spine surgery, necessitating accurate preoperative assessment. This study aims to introduce and validate a novel approach that combines the Fast field echo that resembles a computed tomography using restricted echo spacing (FRACTURE) sequence with Time of Flight (TOF) Magnetic Resonance Angiography (MRA) for comprehensive evaluation of VA courses in the cervical spine.

MATERIALS AND METHODS

A total of eight healthy volunteers and two patients participated in this study. The FRACTURE sequence provided high-resolution bone images of the cervical spine, while TOF MRA offered non-invasive vascular imaging. Fusion images were created by merging FRACTURE and MRA modalities to simultaneously visualize cervical spine structures and VA courses. Board-certified orthopedic spine surgeons independently evaluated images to assess the visibility of anatomical characteristics of the VA course by Likert-scale.

RESULTS

The FRACTURE-MRA fusion images effectively depicted the extraosseous course of the VA at the craniovertebral junction, the intraosseous course of the VA at the craniovertebral junction, the VA entrance level to the transverse foramen, and the side-to-side asymmetry of bilateral VAs. Additionally, clinical cases demonstrated the utility of the proposed technique in identifying anomalies and guiding surgical interventions.

CONCLUSIONS

The integration of the FRACTURE sequence and TOF MRA presents a promising methodology for the precise evaluation of VA courses in the cervical spine. This approach improves preoperative planning for cervical spine surgery with detailed anatomy and is a valuable alternative to conventional methods without contrast agents.

Radiologic Evaluation of Uncinate Processes of the Cervical Spine and the Relationship Between the Uncinate Process and Vertebral Artery: Implication in Anterior Cervical Spine Surgery

OBJECTIVE

To determine the relationship between the uncinate process (UP) and vertebral artery (VA) from a radiologic view and to confirm the surgical safety margin to minimize the risk of VA injury during anterior cervical approaches.

METHODS

We retrospectively reviewed computed tomography angiography of 205 patients by using a contrast-enhanced computed tomography angiography protocol of the VA. Four kinds of images were simultaneously reconstructed to measure all the parameters associated with VA and UP of cervical spine.

RESULTS

The shortest distance from the UP's tip to the VA's medial border (P < 0.001) was at the C-6 level (2.9 ± 0.9 mm on the left and 3.2 ± 1.3 mm on the right), and the longest distance (P < 0.001) was at the C-3 level on both sides. The distance between UP's tip and the medial border of the ipsilateral VA was statistically significantly different at each cervical level, and the right distance was larger than the left (P < 0.05). We found the height of UP gradually increased from C-3 to C5-level and then decreased from C-5 to C-7 level for both sides. The mean distance between the medial borders of left UP and left VA was on average 7.5 ± 1.4 mm. The diameter of VA was on average 3.4 ± 0.6 mm on the left side and 3.2 ± 0.7 mm on the right. The diameter of the VA was statistically significantly different on both sides, and the left side was larger than the right (P < 0.05).

CONCLUSIONS

Detailed radiologic anatomy of VA and UP was reviewed in this study. A deep understanding of the correlation between the UP and VA is essential to perform anterior cervical spine surgery safely and ensure adequate spinal canal decompression.

2. Cervical radicular pain

INTRODUCTION

Cervical radicular pain is pain perceived in the upper limb, caused by irritation or compression of a cervical spine nerve, the roots of the nerve, or both.

METHODS

The literature on the diagnosis and treatment of cervical radicular pain was retrieved and summarized.

RESULTS

The diagnosis is made by combining elements from the patient's history, physical examination, and supplementary tests. The Spurling and shoulder abduction tests are the two most common examinations used to identify cervical radicular pain. MRI without contrast, CT scanning, and in some cases plain radiography can all be appropriate imaging techniques for nontraumatic cervical radiculopathy. MRI is recommended prior to interventional treatments. Exercise with or without other treatments can be beneficial. There is scant evidence for the use of paracetamol, nonsteroidal anti-inflammatory drugs, and neuropathic pain medications such as gabapentin, pregabalin, tricyclic antidepressants, and anticonvulsants for the treatment of radicular pain. Acute and subacute cervical radicular pain may respond well to epidural corticosteroid administration, preferentially using an interlaminar approach. By contrast, for chronic cervical radicular pain, the efficacy of epidural corticosteroid administration is limited. In these patients, pulsed radiofrequency treatment adjacent to the dorsal root ganglion may be considered.

