Journal of Critical Care 29 (2014) 314.e9–314.e13
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Sixty-four–slice computed tomographic scanner to clear traumatic cervical spine injury: Systematic review of the literature☆,☆☆ Hussein D. Kanji, MD, MSc, MPH a, b,⁎, Andrew Neitzel, MD, MSc a, Mypinder Sekhon, MD a, Jessica McCallum, BSc d, Donald E. Griesdale, MD, MPH a, c, d a
Department of Medicine, Division of Critical Care Medicine, University of British Columbia, Vancouver, BC, Canada Department of Emergency Medicine, Fraser Health Region, New Westminster, BC, Canada Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, BC, Canada d Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada b c
a r t i c l e
i n f o
Keywords: Blunt trauma Computed tomography Magnetic resonance imaging Systematic review Critical care
a b s t r a c t Purpose: Cervical spine (CS) injury in blunt trauma is a prevalent and devastating complication. Clearing CS injuries in obtunded patients is fraught with challenges, and no single imaging modality or algorithm is both safe and effective. Increased time in c-spine precautions is associated with greater patient morbidity including increased ventilator associated pneumonia, delirium and ulceration. We systemically reviewed the literature to assess the effectiveness of 64-slice computed tomographic (CT) scanners in clearing traumatic CS injuries. Materials and Methods: Studies were identified using MEDLINE and Embase, the references of identified studies, international experts on CS clearance and authors of primary studies. Three reviewers independently selected and extracted data from studies that reported on both CT and MRI in traumatic CS injury. Results: We included five studies involving a total of 3443 patients; however, heterogeneity and lack of sample size precluded quantitative summation of the results. Qualitative assessment showed that 64-Slice CT scan, when applied within a set protocol, performed favourably in clearing injury. Conclusions: Data suggests that using 64-slice CT scans on obtunded trauma patients with grossly intact motor function, in the context of a defined clearance protocol with interpretation by an experienced radiologist, may be sufficient to safely clear significant CS injury. A prospective study comparing MRI and 64-slice CT scan clearance in this population is necessary to corroborate these conclusions. © 2014 Elsevier Inc. All rights reserved.
1. Introduction Cervical spine (CS) injuries are both a prevalent and serious complication of blunt trauma. Rates of injury are reported at between 2% and 12% with occult or delayed injuries occurring in 1% to 8% of cases [1-3]. Missing an unstable CS injury is a devastating complication resulting in potential significant morbidity for the patient, cost to the healthcare system, and angst to the clinician [4]. In the awake patient, formalized evidence based evaluation and clearance has been established that integrates clinical exam and radiographic imaging [5]. In the unreliable or obtunded patient, CS clearance is far more complicated and the risk of occult injury challenges CS clearance based on radiographic evidence alone. The recent Eastern Association for the Surgery of Trauma guidelines themselves remain elusive on the topic and suggest an individualized, region-based approach to clearing this difficult patient cohort [6]. Delays in clearance can lead to
increased rates of ulcer, airway compromise, and higher intracranial pressure. In addition, longer duration of immobilization can be associated with increased nursing time and workload and risk of associated workplace injury [7]. Consequently, means of safely and expediently clearing patients with potential CS injuries is required. Computed tomographic (CT) scan has become the standard in screening, however, integration of MRI to determine occult or ligamentous injury is recommended as the gold standard [8]. This approach is predicated on historical studies utilizing prior generations of CT scanners. Newer generation CT scanners may obviate the need to perform magnetic resonance imaging (MRI) and subject patients to prolonged duration in CS collars. This new strategy could reduce associated complications, morbidity, and nursing workload. We systematically reviewed the literature in order to evaluate the effectiveness of 64-slice CT scanners to clear CS injuries. 2. Materials and methods
☆ Funding: None. ☆☆ Conflict of Interest: None to declare. ⁎ Corresponding author. Department of Critical Care, BC, Canada V5Z 1M9. Tel.: +1 604 363 8228; fax: +1 604 875 5957. E-mail address: [email protected] (H.D. Kanji). 0883-9441/$ – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcrc.2013.10.022
2.1. Data sources and searching strategy We complied with the PRISMA guidelines for the performance of meta-analysis of observational cohort studies [9]. Studies were
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selected if they met the following criteria: Adult patients (≥16 years of age), trauma (blunt or penetrating), comparison of 64-slice CT and MRI, reported outcomes data related to neurological status and need for intervention defined by surgery or prolonged immobilization. Manuscripts were excluded if they did not report on the listed inclusion criteria, were case reports, or summary articles. See Fig. 1 for a list of excluded manuscripts. Manuscripts were not excluded based on language. The gold standard used to determine the predictive ability of CT scan to assess for injury were MRI or well-documented functional neurological outcome. Therefore, studies comparing the results of CT scan to dynamic radiographs (non gold-standard) were also excluded. Unstable injury was defined as needing intervention in terms of prolonged immobilization, collar placement, surgery, neurological impairment, or radiographic evidence. A medical librarian searched Medline (1966-2011), Embase (1988-2011), and the Cochrane Library using relevant subject headings and text words (Appendix A). The search was updated on April 15, 2013. In addition, cited reference search was carried out in Web of Science and conference proceedings to identify other eligible papers. Reference lists of primary studies were also reviewed, and experts (including primary study authors) were contacted to identify any other studies. If studies did not identify in the methods section the type of CT scanner used, the authors were individually contacted. 2.2. Data extraction and quality assessment Three reviewers (AN, MS, JM) independently screened citations, abstracted data, and assessed methodological quality. If data needed to be clarified we contacted the original investigators. Titles and abstracts
were assessed for appropriateness to include primary literature (case reports excluded) that compared diagnosis of acute CS trauma using 64-slice CT scanner and MRI in adult human patients without neurologic deficits or underlying spine disease; both awake and obtunded patients were included. Disagreements to included studies were arbitrated by a fourth reviewer (HK). Full manuscripts of included papers were reviewed for appropriateness based on the same criteria. Refer to Fig. 1 for the full list of exclusion criteria and summary of excluded papers. Data were abstracted individually with an attempt to summate to perform a meta-analysis and calculation of sensitivity and specificity. Study quality was assessed using the Downs and Black checklist which has a total maximum score of 31 [10]. 2.3. Data analysis A meta-analysis was not performed given that the sample size was inadequate and the between-study heterogeneity was too large to justify. We performed a qualitative assessment of the included manuscripts and reported primary outcomes including sensitivity, specificity, and negative predictive value. 3. Results Overall 717 citations were identified, of which 5 studies fulfilled our eligibility criteria (Fig. 1). Table 1 presents the key characteristics from the 5 studies we included, summarizing the study inclusion and outcomes reported. The quality of the studies was assessed using the Downs and Black score [10]. The average score was 15.8 with the lowest and highest being 15 and 17, respectively, signifying high
Studies Excluded: 649 Duplicates: 14 Pediatric or neonatal: 98 Non-trauma: 49 Not human: 1 Don’t compare CT and MRI: 77 CT not 64-slice: 31 Baseline neurologic deficit: 10 For OR screening: 8 Management: 55 Review, letter to editor, book chapter: 157 Case Report: 122 Vascular: 16 Post Mortem: 5 Survey of current practice: 2 Thoracic: 2 Not acute: 1 Underlying spine disease: 1
Studies screened for possible inclusion Title & Abstract (n= 717)
Full manuscripts reviewed for inclusion (n = 68)
Full manuscripts excluded: 63 Not 64-slice: 37 Don’t compare CT to MRI: 8 Unable to determine scan number: 9 Review or letter to editor: 8 Baseline neurologic deficit: 1
Fig. 1. Study selection flow diagram.
