Qu a d r i p l e g i a due to spinal cord injury is a devastating

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1 Neurosurg Focus 25 (5):E10, 2008 Prevalence of cervical spinal injury in trauma And r e w H. Mi l by, B.S., 1 Ca s e y H. Ha l p e r n, M.D., 1 We n s h e n g Gu o, Ph.D., 2 a n d Sh e r m a n C. St e i n, M.D. 1 1 Department of Neurosurgery, Hospital of the University of Pennsylvania; and 2 Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania Object. Diagnosis of cervical spinal injury (CSI) is an essential aspect of the trauma evaluation. This task is especially difficult in patients who are not clinically able to be evaluated (unevaluable) because of distracting painful injuries, intoxication, or concomitant head injury. For this population, the appropriate use of advanced imaging techniques for cervical spinal clearance remains undetermined. This study was undertaken to estimate the prevalence of unstable CSI, particularly among patients in whom clinical evaluation is impossible or unreliable. Methods. Estimates of the prevalence of CSI in populations consisting of all trauma patients, alert patients only, and clinically unevaluable patients only were determined by variance-weighted pooling of data from 65 publications (281,864 patients) that met criteria for review. Results. The overall prevalence of CSI among all trauma patients was 3.7%. The prevalence of CSI in alert patients was 2.8%, whereas unevaluable patients were at increased risk of CSI with a prevalence of 7.7% (p = 0.007). Overall, 41.9% of all CSI cases were considered to exhibit instability. Conclusions. Trauma patients who are clinically unevaluable have a higher prevalence of CSI than alert patients. Knowledge of the prevalence and risk of such injuries may help establish an evidence-based approach to the detection and management of clinically occult CSI. (DOI: /FOC E10) Ke y Wo r d s cervical spine injury prevalence trauma Qu a d r i p l e g i a due to spinal cord injury is a devastating consequence of trauma to the cervical spine, involving numerous functional, psychosocial, and economic ramifications. 7,12,13,24,25,27 29,45, 49,61 Identification of unstable CSI is therefore an essential aspect of the trauma evaluation in preventing subsequent neurological damage. 6,22,71,72,75,76 This task is especially difficult in patients who are not clinically evaluable (unevaluable group) because of intoxication or concomitant head injury, and has led to the use of advanced imaging techniques such as CT and MR imaging for radiological clearance. 1,2,15,20,58,83,90,91 Continued advances in imaging quality and sensitivity now raise questions about the practice of clearing even alert, low-risk patients by clinical criteria alone, 30 and have precluded the establishment of any consensus regarding the appropriate indications for the use of imaging studies. 58,65,67,85,90 Although a lower threshold for the use of advanced imaging would hypothetically result in the detection and possible prevention of a greater number of CSIs, these benefits must be weighed against the associated risks and considerable costs of performing such studies and the additional treatments initiated due to false-positive results. 18,19,41,77 Indeed, complications have been reported Abbreviations used in this paper: CSI = cervical spine injury; GCS = Glasgow Coma Scale. in 6 71% of critically ill patients during and after transport. 94 Accurate knowledge of the prevalence of CSI in trauma patients is therefore essential for assessing the need for immobilization and/or further imaging. Scattered studies of CSI in clinical series composed of all trauma patients report CSI prevalences ranging from 1 to 14%. 59,87 However, unevaluable patients require a higher index of suspicion than the general trauma population, 5,46,51,64,80,96 with one patient series estimating that a GCS score 8 incurs an almost 6-fold increase in the risk of CSI. 50 Numerous patient series have examined the sensitivities of various imaging modalities in the detection of CSI, and as such represent a large volume of data from which to calculate overall prevalence. However, considerable variation exists in rates of radiographic evidence of CSI, with 1 study reporting CT or MR imaging findings in 40% of obtunded patients. 90 By systematically pooling data from relevant clinical series, more generalizable estimates of CSI prevalence in all trauma patients, alert patients, and unevaluable patients with trauma can be determined, along with the proportion of patients whose unstable injuries confer a risk of quadriplegia. Methods We performed English-language searches of Medline and PubMed for articles published between

