Iatrogenic vertebral artery injury during anterior cervical spine surgery

Extracranial Vertebral Artery Injuries

Paired vertebral arteries (VAs) travel from the subclavian artery through the cervical spine and into the intracranial space where they contribute to posterior cerebral circulation. Blunt and penetrating injuries to the cervical spine risk injury to the VA. Among the most feared complications of vertebral artery injury (VAI) is posterior circulation stroke. Appropriate screening and treatment of these injuries in the trauma setting remain vitally important to aid in the prevention of devastating neurologic sequelae. A robust knowledge of the VA anatomy is required for spine surgeons to avoid VAI during cervical spine approaches and instrumentation. Both anterior and posterior cervical spine surgeries can place the VA at risk. Careful preoperative assessment with the appropriate advanced imaging studies is necessary to verify the course of the VA in the cervical spine and thus prevent iatrogenic injury because anatomic variations along the course of the artery can prove hazardous if not properly anticipated. Iatrogenic VAI can be treated successfully with tamponade. However, in some cases, ligation, repair, or endovascular procedures may be indicated.

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.

A Systematic Review and Meta-Analysis of Vertebral Artery Injury After Cervical Spine Trauma

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVE

Identify the incidence, mechanism of injury, investigations, management, and outcomes of Vertebral Artery Injury (VAI) after cervical spine trauma.

METHODS

A systematic review and meta-analysis were conducted in accordance with the PRISMA guidelines (PROSPERO-ID CRD42021295265). Three databases were searched (PubMed, SCOPUS, Google Scholar, CINAHL PLUS). Incidence of VAI, investigations to diagnose (Computed Tomography Angiography, Digital Subtraction Angiography, Magnetic Resonance Angiography), stroke incidence, and management paradigms (conservative, antiplatelets, anticoagulants, surgical, endovascular treatment) were delineated. Incidence was calculated using pooled proportions random effects meta-analysis.

RESULTS

A total of 44 studies were included (1777 patients). 20-studies (n = 503) included data on trauma type; 75.5% (n = 380) suffered blunt trauma and 24.5% (n = 123) penetrating. The overall incidence of VAI was .95% (95% CI 0.65-1.29). From the 16 studies which reported data on outcomes, 8.87% (95% CI 5.34- 12.99) of patients with VAI had a posterior stroke. Of the 33 studies with investigation data, 91.7% (2929/3629) underwent diagnostic CTA; 7.5% (242/3629) underwent MRA and 3.0% (98/3629) underwent DSA. Management data from 20 papers (n = 475) showed 17.9% (n = 85) undergoing conservative therapy, anticoagulation in 14.1% (n = 67), antiplatelets in 16.4% (n = 78), combined therapy in 25.5% (n = 121) and the rest (n = 124) managed using surgical and endovascular treatments.

CONCLUSION

VAI in cervical spine trauma has an approximate posterior circulation stroke risk of 9%. Optimal management paradigms for the prevention and management of VAI are yet to be standardized and require further research.

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

OBJECTIVE

The V3 segment of the vertebral artery (V3-VA) is at risk during diverse approaches to the craniovertebral junction. Our objective is to present a system of anatomic and topographic landmarks to identify the V3-VA during the paramedian suboccipital approach (PMSOA) with the help of minimal or basic tools.

MATERIAL AND METHODS

The first was a retrospective analysis of the angiotomography (CTA) of 50 patients over 18-years old, and 9 anatomical dissections. A series of lines were defined between the different bony landmarks. Within this lines the risk area of the vertebral artery (RAsV3-VA) and the risk point of the vertebral artery (RPsV3-VA) were defined. The second stage was a prospective study, where the previously defined measurements were carried out by using neuronavigation in 10 patients (20 sides) operated with the PMSO approach in order to confirm the presence of the V3 segment in the RAsV3-VA and RPsV3-VA.

RESULTS

In the first stage, the V3 segment was found in the middle third of the X line in 96,6% of the cases. The distance between the inion and the UCP (percentile 5) was 20 mm and to the LCP (percentile 95) was 40 mm. In the range between the UCP and the LCP, in the middle third of the inion-mastoid line (RAsV3-VA), we found 90% of the V3-VA. The measurements taken during the second stage revealed that the artery was in the middle third of the X line in 97% of the cases. 85% of the patients presented the total of the V3s-VA on the RAsV3-VA and in 85% there was a direct relationship with the V3 segment and the RPV3s-VA.

CONCLUSION

We propose an easy-to-implement system to delimit the risk area of the V3-VA during the PMSOA. We believe that these landmarks provide a practical, reliable, costless and useful tool that could decrease the risk of lesion of the V3-VA during this approach without the need of using.

The Incidence of Vertebral Artery Injury in Cervical Spine Surgery

BACKGROUND

Previously reported estimates of vertebral artery injuries (VAIs) during cervical spine surgery relied on self-reported survey studies and retrospective cohorts, which may not be reflective of national averages. The largest study to date reports an incidence of 0.07%; however, significant variation exists between different cervical spine procedures. This study aimed to identify the incidence of VAIs in patients undergoing cervical spine procedures for degenerative pathologies.

METHODS

In this retrospective cohort study, a national insurance database was used to access data from the period 2010-2020 of patients who underwent anterior cervical discectomy and fusion, anterior corpectomy, posterior cervical fusion (C3-C7), or C1-C2 posterior fusion for degenerative pathologies. Patients who experienced a VAI were identified, and frequencies for the different procedures were compared.

RESULTS

This study included 224,326 patients, and overall incidence of VAIs across all procedures was 0.03%. The highest incidence of VAIs was estimated in C1-C2 posterior fusion (0.12%-1.10%). The number of patients with VAIs after anterior corpectomy, anterior cervical discectomy and fusion, and posterior fusion was 14 (0.06%), 43 (0.02%), and 26 (0.01%), respectively.

CONCLUSIONS

This is the largest study to date to our knowledge that provides frequencies of VAIs in patients undergoing cervical spine surgery in the United States. The overall incidence of 0.03% is lower than previously reported estimates, but significant variability exists between procedures, which is an important consideration when counseling patients about risks of surgery.

Transcervical, retropharyngeal odontoidectomy - Anatomical considerations

Context

Anterior craniocervical junction lesions have always been a challenge for neurosurgeons. Presenting with lower cranial nerve dysfunction and symptoms of brainstem compression, decompression is often required. While posterior approaches offer indirect ventral brainstem decompression, direct decompression via odontoidectomy is necessary when they fail. The transoral and endoscopic endonasal approaches have been explored but come with their own limitations and risks. A novel retropharyngeal approach to the cervical spine has shown promising results with reduced complications.