CONCLUSIONS

There is currently no gold standard for the diagnosis of cervical radicular pain. There is scant evidence for the use of medication. Epidural corticosteroid injection and pulsed radiofrequency adjacent to the dorsal root ganglion may be considered. [Correction added on 12 June 2023, after first online publication: The preceding sentence was corrected.].

Variation in Cervical Pedicle Morphology: Important Considerations for Posterior Cervical Procedures

BACKGROUND

Safe posterior cervical spine surgery requires in-depth understanding of the surgical anatomy and common variations. The cervical pedicle attachment site to the vertebral body (VB) affects the location of exiting nerve roots and warrants preoperative evaluation. The relative site of attachment of the cervical pedicle has not been previously described.

OBJECTIVE

To describe the site of the pedicle attachment to the VB in the subaxial cervical spine.

METHODS

Cervical spine computed tomography scans without any structural, degenerative, or traumatic pathology as read by a board-certified neuroradiologist during 2021 were reviewed. Multiplanar reconstructions were created and cross-registered. The pedicle's attachment to the VB was measured relative to the VB height using a novel calculation system.

RESULTS

Fifty computed tomography scans met inclusion criteria yielding 600 total pedicles between C3-T1 (100 per level). The average patient age was 26 ± 5.3 years, and 21/50 (42%) were female. 468/600 (78%) pedicles attached in the cranial third of the VB, 132/600 (22%) attached in the middle third, and 0 attached to the caudal third. The highest prevalence of variant anatomy occurred at C3 (36/100 C3 pedicles; 36%).

CONCLUSION

In the subaxial cervical spine, pedicles frequently attach to the top third of the VB, but significant variation is observed. The rate of variation is highest at C3 and decreases linearly with caudal progression down the subaxial cervical spine to T1. This is the first report investigating this morphological phenomenon.

Anatomical Characteristics and Variations of Thoracic Segmental Arteries With 3-Dimensional CT Analysis

STUDY DESIGN

Observational study using retrospective contrast-enhanced computed tomography (CT) analysis.

OBJECTIVE

This study aimed to investigate the anatomical characteristics and variations of the thoracic segmental arteries.

SUMMARY OF BACKGROUND DATA

Few cadaver studies of segmental arteries to the thoracic spine have been reported; however, no previous studies have reported the use of contrast-enhanced CT in the upper to middle thoracic spine. Detailed anatomical information of the thoracic segmental arteries is essential to avoid vascular injuries in thoracic spine surgery, such as in the anterior and posterior approaches and minimally invasive surgery.

MATERIALS AND METHODS

Patients who underwent CT angiography of the thoracic spine between 2012 and 2021 were retrospectively analyzed. The pathways of the thoracic segmental arteries were reviewed. Anatomical differences depending on the vertebral level and right/left segmental arteries were investigated.

RESULTS

Thirty-one patients (15 men and 16 women; mean age 55.8 yr) with 591 segmental arteries were surveyed. The distribution of segmental arteries differed depending on the vertebral level, which ran more longitudinally in the upper thoracic region and transversely in the lower thoracic region. Common trunks were frequently observed in the segmental arteries of T3-5. Segmental arteries frequently crossed the disks in the right anterior and left middle areas of the thoracic spine, whereas in the T4/5 disks, segmental arteries crossed the disks over a wide area. The presence of multiple segmental arteries within a single vertebra was higher at the T5-7 vertebral level.

CONCLUSION

The distribution of the segmental arteries was asymmetrical and varied depending on the vertebral level. In the upper to middle thoracic, segmental arteries ran at every position of the vertebral body due to their longitudinal nature and the presence of multiple segmental arteries within a single vertebra, especially in T5-7. The results of this study provide critical information for thoracic spine surgery.