Manuscripts included (n = 5)
H.D. Kanji et al. / Journal of Critical Care 29 (2014) 314.e9–314.e13 Table 1 Summary of studies reporting on 64-slice CT scan compared to MRI Author, year
No. patients
Mechanism
Neuro status
Outcome
Sanchez, 2005 [12]
2854
Blunt 91%
Obtunded
a
215
Blunt 100%
Obtunded
Kaiser, 2012 [14]
114 (29)b
Blunt 100%
Obtunded
Como, 2011 [15]
197 (5)b
Blunt 100%
NR
Blunt 100%
NR
Sn/Sp 99/100 NPV = 99.9% 100/100 NPV = 100% Sn/Sp = NR NPV = 96.5% Sn/Sp = NR NPV = 100% Sp/Sn = 100/100 NPV = 100%
Stelfox, 2007 [13]
Brown, 2010 [11]
63
Neuro status = if any neurological signs at baseline. NR, not reported. a Data obtained upon consultation with authors. b Total of 114 patients with 29 having 64-slice data, Total of 197 with patients 5 having 64-slice data.
quality of studies included in this systematic review. When studied, the mean Downs and Black score for non-randomized controlled trials has been reported to be 11.7. 3.1. CT vs MRI in awake patients A study by Brown et al. retrospectively compared an older generation 4-slice scanner to a newer generation 64-slice CT scanner using MRI as the gold-standard. 64-slice scanners had a 0% missed injury rate. This was a significant improvement from a 7% missed rate in the 4-slice scanner [11]. Inclusion criteria consisted of blunt trauma with no neurological abnormalities, although a certain proportion of patients may have had a Glasgow Coma Scale (GCS) score b15 as per communication with the author (data not recorded). Therefore, we cannot assume that this patient cohort included only an obtunded population. There were only 24 patients who had a negative study with both a 64-slice CT and MRI [11]. The 7% of missed injury in the study by Brown and colleagues were all distributed to the older generation scanner (4-slice), suggesting that newer 64slice scanners have improved ability to discern injury that may have been previously missed. 3.2. CT compared to MRI in obtunded patients Sanchez et al prospectively compared 64-slice scanners to MRI in 2854 trauma patients which included obtunded patients [12]. The majority (91%) of patients had blunt injury and an average injury severity scale of 11. In obtunded patients who were moving all 4 extremities at arrival to emergency department, CS was cleared based on a normal CT scan; 15% of patients with spinal cord injury had normal radiographic findings but were identified by neurological impairment. Sensitivity and specificity for detecting CS injury was 99 and 100%. Risk of missed CS injury in their study was reported at 0.04%. The only patient that had a missed injury on CT had an underlying syringomyelia, which was an underlying pathologic condition. Gold standard for clearance in this study was clinical examination. Most patients did not receive an MRI to document radiographic evidence of injury and therefore, difficult to specifically assert the performance of CT compared to MRI. However, patients were followed up closely within 2 weeks of discharge, thus signs of any clinically relevant neurological injury were very well evaluated. Based on these results, even in obtunded patients moving all 4 limbs upon arrival, clearance using 64-slice CT scan is unlikely to miss significant CS injuries. The study by Stelfox et al identified 140 critically ill, intubated, and mechanically ventilated trauma patients at-risk for CS injury [13]. In this prospective study, they evaluated the ability of CT to predict injury compared to the gold standard of MRI or physical examination,
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followed by a subsequent protocol that cleared CS injury based on CT scan findings alone. It was demonstrated that a CT only approach was associated with fewer days of immobilization (2 vs 6 days, P b .001) and fewer days of mechanical ventilation (3 vs. 4, P = .011). Through communication with author we were able to discern that 64-slice CT vs MRI had a 100% sensitivity and specificity to clear injury in the cohort. There were only 7 patients evaluated by both CT and MRI scans, but there was full concordance between both modalities. Using clinical assessment on follow up, there was no missed injury by CT scan in the entire 75 patient cohort. Kaiser et al performed a retrospective study of the ability of 64slice CT scans to clear CS injury in blunt trauma patients with GCS score b 14 [14]. CT scans were interpreted by attending radiologists, orthopedists, and neurosurgeons. Of the 114 patients included with no injury identified on CT scan, 6% had MRI findings that altered management. In this study the three different generation scanners were utilized (single, 16- and 64-slice). MRI was completed without contrast using a 1.5-Telsa system. 3 of the 7 patients with clinically significant injury identified by MRI had neurological deficits. The remaining 4 patients were treated conservatively with no operative fixation necessary. The use of single-slice CT scanner was the only identifiable risk factor for missed injury (OR = 2.62, P b .023). There was no significant difference in MRI findings of patients undergoing 16 or 64-slice CT scans. Como et al performed a prospective study evaluating the clearance and removal of collars in obtunded blunt trauma patients with preserved gross motor function on exam. This was based on both 16and 64-slice CT scan data images [15]. One hundred and ninety-seven patients were evaluated and had collars removed on the basis of CT scan finding. Of the scans, 192 were performed using 16-slice scanner and 5 were performed using the newer 64-slice scanner. Neuroradiologists interpreted all CT scans and follow up was conducted when patients were no longer obtunded to determine neurological function. Using a serial clinical exam and follow up, no patients had significant CS injuries when cleared based on CT alone. 