There are some areas in our practice where the literature grants us a somewhat sure path forward in the evaluation of our patients. The decision whether or not to pursue cervical spine imaging studies following a traumatic mechanism of injury is one of these areas. The NEXUS criteria and Canadian C-Spine Rule are useful guides for the evaluation of these patients. What comes after the imaging can be a bit more challenging. What do we do with patients who have persistent pain but negative imaging? To what extent do we pursue the possibility of a ligamentous injury? Must we wait for all patients to be sober so that we can "clinically clear" them in addition to our radiographic clearance. The 3 articles below seek to answer some of these challenging questions. Take a listen to the podcast and read the summaries to familiarize yourself with some of the latest literature addressing these challenging patient care scenarios.
MD BT, FACS JMSM, FACS APEMM. Are Flexion Extension Films Necessary for Cervical Spine Clearance in Patients with Neck Pain after Negative Cervical CT Scan? Journal of Surgical Research 2013;184(1):411–3.
This paper examines the use of flexion extension films (FEF) to clear the cervical spine in neurologically intact patients following blunt trauma who have a negative non-contrast CT of the cervical spine but have persistent midline neck tenderness. The records of 354 blunt trauma patients were retrospectively reviewed at a single level 1 trauma center. Each of these patients were GCS 15, non-intoxicated, neurologically intact and had an initial negative CT of the cervical spine. And, they all had flexion extension films subsequent to their CT scans due to persistent cervical tenderness.
Only 1.4% (n=5) of patients had a positive FEF. Those five patients either moved on to MRI or were evaluated by a spine surgeon. In all 5 cases, the patient was determined to not have any significant injury and subsequently had their c-collar removed with no neurological deterioration. The authors also calculated the total charge for the 354 FEF performed during the study. These amounted to $171,902.40 (nearly $500/person for study that provided no additional information, as well as led to an MRI charge for 2 patients and spine surgery consultation fees/charges for 3 others).
Why is this important? Well, this study is one of several that suggest that there is no utility to obtaining FEF in neurologically intact trauma patients who already have negative imaging. Previously, the 2009 Eastern Association for the Surgery of Trauma Guidelines recommended that neurologically intact trauma patients with neck pain and a negative CT should undergo either MRI or FEF before clearing the c-collar. In response to the growing body of evidence against FEF, like this study, the updated 2015 guidelines have now conditionally recommended that a negative high-quality C-spine CT is sufficient for removal of the collar. FEF is no longer included as an option. Other studies looking at FEF have also shown that there are frequent “positive” FEF that ultimately have no true ligamentous injury (as was seen in this study) and found that up to 69% of these films were inadequate. In addition to evidence against FEF there have also been numerous studies demonstrating the high negative predictive value of high-quality CT imaging in excluding significant unstable C-spine injuries. The reported sensitivity and specificity of CT CS for detecting CS injury has been reported as high as 99% and 100%, respectively.
Bush L, Brookshire R, Roche B, et al. Evaluation of Cervical Spine Clearance by Computed Tomographic Scan Alone in Intoxicated Patients With Blunt Trauma. JAMA Surg 2016;151(9):807–7.
This was a single-center, prospective, observational study evaluating whether or not modern cervical spine CT scans were able to reliably exclude clinically relevant cervical spine injuries in intoxicated blunt trauma patients. The authors defined clinically relevant cervical spine injuries as potentially unstable injuries requiring either surgical stabilization or prolonged immobilization. 1429 blunt trauma patients undergoing cervical spine CTs were evaluated for intoxication with serum ethanol levels or urine drug screens. 632 (44.2%) of these patients were found to be intoxicated. One of 8 radiologists at this institution interpreted the 2mm slice thickness CT images to evaluate for injuries.
There were 65 (10.3%) abnormal CT scans in the study cohort. There were 5 patients with significant injuries among the 567 with normal CT scans. All 5 of these patients had clinical evidence of spinal cord injuries: 4 with central cord syndrome that was noted on their initial physical examination and 1 with clear quadriplegia on exam had an unstable ligamentous injury that was misread as normal on his initial CT scan. The negative predictive value of a normal cervical spine CT among all intoxicated patients was found to be 99.2% for all injuries and 99.8% for unstable cervical spine injuries. The sensitivity was 92.9% and specificity 99.8%. The time to average cervical spine clearance (noted by the time from presentation to when cervical collar was removed or when the order for cervical spine precautions was discontinued) was significantly longer among the intoxicated patients: 15.1 hours vs 3.7 hours for sober patients (P < 0.01).
Cervical spine clearance based upon a normal high-quality CT scan and a normal neurological exam in intoxicated patients is supported by this data. The limitations of this study include that it was single center in its design. Also, low prevalence diseases (like patients with clinically significant traumatic spinal cord and cervical spine injuries with negative CT imaging) are challenging to study. Studies looking into these disease states often report extremely favorable negative predictive values that owe their generous values as much to the prevalence of the disease as they do the performance characteristics of the diagnostic study.