Morphometric Study of the Intracranial Segment of the Vertebral Artery

Background

The vertebral artery (VA) forms the caudal part of the circle of Willis and is responsible for one-third of the blood supply of the cerebellum, pons, middle ear, and the upper part of the spinal cord and its meninges. The highest potential risk of injury to VA during cervical pedicle screw implantation is at C3 and then at C6. Knowledge about the morphometry of VA provides a better understanding of clinical conditions such as vertebra basilar insufficiency (VBI). Similarly, the knowledge of variation in the VA is needed during cervical pedicle screw implantation, which possesses the highest potential risk to VA at the C3 level. The origin of the vertebral artery from the aortic arch reached the upper cervical vertebra than the vertebral artery of subclavian origin. The length of the VA is greater on the left side than the right-side artery. Understanding and reporting of the same are essential to creating awareness that can aid in endarterectomy, angioplasty, and radiological procedures. Variations are noted in morphometry between sides.

Aim

To determine the morphometry of the vertebral artery (VA) with emphasis on the fourth segment (V4) and its variations using computed tomography angiogram (CTA).

Materials and methods

This present retrospective study was conducted in the Departments of Anatomy and Radiology and Imaging Sciences, Saveetha Medical College and Hospital. Participants were patients who took a head and neck CT for various clinical reasons. About 50 CT images, 33 male and 17 females, were selected from the archives. The length, diameter, and entry level of VA were studied. The data were tabulated and statistically analyzed.

Result

The mean length of VA was 24.49 ± 3.02 (cm) on the left side and 24.28 ± 3.91 (cm) on the right side in female subjects and was found to be 22.78 ± 1.7 (cm) on the left side and 21.5 ± 2.7 (cm) on the right side in male subjects. The mean diameter of VA at the level of the foramen magnum was 0.32 ± 0.05 (cm) on the right side and 0.322 ± 0.07 (cm) on the left side in females, 0.3 ± 0.064 (cm) on the left side and 0.26 ± 0.086 (cm) on the right side in males.

Conclusion

The length of VA was found to be statistically more on the left side than on the right side. The variations in morphometry seen can aid in various surgical and radiological procedures.

Anatomical Variations of the Vertebral Artery: Analysis by Three-Dimensional Computed Tomography Angiography in Chinese Population

OBJECTIVE

To analyze the anatomical variations of V3 and V2 segments of the vertebral artery in the Chinese population.

METHODS

The current retrospective study was an observational, anatomical, radiological research. Between 1 January 2018 to 31 December 2019, the data of 589 continuous head-and-neck three-dimensional computed tomography angiography were observed and analyzed using the open-source software of Horos. There were 415 males and 174 females with an average age of 44.63 ± 2.5(18-74) years. The variations of the V3 segment were defined as persistent first intersegmental artery (PFIA) and paracondylar processes (PP). The variations of V2 segments were unusual vertebral artery entrance transverse foreman (UE-V2S) and midline migration (MM). The incidences of all variations were summarized and the gender, side characters were compared.

RESULTS

Among the patients, 4.34% (18/415) males and 4.60% (8/174) females were with the variation of PFIA. Meanwhile, 12.29% (51/415) males and 10.92% (19/174) females were with the variation of PP. Then 18.80% (78/415) males and 16.67% (29/174) females were with UE-V2S. All the variations above were not different in genders. As for the variation of MM, 3.86% (16/415) males and 8.62% (15/174) females were identified, and the difference of genders was significant for this type of variation (P < 0.05). The differences between each side were also observed and analyzed for all variations and no differences were found.

CONCLUSION

There are several variations of V3 and V2 segments of the vertebral artery are associated with the cervical surgeries, most were without differences in genders and sides, except the variation of MM.

The position of the vertebral artery V1 segment relative to the C7 vertebra

BACKGROUND

The vertebral artery (VA) usually enters the transverse foramen at the C6 level. Thus, surgeons prefer to insert pedicle screws (PSs) at C7, but this does not eliminate the risk of VA injury. We aimed to clarify anatomical features of the VA V1 segment at the C7 pedicle level, based on computed tomographic angiography (CTA) of 81 consecutive patients.

METHODS

We examined the course of the VA V1 segment on axial CTA images. VA position was classified according to its alignment with the anterior (A), middle (M), or posterior (P) third of the C7 vertebral body at the pedicle level. We also assessed the prevalence of hypoplastic VA (HVA). We measured the distance (VED) from the optimum C7 PS entry point (Ep) to the center of the VA. We also measured the angles formed by the vertebral midline and a line from the inner edge of the VA to the Ep (the VEA), and by the vertebral midline and a line from the inner edge of the pedicle to the Ep (the PEA).