4. Discussion In this systematic review, we sought to summate and analyze the recent data on the sensitivity and specificity of 64-slice CT scan as a modality to clear cervical spine injury in trauma. Specifically, we wanted to address the utility of 64-slice CT scanners as a clearance modality in the obtunded blunt trauma patient. There is sufficient data suggesting CT scan is at least as good as, and likely superior to, dynamic (flexion-extension) radiographs in screening for CS injury [6,16,17]. As a result, CT scan has supplanted dynamic radiographs and plain film XR as the modality of choice for initial screening and is endorsed by the Eastern Association for the Surgery of Trauma guidelines. The controversy and debate in the literature surrounds the role and integration of MRI in clearing potential CS injury in the unreliable patient. Incorporating MRI into the algorithm has been shown to have a negative predictive value of 100% but, results in a greater amount of false positive scans [8]. Our systematic review identified 5 studies including 3443 patients addressing the use of 64-slice CT scans as the imaging modality in both the awake, examinable and the obtunded trauma patient cohort (Table 1). Due to the heterogeneity in the studies, we were unable to pool the data but, the results of the studies do suggest that newer generation 64-slice CT scans, when interpreted by neuroradiologists, can potentially be utilized, in conjunction with the physical exam, as a single imaging modality to clear cervical spine injuries. The ability to perform an adequate neurological exam in an obtunded population is often impaired and thus, clinicians have trepidation about relying solely on CT scan results, which is indeed reasonable given the potentially catastrophic repercussions of a missed injury. A GCS score of b 8 is associated with a 50% increased
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compared to a historical control they found a significantly earlier collar removal (3.3 vs 7.5 days, P b .001) and decreased length of stay (13.8 vs 23.4 days, P b .001) [15]. This was also associated with fewer decubitus ulcers and morbidity for the patients. Earlier mobilization is being increasingly recognized as a very important factor to abate delirium, lessen ventilator duration, decrease infectious complications, shorten hospital admission duration and improve overall functional outcomes [22,23]. Como et al reported that the limited availability of MRI in some centers, increased cost, and safety concerns due to impaired patient access for prolonged periods of time associated with MRI as barriers, can be overcome by using 64-slice CT scanners [15]. They further comment that eliminating MRI in this population was not only safe but would have decreased costs by over $250,000 during the study period [24]. Future work in this area should expand on outcomes to include immobilization-related complications, cost and resource allocation, as well as details of injuries confirmed and missed by CT scanners. These complications and morbidity of prolonged immobilization are significant and should be highlighted [25,26]. Conversely, missed ligamentous injury could have disastrous implications for the patient and their family and are associated with significant costs to the healthcare system [12]. Missed ligamentous injuries using CT scanners was a concern identified in all 5 studies. There was limited data on types of injuries identified by the 64-slice CT scan. One study reported that 12 (39%) of 31 abnormal studies using 4and 64-slice CT scans revealed evidence of ligamentous or spinal cord injury without evidence of a fracture, however the details of the ligamentous injuries identified were not recorded, and were not available through correspondence with the author [11]. Three studies excluded patients with a negative CT scan so they did not record details of injuries identified using the CT scan [13-15]. Though not explicitly reported, the careful clinical follow-up in the included studies would suffice to identify clinically relevant ligamentous injuries. Clearance of CS injury based on CT alone is challenged by several studies and summarized by a meta-analysis by Schoenfeld et al [27]. The study included 1550 patients with negative CS CT and concomitant MRI in obtunded patients. Significant injuries altering management were identified in 96 (6%) of patients with MRI. The negative predictive value for MRI was 100%; however, the pooled false positive rate was 6% (95% CI, 1-11). The previous meta-analysis by Muchow et al showed similar results although, it included more heterogeneous imaging protocols as well as pediatric patients [8]. Two very important differences in these studies need to be noted and may account for the discrepancy in results we are presenting. First, the generation of CT scanners were quite variable and largely comprised of earlier generation scanners. We know that there is greater spatial resolution with newer 64-slice scanners that may allow better recognition of what would be previously considered occult injury. Second, most of the studies we present include cohorts with an intact gross neurological evaluation, which was not the case in the studies included in the meta-analysis. Thus, the power of 64-slice CT scan to clear CS injury may be limited to evaluating patients with a grossly intact neurological exam. We believe our systematic review suggests that a 64-slice CT cervical spine scan, within the context of a grossly intact neurological exam and no underlying spine pathology and interpretation by an experienced radiologist, may have utility as a modality to clear injury
in incidence of CS injury [18]. This has been reiterated in a study by Holly et al. reporting a disproportionately higher rate of CS injury in patients with severe head injury [19]. The significant rates of missed injury reported in older generation scanners are quite prevalent and may exacerbate this fear (Table 2) [20,21]. Thus, there is a heighted attention and careful evaluation of CS clearance of these patients. By the addition of grossly intact 4-limb motor exam, evaluation with the 64-slice CT scan, the data presented in this systematic review suggests that even this high-risk population may be safely evaluated; though, it is to be noted that the data is by-in-large retrospective and needs further corroboration. We were able to confirm with 4 of the authors that the spine surgeons and radiology departments at their respective institutions support the use of 64-slice scanners to clear CS injury in obtunded blunt trauma patients [11-13,15]. One author did not respond to our request for more information [14]. The results of this systematic review suggest that 64-slice scanners may be the first generation to safely clear CS injury in patients with grossly intact neurologic motor exam. Several of the 5 included studies used results of the physical exam in conjunction with results of the 64-slice CT scan which appears to be pivotal in the utility of CT scanners to clear injury with more confidence. In the study by Sanchez et al, patients were cleared on the basis