Aims

This study aims to explore the feasibility and potential advantages of the anterior retropharyngeal approach for accessing the odontoid process.

Methods and Surgical Technique

To investigate the anatomical aspects of the anterior retropharyngeal approach, a paramedian skin incision was performed below the submandibular gland on two cadaveric specimens. The subcutaneous tissue followed by the platysma is dissected, and the superficial fascial layer is opened. The plane between the vascular sheath laterally and the pharyngeal structures medially is entered below the branching point of the facial vein and internal jugular vein. After reaching the prevertebral plane, further dissection cranially is done in a blunt fashion below the superior pharyngeal nerve and artery. Various anatomical aspects were highlighted during this approach.

Results

The anterior, submandibular retropharyngeal approach to the cervical spine was performed successfully on two cadavers highlighting relevant anatomical structures, including the carotid artery and the glossopharyngeal, hypoglossal, and vagus nerves. This approach offered wide exposure, avoidance of oropharyngeal contamination, and potential benefit in repairing cerebrospinal fluid fistulas.

Conclusions

For accessing the craniocervical junction, the anterior retropharyngeal approach is a viable technique that offers many advantages. However, when employing this approach, surgeons must have adequate anatomical knowledge and technical proficiency to ensure better outcomes. Further studies are needed to enhance our anatomical variations understanding and reduce intraoperative risks.

VertebralArtery Injury with Anterior Cervical Spine Operations: A Systematic Review of Risk Factors, Clinical Outcomes, and Management Strategies

OBJECTIVE

Anterior cervical spine operations are commonly performed on cervical spine pathologies and to a large extent are safe and successful. However, these surgical procedures expose the vertebral artery, posing a risk of harm to it.

METHODS

A systematic review was conducted using PubMed, Google Scholar, and Web of Science electronic databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to critically assess primary articles discussing treatment strategies "vertebral artery injury" AND "anterior cervical spine" and develop a management strategy based on our experience and meta-analysis of the literature. In addition, we present an illustrative case of iatrogenic vertebral artery injury presenting with 6 to 7 months' history of progressive dysphagia was transferred to our care from an outside institution.

RESULTS

Included and analyzed were 43 articles that detailed 75 cases involving vertebral artery injury (VAI) in anterior cervical spine operations. Preoperatively, frequent clinical findings reported were sensory deficit (26 patients [63.41%]), motor deficit (20 patients [48.78%]), and pain (17 patients [41.46%]). In total, 32 patients (50.00%) endured injury of their left VA, and 30 patients had a right VAI. The 2 common causes of VAI were drilling (24 patients [40.00%]) and instrumentation (8 patients [13.33%]).

CONCLUSIONS

Altogether, our review recommends repair or tamponade packing with a hemostatic agent for primary management. Should tamponade packing with a hemostatic agent be used for primary management, secondary management should entail either repair, stenting occlusion, embolization, anticoagulants, or ligation. Further examination of this treatment strategy based on a larger cohort is necessary.

Vertebral Artery Dissection Following Anterior Cervical Decompression and Artificial Disc Replacement

Vertebral artery dissection (VAD) is a rare vascular cause of acute stroke. Although VAD may be classified as spontaneous or traumatic, it is increasingly recognized that trivial mechanical stress typically precipitates this potentially dangerous condition. Herein, we report a rare case of VAD and acute stroke following anterior cervical decompression and artificial disc replacement (ADR). To our knowledge, there have been no other cases of acute vertebrobasilar stroke caused by VAD following anterior cervical decompression and ADR. This case highlights that, although rare, acute vertebrobasilar stroke may occur after the anterior cervical approach.

The Role of Intraoperative Neuromonitoring Modalities in Anterior Cervical Spine Surgery

Background: Intraoperative neuromonitoring (IONM) is frequently used during spine surgery to mitigate the risk of neurological injuries. Yet, its role in anterior cervical spine surgery remains controversial. Without consensus on which anterior cervical spine surgeries would benefit the most from IONM, there is a lack of standardized guidelines for its use in such procedures. Purpose: We sought to assess the alerts generated by each IONM modality for 4 commonly performed anterior cervical spinal surgeries: anterior cervical diskectomy and fusion (ACDF), anterior cervical corpectomy and fusion (ACCF), cervical disk replacement (CDR), or anterior diskectomy. In doing so, we sought to determine which IONM modalities (electromyography [EMG], motor evoked potentials [MEP], and somatosensory evoked potentials [SSEP]) are associated with alert status when accounting for procedure characteristics (number of levels, operative level). Methods: We conducted a retrospective review of IONM data collected by Accurate Neuromonitoring, LLC, a company that supports spine surgeries conducted by 400 surgeons in 8 states, in an internally managed database from December 2009 to September 2018. The database was queried for patients who underwent ACCF, ACDF, anterior CDR, or anterior diskectomy in which at least 1 IONM modality was used. The IONM modalities and incidence of alerts were collected for each procedure. The search identified 8854 patients (average age, 50.6 years) who underwent ACCF (n = 209), ACDF (n = 8006), CDR (n = 423), and anterior diskectomy (n = 216) with at least 1 IONM modality. Results: Electromyography was used in 81.3% (n = 7203) of cases, MEP in 64.8% (n = 5735) of cases, and SSEP in 99.9% (n = 8844) of cases. Alerts were seen in 9.3% (n = 671), 0.5% (n = 30), and 2.7% (n = 241) of cases using EMG, MEP and SSEP, respectively. In ACDF, a significant difference was seen in EMG alerts based on the number of spinal levels involved, with 1-level ACDF (6.9%, n = 202) having a lower rate of alerts than 2-level (10.0%, n = 272), 3-level (15.2%, n = 104), and 4-level (23.4%, n = 15). Likewise, 2-level ACDF had a lower rate of alerts than 3-level and 4-level ACDF. A significant difference by operative level was noted in EMG use for single-level ACDF, with C2-C3 having a lower rate of use than other levels. Conclusions: This retrospective review of anterior cervical spinal surgeries performed with at least 1 IONM modality found that SSEP had the highest rate of use across procedure types, whereas MEP had the highest rate of nonuse. Future studies should focus on determining the most useful IONM modalities by procedure type and further explore the benefit of multimodal IONM in spine surgery.

Delayed Hemorrhage Followed by Vertebral Artery Injury during Cervical Anterior Controllable Antedisplacement and Fusion Surgery: Case Report and Literature Review

Background

Vertebral artery injury (VAI) during cervical spine surgery is rare. Anterior controllable ante‐displacement and fusion (ACAF) surgery is a novel technique for treating degenerative cervical spine disorders, especially ossification of the posterior longitudinal ligament. To date, there have been no reports of VAI during cervical ACAF surgery. Here, we report a rare case of perioperative complication of VAI during ACAF surgery. The available English literature that provides treatment instructions were reviewed.

