Neurological outcomes following iatrogenic vascular injury during posterior atlanto-axial instrumentation

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.

Prevalence of anatomical variations at the suboccipital (V3) segment of the vertebral artery: a systematic review

BACKGROUND AND OBJECTIVE

A recent meta-analysis on the incidence of iatrogenic injury to the VA has revealed that patients with variant anatomy are more prone to iatrogenic injury. Therefore, this review is designed to investigate the incidence of variations in the suboccipital component of the vertebral artery in different population groups according to the available literature.

METHODS

This systematic review was conducted according to PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The review is based on a comprehensive and extensive search of PubMed, Google Scholar, and ResearchGate. The following search terms were used: "vertebral artery" AND "suboccipital segment" AND "anomalies/anatomical variations of the V3 segment." Reference lists of all extracted articles were also extensively searched for references to any further relevant publications.

RESULTS

A total of 17 papers met the inclusion criteria. The 17 studies corresponded to a total of 10,820 patients. A persistent first intersegmental artery was registered in 1.8% (197 out of 10,820) of the patients. Extradural PICA origin was observed in 1.6% (175 out of 10,820) of the patients. Fenestration was detected in 0.7% (72 out of 10,820) of the patients.

CONCLUSION

The authors summarize the incidence of vascular variation at the suboccipital segment of the VA in different population groups across the Asian, European, American, and African continents. Awareness of the extent of possible anatomical variation will help interpret radiographs, which will enhance the identification of vascular pathologies and reduce the risk of iatrogenic injury.

Referencing for anterior atlantoaxial trans-articular osteosynthesis: a radiological study and proposal of a decisional algorithm

PURPOSE

Anterior trans-articular C1-C2 screw placement can be considered as a surgical alternative in different conditions affecting the atlantoaxial region. While its rigidity is similar to posterior Magerl and Harms techniques, it also provides some surgical advantages. However, the literature lacks papers exhaustively describing indication criteria, surgical steps, and pitfalls.

METHODS

This is a radiological study on 100 healthy subjects. Thin-layer CT scans of the craniovertebral junction were retrieved from the institutional database. The coronal inclination of the C1-C2 joint rim and the depth of the entry point of the screw with respect to the anterior profile of C2 were measured. The antero-posterior and the medio-lateral surgical corridors for the screw placement, and the wideness of the target area on the upper surface of C1 were also measured.

RESULTS

The multivariate analysis showed that the coronal inclination of the C1-C2 articular joint rim strongly influences the surface extension of the C1 target area; the depth of the entry point and the C1-C2 articular rim inclination seem to be independent factors in influencing both the medio-lateral and the antero-posterior surgical corridors wideness. A decisional algorithm on whether to perform an anterior or posterior approach to the atlantoaxial region was also proposed.

CONCLUSIONS

We can conclude that, as much as the C1-C2 articular rim is tending to the horizontal line, and as deeper is the entry point of the screw on the anterior profile of C2, as easier the anterior C1-C2 trans-articular screw placement will result.

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.

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation.

METHODS

A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications.

RESULTS

The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed.

CONCLUSIONS

The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Cerebral infarction due to malposition of cervical pedicle screw: A case report

RATIONALE

Malposition of cervical pedicle screw (CPS) has a risk of vertebral artery (VA) injury which sometimes may cause unexpected and catastrophic outcome. A rare case of delayed onset of cerebral infarction caused by malposition of CPS was reported.

PATIENT CONCERNS

A 23-year-old man who underwent a posterior cervical reduction and fusion of C4-5 using CPS fixation and allograft for cervical spine injury is presented. The patient suffered progressively weakness and numbness for both of upper and lower extremities 1 day after the operation. Computed tomography scans revealed bilateral occupation of the pedicle screws in the foramen of C4 and C5 and the magnetic resonance imaging (MRI) displayed several areas of infarction in the brainstem and cerebellum.

DIAGNOSES

Plain radiographs of the cervical spine revealed the C4 vertebral body and MRI displayed a disruption of the anterior longitudinal ligament on the level of C4-5 and severe injury to the soft tissues of the cervical spine at admission. Brainstem and cerebellum infarction was diagnosed at postoperative.

INTERVENTION

A revision surgery was decided to remove all of the pedicle screws and place lateral mass screws instead.

OUTCOMES

The patient felt better on his all of 4 extremities following revision surgery. Fortunately, he was neurologically close to normal at a 3-month follow-up.

LESSONS

Delayed onset of cerebral infarction is rarely reported complication caused by malposition of CPS. When a CPS perforates the transverse foramen and causes symptom of cerebral infarction, a revision surgery in time is strongly recommended to prevent further sequelae.