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

Geriatric Odontoid Fractures: Treatment Algorithms of the German Society for Orthopaedics and Trauma Based on Expert Consensus and a Systematic Review

STUDY DESIGN

Systematic review/expert consensus.

OBJECTIVES

Fractures of the axis represent the most frequent injury of the spine in elderly patients. Both, operative and non-operative treatment are associated with a high rate of complications and mortality. The aim of this article was to summarize the current literature on the management of odontoid fractures in geriatric patients and to weigh it based on an expert consensus process.

METHODS

In a joint consensus process, members of the Spine Section of the German Orthopaedic and Trauma Society (DGOU) aimed to formulate recommendations for the diagnostic workup and treatment of odontoid fractures in geriatric patients. Based on the previously published recommendations, this article is an updated version with incorporating a systematic review of the recent literature.

RESULTS

Based on the new data available, the recommendations established in the initial consensus process were adapted.

CONCLUSIONS

Computed tomography represents the diagnostic standard for patients with suspected injuries of the upper cervical spine. Anderson/D'Alonzo odontoid fractures type 1, non-displaced type 2, and type 3 can be treated conservatively. Even non-unions do not necessarily result in poor clinical outcome. In Anderson/D'Alonzo type 2 fractures, surgical therapy offers the advantage of relatively safe osseous healing with no increased complication rate even in elderly patients and can thus be recommended. In very high aged patients, however, a case-by-case decision should be made. When surgical stabilization of osteoporotic odontoid fractures is indicated, posterior techniques are biomechanically advantageous and can be considered the standard.

The diagnostic accuracy of MRI and nonenhanced CT for high-risk vertebral artery anatomy for subaxial anterior cervical spine surgery safety

OBJECTIVE

Medial migration of the vertebral artery (VA) can be a risk factor for injury during anterior procedures. CT angiography (CTA) has been considered the gold standard for the evaluation of various areas of the arterial anatomy. MRI and nonenhanced CT are more commonly used as routine preoperative imaging studies, but it is unclear if these modalities can safely exclude the anomalous course of the VA. The aims of this cross-sectional observational study were to investigate risk factors for medially migrated VA on CTA and to evaluate the diagnostic accuracy of MRI and nonenhanced CT for high-risk VA anatomy in the subaxial cervical spine.

METHODS

The records of 248 patients who underwent CTA for any reason at a single academic institution between 2007 and 2018 were reviewed. The authors included MRI and nonenhanced CT taken within 1 year before or after CTA. An axial VA position classification was used to grade VA anomalies in the subaxial cervical spine. The multivariable linear regression analysis with mixed models was performed to identify the risk factors for medialized VA. The sensitivity and specificity of MRI and nonenhanced CT for high-risk VA positions were calculated.

RESULTS

A total of 175 CTA sequences met the inclusion criteria. The mean age was 63.8 years. Advanced age, disc and pedicle levels, lower cervical levels, and left side were independent risk factors for medially migrated VA. The sensitivities of MRI and nonenhanced CT for the detection of grade 1 or higher VA position were only fair, and the sensitivity of MRI was lower than that of nonenhanced CT (0.31 vs 0.37, p < 0.001), but the specificities were similarly high for both modalities (0.97 vs 0.97). With the combination of MRI and nonenhanced CT, the sensitivity significantly increased to 0.50 (p < 0.001 vs MRI and vs CT alone) with a minimal decrease in specificity.

CONCLUSIONS

Axial images of MRI and nonenhanced CT demonstrated high specificities but only fair sensitivities. Nonenhanced CT demonstrated better diagnostic value than MRI. When combining both modalities the sensitivity improved, but a substantial proportion of medialized VAs could not be diagnosed.

An anatomical investigation of the proximal vertebral arteries (V1, V2) in a select South African population

Introduction

The most common type of vascular complication during cervical spine surgery is the vertebral artery (VA) injury. The presence of anatomical variation in the artery's morphology has been a significant factor for arterial injury during surgery. Therefore, physicians planning interventions in the craniospinal region need to be aware of the extents of variations. In addition to vascular injury, anatomical variations can predispose to some pathologies in the posterior circulation territory. To provide useful data to interventional radiologists, anatomists, and surgeons, we evaluated the anatomical features of the V1 and V2 segments of the VA in a South African population.

Materials and methods

The study is an observational, retrospective chart review of 554 consecutive South African patients (Black, Indian and White) who had undergone computed tomography angiography (CTA) from January 2009 to September 2019.