Case Presentation

A patient diagnosed with mixed ossification of the posterior longitudinal ligament (OPLL) underwent ACAF surgery from C2–C6. Two level transverse foramina were ruptured, and severe bleeding was encountered during ACAF osteotomy. Hemostatic tamponade was performed using bone waxes. The patient had delayed hemorrhage on postoperative day 6. Emergence angiography revealed two vertebral artery pseudoaneurysms in the ruptured transverse foramina. A balloon‐expandable covered stent was deployed to treat the pseudoaneurysm. The patient recovered without complications.

Conclusion

ACAF surgery is a good choice for multiple‐level OPLL disease, but special attention should be paid to VAI in the perioperative period. Intraoperative tamponade with bone wax and postoperative digital subtraction angiography (DSA) are effective in preventing disaster‐related hemorrhage.

Surgical treatment for kyphotic deformity after anterior cervical fusion with a severely tortuous vertebral artery: a case report

We performed salvage surgery on a patient with kyphotic deformity after anterior cervical fusion with a tortuous vertebral artery (VA). A 69-year-old woman had undergone anterior cervical corpectomy and fusion 12 years ago. Her cervical alignment gradually became kyphotic because of bone graft collapse. Ten years after surgery, she experienced severe neck pain, recurrence of myelopathic symptoms and difficulty in keeping her head straight. The patient was diagnosed with rigid cervical kyphosis at C4–6 vertebral levels, with the right tortuous VA invaginating into the C4 vertebral body. We selected a three-stage, anterior–posterior–anterior approach to reduce cervical alignment. The key to a successful surgery in this case was to retract the tortuous VA within the C4 vertebral body, followed by total uncinectomy. Careful preoperative VA evaluation was a decisive factor in surgical planning.

Comparison of Using Intraoperative Computed Tomography-Based 3-Dimensional Navigation and Fluoroscopy in Anterior Cervical Diskectomy and Fusion for Cervical Spondylosis

OBJECTIVE

Anterior cervical diskectomy and fusion (ACDF) is a highly successful procedure to treat spinal cord or nerve root compression; however, complications can still occur. With advancements in imaging, 3-dimensional (3D) reconstruction allows real-time instrument tracking in a surgical field relative to the patient's anatomy. Here, we compare plate positioning and short-term outcomes when using 3D navigation to fluoroscopy in ACDF for degenerative spine disease.

METHODS

All ACDFs for cervical spondylosis performed by 6 surgeons at a single center between 2010 and 2018 were included. ACDFs were divided into those performed using 3D navigation or fluoroscopy. Records were assessed for patient demographics, American Society of Anesthesiology score, number of operated interspaces, operative time, length of stay, perioperative complications, and 90-day readmissions. Postoperative images were reviewed for lateral and angular plate deviations.

RESULTS

A total of 193 ACDFs performed with 3D navigation and 728 performed with fluoroscopy were included. After controlling for demographics and surgical characteristics, using 3D navigation was associated with less lateral plate deviation (P = 0.048) and longer operative times per interspace (P < 0.001) but was not associated with angular plate deviation (P = 0.724), length of stay (P = 0.393), perioperative complications (P = 0.844), and 90-day readmissions (P = 0.539).

CONCLUSIONS

Using 3D navigation in ACDF for degenerative disease is associated with slightly more midline plate positioning and comparable short-term outcomes as using fluoroscopy and can be a suitable alternative. Advantages of using this technology, such as improved visualization of anatomy, should be weighed against disadvantages, such as increased operative time, on a per-patient basis.

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.

Spinal Cord Medial Safe Zone for C2 Pedicle Instrumentation: An MRI Measurement Analysis

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

The aim of this study was to investigate the spinal cord safety margins for C2 instrumentation.

SUMMARY OF BACKGROUND DATA

Intraoperative spinal cord injury during C2 spine surgery is a rare, but potentially life-threatening complication. Preoperative planning for C2 instrumentation mainly focuses on C2 pedicle bony dimensions on CT and the vertebral artery location and few studies have evaluated C2 spinal cord safety margins.

METHODS

We measured two distances in C2 bilaterally: C2 pedicle to dura distance (P-D), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and the dural sac, and C2 pedicle to spinal cord (P-SC), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and spinal cord. We defined the distances >4 mm as safe for instrumentation.

RESULT

A total of 146 patients (mean age 71.2, 50.7% female) were included. The average distances were 5.5 mm for C2 left PD, 5.9 mm for C2 right P-D, 10.1 mm for C2 left P-SC, and 10.6 mm for C2 right P-SC. Twenty-eight (21.4%) patients had C2 P-D distances <4 mm and of those two (7%) patients had distances <2 mm. There were more female patients with C2 P-D distances under 4 mm compared to males. No patient had C2 P-SC distances <4 mm.

CONCLUSION

We demonstrated that around 20% of patients had C2 P-D distance <4 mm, but no patient had C2 P-SC distance <4 mm. Since a lateral misplacement can lead to a potentially fatal vertebral artery injury, medial screw trajectory is recommended for C2 pedicle instrumentation with consideration of these safety margins.Level of Evidence: 3.

Vertebral Artery Variations at the Craniovertebral Junction in "Sandwich" Atlantoaxial Dislocation Patients

Objective

To summarize the vertebral artery (VA) pattern of 96 “sandwich” atlantoaxial dislocation (AAD) patients and to describe the strategies of reducing the injury of VA during surgery.

Methods

From 2009 to 2020, we retrospectively reviewed the 3-dimensional computed tomography angiography data of 96 AAD patients combined with atlas occipitalization and C2–3 fusion, which were diagnosed as “sandwich” AAD and 96 patients as control group patients who were without atlas occipitalization, C2–3 fusion and any other cervical bone deformity at our institution. The variations of each side of VA were described in 3 different parts (C0–1, C1–2, and C2–3) according to the characteristics of the 3-part pathological structures in “sandwich” subgroup.

Results

One hundred ninety-two sides of VAs in every group of patients were analyzed and every VA was described separately at 3 different level regions. There were different variations in these 3 different regions: 4 variations in the upper fusion region, 5 variations in the sandwiched region, and 6 variations in the lower fusion region in sandwich AAD patients. And the rate of VA deformity in sandwich AAD patients was much higher and more types of VA variations existed.