2 A. H. Milby et al. Table 1: Prevalence of CSI in all trauma patients Author & Year Setting Case Accrual Method Patient Population Injury Incidence Banit et al., 2000 single US Level I trauma center retrospective evaluation of clinical algorithm all trauma admissions Bayless & Ray, 1989 single US Level I trauma center retrospective observational blunt head trauma admissions Borock et al., 1991 single US Level I trauma center retrospective evaluation of clinical algorithm blunt trauma admissions Cox et al., 2001 single US Level I trauma center prospective evaluation of clinical algorithm all trauma admissions Demetriades et al., 2000 single US Level I trauma center retrospective observational blunt trauma admissions 14, Edwards et al., 2001 single Netherlands Level I trauma center prospective evaluation of clinical algorithm high-energy trauma admissions Gale et al., 2005 single US Level I trauma center retrospective evaluation of clinical algorithm blunt trauma admissions Grossman et al., US Level I III trauma centers retrospective survey all trauma admissions 111, Hanson et al., 2000 single US Level I trauma center retrospective evaluation of clinical algorithm all trauma admissions Harris et al., 2000 single US Level I trauma center prospective evaluation of clinical algorithm trauma patients with nonspinal injuries Insko et al., 2002 single US Level I trauma center retrospective observational trauma patients undergoing flexion-extension radiography Kreipke et al., 1989 single US Level I trauma center prospective observational all trauma admissions Lee et al., 2001 single US Level I trauma center retrospective observational trauma patients undergoing both radiography and CT Mathen et al., 2007 single US Level I trauma center prospective observational patients with neck pain, neurological deficit, or intoxication McCulloch et al., 2005 single US Level I trauma center prospective observational trauma patients undergoing both radiography and CT MacDonald et al., 1990 single Canadian Level I trauma center retrospective observational motor vehicle crash trauma admissions Mower et al., US university and community hospitals prospective observational blunt trauma admissions 34, Neifeld et al., 1988 four US trauma centers retrospective evaluation of clinical algorithm blunt head or neck trauma admissions Nguyen & Clark, 2005 single US Level I trauma center prospective observational patients with neck pain, neurological deficit, or intoxication Prasad et al., 1999 single Canadian Level I trauma center retrospective observational multitrauma admissions Ptak et al., 2001 single US Level I trauma center retrospective observational all trauma admissions undergoing CT Roberge et al., 1988 single US Level I trauma center prospective evaluation of clinical algorithm blunt trauma admissions Roberge & Wears, 1992 single US Level I trauma center prospective evaluation of clinical algorithm blunt trauma admissions Ross et al., 1992 single US Level I trauma center prospective observational blunt trauma admissions Sanchez et al., 2005 single US Level II trauma center prospective observational all trauma admissions Sharma et al., 2007 single US university hospital emergency prospective observational all trauma admissions department Spiteri et al., 2006 single UK trauma center retrospective evaluation of clinical algorithm trauma admissions undergoing cervical CT Williams et al., 1992 single US Level I trauma center retrospective observational all trauma admissions Yanar et al., 2007 Trauma registry, US county prospective observational adult pedestrians injured by vehicles

3 Prevalence of cervical spine injury in trauma Table 2: Prevalence of CSI in alert trauma patients Injury Incidence Author & Year Setting Case Accrual Method Patient Population Barba et al., 2001 single US Level I trauma center retrospective evaluation of clinical algorithm trauma admissions undergoing cervical CT Ersoy et al., 1995 single Turkish university hospital emergency retrospective observational conscious and oriented blunt trauma admissions department Gonzalez et al., 1999 single US Level I trauma center prospective observational awake and alert blunt trauma admissions McNamara et al., 1988 single US Level II trauma center prospective observational patients with neck pain following traumatic injury McNamara et al., 1990 single US Level II trauma center retrospective observational alert, nonintoxicated blunt trauma admissions Roth