of being neurologically intact and were assessed to be moving all 4 limbs upon arrival [12]. Similarly, Como et al included patients with gross motor movement of all 4 extremities [15] and Brown et al excluded all patients with a focal neurologic deficit [11]. Stelfox et al are no longer using physical exam as part of the 64-slice CT scan algorithm but, in communication with the author the results of this study are being applied at 2 local institutions to clear CS injury more expeditiously with no significant complications thus far. Kaiser et al. did not include physical examination in their CT scan clearance algorithm [14]. Of 114 patients with a negative CT scan, 23 had positive findings on MRI. Only 7 of these 23 patients had a clinically significant injury, and 3 of the 7 patients with a clinically significant injury had a focal neurologic deficit on physical exam. This again highlights the importance of including physical exam findings in the CT clearance algorithm. It should be noted that Kaiser et al used 3 generations of CT scan (1-slice, 16-slice, and 64-slice) and the authors did not respond to our requests for information regarding which generation of CT scan had the false negative results. Importantly, clearance in several of the 5 included studies is based on a hybrid of radiographic data as well as evaluation physical exam by movement and localization of 4 limbs. It appears that it is by this method that accuracy and safety of clearance is achieved. A major limitation of studies comparing 64-slice CT to MRI to clear cervical spinal injury is the limited power of these studies to detect a relatively rare outcome such as missed injury on a CT scan [15]. Several of the studies did comment on alternative outcomes. Stelfox et al addressed the deleterious impact of sustained immobilization and delayed CS clearance that is associated with using MRI to clear cervical spine injuries. They showed that patients with clearance by CT scan alone had a shorter duration of immobilization which was associated with 67% fewer immobilization-related complications including pressure ulcers, delirium and pneumonia [13]. Additionally, early removal of collars was associated with fewer days on mechanical ventilation. Similarly, when Como et al. assessed clearing on CT alone
Table 2 Summary of studies reporting on older generation CT scanners Author, yr
Scanner Slice Number
Number of Patients
Mechanism
Neuro status
% Missed Injuries
Change in management
Soult, 2012 [24] Khanna, 2012 [25] Tomycz, 2008 [26] Como, 2007 [27] Hogan, 200528
8 16 4 16 4, 16
24 150 180 115 88, 278
Blunt Blunt Blunt Blunt Blunt
Obtunded Obtunded Obtunded Obtunded Obtunded
20 49 21.1 5.2 3.3
0 0 0 0 0
100% 100% 100% 100% 100%
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in obtunded blunt trauma patients. There are certainly limitations to our systematic review. The number of studies we were able to find in each obtunded and non-obtunded patient cohort was small, thus limiting the overall sample size. The relatively few studies evaluating newer generation scanners demonstrate that there is still a paucity of 64-slice (and newer) CT data, although the studies summarized support this practice. In addition, the limited number of studies and the heterogeneity in the study design precluded us from performing a meta-analysis. The retrospective nature of the studies can make them prone to a selection bias, though this may favor a higher risk cohort, as the patients selected for MRI would have the highest suspicion of missed CS injury. The timing of MRI scan was not explicitly stated which could effect the interpretation. Also, gross physical examination and clearance is variable amidst the manuscripts described. By reporting on obtunded patients with a grossly intact neurologic exam, the conclusions of CT for predicting CS clearance in an obtunded patients is limited to this cohort. The results of this review cannot be applied to patients in whom gross neurological exam cannot be conducted. Despite these limitations, the included studies were methodologically sound and provide a strong foundation of literature that supports newer generation scanners to clear CS injury expeditiously in a high-risk population. A prospective study comparing MRI and 64-slice CT scan clearance of CS obtunded trauma patients with intact gross motor exam using composite outcomes including, duration of immobilization, mechanical ventilation, and immobilization-related complications, needs to be completed to corroborate the conclusions of this systematic review. Acknowledgments Librarians Niki Baumann and Judy Neill assisted with the search strategy and execution. Disclosures: None. Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.jcrc.2013.10.022. References [1] Sliker CW, Mirvis SE, Shanmuganathan K. Assessing cervical spine stability in obtunded blunt trauma patients: review of medical literature. Radiology 2005;234:733–9. [2] Demetriades D, Charalambides K, Chahwan S, Hanpeter D, Alo K, Velmahos G, et al. Nonskeletal cervical spine injuries: epidemiology and diagnostic pitfalls. J Trauma 2000;48:724–7. [3] Reid DC, Henderson R, Saboe L, Miller JD. Etiology and clinical course of missed spine fractures. J Trauma 1987;27:980–6. [4] Blackmore CC, Ramsey SD, Mann FA, Deyo RA. Cervical spine screening with CT in trauma patients: a cost-effectiveness analysis. Radiology 1999;212:117–25. [5] Hoffman JR, Wolfson AB, Todd K, Mower WR. Selective cervical spine radiography in blunt trauma: methodology of the National Emergency X-Radiography Utilization Study (NEXUS). 1998;32:461–9 [Ymem].