RESULTS

The variant location of the VA to the C7 vertebra was A in 13 courses (8.1%), M in 123 (76.9%), and P in 20 (12.5%). HVA was present in the contralateral side in 7 of 20 courses (35%) in the P group, and in 8 of 127 courses (6.3%) in the M group (p < 0.05). The mean VED was 20.2 mm, the mean VEA 6.9°, and the mean PEA angle was 36.3°.

CONCLUSION

The 20 VA courses in the P group (12.5% of the total VA courses) were relatively close to the C7 Ep. HVA was present contralateral to the VA in 7 of 20 courses in the P group. CTA should be considered before proceeding with, even if, C7 PS instrumentation, to avoid unexpected pitfall.

Extraforaminal Vertebral Artery Anomalies and Their Associated Surgical Implications: An Epidemiologic and Anatomic Report on 1000 Patients

OBJECTIVE

Extraforaminal vertebral anomalies involve entry at cervical transverse foramina other than at C6 and can appear with other anatomic variations along the V2 segment. Such unexpected vessel courses can have implications on surgical planning. We sought to evaluate the incidence of anomalous V2 segment entries, as well as their associations with vessel dominance, medialization, and C7 pedicle width.

METHODS

We conducted a retrospective study on 1000 consecutive computed tomography angiograms, documenting level and laterality of vessel of entry, as well as vertebral dominance patterns. Patients with rostral C4 anomalies were assessed for medialization. The pedicle widths ipsilateral to caudal C7 anomalies were compared with those of contralateral and matched controls.

RESULTS

A total of 157 patients were identified with extraforaminal entries, with 25 having bilateral findings. The most common alternative entry was at C5 (70.3%), followed by C4 (17.6%) and C7 (11.5%). Among patients with unilateral anomalies, there was an increased representation of contralateral vertebral dominance, relative to ipsilateral dominance (79.6% vs 20.4%, P < 0.0001). Among anomalous C4 entries, vertebral medialization was seen along the right (35%) and left sides (23.1%) spanning C6-T1. Among C7 anomalous entries there was no statistical difference in pedicle width.

CONCLUSIONS

Extraforaminal anomalies may be more frequent than previously reported and are important considerations during subaxial cervical spine surgery planning. Particular attention should be paid to the contralateral dominance pattern within this subgroup. In patients with anomalous V2 segment entries, adherence to the standard, anatomic landmarks remains desirable.

A Novel and Reproducible Classification of the Vertebral Artery in the Subaxial Cervical Spine

BACKGROUND

An injury of the vertebral artery (VA) is one of the most catastrophic complications in the setting of cervical spine surgery. Anatomic variations of the VA can increase the risk of iatrogenic lacerations.

OBJECTIVE

To propose a novel and reproducible classification system that describes the position of the VA based on a 2-dimensional map on computed tomography angiographs (CTA).

METHODS

This cross-sectional retrospective study reviewed 248 consecutive CTAs of the cervical spine at a single academic institution between 2007 and 2018. The classification consists of a number that characterizes the location of the VA from the medio-lateral (ML) aspect of the vertebral body. In addition, a letter describes the VA location from the anterior-posterior (AP) aspect. The reliability and reproducibility were assessed by 2 independent raters on 200 VAs.

RESULTS

The inter- and intrarater reliability values showed the classification's reproducibility. The inter-rater reliability weighted κ-value for the ML aspect was 0.93 (95% CI: 0.93-0.93). The unweighted κ-value was 0.93 (95% CI: 0.86-1.00) for "at-risk" positions (ML grade ≥1), and 0.87 (95% CI: 0.75-1.00) for "high-risk" positions (ML grade ≥2). The weighted κ-value for the intrarater reliability was 0.94 (95% CI: 0.95-0.95). The unweighted κ-values for the intrarater reliability were 0.95 (95% CI: 0.91-0.99) for "at-risk" positions, and 0.87 (95% CI: 0.78-0.96) for "high-risk" positions.

CONCLUSION

The proposed classification is reliable, reproducible, and independent of individual anatomic size variations. The use of this novel grading system could improve the understanding and interdisciplinary communication about VA anomalies.