et al., 1994 single US military medical center prospective cohort alert, nonintoxicated blunt trauma admissions Stiell et al., Canadian trauma centers prospective evaluation of clinical algorithm patients with acute blunt trauma to head or neck Stiell et al., Canadian tertiary care hospitals prospective evaluation of clinical algorithm patients with acute blunt trauma to head or neck Zabel et al., 1997 single US Level I trauma center retrospective observational alert trauma admissions and January The search used various combinations of the key words spinal injuries, cervical vertebrae, instability, trauma, clearance, neck, diagnosis, epidemiology, prevalence, and incidence. We refined the search by eliminating laboratory studies, case reports, editorials, or reviews without newly reported data, and case series with duplicated or overlapping data. These findings were supplemented by using the Find Similar and Find Citing Articles features of Medline and Related Articles feature of PubMed, as well as the bibliographies of selected articles. Articles were analyzed and compared with reference to the setting, study organization, definitions of clinical criteria, and data collection methods. Studies restricted to children < 15 years of age were excluded. If a study reported prevalence rates from pediatric cases separately from those in an adult population, these data were also excluded from the analysis. Studies meeting our criteria for inclusion were organized into 3 categories: those composed of all trauma patients, alert patients, and unevaluable patients with trauma. Those studies reporting rates of instability upon detection of CSI were also placed into a fourth category, which overlapped in part with the previously listed categories. The all trauma category contained series in which patients were not further classified by clinical evaluability on presentation. These series were composed of patients with either unrestricted blunt and penetrating trauma or blunt trauma alone, whereas those composed solely of patients with penetrating trauma were excluded. were deemed alert if they had reliable clinical examination findings, consisting minimally of being able to respond to questions regarding neck pain and cooperate with neck movement instructions. were considered unevaluable if impaired consciousness, inebriation, confusion, endotracheal intubation, or distracting injuries rendered the clinical examination of the cervical spine unreliable. An unstable injury was defined as any fracture, dislocation, or purely ligamentous injury necessitating external stabilization and/or operative fixation. Data concerning unstable injuries were pooled from all series reporting their prevalence without subclassification on the basis of clinical evaluability. Mean prevalence values for each group were obtained using variance-weighted pooling. A mixed-effects logistic regression model was used, using SAS PROC NLMIXED (SAS, Inc.). Data within each study were considered a cluster and a hierarchical model was used to calculate the average prevalence rate. The binary nature of the outcome allowed the use of summary statistics as a proxy for the entire data set. The effect across studies was assumed to vary as a normal distribution. The overall prevalence rate was calculated as the population-average estimate, together with its 95% confidence intervals. Mean prevalence values for alert and unevaluable patients were compared, using a likelihood ratio test for pooled data. 60 We considered differences with a probability value < 0.05 to be statistically significant. Results Sixty-five studies with a total of 281,864 subjects 3

4 A. H. Milby et al. Table 3: Prevalence of CSI in clinically unevaluable trauma patients* Author & Year Setting Case Accrual Method Patient Population Injury Incidence Bolinger et al., 2004 single US Level I trauma center prospective evaluation of clinical algorithm patients with TBI and GCS scores < Brooks & Willett, 2001 single UK trauma center retrospective observational unconscious trauma patients Chiu et al., 2001 single US Level I trauma center retrospective observational patients with GCS scores < 15 on admission D'Alise et al., US Level I trauma centers retrospective observational intubated for head or severe multisystem injuries Davis et al., 2001 single US Level I trauma center prospective evaluation of clinical algorithm head-injured ICU admissions 14, Diaz et al., 2003 single US Level I trauma center prospective observational altered mental status or distracting injuries Freedman et al., 2005 single