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[6] Como JJ, Diaz JJ, Dunham CM, Chiu WC, Duane TM, Capella JM, et al. Practice management guidelines for identification of cervical spine injuries following trauma: update from the Eastern Association for the Surgery of Trauma Practice Management Guidelines Committee. J Trauma 2009;67:651–9. [7] Pheasant S, Stubbs D. Back pain in nurses: epidemiology and risk assessment. Appl Ergon 1992;23:226–32. [8] Muchow RD, Resnick DK, Abdel MP, Munoz A, Anderson PA. Magnetic resonance imaging (MRI) in the clearance of the cervical spine in blunt trauma: a metaanalysis. J Trauma 2008;64:179–89. [9] Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. 2009;62: e1-34. [10] Downs SH, Black N. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health 1998;52:377–84. [11] Brown CV, Foulkrod KH, Reifsnyder A, Bui E, Lopez I, Hummell M, et al. Computed tomography versus magnetic resonance imaging for evaluation of the cervical spine: how many slices do you need? Am Surg 2010;76:365–8. [12] Sanchez B, Waxman K, Jones T, Conner S, Chung R, Becerra S. Cervical spine clearance in blunt trauma: evaluation of a computed tomography–based protocol. J Trauma 2005;59:179–83. [13] Stelfox HT, Velmahos GC, Gettings E, Bigatello LM, Schmidt U. Computed tomography for early and safe discontinuation of cervical spine immobilization in obtunded multiply injured patients. J Trauma 2007;63:630–6. [14] Kaiser ML, Whealon MD, Barrios C, Kong AP, Lekawa ME, Dolich MO. The current role of magnetic resonance imaging for diagnosing cervical spine injury in blunt trauma patients with negative computed tomography scan. Am Surg 2012;78: 1156–60. [15] Como JJ, Leukhardt WH, Anderson JS, Wilczewski PA, Samia H, Claridge JA. Computed tomography alone may clear the cervical spine in obtunded blunt trauma patients: a prospective evaluation of a revised protocol. J Trauma 2011;70: 345–51. [16] Hennessy D, Widder S, Zygun D, Hurlbert RJ, Burrowes P, Kortbeek JB. Cervical spine clearance in obtunded blunt trauma patients: a prospective study. J Trauma 2010;68:576–82. [17] Spiteri V, Kotnis R, Singh P, Elzein R, Madhu R, Brooks A, et al. Cervical dynamic screening in spinal clearance: now redundant. J Trauma 2006;61:1171–7. [18] Hills MW, Deane SA. Head injury and facial injury: is there an increased risk of cervical spine injury?J Trauma 1993;34:549–53 [discussion553–4]. [19] Holly LT, Kelly DF, Counelis GJ, Blinman T, McArthur DL, Cryer HG. Cervical spine trauma associated with moderate and severe head injury: incidence, risk factors, and injury characteristics. J Neurosurg 2002;96:285–91. [20] Menaker J, Philp A, Boswell S, Scalea TM. Computed tomography alone for cervical spine clearance in the unreliable patient? Are we there yet? J Trauma 2008;64: 898–904. [21] Sarani B, Waring S, Sonnad S, Schwab CW. Magnetic resonance imaging is a useful adjunct in the evaluation of the cervical spine of injured patients. J Trauma 2007;63:637–40. [22] Clark DE, Lowman JD, Griffin RL, Matthews HM, Reiff DA. Effectiveness of an early mobilization protocol in a trauma and burns intensive care unit: a retrospective cohort study. Phys Ther 2013;93:186–96. [23] Stiller K. Physiotherapy in intensive care: an updated systematic review. Chest 2013;144:825–47. [24] Como JJ, Thompson MA, Anderson JS, Shah RR, Claridge JA, Yowler CJ, et al. Is magnetic resonance imaging essential in clearing the cervical spine in obtunded patients with blunt trauma? J Trauma 2007;63:544–9. [25] Dunham CM, Brocker BP, Collier BD, Gemmel DJ. Risks associated with magnetic resonance imaging and cervical collar in comatose, blunt trauma patients with negative comprehensive cervical spine computed tomography and no apparent spinal deficit. Crit Care 2008;12:R89. [26] Ackland HM, Cooper JD, Malham GM, Kossmann T. Factors predicting cervical collarrelated decubitus ulceration in major trauma patients. Spine 2007;32:423–8. [27] Schoenfeld AJ, Bono CM, McGuire KJ, Warholic N, Harris MB. Computed tomography alone versus computed tomography and magnetic resonance imaging in the identification of occult injuries to the cervical spine: a meta-analysis. J Trauma 2010;68:109–13 [discussion113–4].
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Sixty-four–slice computed tomographic scanner to clear traumatic cervical spine injury: Systematic review of the literature☆,☆☆ Hussein D. Kanji, MD, MSc, MPH a, b,⁎, Andrew Neitzel, MD, MSc a, Mypinder Sekhon, MD a, Jessica McCallum, BSc d, Donald E. Griesdale, MD, MPH a, c, d a
Department of Medicine, Division of Critical Care Medicine, University of British Columbia, Vancouver, BC, Canada Department of Emergency Medicine, Fraser Health Region, New Westminster, BC, Canada Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, BC, Canada d Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada b c
a r t i c l e
i n f o
Keywords: Blunt trauma Computed tomography Magnetic resonance imaging Systematic review Critical care
a b s t r a c t Purpose: Cervical spine (CS) injury in blunt trauma is a prevalent and devastating complication. Clearing CS injuries in obtunded patients is fraught with challenges, and no single imaging modality or algorithm is both safe and effective. Increased time in c-spine precautions is associated with greater patient morbidity including increased ventilator associated pneumonia, delirium and ulceration. We systemically reviewed the literature to assess the effectiveness of 64-slice computed tomographic (CT) scanners in clearing traumatic CS injuries. Materials and Methods: Studies were identified using MEDLINE and Embase, the references of identified studies, international experts on CS clearance and authors of primary studies. Three reviewers independently selected and extracted data from studies that reported on both CT and MRI in traumatic CS injury. Results: We included five studies involving a total of 3443 patients; however, heterogeneity and lack of sample size precluded quantitative summation of the results. Qualitative assessment showed that 64-Slice CT scan, when applied within a set protocol, performed favourably in clearing injury. Conclusions: Data suggests that using 64-slice CT scans on obtunded trauma patients with grossly intact motor function, in the context of a defined clearance protocol with interpretation by an experienced radiologist, may be sufficient to safely clear significant CS injury. A prospective study comparing MRI and 64-slice CT scan clearance in this population is necessary to corroborate these conclusions. © 2014 Elsevier Inc. All rights reserved.
1. Introduction Cervical spine (CS) injuries are both a prevalent and serious complication of blunt trauma. Rates of injury are reported at between 2% and 12% with occult or delayed injuries occurring in 1% to 8% of cases [1-3]. Missing an unstable CS injury is a devastating complication resulting in potential significant morbidity for the patient, cost to the healthcare system, and angst to the clinician [4]. In the awake patient, formalized evidence based evaluation and clearance has been established that integrates clinical exam and radiographic imaging [5]. In the unreliable or obtunded patient, CS clearance is far more complicated and the risk of occult injury challenges CS clearance based on radiographic evidence alone. The recent Eastern Association for the Surgery of Trauma guidelines themselves remain elusive on the topic and suggest an individualized, region-based approach to clearing this difficult patient cohort [6]. Delays in clearance can lead to