Is the Vertebral Posterior Line a Safety Landmark for Cervical Posterior Screw Insertion? - Radiological Study of the Vertebral Artery in the Cervical Spine

At posterior cervical fixation, iatrogenic injury of the vertebral artery (VA) must be avoided. As the VA is usually located in front of the posterior line of the vertebral body, intraoperative lateral fluoroscopy is used to identify the line. We investigated in how many of 105 patients (210 VAs) this line is a safe marker. We also inspected the original cervical magnetic resonance angiograms (MRA) of 105 consecutive patients who had been treated for other than cervical spine diseases to study some anatomical characteristics of the VA in the cervical spine. The distance from the posterior line of the vertebral body to the posterior VA surface was classified as safe, as requiring attention, and as unsafe. Among the 210 VAs, four hypoplastic vessels were excluded from this study; consequently, 206 VAs were available for assessment. The average distance exceeded 6 mm, it was shorter at the upper cervical level. Although in at least 200 VAs (97.1%) the distance between C4 and C7 was safe, in only 170 VAs (82.5%) was it safe at C3. We observed a total of 31 tortuous loops in 17 VAs; their presence had a significant negative effect on the usefulness of the safety line. Although the posterior line of the vertebral body may be useful for safe screw insertion at the C4-C7 level, it may be less useful at C3. In the presence of tortuous VA loops, close attention must be paid to the reliability of the safety line during cervical spine surgery.

The case for T2 pedicle subtraction osteotomy in the surgical treatment of rigid cervicothoracic deformity

OBJECTIVE

Rigid cervicothoracic kyphotic deformity (CTKD) remains a difficult pathology to treat, especially in the setting of prior cervical instrumentation and fusion. CTKD may result in chronic neck pain, difficulty maintaining horizontal gaze, and myelopathy. Prior studies have advocated for the use of C7 or T1 pedicle subtraction osteotomies (PSOs). However, these surgeries are fraught with danger and, most significantly, place the C7, C8, and/or T1 nerve roots at risk.

METHODS

The authors retrospectively reviewed their experience with performing T2 PSO for the correction of rigid CTKD. Demographics collected included age, sex, details of prior cervical surgery, and coexisting conditions. Perioperative variables included levels decompressed, levels instrumented, estimated blood loss, length of surgery, length of stay, complications from surgery, and length of follow-up. Radiographic measurements included C2-7 sagittal vertical axis (SVA) correction, and changes in the cervicothoracic Cobb angle, lumbar lordosis, and C2-S1 SVA.

RESULTS

Four male patients were identified (age range 55-72 years). Three patients had undergone prior posterior cervical laminectomy and instrumented fusion and developed postsurgical kyphosis. All patients underwent T2 PSO: 2 patients received instrumentation at C2-T4, and 2 patients received instrumentation at C2-T5. The median C2-7 SVA correction was 3.85 cm (range 2.9-5.3 cm). The sagittal Cobb angle correction ranged from 27.8° to 37.6°. Notably, there were no neurological complications.

CONCLUSIONS

T2 PSO is a powerful correction technique for the treatment of rigid CTKD. Compared with C7 or T1 PSO, there is decreased risk of injury to intrinsic hand muscle innervators, and there is virtually no risk of vertebral artery injury. Laminectomy may also be safer, as there is less (or no) scar tissue from prior surgeries. Correction at this distal level may allow for a greater sagittal correction. The authors are optimistic that these findings will be corroborated in larger cohorts examining this challenging clinical entity.

Surgicoanatomical aspect in vascular variations of the V3 segment of vertebral artery as a risk factor for C1 instrumentation

OBJECT

Awareness of vascular anomalies in V3 segment of vertebral artery (VA) is crucial to avoid iatrogenic injuries during surgical procedure. This study aimed to analyze the incidence of V3 segment vascular variations and demonstrate the importance of deciding the surgical strategy for C1 screw placement.

METHODS

Prevalence of vascular variations and morphometric measurements of the VA in the region of the craniocervical junction in 200 cases based on three-dimensional computed tomographic angiography (3D-CTA) scans were studied.