BS XW, MMM AMM, BS BG, et al. Cost-effectiveness of Magnetic Resonance Imaging in Cervical Spine Clearance of Neurologically Intact Patients With Blunt Trauma. Annals of Emergency Medicine 2018;71(1):64–73.
This is a cost-utility analysis performed by Wu and colleagues. Previously, this same group had explored the ability of MRI to detect clinically significant cervical spine injuries following negative CT imaging in alert patients. Having found a pooled incidence of injury of 0.011% in their previous study, the authors sought, in this paper, to answer the question, “is it cost effective to obtain a MRI for cervical spine clearance after negative CT imaging in a neurologically intact patient after blunt trauma?”
A cost-effectiveness analysis is a type of economic analysis that compares both the clinical outcomes and the costs of new treatment options to current treatment options or standards of care. The outcomes are expressed in quality adjusted life years (QALY), which is calculated by taking the length of time effected by the injury or outcome (i.e. life expectancy) and multiplying it by a utility value assigned (0-1.0). A cost-utility analysis involves expressing the outcomes in terms of an incremental cost effectiveness ratio (ICER) which is the ratio of change in costs to the change in outcomes (in this case QALY).
Using a decision analytic model combining clinical parameters derived from published literature, expert opinion, and Medicare reimbursement numbers, the authors produce predictions for outcomes and define the costs associated with those outcomes. The authors performed single and multivariate sensitivity analyses on the data. This allowed the authors to introduce variation into the model inputs to better identify those inputs having significant effects on outcomes.
The base model for this study is a 40 year old neurologically intact patient with a negative CT after blunt trauma. The 2 main strategies considered were No Follow Up and MRI Imaging. The full outline of their decision model is seen in Figure 1 below. The costs analyzed included the cost of the MRI itself, cost of cervical collar, yearly health care and living expenses, and the cost directly attributable to the injury. They did not include indirect costs such as lost wages, productivity in the analysis.
So what were the results of the cost-utility analysis? For injuries resulting in tetraplegia, the No Follow-Up strategy cost $6,432, with a utility of 24.08 quality-adjusted life-years. The MRI strategy cost was $11,477, with a utility of 24.03 quality-adjusted life-years. “No Follow-Up” was therefore found to be the dominant strategy as it was both cheaper and more “effective” based on utility. When paraplegia was the outcome of permanent neurologic deficit, the cost for the MRI strategy changed to $4,845 and utility 24.07 quality-adjusted life-years. The “No Follow-Up” option remained the most optimal strategy, with a cost of $2,563 and a utility of 24.10 quality-adjusted life-years.
When performing their sensitivity analysis the authors found that the “No Follow-Up” strategy was the cheaper and more effective strategy in all 10,000 iterations. Furthermore, when the NPV of the initial CT was varied, the “No Follow-Up” strategy was the dominant strategy across the entire range of values (0-100%). There were only 4 scenarios where MRI Imaging became the dominant strategy:
- When the risk of missed unstable injuries on initial CT developing into permanent neurologic injuries was greater than 64.2%.
- When the risk of developing permanent neurologic deficit for patients with unstable injury who received a collar was less than 19.7%.
- When initial year cost were 1.95x as high or subsequent year costs 3.75x higher.
- If risk of litigation from missed unstable injury leading to tetraplegia was greater than 27.5%.
This paper serves as an excellent reminder of the consequences of additional, and potentially unnecessary, imaging studies (in this case pressure ulcerations from cervical collars, incidental findings, unnecessary procedures, and additional financial cost).
The limitations of this study are limitations inherent to all cost-effectiveness studies, especially those that use a decision model compiling input data from previously published literature. There is a paucity of good data and significant heterogeneity in the literature leads to wide range of published values for the clinical parameters used as inputs to the model. While sensitivity analyses do attempt to compensate for this variability if the control assumptions are flawed then results are inaccurate.
- MD BT, FACS JMSM, FACS APEMM. Are Flexion Extension Films Necessary for Cervical Spine Clearance in Patients with Neck Pain after Negative Cervical CT Scan? Journal of Surgical Research 2013;184(1):411–3.
- Bush L, Brookshire R, Roche B, et al. Evaluation of Cervical Spine Clearance by Computed Tomographic Scan Alone in Intoxicated Patients With Blunt Trauma. JAMA Surg 2016;151(9):807–7.
- BS XW, MMM AMM, BS BG, et al. Cost-effectiveness of Magnetic Resonance Imaging in Cervical Spine Clearance of Neurologically Intact Patients With Blunt Trauma. Annals of Emergency Medicine 2018;71(1):64–73.
- Flexion Extension Films - Alexa Sabedra, MD
- Cervical Spine Clearance in Intoxicated Patients - Sara Continenza, MD
- Cost-Effectiveness - Collins Harrison, MD
- Intro, Peer Review, Images, Editing - Jeffery Hill, MD MEd