Conclusion

In “sandwich” AAD patients, deformities of vertebral arteries in craniovertebral junction are more common, and the same VA may have deformities at different levels that severely affect surgical procedures. Therefore, preoperative imaging examination of VA for “sandwich” AAD patients is vital of guiding surgeons to avoid injury of VA during surgery.

Iatrogenic Vascular Injury Associated with Cervical Spine Surgery: A Systematic Literature Review

BACKGROUND

Iatrogenic vascular injury is an uncommon complication of anterior and/or posterior surgical approaches to the cervical spine. Although the results of this injury may be life-threatening, mortality/morbidity can be reduced by an understanding of its mechanism and proper management.

METHODS

We conducted a literature review to provide an update of this devastating complication in spine surgery. A total of 72 articles including 194 cases of vascular lesions following cervical spine surgery between 1962 and 2021 were analyzed.

RESULTS

There were 53 female and 41 male cases (in addition to 100 cases with unreported sex) with ages ranging from 3 to 86 years. The vascular injuries were classified according to the spinal procedures, such as anterior or posterior cervical spine surgery. The interval between the symptom of the vascular injury and the surgical procedure ranged from 0 to 10 years. Only two-thirds of patients underwent intra- or postoperative imaging and the most frequently injured vessel was the vertebral artery (86.60%). Laceration was the most common lesion (41.24%), followed by pseudoaneurysm (16.49%) and dissection (5.67%). Vascular repair was performed in 114 patients. The mortality rate was 7.22%, and 18.04% of patients had 1 or more other complications. Most presumed causes of vascular lesions were by instrumentation/screw placement (31.44%) or drilling (20.61%). Sixteen patients had an anomalous artery. Direct microsurgical repair was achieved in only 15 cases.

CONCLUSIONS

Despite increased anatomical knowledge and advanced imaging techniques, we need to consider the risk of vascular injury as a surgical complication in patients with cervical spine pathologies.

Anastomosis and Endovascular Treatment of Iatrogenic Vertebral Artery Injury

Iatrogenic vertebral artery injury (VAI) that occurs during cervical spine surgery can cause life-threatening complications, such as arteriovenous fistulas, catastrophic bleeding, neurological impairment, cerebral ischemia, and death. We report a case of dominant VAI during surgery and the treatment of a 60-year-old man diagnosed with a C1-2-3 metastatic spine tumor from urothelial carcinoma. Active bleeding occurred during tumor resection using pituitary forceps, immediately followed by gauze packing and manual compression. Post further resection, we found that the vertebral artery (VA) was completely severed. After temporary clamping on both sides of the damaged VA, an artificial graft anastomosis was performed. After verifying that the flow was intact using Doppler Sonography, Occiput-C1-4-5-6 posterolateral fusion was performed. Angiography was performed immediately after surgery. We found a thrombus occluding the left VA, and performed mechanical thrombectomy and stent insertion. The final angiography showed good VA flow with no emboli. In this case, VA anastomosis and endovascular treatment were performed within a relatively short period of time post VAI, and the patient was able to recover without any neurological deficits.

Free Tissue Transfer for Repair of Chronic Esophageal Perforations

Objective

Anterior cervical discectomy and fusion have become a common intervention for cervical spine stabilization. However, complications can cause life-threatening morbidity. Among them, esophageal perforation is associated with severe morbidity, including dysphagia, malnutrition, and infection with the potential development of mediastinitis. Presentation is variable but often results in chronic morbidity. Herein we examine our experiences in the management of esophageal perforation with microvascular free tissue transfer.

Study Design

Retrospective review from January 2013 to September 2020.

Setting

Single academic tertiary care center.

Methods

This study comprised all patients (age, 41-73 years) undergoing free tissue transfer for the repair of chronic esophageal perforation secondary to anterior cervical discectomy and fusion at an academic tertiary care center. Four patients underwent repair via vastus lateralis myofascial onlay grafting for defects ≤2 cm in greatest dimension, while 1 patient underwent a fasciocutaneous radial forearm free flap repair of an 11 × 5-cm defect.

Results

Defect location ranged from hypopharynx to cervical esophagus. Mean operative time was 6.2 hours; the average length of stay for all patients was 6.6 days. Of 5 patients, 1 required additional hardware placement for spine stabilization. All patients underwent gastrostomy tube placement to bypass the surgical site during healing, and all eventually resumed an oral diet postoperatively. Recurrent fistula occurred in 1 of 5 patients. No flap failures were encountered in the study population.

Conclusion

Vastus lateralis myofascial onlay grafting and fasciocutaneous radial forearm free flap are robust, relatively low-morbidity interventions with a high success rate for definitive repair of chronic esophageal perforation. Repair should be undertaken in concert with a spine surgeon for management of the cervical spine.

Anomalous Vertebral Artery During Cranio Vertebral Junction Surgery Using DCER (Distraction, Compression, Extension, and Reduction): Approach. and Its Repair

Introduction

Vertebral artery (VA) may run an anomalous course in congenital craniovertebral junction anomalies. Anomalous VA, though rare, is challenging to handle. An anomalous VA can get injured during exposure of craniovertebral junction, even in the experienced hands.

Objective

The objective of this article was to describe the technique of repairing the VA in case of its damage during exposure in the craniovertebral junction (atlantoaxial dislocation [AAD] with basilar invagination [BI]).

Procedure

The authors describe a case of VA artery injury in a case of severe BI & AAD, which was anomalous and coursing over the joints. Following the repair of injured VA, we proceeded with the surgery (distraction, compression, extension, and reduction [DCER]).

Conclusion

To avoid injury, it is important to always perform a CT 3-D angiogram, perform meticulous dissection under the microscope while exposing the joints, use variable impedance bipolar to control venous bleeding and always expose the side with non-dominant VA first.

First reported use of real-time intraoperative computed tomography angiography image registration using the Machine-vision Image Guided Surgery system: illustrative case

BACKGROUND

Vertebral artery injury is a devastating potential complication of C1–2 posterior fusion. Intraoperative navigation can reduce the risk of neurovascular complications and improve screw placement accuracy. However, the use of intraoperative computed tomography (CT) increases radiation exposure and operative time, and it is unable to image vascular structures. The Machine-vision Image Guided Surgery (MvIGS) system uses optical topographic imaging and machine vision software to rapidly register using preoperative imaging. The authors presented the first report of intraoperative navigation with MvIGS registered using a preoperative CT angiogram (CTA) during C1–2 posterior fusion.

OBSERVATIONS

MvIGS can register in seconds, minimizing operative time with no additional radiation exposure. Furthermore, surgeons can better adjust for abnormal vertebral artery anatomy and increase procedure safety.