RESULTS

The VA has a variable course through C2 before it passes above its groove on the posterior arch of C1. Following the vascular variations of V3 segments of VA were persistent including first intersegmental artery (FIA), fenestration (FEN) of the VA, high-riding (HRVA and the posterior inferior cerebellar artery (PICA) branch originating from the C1/2 part of VA. HRVA was observed in 10.1% of patients, FIA in 1.8%, FEN in 1.3%, and PICA in 1.3%. One hundred and twenty-three (24.1%) patients were identified to have HRVA, 6% present on both sides.

CONCLUSION

The VA with FIA and FEN were rare in this study as many as a 10% the VA present over the starting point for C1 lateral screw. With respect to the vascular anatomy of V3 and more frequent left-sided VA dominancy, standard screw insertion should be started from the right side. Routine preoperative 3D-CTA evaluation is mandatory to prevent the VA injury when C1-C2 instrumentation is planned.

Comparison of Freehand Sagittal Trajectories for Inserting Pedicle Screws Between C7 and T5

STUDY DESIGN

Anatomic study using computed tomographic scans.

OBJECTIVE

The purpose of this paper was to determine the trajectory of pedicle screw insertions, in regard to posterior bony landmarks encountered during standard posterior exposure of the spine between the seventh cervical (C7) and the fifth thoracic (T5) vertebrae, when lateral fluoroscopic and radiographic guidance may be obstructed by the scapula and shoulders.

SUMMARY OF BACKGROUND DATA

Only a few studies have evaluated the intraoperative sagittal trajectory of pedicle screw insertion.

MATERIALS AND METHODS

We assessed 64 participants of a health screening program using whole-spine computed tomographic scans. On the basis of 5 previously reported methods, we designed 3 freehand trajectories: lamina surface method (angle between the superior vertebral endplate and the surface of the lamina), spinous process method (angle between the superior vertebral endplate and a line connecting the tips of the index spinous process and the one cephalad to it), and facet tilt method (angle between the superior endplate and the superior facet tilt). We calculated each of the angles for the C7-T5 vertebrae and determined the most reliable method using coefficients of variation (CV) and intraobserver and interobserver reliability.

RESULTS

The lamina surface method had the smallest CVs for C7 and T1, and the mean angles were larger than 90 degrees (range, 94.7-102.4 degrees). The spinous process method had the smallest CVs between T2 and T5, and the mean angles were <90 degrees (range, 85.0-87.0 degrees). The intraobserver and interobserver reliabilities were good or excellent for both methods.

CONCLUSIONS

The ideal sagittal trajectories for pedicle screw insertion are nearly orthogonal to the lamina surface or the line connecting the spinous processes, but were different for each of the vertebrae. The lamina surface method was the most reliable for C7 and T1, whereas the spinous process method was most reliable between T2 and T5.

LEVEL OF EVIDENCE

Level III.

The C7 pedicle as a superior fixation point in spinal stabilization for spinal metastatic disease

Spinal metastatic disease (SMD) often requires spinal stabilization; however, the cervicothoracic junction can be a challenging area to instrument. An anterior approach may require division of the sternum. A posterior or posterolateral approach may rely on cervical lateral mass screws for superior construct fixation that are more prone to pullout than screws placed in a pedicle. The C7 pedicle is able to support pedicle screw fixation in most instances based on morphological features of the vertebra. When the C7 pedicle is used as a superior fixation point, it aligns with the thoracic pedicles below to create a streamlined posterior construct. In this study, patients undergoing posterior stabilization with C7 pedicle superior fixation were examined. One hundred and thirty-nine consecutive spinal operations at a National Cancer Institute designated cancer center were retrospectively reviewed to identify patients who underwent spinal stabilization for SMD with a C7 pedicle screw placed as the superior fixation point of a posterior construct. Patient age, the primary disease, and clinical and radiographic information were identified. Follow-up duration was noted, and follow-up outcomes were recorded on the basis of the clinical history and the findings on computed tomography (CT) spinal imaging. Three patients were identified who underwent separation surgery for SMD that included posterior spinal stabilization with C7 pedicle screws as the superior fixation point. The average patient age was 70 years and one patient was a woman. The average follow-up time was 20.7 months. There were no occurrences of hardware failure, neurologic deterioration, or protracted pain in the cases analyzed. Overall, there were good surgical outcomes with improvement in pain without neurovascular injury or evidence of hardware failure during follow-up evaluation. These findings add to a small but notable number of studies showing the effectiveness of C7 pedicle screws as a superior fixation point in spinal oncology, specifically in metastatic lesions. In our experience the C7 pedicle has provided a useful superior fixation point solution for the posterior stabilization of high thoracic vertebral body metastases. This surgical option may help spinal surgeons address the stabilization of SMD in the cervicothoracic region.