Results

The VA exhibited morphological variation in its course. We report the incidence of variant origin of the left VA, all from the aortic arch. Variation in the level of entry into the transverse foramen ranged between C7 and C3. A left dominant pattern was observed; we also report on hypoplasia of the VA. In addition, we report incidence of VA tortuosity at V1, V2 to be 76.6% and 32.1%, respectively.

Conclusions

The baseline data established in this study regarding the diameter, variant origin, and level of entry into the transverse foramen will assist neurosurgeons and interventional radiologists in interpreting, diagnosing, and planning and executing various vascular procedures and treatment of pathology in the vicinity of the VA.

Anterior Approach to the Subaxial Cervical Spine: Pearls and Pitfalls

Since its introduction by Smith and Robinson, the anterior approach to the subaxial cervical spine has become one of the standard procedures for numerous cervical spine pathologies, including, but not limited to degenerative disease, trauma, tumor, deformity, and instability. Along with its increasing popularity and improvements in anterior instrumentation techniques, a comprehensive knowledge of the surgical anatomy during the anterior exposure is critical for trainees and experienced spine surgeons alike to minimize the infrequent but potentially devastating risks associated with this approach. Understanding the anatomy and techniques to minimize damage to relevant structures can reduce the risks of developing notable postoperative complications and morbidity.

Vertebral Artery Loops and Cervicobrachial Pain

Vertebral artery loop formation is an uncommon anatomical variation which may be asymptomatic or can cause cervicobrachial pain, radiculopathy, or even bone erosions and enlargement of neural foramina. As this entity is one of the uncommon causes of cervical radiculopathy, this report aims to create awareness among radiologists and clinicians, as vertebral artery loops may be seen incidentally in routine neuroimaging. magnetic resonance imaging (MRI) with magnetic resonance (MR) angiography or multislice computerized tomography (CT) angiography plays an important role in diagnosing as well as creating a roadmap for the surgery.

Vertebral artery loop formation as a cause of radiculopathy is an uncommon condition. An abnormal course of vessel can lead to vascular injury during surgery, hence preoperative evaluation with CT or MRI is essential.1 2 Anomalous looping of vertebral artery can cause neurovascular compression apart from bony erosion, widening of vertebral foramen, and even vertebrobasilar insufficiency. Clinical features of vertebral artery loop formation can be radiculopathy, compression over cervical cord leading to sensory and motor deficit, and vertigo when associated with vertebra–basilar insufficiency, which is known as vascular vertigo. It has also been postulated that loop formation of vertebral artery can also lead to posterior circulation infarcts. Left vertebral artery is more prone for loop formation than the right vertebral artery, probably due to increased caliber in greater proportion of individuals. Multilevel and bilateral tortuosity can occur in younger patients rarely where imaging plays an important role.

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.

Cervical Radiculopathy Caused by a Vertebral Artery Loop: Is a Focused Fluoroscopic-Guided Cervical Epidural Steroid Injection a Possible Treatment Modality?

We describe a case of a patient suffering with cervical radiculopathy due to vertebral artery loop with nerve root compression, treated with an epidural steroid injection. A 37-year-old man presented with a 2-year history of right-sided radicular pain along the C7 dermatome. Imaging showed a right-sided loop of the vertebral artery at the V1-V2 transition with contact on the C7 nerve root. The pain was resistant to conservative treatment, and the decision was made to perform a focused fluoroscopy-guided translaminar epidural steroid injection near the C7 nerve root. The procedure was uneventful, and the symptoms resolved completely after the procedure. Targeted epidural steroid injection might be a useful and safe diagnostic and therapeutic approach in patients affected by cervical radiculopathy due to a VA loop. To our knowledge, this is the first case of a VA loop associated with cervical radiculopathy treated with this technique.

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.

Surgical Interventions for Cervical Radiculopathy Caused by a Vertebral Artery Loop: A Case Report and Review of the Literature

BACKGROUND

Aberrant vertebral artery loops are a rare clinical condition, with sparse data regarding the optimal treatment guidelines for individual patients. The heterogeneity of treatment options in the literature creates a problem when tailoring treatments to individual patients. In this review of the literature, multiple surgical treatments for cervical vertebral artery loops were analyzed and compared. In addition, this article provides a clinical case of a patient with a vertebral artery loop.

METHODS

A literature review was conducted to identify studies investigating surgical treatments for a vertebral artery loop. Different surgical techniques were examined and the involved techniques and approaches described. The outcomes were assessed for each study and the effectiveness of the treatment determined.

RESULTS

Twelve articles met the inclusion criteria for this review. Six types of surgical interventions were found in the literature. Each intervention had similar postoperative results, leading to either a significant improvement or a complete resolution of symptoms.