LESSONS

CTA-guided navigation generated a three-dimensional reconstruction of cervical spine anatomy that assisted surgeons during the procedure. Although further study is needed, the use of intraoperative MvIGS may reduce the risk of vertebral artery injury during C1–2 posterior fusion.

Endovascular Management of Iatrogenic Vertebral Artery Transection During Anterior Cervical Spine Surgery: A Case Report

Anterior surgical approaches to the cervical spinal pathology have become a frequently used technique. Anterior cervical spine surgeries are generally considered to be safe with low incidence of neurological complications. Vertebral artery (VA) injuries are infrequent during an anterior cervical spine approach but can be devastating. A retrospective review of these injuries documents an incidence of 0.3%-0.5%. However, there is no established strategy or guidelines for managing iatrogenic VA injuries. We describe a case of iatrogenic VA injury at C5 vertebral level during an anterior cervical approach for C5 cervical osteoblastoma; successful managed by endovascular coiling using detachable coils achieving complete occlusion. The patient had a good clinical outcome, with no symptoms of vertebrobasilar insufficiency at 2-year follow-up. There is a paradigm shift in the management of the VA injury after introduction of the interventional angiography. Endovascular embolization is a safe and effective treatment option, which offers certain advantages over open surgery such as minimal invasion, lower risk of neurological injury, lower morbidity, and recurrence rates.

Morphologic Changes in the Vertebral Artery Subsequent to Cervical Spine Degeneration and Aging: Analyses by Computed Tomography Angiography Using Multiplanar and 3-Dimensional Reconstructions

OBJECTIVE

To identify the morphologic changes in the vertebral artery (VA) subsequent to cervical spine degeneration and aging and to investigate the risk factors for iatrogenic VA injury or occlusion.

METHODS

Eighty-eight consecutive patients (176 bilateral VAs) were retrospectively analyzed using radiographs, computed tomography, and computed tomography angiography images. The Kellgren and Lawrence (KL) score and its modified subscores were used to grade the severity of degenerative changes in the cervical spine. VA tortuosity widths and diameters were measured between the C2 and C6 transverse foramens. The outcome measures were statistically analyzed for difference, correlation, and explanatory variable. The level with a high prevalence of VA stenosis was also evaluated.

RESULTS

There were significant positive correlations between the KL score and VA tortuosity width, and between age and VA tortuosity width. Osteophyte formation in the facet joint was the predominant explanatory variable for medial deviation of the VA. Significant positive correlations were evident between the dominant VA diameter and KL score or age. VA stenosis occurred at C3/C4 (24.5%) with the highest prevalence and it was caused by uncovertebral joint osteophytes (52.0%) with the highest incidence.

CONCLUSIONS

The present study provides important evidence for decisions of surgical strategy and for avoiding catastrophic VA injury or occlusion in cervical spine surgeries.

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.

Biologic Agents Preserve the C-2 Pedicle in Patients with Rheumatoid Arthritis: A Comparative Imaging Study Using Three-Dimensional Computed Tomography

OBJECTIVE

To investigate whether biologic agents (BAs) reduce a narrow C-2 pedicle screw trajectory, which is often a key stabilizer in surgical treatment, in patients with rheumatoid arthritis (RA).

METHODS

A total of 100 patients with RA treated with and without BAs (BA [+] group [n = 50] and BA [-] group [n = 50]), respectively, were included in the present study. Computed tomography (CT) images of their cervical spine, including C-2, were analyzed. The maximum screw diameter at C-2 that could be inserted without breaching the cortex, measured on 3-dimensional images using a CT-based navigation system, was compared between the groups with and without BA administration. Furthermore, the destruction of the atlantoaxial joint was examined using CT images. The risk factors for a narrow C-2 pedicle were elucidated among the patients treated with BAs.

RESULTS

The pedicle in the BA (+) group had a significantly larger C-2 maximum screw diameter than the BA (-) group (6.00 mm vs. 5.13 mm, P < 0.001), with less destruction of the atlantoaxial joint. Among the BA (+) group, a longer period until the initial administration of BAs and RA disease duration were associated with a narrow C-2 pedicle.

CONCLUSIONS

This study suggests that BAs can maintain the trajectory for C-2 pedicle screws, which acts as a key stabilizer in surgical management for the rheumatoid cervical spine, by halting the destruction of the atlantoaxial joint. Early introduction of BAs can be especially important to prevent the narrowing of the C-2 pedicle.

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

»

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).

»

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.

»

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.

»

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.

DEGENERATIVE CERVICAL MYELOPATHY: A REVIEW OF CURRENT CONCEPTS

ABSTRACT Herbert von Luschka, a German anatomist, was the first to describe the developmental changes in the anatomical structures of the cervical spine. Degenerative cervical myelopathy (DCM) represents a collection of pathological entities that cause compression of the cervical spinal cord, resulting in a clinical syndrome typified by spasticity, hyperreflexia, pathologic reflexes, finger/hand clumsiness, gait disturbance and sphincter dysfunction. In the cervical spine, certain patients are more likely to have myelopathy due to a congenitally narrowed cervical spine canal. Degenerative changes are more common at C5 and C6 or C6 and C7 due to the increased motion at these levels. Additional contributors to canal narrowing are infolding of the ligamentum flavum, olisthesis, osteophytes, and facet hypertrophy. Myelopathy will develop in approximately 100% of patients with canal stenosis greater than 60% (less than 6 mm sagittal disc cord space). Classically it has an insidious onset, progressing in a stepwise manner with functional decline. Without treatment, patients may progress toward significant paralysis and loss of function. Treatment requires surgery with either anterior or posterior decompression of the area of narrowing, and probable fusion. Factors of a poor prognosis include symptoms lasting for more than 18 months, increased range of motion in the cervical spine, and female gender. In this study, we give an overview of the state-of-the-art in DCM, with a focus on the pathophysiology, clinical presentation, differential diagnosis, imaging evaluation, natural history, treatment options and complications. Level of evidence III; Review article.

Cervical disc degeneration reduces distance between vertebral artery and surgical landmarks

PURPOSE

Anterior cervical decompression surgery exposes the vertebral artery to the risk of injury. This risk can increase if the natural course of the vertebral artery is altered. Therefore, this study evaluated if the distance between surgical landmarks and the vertebral artery decrease with the progression of cervical disc degeneration.

METHODS

This study analyzed 40 patients with cervical magnetic resonance imaging. We evaluated the distance between the uncinate process and the vertebral artery in axial-plane T2 weighted sequences of the cervical levels C3-C6. The cervical disc degeneration was graded according to the Pfirrmann- and Suzuki classification. The decrease of the distance was evaluated using a one-way ANOVA.