Variations of transverse foramina in cervical vertebrae: what happens to the vertebral artery?

PURPOSE

The purpose of this study is to examine variations of the foramen transversarium and the vertebral artery in computed tomography angiographies (CTa) of the cervical spine, investigate their coexistence, and present possible considerations regarding such variations in spine surgical procedures.

METHODS

Fifty CTa of the neck were retrospectively reviewed. Transverse and anteroposterior diameter of the foramen and diameter of the vertebral artery were measured. Variations of the foramen and the vertebral artery were detected.

RESULTS

Cervical CTa of 32 males and 18 females (mean age 66.4 ± 10.78 years), all belonging to the Indo-European race, were reviewed. Variations of the foramen transversarium were found in 17 vertebrae (4.85%) of 15 patients (30%). Duplication of the foramen was the most frequent variation, followed by the open foramen, the absence of the foramen, the triple foramen, and the hypoplastic foramen. Variations of the vertebral artery were found in 7 patients (14%) and asymmetry was found in 12 (24%) patients. Moreover, six patients presented with hypoplastic vertebral arteries (12%). When examining coexistence, 60% of patients exhibiting variations in the transverse foramen were also exhibiting variations or asymmetry in the vertebral artery, compared to 25.7% of patients with no foramen variations (p = 0.02).

CONCLUSIONS

Vertebral artery injury is not common but may be a disastrous complication during cervical spine surgery. Proper preoperative planning is essential for any surgeon and exact knowledge of the anatomy in each patient is essential. This study strongly recommends the preoperative use of a CTa when suspicion of a variation is present and implied by a foramen variation. These slides can be retrieved under Electronic Supplementary Material.

[Injuries of the upper cervical spine : Update on diagnostics and management]

Injuries to the upper cervical spine represent a diagnostic and therapeutic challenge to the treating surgeon due to the complex anatomical relationships and biomechanical features. In this further education article the diagnostic principles, established classifications and therapeutic recommendations as well as injury-specific characteristics of bony and ligamentous injuries to the upper cervical spine (C0-C2) are presented.

Vertebral artery loops in surgical perspective

PURPOSE

Vertebral artery loop is a congenital or acquired anomaly. Vertebral artery loops are incidentally diagnosed during evaluation of neck problems and trauma. We aimed to present the incidence of VA loops using magnetic resonance angiography in consecutive patients and discuss epidemiological data including the gender, age, location, signs and symptoms, treatment approaches and outcomes of VA loops via analyzing literature.

METHODS

In the first leg of our two-legged study, consecutive patients were evaluated using magnetic resonance angiography to detect any medial loop of vertebral arteries. The study period was from October 2015 to March 2016. In the second leg, academic databases about medial loop of vertebral artery were screened. Case reports, case series, abstracts and references of relevant literature were searched manually to avoid any missing cases.

RESULTS

We evaluated 239 consecutive patients using magnetic resonance angiography. Twenty-one patients were excluded from the study due to inadequate image acquisition, aplastic vertebral artery and/or concomitant vertebral artery stenosis. Medial loop of V2 vertebral artery was observed in 13 patients (5.9 %): 9 with left, 2 with right and 2 with bilateral medial V2 loop. Patients with medial V2 loop were significantly older than patients with straight vertebral arteries (70.30 vs. 62.36, p = 0.028). In the literature analysis, VA loops were more commonly observed at V2 segment (90.5 %). Vertebral artery loops were mostly diagnosed at the 5th and 6th decades of life predominantly in females. The most common signs and symptoms were radiculopathy and/or neck pain, and signs and symptoms of vertebrobasilar insufficiency.