CONCLUSIONS

Multiple successful surgical interventions have been described in the medical literature. However, because of the lack of evidence-based studies, no surgical intervention protocol could be determined. Treatment should therefore be tailored to individual patients' characteristics. Because not every radiologically detected vertebral artery loop is the main reason for a patient's symptoms, a thorough multidisciplinary approach is justified and advocated in patients with an atypical presentation, before a neurosurgical intervention takes place. More deliberate clinical decisions can be made once the understanding of the pathogenesis of this rare disease entity has been established and treatment protocols formulated.

Recommendations for Diagnosis and Treatment of Odontoid Fractures in Geriatric Patients

BACKGROUND

Odontoid fractures in geriatric patients represent an entity of increasing incidence with a high rate of morbidity and mortality. The optimal diagnostic and therapeutic management is being controversially discussed in the literature.

METHODS

In a consensus process and based on the current literature, the members of the working groups "Osteoporotic Fractures" and "Upper Cervical Spine" of the German Society for Orthopaedics and Trauma Surgery (DGOU) defined recommendations for the diagnostics and treatment of odontoid fractures in geriatric patients.

RESULTS

For the diagnosis of odontoid fractures in symptomatic patients, computed tomography represents the gold standard, along with conventional radiographs. Magnetic resonance and dynamic imaging can be used as ancillary imaging modalities. With regard to fracture classification, the systems described by Anderson/D'Alonzo and by Eysel/Roosen have proved to be of value. A treatment algorithm was developed based on these classifications. Anderson/D'Alonzo type 1, type 3, and non-displaced type 2 fractures usually can be treated non-operatively. However, a close clinical and radiological follow-up is essential. In Anderson/D'Alonzo type 2 fractures, operative treatment is associated with better fracture healing. Displaced type 2 and type 3 fractures should be stabilized operatively. Type 2 fractures with suitable fracture patterns (Eysel/Roosen 2A/B) can be stabilized anteriorly. Posterior C I/II-stabilization procedures are well established and suitable for all fracture patterns.

C1-2 Fixation Approach for Patients With Vascular Irregularities: A Case Report

In posterior spinal fusion (PSF), the vertebral artery is most vulnerable to injury at C1-2. C2 pedicle screws are often placed into the dorsomedial isthmus of C2. Alternative techniques include C2 laminar screws and wiring techniques. A 67-year-old male underwent PSF for persistent severe intractable neck pain and degeneration at C1-2. The patient had an enlarged left vertebral artery with midline migration into the C2 body. This pattern was within one standard deviation of normal; however, it rendered typical placement of a C2 pedicle screw unsafe. As a salvage, a C2 laminar screw was placed on the left to avoid risk of vertebral artery injury. The operation and recovery were without complication. C2 laminar screws can be viable alternatives to C2 pedicle screws in cases of midline vertebral artery migration or other vascular anomalies preventing normal safe placement of C2 pedicle screws.

[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.

Iatrogenic Vertebral Artery Injury During Anterior Cervical Spine Surgery: A Systematic Review

BACKGROUND

Iatrogenic vertebral artery injury (VAI) during anterior cervical surgery is rare but potentially catastrophic.

METHODS

Causes, presentation, diagnosis, management, prognosis, and prevention of VAI were reviewed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. English language studies and case reports published from 1980 to 2017 were retrieved. Data on diagnosis, surgical procedures and approach, site and cause of VAI, management, outcomes, and vertebral artery (VA) status were extracted.

RESULTS

In 25 articles including 54 patients, VAI was diagnosed during or after surgery commonly indicated for cervical degenerative diseases (64%), tumors (14%), and trauma (9%). The incidence of VAI for each side was similar regardless of approach. Common presentations were unexpected copious surgical bleeding, delayed hemorrhage of pseudoaneurysm with neck swelling, dyspnea, hypotension, and cervical bruits caused by arteriovenous fistula. Causes included drilling (61%), instrumentation (16%), and soft tissue retraction (8%). Direct exposure or angiography confirmed VAI. Ten patients had VA anomalies; collateral status was verified in 9 before definitive treatment. Tamponade was adopted for urgent hemostasis in most cases but with a high incidence of pseudoaneurysm (48%). Unknown VA status increased occlusion risk and neurologic sequelae (41%). VA repair and stent placement had excellent outcomes.

CONCLUSIONS

Extensive lateral decompression, loss of landmarks, and anatomic variations or pathologic status of VA increased VAI risk. Evaluation of collateral vessels before definitive treatment helped determine appropriate management and avoid neurologic sequelae. Tamponade was not recommended as definitive treatment. Meticulous preoperative evaluation, cautious intraoperative manipulation, and real-time radiographic guidance reduced VAI risk.

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.