Australian trauma center retrospective observational unconscious trauma patients admitted to ICU Geck et al., 2001 single US Level I trauma center retrospective observational patients with high-energy mechanisms of injury 111, Griffen et al., 2003 single US Level I trauma center retrospective observational altered mental status or neurological deficit Griffiths et al., 2002 single US Level I trauma center retrospective observational unconscious or semiconscious trauma patients Hogan et al., 2005 single US Level I trauma center retrospective observational obtunded trauma patients Holly et al., US Level I trauma centers retrospective observational head injury with GCS scores 3-12, or GCS score >12 with CT abnormality Jelly et al., 2000 single UK trauma center prospective observational patients intubated for polytrauma Kihiczak et al., 2001 single US Level I trauma center retrospective observational unevaluable patients undergoing MR imaging after negative CT Padayachee et al., 2006 single UK trauma center prospective observational unconscious with TBI in ICU Piatt et al., 2006 all Pennsylvania trauma centers retrospective observational TBI w/ GCS scores < Schenarts et al., 2001 single US Level I trauma center prospective evaluation of clinical algorithm altered mental status after blunt traumatic injury 34, Sees et al., 1998 single US military medical center retrospective observational unresponsive or obtunded with GCS scores Stassen et al., 2006 single US Level I trauma center retrospective evaluation of clinical algorithm obtunded blunt trauma patients Widder et al., 2004 single Canadian Level I trauma center prospective observational obtunded blunt trauma patients * ICU = intensive care unit; TBI = traumatic brain injury. 4

5 Prevalence of cervical spine injury in trauma Table 4: Prevalence of unstable CSIs in all trauma patients Author & Year Setting Case Accrual Method Patient Population Injury Incidence Banit et al., 2000 single US Level I trauma center retrospective evaluation of clinical algorithm all trauma admissions Berne et al., 1999 single US Level I trauma center prospective observational blunt trauma with intoxication or paralytics Chiu et al., 2001 single US Level I trauma center retrospective observational patients with GCS scores < 15 on admission Davis et al., US trauma centers retrospective observational all trauma admissions Demetriades et al., 2000 single US Level I trauma center retrospective observational blunt trauma admissions Freedman et al., 2005 single Australian trauma center retrospective observational unconscious trauma patients admitted to ICU Geck et al., 2001 single US Level I trauma center retrospective observational patients with high-energy mechanisms of injury Gerrelts et al., 1991 single US Level I trauma center retrospective observational blunt trauma admissions Goldberg et al., US university and community hospitals retrospective observational blunt trauma admissions Griffiths et al., 2002 single US Level I trauma center retrospective observational unconscious or semiconscious trauma patients Harris et al., 2000 single US Level I trauma center prospective evaluation of clinical algorithm trauma patients with nonspinal injuries Holly et al., US Level I trauma centers retrospective observational head injury with GCS scores 3 12, or GCS scores > with CT abnormality MacDonald et al., 1990 single Canadian Level I trauma center retrospective observational motor vehicle accident trauma admissions Mathen et al., 2007 single US Level I trauma center prospective observational patients with neck pain, neurological deficit, or intoxication Reid et al., 1987 single Canadian Level I trauma center retrospective observational cohort of patients with known CSIs Ross et al., 1992 single US Level I trauma center prospective observational blunt trauma admissions Schenarts et al., 2001 single US Level I trauma center prospective evaluation of clinical algorithm altered mental status after blunt traumatic injury Sliker et al., 2005 multiple Level I trauma centers retrospective literature review obtunded blunt trauma patients Spiteri et al., 2006 single UK trauma center retrospective evaluation of clinical trauma admissions undergoing cervical CT algorithm Widder et al., 2004 single Canadian Level I trauma prospective observational obtunded blunt trauma patients center Yanar et al., US Level I trauma centers retrospective observational pedestrians injured by automobiles