CONCLUSIONS

Concise pre-operative evaluation of the vertebral arteries is essential to avoid the injury of undiagnosed VA loops during surgery, which might result in catastrophic circumstances. Further evaluation of the vertebral arteries using MR angiography is required, especially in elder age, before cervical spine surgeries.

Osteotomies in the Cervical Spine

Rigid cervical deformities are difficult problems to treat. The goals of surgical treatment include deformity correction, achieving a rigid fusion, and performing a thorough neural decompression. In stiff and ankylosed cervical spines, osteotomies are required to restore sagittal and coronal balance. In this chapter, we describe the clinical and radiographic workup for patients with cervical deformities, and delineate the various factors that must be considered when planning surgical treatment. We also describe in detail the various types of cervical osteotomies, along with their surgical technique, advantages, and potential complications.

Risks for Vascular Injury During Anterior Cervical Spine Surgery: Prevalence of a Medial Loop of Vertebral Artery and Internal Carotid Artery

STUDY DESIGN

Observational study using a retrospective single-institute database.

OBJECTIVE

To investigate the prevalence of a medial loop (ML) of the vertebral artery (VA) and internal carotid artery (ICA), which might be an anatomical risk factor for arterial injury in anterior cervical surgeries.

SUMMARY OF BACKGROUND DATA

Anterior cervical spine surgeries are generally considered to be safe and effective. VA injury is one of the most serious complications during anterior procedures. Several articles have reported this complication, which might be because of the anomalous course of VA at V2 segment. The prevalence and anatomical features of those high-risk cases were, however, not investigated.

METHODS

Consecutive Japanese subjects, who underwent contrast-enhanced computed tomography (CT) or computed tomographic angiography (CTA) for reasons other than evaluation of cervical artery disease from November 2011 to October 2012 in our institution, were reviewed. Exclusion criteria included poor images, past surgery, and endovascular intervention of cervical spine and its vessels. The definition of ML was set as the course of VA and ICA extended medially inside the uncovertebral joint. We also investigated whether those anomalous courses were detectable by plain CT.

RESULTS

A total of 1251 subjects with age ranging from 14 to 93 years with a mean of 56.1 years were surveyed. Among them, 1054 subjects were eligible and the others were excluded. A total of 421 subjects were male, and 633 were female. There were 10 cases (1%) with an ML of the VA, and 2 (0.2%) cases with a medial loop of internal carotid artery. Five of the 10 cases with a medial loop of vertebral artery were aberrant into the vertebral body, which were detectable by plain CT. Importantly, the other five cases could not be seen on the CT.

CONCLUSION

One percent of all subjects showed higher anatomical risk for VA and ICA injury during anterior surgery, half of which were undetectable by plain CT. Preoperative evaluation for vascular anatomy may be necessary for safer surgical treatment.

LEVEL OF EVIDENCE

4.

Radiological anatomy of the C7 vertebra: Clinical implications in spine surgery

Context:

This study was designed to understand and define the special radio-anatomic morphometry of C7 vertebra by using multidetector computed tomography (MDCT).

Aims:

The major aim of the study was to detect the gender- and side-related morphometric differences of C7 vertebra among subjects.

Setting and design:

Our radiology unit database scanned for MDCT sections of the C7 vertebra.

Materials and Methods:

A total of 214 patients (134 men, 80 women) were selected. A detailed morphometric evaluation of C7 was done.

Statistical analysis used:

T test, ANOVA. Lamina length (P < 0.001), pedicle length (P < 0.001), outer cortical (P = 0.01) and inner cancellous pedicle (P < 0.001) width, pedicle angle to sagittal plane (P < 0.001) values were statistically significantly different on the right versus left side. When the results were stratified by gender, lamina length, inner cancellous lamina height, pedicle length, inner cancellous pedicle height, outer cortical pedicle width, lateral mass anteroposterior length, anteroposterior length of C7 corpus, height of C7 corpus (P < 0.001), C6-7 (P = 0.013) and C7-T1disc height (P = 0.04), transverse foramina perpendicular width at C7 (P = 0.046) values were found to be statistically significantly different. Vertebral artery most commonly enters into the transverse foramina at C6 level.

Conclusions:

Gender and side differences are important factors for preoperative planning and showed significant differences among subjects. MDCT is a practical option for investigating the exact anatomical features of osseous structures.