RESULTS

The distance between the uncinate process and the vertebral artery decreased with increasing disc degeneration (p ≤ 0.015). ROC analysis provided an acceptable area under the curve in both classifications for the detection of a vertebral artery to the uncinate process distance of zero. The presence of Pfirrmann grade V had a positive predictive value of 69% for the presence of contact between the uncinate process and the vertebral artery.

CONCLUSION

High-grade cervical disc degeneration according to the Pfirrmann- and the Suzuki classification decrease the distance between the uncinate process and the vertebral artery. High-grade disc degeneration therefore should raise the awareness of the surgeon for the loss of the distance between surgical landmarks and the vertebral artery. However, screening for high-grade disc degeneration alone cannot substitute the thorough evaluation of the anatomical course of the vertebral artery before surgery.

Covering of Plate after Anterior Cervical Fusion in Patients with Complete Spinal Cord Injury to Prevent Esophageal Injury: Technical Note

BACKGROUND

 Esophageal injury after anterior corpectomy and fusion is a rare but life-threatening complication. It may cause mediastinitis due to anatomical continuity between the retropharyngeal space and the mediastinum, with reported high mortality rates. The acute and subacute injuries are most commonly of iatrogenic origin, while late perforation has been described several weeks to years later as a result of continuous friction or pressure of the instruments against the posterior wall of the esophagus, leading to ischemia and necrosis. This phenomenon is more common among quadriplegic patients who have undergone corpectomy and insertion of expandable or mesh cages and plate probably due to chronic erosion by hardware at the supine position.

METHODS

 Since 2015, we have applied the technique of using a patch of autologous fascia lata to cover the anterior cervical plate by suturing to the longus colli muscles in 58 quadriplegic patients; the mean follow-up was 35.2 (28-41) months.

RESULTS

 Since we started using this procedure, based on our follow-up at our center, there have been no cases of late esophageal perforation among quadriplegic patients.

CONCLUSION

 As a technical note, it seems like this method would be able to reduce the prevalence of esophagus injury among quadriplegic patients. However, to substantiate the efficacy of this technique, long-term follow-up and larger sample size are needed because esophageal injury occurs rarely.

Choice and management of negative pressure drainage in anterior cervical surgery

BACKGROUND

Postoperative unobstructed drainage is an important measure for avoiding hematoma formation and preventing complications from anterior cervical surgery.

AIM

To discuss the characteristics and key points of clinical management of two types of commonly used negative pressure drainage systems in clinical settings.

METHODS

Two types of commonly used silica gel negative pressure drainage balls and a type of gastrointestinal decompression apparatus were fully emptied and then injected with different amounts of water and air. Following this, the negative pressure values of the three devices were measured. Meanwhile, we undertook a retrospective analysis of the clinical data of 1328 patients who had been treated with different negative pressure drainage apparatuses during their anterior cervical surgery in our department between January 2007 and January 2018.

RESULTS

As the amount of injected air or water increased, the negative pressure of the silica gel negative pressure drainage ball decreased rapidly, dropping to zero when 150 mL of water or air was injected. In contrast, the negative pressure of gastrointestinal decompression apparatus decreased slowly, maintaining an ideal value even when 300 mL of water or air was injected. And statistical analysis demonstrated that patients who had been treated with the gastrointestinal decompression apparatus were less likely to develop severe complications than those who had been treated with the silica gel negative pressure drainage ball (P < 0.05).

CONCLUSION

This study showed that the gastrointestinal decompression apparatus has the advantages of large suction capacity, long duration of continuous negative pressure, and good drainage effect, all of which are the favorable factors for the use of this apparatus for negative pressure drainage in anterior cervical surgery.

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.

Tissue-Sparing Posterior Cervical Fusion With Interfacet Cages: A Systematic Review of the Literature

STUDY DESIGN

Literature review.

OBJECTIVES

Posterior cervical interfacet cages are an alternative to lateral mass fixation in patients undergoing cervical spine surgery. Recently, a percutaneous, tissue-sparing system for interfacet cage placement has been developed, however, there is limited clinical evidence supporting its widespread use. The aim was to review studies published on this system for patient reported outcomes, radiographic outcomes, intraoperative outcomes, and complications.

METHODS

Four electronic databases (PubMed, EMBASE, Scopus, and MEDLINE) were queried for original published studies that evaluated the percutaneous, tissue-sparing technique for posterior cervical fusion with interfacet cage placement. All studies reporting on open techniques and purely biomechanical studies were excluded.

RESULTS

The extensive literature search returned 7852 studies. After systematic review, a total of 7 studies met inclusion criteria. Studies were independently classified as retrospective or prospective cohort studies and each assessed by the GRADE criteria. Patient reported outcomes, radiographic outcomes, intraoperative outcomes, and complications were extracted from each study and presented.

CONCLUSIONS

Tissue-sparing, posterior cervical fusion with interfacet cages may be considered a safe and effective surgical intervention in patients failing conservative management for cervical spondylotic disease. However, the quality of evidence in the literature is lacking, and controlled, comparative studies are needed for definitive assessment.

Complications of anterior cervical spine surgery: a systematic review of the literature

The anterior approach to the cervical spine is commonly utilized for a variety of degenerative, traumatic, neoplastic, and infectious indications. While many potential complications overlap with those of the posterior approach, the distinct anatomy of the anterior neck also presents a unique set of hazards. We performed a systematic review of the literature to assess the etiology, presentation, natural history, and management of these complications. Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), a PubMed search was conducted to evaluate clinical studies and case reports of patients who suffered a complication of anterior cervical spine surgery. The search specifically included articles concerning adult human subjects, written in the English language, and published from 1989 to 2019. The PubMed search yielded 240 articles meeting our criteria. The overall rates of complications were as follows: dysphagia 5.3%, esophageal perforation 0.2%, recurrent laryngeal nerve palsy 1.3%, infection 1.2%, adjacent segment disease 8.1%, pseudarthrosis 2.0%, graft or hardware failure 2.1%, cerebrospinal fluid leak 0.5%, hematoma 1.0%, Horner syndrome 0.4%, C5 palsy 3.0%, vertebral artery injury 0.4%, and new or worsening neurological deficit 0.5%. Morbidity rates in anterior cervical spine surgery are low. Nevertheless, the unique anatomy of the anterior neck presents a wide variety of potential complications involving vascular, aerodigestive, neural, and osseous structures.