increased rates of ulcer, airway compromise, and higher intracranial pressure. In addition, longer duration of immobilization can be associated with increased nursing time and workload and risk of associated workplace injury [7]. Consequently, means of safely and expediently clearing patients with potential CS injuries is required. Computed tomographic (CT) scan has become the standard in screening, however, integration of MRI to determine occult or ligamentous injury is recommended as the gold standard [8]. This approach is predicated on historical studies utilizing prior generations of CT scanners. Newer generation CT scanners may obviate the need to perform magnetic resonance imaging (MRI) and subject patients to prolonged duration in CS collars. This new strategy could reduce associated complications, morbidity, and nursing workload. We systematically reviewed the literature in order to evaluate the effectiveness of 64-slice CT scanners to clear CS injuries. 2. Materials and methods
☆ Funding: None. ☆☆ Conflict of Interest: None to declare. ⁎ Corresponding author. Department of Critical Care, BC, Canada V5Z 1M9. Tel.: +1 604 363 8228; fax: +1 604 875 5957. E-mail address: [email protected] (H.D. Kanji). 0883-9441/$ – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcrc.2013.10.022
2.1. Data sources and searching strategy We complied with the PRISMA guidelines for the performance of meta-analysis of observational cohort studies [9]. Studies were
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selected if they met the following criteria: Adult patients (≥16 years of age), trauma (blunt or penetrating), comparison of 64-slice CT and MRI, reported outcomes data related to neurological status and need for intervention defined by surgery or prolonged immobilization. Manuscripts were excluded if they did not report on the listed inclusion criteria, were case reports, or summary articles. See Fig. 1 for a list of excluded manuscripts. Manuscripts were not excluded based on language. The gold standard used to determine the predictive ability of CT scan to assess for injury were MRI or well-documented functional neurological outcome. Therefore, studies comparing the results of CT scan to dynamic radiographs (non gold-standard) were also excluded. Unstable injury was defined as needing intervention in terms of prolonged immobilization, collar placement, surgery, neurological impairment, or radiographic evidence. A medical librarian searched Medline (1966-2011), Embase (1988-2011), and the Cochrane Library using relevant subject headings and text words (Appendix A). The search was updated on April 15, 2013. In addition, cited reference search was carried out in Web of Science and conference proceedings to identify other eligible papers. Reference lists of primary studies were also reviewed, and experts (including primary study authors) were contacted to identify any other studies. If studies did not identify in the methods section the type of CT scanner used, the authors were individually contacted. 2.2. Data extraction and quality assessment Three reviewers (AN, MS, JM) independently screened citations, abstracted data, and assessed methodological quality. If data needed to be clarified we contacted the original investigators. Titles and abstracts
were assessed for appropriateness to include primary literature (case reports excluded) that compared diagnosis of acute CS trauma using 64-slice CT scanner and MRI in adult human patients without neurologic deficits or underlying spine disease; both awake and obtunded patients were included. Disagreements to included studies were arbitrated by a fourth reviewer (HK). Full manuscripts of included papers were reviewed for appropriateness based on the same criteria. Refer to Fig. 1 for the full list of exclusion criteria and summary of excluded papers. Data were abstracted individually with an attempt to summate to perform a meta-analysis and calculation of sensitivity and specificity. Study quality was assessed using the Downs and Black checklist which has a total maximum score of 31 [10]. 2.3. Data analysis A meta-analysis was not performed given that the sample size was inadequate and the between-study heterogeneity was too large to justify. We performed a qualitative assessment of the included manuscripts and reported primary outcomes including sensitivity, specificity, and negative predictive value. 3. Results Overall 717 citations were identified, of which 5 studies fulfilled our eligibility criteria (Fig. 1). Table 1 presents the key characteristics from the 5 studies we included, summarizing the study inclusion and outcomes reported. The quality of the studies was assessed using the Downs and Black score [10]. The average score was 15.8 with the lowest and highest being 15 and 17, respectively, signifying high
Studies Excluded: 649 Duplicates: 14 Pediatric or neonatal: 98 Non-trauma: 49 Not human: 1 Don’t compare CT and MRI: 77 CT not 64-slice: 31 Baseline neurologic deficit: 10 For OR screening: 8 Management: 55 Review, letter to editor, book chapter: 157 Case Report: 122 Vascular: 16 Post Mortem: 5 Survey of current practice: 2 Thoracic: 2 Not acute: 1 Underlying spine disease: 1
Studies screened for possible inclusion Title & Abstract (n= 717)
Full manuscripts reviewed for inclusion (n = 68)
Full manuscripts excluded: 63 Not 64-slice: 37 Don’t compare CT to MRI: 8 Unable to determine scan number: 9 Review or letter to editor: 8 Baseline neurologic deficit: 1
Fig. 1. Study selection flow diagram.
Manuscripts included (n = 5)
H.D. Kanji et al. / Journal of Critical Care 29 (2014) 314.e9–314.e13 Table 1 Summary of studies reporting on 64-slice CT scan compared to MRI Author, year
No. patients
Mechanism
Neuro status
Outcome
Sanchez, 2005 [12]
2854
Blunt 91%
Obtunded
a
215
Blunt 100%
Obtunded
Kaiser, 2012 [14]
114 (29)b
Blunt 100%
Obtunded
Como, 2011 [15]
197 (5)b
Blunt 100%
NR
Blunt 100%
NR
Sn/Sp 99/100 NPV = 99.9% 100/100 NPV = 100% Sn/Sp = NR NPV = 96.5% Sn/Sp = NR NPV = 100% Sp/Sn = 100/100 NPV = 100%
Stelfox, 2007 [13]
Brown, 2010 [11]
63
Neuro status = if any neurological signs at baseline. NR, not reported. a Data obtained upon consultation with authors. b Total of 114 patients with 29 having 64-slice data, Total of 197 with patients 5 having 64-slice data.
