David J. Lunardini, MD

Abstract
Background Context
Vertebral artery injuries (VAI) are rare but serious complications of cervical spine surgery, with the potential to cause catastrophic bleeding, permanent neurologic impairment and even death. The current literature regarding incidence of this complication is largely comprised of single surgeon or small multi-center case series.

Purpose
We sought to gather a large sample of high volume surgeons to adequately characterize the incidence and risk factors for VAI, management strategies employed, and patient outcomes after VAI.

Study Design/Setting: The study was constructed as a cross-sectional study, compromised of all cervical spine patients operated on by the members of the international Cervical Spine Research Society (CSRS).

Patient Sample
All patients who have undergone cervical spine surgery by a current member of CSRS, as of the spring of 2012.

Outcome Measures
For each surgeon surveyed we collected self reported measures to include: the number of cervical cases performed in the surgeons career, the number vertebral artery injuries encountered, the stage of the case during which injury occurred, the management strategy(ies) employed, and the overall patient outcome after injury.

Methods
An anonymous ten question web-based survey was distributed to the members of the CSRS. Statistical analysis was performed using student’s t-tests for numerical outcomes, and chi squared analysis for categorical variables. There was no outside funding for this study, and this study contains no potential conflicts of interest by any of the authors.

Results
One hundred and forty one CSRS members (out of 195 total, 72%) responded to the survey, accounting for a total of 163,324 cervical spine surgeries performed. The overall incidence of VAI was 0.07% (111/163,324). Posterior instrumentation of the upper cervical spine (32.4%), anterior corpectomy (23.4%), and posterior exposure of the cervical spine (11.7%) were the most common stages of the case to result in injury to the vertebral artery. Discectomy (9%) and anterior exposure of the spine (7.2%) were also common timepoints for arterial injury. One fifth (22/111) of all VAI involved an anomalous course of the vertebral artery. The most common management of VAI was by direct tamponade. The outcomes of VAIs included no permanent sequelae in 90% of patients, permanent neurologic sequelae in 5.5%, and death in 4.5%. Surgeons at academic and private centers had nearly identical rates of vertebral artery injuries. However, surgeons who had performed 300 or fewer cervical spine surgeries in their career had a VAI incidence of 0.33%, compared to 0.06% in those with >300 lifetime cases (p=0.028).

Conclusions
The overall incidence of VAI during cervical spine surgery reported from this survey was 0.07%. Less experienced surgeons had a higher rate of VAI compared to their more experienced peers. The results of VAI are highly variable, resulting in no permanent harm a majority of the time; however, permanent neurologic injury or death occur in 10% of cases.

Journal Abstract:  http://www.sciencedirect.com/science/article/pii/S1529943013015568