Posterior Inferior Cerebellar Artery Infarction Originating at C1-2 after C1-2 Fusion

Vertebral artery injuries associated with C1 lateral mass screw insertion rarely occur during C1-2 fusion. The posterior inferior cerebellar artery (PICA) is uncommonly located at the C1 lateral mass insertion position. A 71-year-old woman with atlanto-axial subluxation and cord compression underwent C1-2 fusion. Sixth nerve palsy and diplopia were detected postoperatively, and decreased consciousness occurred on postoperative day 4. Brain magnetic resonance image (MRI) and computed tomography (CT) revealed PICA infarction. In the preoperative CT angiography, the PICA originated between the C1 and C2 level. In the postoperative CT scan, the PICA was not visible. The patient was treated conservatively for two weeks and recovered. PICA originating between the C1 and C2 level comprises 1.1–1.3% of cases. Therefore, vertebral artery anomalies should be evaluated prior to C1-2 fusion to prevent vessel injuries.

Risk assessment of vertebral artery injury in anterior controllable antedisplacement and fusion (ACAF) surgery: a cadaveric and radiologic study

PURPOSE

We have introduced a novel surgery technique named anterior controllable antedisplacement and fusion (ACAF) for the treatment of ossification of the posterior longitudinal ligament. As reported, the satisfactory postoperative outcome can be attributed to the larger decompression width. However, it may associate with high prevalence of vertebral artery injury (VAI) theoretically. Thus, assessment of the vulnerability of vertebral artery in ACAF is of great importance.

METHODS

Computed tomographic scan data of 28 patients were retrospectively studied. Seven radiographic parameters were evaluated: uncinate process (UP) tips distance, transverse foramen (TF)-UP tips distance, TF-LWL (the ipsilateral limited wedging line) distance, the limited distance of lateral decompression, the maximum oblique angle of LWL, TF-LWG (the lateral wall of groove) distance, and width of groove. Eleven fresh cadaveric spines undergoing ACAF surgery were also studied. Two anatomic parameters were evaluated: width of groove and LWG-TF distance.

RESULTS

The UP tips distance increased from C3 to C6 and tended to be larger in males. The UP tip-TF distance and LWL-TF distance were smallest at C4, but both were larger than 2 mm. Maximum oblique angle decreased from C3 to C6. Postoperatively, both radiographic and cadaveric measurements showed the width of groove was larger than UP tips distance, but LWG-TF distance was larger than 2 mm in all levels.

CONCLUSION

UP can be used as anatomical landmarks to avoid VAI during ACAF surgery. Radiographic and cadaveric measurements verified the safety of ACAF surgery, even for those cases with wedging and lateral slotting.

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

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

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.

Disaster Scenarios in Spine Surgery: A Survey Analysis

STUDY DESIGN

Survey analysis among spine surgeons.

OBJECTIVE

To identify current consensus and discrepancies in managing adverse intraoperative events among spine surgeons.

SUMMARY OF BACKGROUND DATA

Major intraoperative events are not commonly the subject of formal medical training, in part due to the relative paucity of their occurrence and in part due to an insufficient evidence base. Given the clinical impact of appropriate complication management, it is important to identify where surgeons may be able to improve decision making when choosing interventions.

METHODS

A survey was created including five hypothetical unpredicted scenarios affecting different organ systems to assess the respondents' preferred reactions. The five clinical vignettes that were selected by the researchers involved: 1) loss of spinal signals in neuro-monitoring, 2) prone position cardiac arrest, 3) prone position hypoxia during thoracic corpectomy and instrumentation, 4) supine cervical vertebral artery injury, and 5) sudden onset hypotension in major prone position reconstructive spine surgery. Twenty-eight surveys (Spine Fellows n = 11; Spine surgeon Faculty n = 17) were completed and returned to the investigators. Results were sorted and ranked according to the frequency each action was identified as a top five choice.

RESULTS

Following formal statistical evaluation loss of signals in neuro-monitoring had the statistically significantly most uniform response while the scenario involving cardiac compromise had the most heterogeneous. Many "best" responses had near or complete consensus while some "distractor" possibilities that could harm a patient were also selected by the respondents.

CONCLUSION

The heterogeneity of responses in the face of "disaster scenario" intraoperative events shows there is room for more thorough and directed education of spine surgeons during training. As surgical teaching moves toward increased use of patient simulation and situational learning, these vignettes hopefully serve to provide direction for training future spine surgeons on how best to approach difficult situations.

LEVEL OF EVIDENCE

4.

Anatomical Relationship of the Vertebral Artery With the Lateral Recess: Clinical Importance for Posterior Cervical Foraminotomy

Objective

Vertebral artery injuries during posterior cervical foraminotomy are rare, but can be fatal. Therefore, we investigated the anatomical correlation between the lateral recess and the vertebral artery.

Methods

On axial cuts of cervical magnetic resonance imaging from 108 patients, we measured the distance between the vertebral arteries and the medial border of the facet joints. The anatomical vertebro-facet distance (AVFD), surgical vertebro-facet distance (SVFD), and vertebro-facet angle (VFA) were measured.

Results

The mean AVFD values on the right side at the C3–4, C4–5, C5–6, and C6–7 levels showed statistically significant differences. On the right side, the mean SVFD values were equivalent to the AVFD values. The mean values of the VFA on the right side at all levels showed statistically significant differences. For all measurements, the greatest differences were seen between the C5–6 and C6–7 levels, and higher levels were associated with smaller distances from the lateral recess. The mean values of the AVFD on the right and left sides showed statistically significant differences at all levels, and the distances on the left were smaller than those on the right.

Conclusion

The vertebral artery is closer to the lateral recess at higher cervical levels than at lower cervical levels. The largest distances were found at the C5–6 and C6–7 levels, and the left vertebral arteries were closer to the lateral recess than the right vertebral arteries.

Clinically-relevant morphometric parameters and anatomical variations of the aortic arch branching pattern

INTRODUCTION

The ever expanding advances in various domains of cardiac and endovascular interventions has drawn tremendous attention toward the importance of the anatomical variability and morphometric parameters of the aortic arch (AA) and its branches.

METHODS

The current study delineates the morphometry and anatomical variations of the AA branches by evaluating coronal, axial and sagittal CT multiplanar reformatted three-dimensional angiograms. Correlations between morphometric data as well as the distribution of morphometric data in relation to the anatomical variations were also illustrated.

RESULTS

35% of the examined AA showed abnormal branching patterns, the most common of which was the "bovine arch" (24%), followed by common ostium variant (6%) and aberrant left vertebral artery arising directly from AA (5%). The outer diameter of AA at its origin and its end was 33.83 and 22.06 mm, respectively. The distance between the origin of AA and the origin of brachiocephalic trunk (BCT), left common carotid artery (LCCA) and left subclavian artery (LSA) was 19.59, 23.01 and 26.01 mm, respectively. The outer diameter of BCT, LCCA and LSA was 15.7, 11.42 and 14.02 mm, respectively. The angles between the AA and the BCT, LCCA and LSA were 59.01°, 68.59° and 59.92°, respectively. The mean distance between the BCT and LCCA was 19.59 mm and the distance between the LCCA and the LSA was 23.01 mm. Significant positive and negative correlations between morphometric data as well as the distribution of morphometric parameters in relation to the anatomical variations have been identified.