quality of studies included in this systematic review. When studied, the mean Downs and Black score for non-randomized controlled trials has been reported to be 11.7. 3.1. CT vs MRI in awake patients A study by Brown et al. retrospectively compared an older generation 4-slice scanner to a newer generation 64-slice CT scanner using MRI as the gold-standard. 64-slice scanners had a 0% missed injury rate. This was a significant improvement from a 7% missed rate in the 4-slice scanner [11]. Inclusion criteria consisted of blunt trauma with no neurological abnormalities, although a certain proportion of patients may have had a Glasgow Coma Scale (GCS) score b15 as per communication with the author (data not recorded). Therefore, we cannot assume that this patient cohort included only an obtunded population. There were only 24 patients who had a negative study with both a 64-slice CT and MRI [11]. The 7% of missed injury in the study by Brown and colleagues were all distributed to the older generation scanner (4-slice), suggesting that newer 64slice scanners have improved ability to discern injury that may have been previously missed. 3.2. CT compared to MRI in obtunded patients Sanchez et al prospectively compared 64-slice scanners to MRI in 2854 trauma patients which included obtunded patients [12]. The majority (91%) of patients had blunt injury and an average injury severity scale of 11. In obtunded patients who were moving all 4 extremities at arrival to emergency department, CS was cleared based on a normal CT scan; 15% of patients with spinal cord injury had normal radiographic findings but were identified by neurological impairment. Sensitivity and specificity for detecting CS injury was 99 and 100%. Risk of missed CS injury in their study was reported at 0.04%. The only patient that had a missed injury on CT had an underlying syringomyelia, which was an underlying pathologic condition. Gold standard for clearance in this study was clinical examination. Most patients did not receive an MRI to document radiographic evidence of injury and therefore, difficult to specifically assert the performance of CT compared to MRI. However, patients were followed up closely within 2 weeks of discharge, thus signs of any clinically relevant neurological injury were very well evaluated. Based on these results, even in obtunded patients moving all 4 limbs upon arrival, clearance using 64-slice CT scan is unlikely to miss significant CS injuries. The study by Stelfox et al identified 140 critically ill, intubated, and mechanically ventilated trauma patients at-risk for CS injury [13]. In this prospective study, they evaluated the ability of CT to predict injury compared to the gold standard of MRI or physical examination,
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followed by a subsequent protocol that cleared CS injury based on CT scan findings alone. It was demonstrated that a CT only approach was associated with fewer days of immobilization (2 vs 6 days, P b .001) and fewer days of mechanical ventilation (3 vs. 4, P = .011). Through communication with author we were able to discern that 64-slice CT vs MRI had a 100% sensitivity and specificity to clear injury in the cohort. There were only 7 patients evaluated by both CT and MRI scans, but there was full concordance between both modalities. Using clinical assessment on follow up, there was no missed injury by CT scan in the entire 75 patient cohort. Kaiser et al performed a retrospective study of the ability of 64slice CT scans to clear CS injury in blunt trauma patients with GCS score b 14 [14]. CT scans were interpreted by attending radiologists, orthopedists, and neurosurgeons. Of the 114 patients included with no injury identified on CT scan, 6% had MRI findings that altered management. In this study the three different generation scanners were utilized (single, 16- and 64-slice). MRI was completed without contrast using a 1.5-Telsa system. 3 of the 7 patients with clinically significant injury identified by MRI had neurological deficits. The remaining 4 patients were treated conservatively with no operative fixation necessary. The use of single-slice CT scanner was the only identifiable risk factor for missed injury (OR = 2.62, P b .023). There was no significant difference in MRI findings of patients undergoing 16 or 64-slice CT scans. Como et al performed a prospective study evaluating the clearance and removal of collars in obtunded blunt trauma patients with preserved gross motor function on exam. This was based on both 16and 64-slice CT scan data images [15]. One hundred and ninety-seven patients were evaluated and had collars removed on the basis of CT scan finding. Of the scans, 192 were performed using 16-slice scanner and 5 were performed using the newer 64-slice scanner. Neuroradiologists interpreted all CT scans and follow up was conducted when patients were no longer obtunded to determine neurological function. Using a serial clinical exam and follow up, no patients had significant CS injuries when cleared based on CT alone. 4. Discussion In this systematic review, we sought to summate and analyze the recent data on the sensitivity and specificity of 64-slice CT scan as a modality to clear cervical spine injury in trauma. Specifically, we wanted to address the utility of 64-slice CT scanners as a clearance modality in the obtunded blunt trauma patient. There is sufficient data suggesting CT scan is at least as good as, and likely superior to, dynamic (flexion-extension) radiographs in screening for CS injury [6,16,17]. As a result, CT scan has supplanted dynamic radiographs and plain film XR as the modality of choice for initial screening and is endorsed by the Eastern Association for the Surgery of Trauma guidelines. The controversy and debate in the literature surrounds the role and integration of MRI in clearing potential CS injury in the unreliable patient. Incorporating MRI into the algorithm has been shown to have a negative predictive value of 100% but, results in a greater amount of false positive scans [8]. Our systematic review identified 5 studies including 3443 patients addressing the use of 64-slice CT scans as the imaging modality in both the awake, examinable and the obtunded trauma patient cohort (Table 1). Due to the heterogeneity in the studies, we were unable to pool the data but, the results of the studies do suggest that newer generation 64-slice CT scans, when interpreted by neuroradiologists, can potentially be utilized, in conjunction with the physical exam, as a single imaging modality to clear cervical spine injuries. The ability to perform an adequate neurological exam in an obtunded population is often impaired and thus, clinicians have trepidation about relying solely on CT scan results, which is indeed reasonable given the potentially catastrophic repercussions of a missed injury. A GCS score of b 8 is associated with a 50% increased
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compared to a historical control they found a significantly earlier collar removal (3.3 vs 7.5 days, P b .001) and decreased length of stay (13.8 vs 23.4 days, P b .001) [15]. This was also associated with fewer decubitus ulcers and morbidity for the patients. Earlier mobilization is being increasingly recognized as a very important factor to abate delirium, lessen ventilator duration, decrease infectious complications, shorten hospital admission duration and improve overall functional outcomes [22,23]. Como et al reported that the limited availability of MRI in some centers, increased cost, and safety concerns due to impaired patient access for prolonged periods of time associated with MRI as barriers, can be overcome by using 64-slice CT scanners [15]. They further comment that eliminating MRI in this population was not only safe but would have decreased costs by over $250,000 during the study period [24]. Future work in this area should expand on outcomes to include immobilization-related complications, cost and resource allocation, as well as details of injuries confirmed and missed by CT scanners. These complications and morbidity of prolonged immobilization are significant and should be highlighted [25,26]. Conversely, missed ligamentous injury could have disastrous implications for the patient and their family and are associated with significant costs to the healthcare system [12]. Missed ligamentous injuries using CT scanners was a concern identified in all 5 studies. There was limited data on types of injuries identified by the 64-slice CT scan. One study reported that 12 (39%) of 31 abnormal studies using 4and 64-slice CT scans revealed evidence of ligamentous or spinal cord injury without evidence of a fracture, however the details of the ligamentous injuries identified were not recorded, and were not available through correspondence with the author [11]. Three studies excluded patients with a negative CT scan so they