CONCLUSION

The illustrated anatomical variations and morphometric data provide cardinal information especially for patients undergoing aortic endovascular intervention, principally for choosing the size, shape and type of the angiographic catheters and devices to be delivered.

C3 segmental vertebral artery diagnosed by computed tomography angiography

Extremely rarely, the vertebral artery (VA) enters the subarachnoid space via the intervertebral space of the C2-3 vertebrae. We have identified three cases with this anomalous VA in the literature. We report here another case involving aberrant VA penetration of the dura at the C2-3 vertebral level diagnosed by computed tomography (CT) angiography. A 71-year-old-woman with memory disturbance underwent brain CT and CT angiography. The right VA was aberrant and penetrated the dura at the C1-2 vertebral level. On the left side, the VA penetrated the dura at the C2-3 vertebral level. To our knowledge, this anomalous VA is the first case of C3 segmental VA diagnosed by CT angiography. To prevent VA injury, it is important to identify this variation before performing a posterior fusion of the cervical vertebrae.

Surgical Complications Associated With Cervical Spine Surgery

Cervical spine complaints are routinely evaluated in the office and urgent care facilities. Many of these complaints will resolve with conservative modalities. However, when operative intervention is necessary for nontraumatic pathology, recognition of pre-, intra-, and postoperative complications is imperative. This article reviews basic anatomy and surgical anatomy of the cervical spine. The common surgical approaches to the cervical spine as well complications that can occur from an anterior and posterior perspective are discussed. Cervical spine surgery when used in the appropriate clinical scenarios can be very successful. It is important to remember that risk reduction begins prior to the surgery with appropriate planning, identification of any anatomical anomalies, and adequate preparation.

Frequency and Acceptability of Adverse Events After Anterior Cervical Discectomy and Fusion: A Survey Study From the Cervical Spine Research Society

PURPOSE

Anterior cervical discectomy and fusion has a low but well-established profile of adverse events. The goal of this study was to gauge surgeon opinion regarding the frequency and acceptability of these events.

METHODS

A 2-page survey was distributed to attendees at the 2015 Cervical Spine Research Society (CSRS) meeting. Respondents were asked to categorize 18 anterior cervical discectomy and fusion-related adverse events as either: "common and acceptable," "uncommon and acceptable," "uncommon and sometimes acceptable," or "uncommon and unacceptable." Results were compiled to generate the relative frequency of these responses for each complication. Responses for each complication event were also compared between respondents based on practice location (US vs. non-US), primary specialty (orthopedics vs. neurosurgery) and years in practice.

RESULTS

Of 150 surveys distributed, 115 responses were received (76.7% response rate), with the majority of respondents found to be US-based (71.3%) orthopedic surgeons (82.6%). Wrong level surgery, esophageal injury, retained drain, and spinal cord injury were considered by most to be unacceptable and uncommon complications. Dysphagia and adjacent segment disease occurred most often, but were deemed acceptable complications. Although surgeon experience and primary specialty had little impact on responses, practice location was found to significantly influence responses for 12 of 18 complications, with non-US surgeons found to categorize events more toward the uncommon and unacceptable end of the spectrum as compared with US surgeons.

CONCLUSIONS

These results serve to aid communication and transparency within the field of spine surgery, and will help to inform future quality improvement and best practice initiatives.

Posterior identification and exposure of the V3 segment of the vertebral artery

Objective:

The purpose of this study was to define the anatomy of the V3 segment of the vertebral artery (VA) from the posterior approach.

Methods:

Ten formalin-fixed cadavers were carefully dissected bilaterally using landmark features to identify and safely expose the VA from the posterior. Measurements regarding morphometric characteristics of landmark features and feasible resection quantifications were obtained and analyzed. The C2 pars was resected completely in all cadavers, averaging 15.03 ± 1.06 mm in thickness.

Results:

The average diameter of the VA at the midline of C2 on the right side was 4.66 ± 0.51 mm compared to the left 5.2 ± 0.49 mm (P = 0.002). The distance of the VA from the midline increased from caudal to rostral. The distance between the VA to the lateral edge of the dura in the middle of the window of approach was 9.67 ± 0.81 mm. The rostral-caudal length of the window of approach was 21.94 ± 1.60 mm. The percentage of C2 body removal was 28.04% ± 6.09% through each side (249.55 ± 55.5/898.2 ± 146.17 mm²). While carefully exposing the VA, a posterior approach can be feasible in cases of injury during C1–C2 instrumentation or during resection of tumors of the C2 pars with or without extension into the C2 body.

Discussion:

The posterior approach for a C2 partial corpectomy can also be used as an adjunct to anterior approaches when necessary to widen the extent of bone resection.

Conclusion:

Exposure of the V3 segment of the vertebral artery was defined as well as the extent of C2 corpectomy through the posterior approach.

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.

A cadaveric study of aortic arch variation in an Irish population

AIM

The aim of this study is to investigate the incidence of variation in the branching pattern of aortic arch (AA) vessels in an Irish population.

METHOD

A cadaveric study of 24 subjects was conducted. The vessels of the AA were identified, their branching patterns were noted and photographed and the following measurements were recorded: the angle of the AA to the coronal plane, the distance from the midline to the brachiocephalic trunk (BCT); the left common carotid artery (LCC) ; the left subclavian artery (LSC), the distance between the BCT and the right subclavian artery (RSC); the RSC and the right vertebral artery (RVA), and between the LSC and left vertebral artery (LVA).

RESULTS

The 'normal' branching pattern (BCT, LCC, LSC) was observed in 79%. Thirteen percent had a two-branched AA (bovine variant), while the remainder had an aberrant left vertebral artery (LVA) originating from the AA. The mean distances from the midline to the BCT, LCC and LSC were 9.1, 10.8 and 21.4 mm, respectively. Mean distance from BCT to RSC was 34.09 mm. The mean distance from LSC to LVA was 39.79 mm, and the mean distance from RSC to RVA was 23.38 mm. The mean angle of the AA to the coronal plane was 59.02°.

CONCLUSION

This is the first study documenting the rates of variation of the AA in Ireland. Variation of AA branching is of radiological and surgical significance, particularly in the diagnosis and treatment of thoracic and head and neck diseases. Awareness of these variations is particularly relevant for interventionalists who access these vessels during endovascular surgery.