did not record details of injuries identified using the CT scan [13-15]. Though not explicitly reported, the careful clinical follow-up in the included studies would suffice to identify clinically relevant ligamentous injuries. Clearance of CS injury based on CT alone is challenged by several studies and summarized by a meta-analysis by Schoenfeld et al [27]. The study included 1550 patients with negative CS CT and concomitant MRI in obtunded patients. Significant injuries altering management were identified in 96 (6%) of patients with MRI. The negative predictive value for MRI was 100%; however, the pooled false positive rate was 6% (95% CI, 1-11). The previous meta-analysis by Muchow et al showed similar results although, it included more heterogeneous imaging protocols as well as pediatric patients [8]. Two very important differences in these studies need to be noted and may account for the discrepancy in results we are presenting. First, the generation of CT scanners were quite variable and largely comprised of earlier generation scanners. We know that there is greater spatial resolution with newer 64-slice scanners that may allow better recognition of what would be previously considered occult injury. Second, most of the studies we present include cohorts with an intact gross neurological evaluation, which was not the case in the studies included in the meta-analysis. Thus, the power of 64-slice CT scan to clear CS injury may be limited to evaluating patients with a grossly intact neurological exam. We believe our systematic review suggests that a 64-slice CT cervical spine scan, within the context of a grossly intact neurological exam and no underlying spine pathology and interpretation by an experienced radiologist, may have utility as a modality to clear injury
in incidence of CS injury [18]. This has been reiterated in a study by Holly et al. reporting a disproportionately higher rate of CS injury in patients with severe head injury [19]. The significant rates of missed injury reported in older generation scanners are quite prevalent and may exacerbate this fear (Table 2) [20,21]. Thus, there is a heighted attention and careful evaluation of CS clearance of these patients. By the addition of grossly intact 4-limb motor exam, evaluation with the 64-slice CT scan, the data presented in this systematic review suggests that even this high-risk population may be safely evaluated; though, it is to be noted that the data is by-in-large retrospective and needs further corroboration. We were able to confirm with 4 of the authors that the spine surgeons and radiology departments at their respective institutions support the use of 64-slice scanners to clear CS injury in obtunded blunt trauma patients [11-13,15]. One author did not respond to our request for more information [14]. The results of this systematic review suggest that 64-slice scanners may be the first generation to safely clear CS injury in patients with grossly intact neurologic motor exam. Several of the 5 included studies used results of the physical exam in conjunction with results of the 64-slice CT scan which appears to be pivotal in the utility of CT scanners to clear injury with more confidence. In the study by Sanchez et al, patients were cleared on the basis of being neurologically intact and were assessed to be moving all 4 limbs upon arrival [12]. Similarly, Como et al included patients with gross motor movement of all 4 extremities [15] and Brown et al excluded all patients with a focal neurologic deficit [11]. Stelfox et al are no longer using physical exam as part of the 64-slice CT scan algorithm but, in communication with the author the results of this study are being applied at 2 local institutions to clear CS injury more expeditiously with no significant complications thus far. Kaiser et al. did not include physical examination in their CT scan clearance algorithm [14]. Of 114 patients with a negative CT scan, 23 had positive findings on MRI. Only 7 of these 23 patients had a clinically significant injury, and 3 of the 7 patients with a clinically significant injury had a focal neurologic deficit on physical exam. This again highlights the importance of including physical exam findings in the CT clearance algorithm. It should be noted that Kaiser et al used 3 generations of CT scan (1-slice, 16-slice, and 64-slice) and the authors did not respond to our requests for information regarding which generation of CT scan had the false negative results. Importantly, clearance in several of the 5 included studies is based on a hybrid of radiographic data as well as evaluation physical exam by movement and localization of 4 limbs. It appears that it is by this method that accuracy and safety of clearance is achieved. A major limitation of studies comparing 64-slice CT to MRI to clear cervical spinal injury is the limited power of these studies to detect a relatively rare outcome such as missed injury on a CT scan [15]. Several of the studies did comment on alternative outcomes. Stelfox et al addressed the deleterious impact of sustained immobilization and delayed CS clearance that is associated with using MRI to clear cervical spine injuries. They showed that patients with clearance by CT scan alone had a shorter duration of immobilization which was associated with 67% fewer immobilization-related complications including pressure ulcers, delirium and pneumonia [13]. Additionally, early removal of collars was associated with fewer days on mechanical ventilation. Similarly, when Como et al. assessed clearing on CT alone
Table 2 Summary of studies reporting on older generation CT scanners Author, yr
Scanner Slice Number
Number of Patients
Mechanism
Neuro status
% Missed Injuries
Change in management
Soult, 2012 [24] Khanna, 2012 [25] Tomycz, 2008 [26] Como, 2007 [27] Hogan, 200528
8 16 4 16 4, 16
24 150 180 115 88, 278
Blunt Blunt Blunt Blunt Blunt
Obtunded Obtunded Obtunded Obtunded Obtunded
20 49 21.1 5.2 3.3
0 0 0 0 0
100% 100% 100% 100% 100%
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in obtunded blunt trauma patients. There are certainly limitations to our systematic review. The number of studies we were able to find in each obtunded and non-obtunded patient cohort was small, thus limiting the overall sample size. The relatively few studies evaluating newer generation scanners demonstrate that there is still a paucity of 64-slice (and newer) CT data, although the studies summarized support this practice. In addition, the limited number of studies and the heterogeneity in the study design precluded us from performing a meta-analysis. The retrospective nature of the studies can make them prone to a selection bias, though this may favor a higher risk cohort, as the patients selected for MRI would have the highest suspicion of missed CS injury. The timing of MRI scan was not explicitly stated which could effect the interpretation. Also, gross physical examination and clearance is variable amidst the manuscripts described. By reporting on obtunded patients with a grossly intact neurologic exam, the conclusions of CT for predicting CS clearance in an obtunded patients is limited to this cohort. The results of this review cannot be applied to patients in whom gross neurological exam cannot be conducted. Despite these limitations, the included studies were methodologically sound and provide a strong foundation of literature that supports newer generation scanners to clear CS injury expeditiously in a high-risk population. A prospective study comparing MRI and 64-slice CT scan clearance of CS obtunded trauma patients with intact gross motor exam using composite outcomes including, duration of immobilization, mechanical ventilation, and immobilization-related complications, needs to be completed to corroborate the conclusions of this systematic review. Acknowledgments Librarians Niki Baumann and Judy Neill assisted with the search strategy and execution. Disclosures: None. Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.jcrc.2013.10.022. References [1] Sliker CW, Mirvis SE, Shanmuganathan K. Assessing cervical spine stability in obtunded blunt trauma patients: review of medical literature. Radiology 2005;234:733–9. [2] Demetriades D, Charalambides K, Chahwan S, Hanpeter D, Alo K, Velmahos G, et al. Nonskeletal cervical spine injuries: epidemiology and diagnostic pitfalls. J Trauma 2000;48:724–7. [3] Reid DC, Henderson R, Saboe L, Miller JD. Etiology and clinical course of missed spine fractures. J Trauma 1987;27:980–6. [4] Blackmore CC, Ramsey SD, Mann FA, Deyo RA. Cervical spine screening with CT in trauma patients: a cost-effectiveness analysis. Radiology 1999;212:117–25. [5] Hoffman JR, Wolfson AB, Todd K, Mower WR. Selective cervical spine radiography in blunt trauma: methodology of the National Emergency X-Radiography Utilization Study (NEXUS). 1998;32:461–9 [Ymem].
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