6 A. H. Milby et al. Table 5: Pooled prevalences of CSIs* Patient Population Pooled Mean (%) 95% CI all trauma 209, alert patients 21, unevaluable patients 49, proportion of unstable injuries 3, * CI = confidence interval. Fig. 1. Flow chart showing the evidentiary value with regard to prevalence of CSI in publications fulfilling the initial search criteria. Bold numbers represent the number of publications in each category. were selected with information on the prevalence of CSI or the proportion of instability in CSI. 3,4,8 11,14,16,17,21,23,26,31 40,42 44,47,48,52 57,62,63,66,68 70,73,74,78,79,81,84,86,88,92,93,95,97,98 Twentynine of these reports included 209,320 patients who sustained nonspecific trauma and were not categorized by level of consciousness (Table 1). Nine series with 21,286 cases pertained specifically to alert patients with reliable clinical examination findings (Table 2). Twenty series contained 49,938 unconscious or obtunded patients who met our criteria for unevaluable (Table 3). Twenty-one series composed of 3555 patients with known CSI reported data on the proportion of these injuries considered to be unstable (Table 4; Fig. 1). Tables 1 through 4 analyze the evidentiary characteristics of these series. The overall prevalence of CSI in all trauma patients was 3.7% (Tables 1 and 5). In alert patients only, the prevalence of CSI was 2.8% (Tables 2 and 5). Clinically unevaluable patients were found to be at increased risk of CSI with a prevalence of 7.7% (Tables 3 and 5). Once detected, 41.9% of all CSI were subsequently determined to be unstable (Tables 4 and 5). The difference in prevalence of CSI between the alert and unevaluable groups was statistically significant, with unevaluable patients at a significantly greater risk for CSI than alert patients (p = ). Discussion Our findings demonstrate a higher prevalence of CSI in clinically unevaluable patients with trauma compared with alert patients with trauma. Hence, this high-risk patient population may be subject to increased occult unstable injuries. The potential for quadriplegia following CSI that is undiagnosed underscores the importance of detecting such injuries, but it is unknown whether the use of advanced imaging techniques for cervical spinal clearance is cost effective when compared with prolonged semirigid collar immobilization. A more precise quantification of the prevalence of CSI in these populations allows us for the first time to make evidence-based decisions in guiding large-scale resource utilization. It is our expectation that these prevalence figures will aid in the calculations needed for indicated cost-effectiveness studies. There are several important limitations to this study. Many of these limitations are inherent to the technique of meta-analysis, and are the result of variations in the definition of certain clinical terms used by articles that met our inclusion criteria. Most notable of these is the distinction between alert and unevaluable trauma patient populations. Every attempt was made to categorize the included studies systematically, although the existence of minor disparities between study populations is acknowledged. Authors also differed as to whether the overall trauma populations included patients with penetrating trauma or were restricted to those with blunt trauma. The regional variability in rates of penetrating trauma limits the generalizability of these data to all trauma centers, although these rates were invariably quite low. Conclusions Trauma patients who are clinically unevaluable have a higher prevalence of CSI than alert patients. Detection of CSI in this population is especially challenging, and places these patients at increased risk for cervical instability and quadriplegia. Knowledge of the prevalence and risk of such injuries may help establish an evidence-based approach to the detection and management of clinically occult CSI. Disclaimer The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. References 1. Adams JM, Cockburn MI, Difazio LT, et al: Spinal clearance in the difficult trauma patient: a role for screening MRI of the spine. Am Surg 72: , Antevil JL, Sise MJ, Sack DI, et al: Spiral computed tomogra- 6

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9 Prevalence of cervical spine injury in trauma additional spinal trauma in patients with cervical spine injury. Am Surg 73:70 74, Sliker CW, Mirvis SE, Shanmuganathan K: Assessing cervical spine stability in obtunded blunt trauma patients: review of medical literature. Radiology 234: , Spiteri V, Kotnis R, Singh P, et al: Cervical dynamic screening in spinal clearance: now redundant. J Trauma 61: , Stassen NA, Williams VA, Gestring ML, et al: Magnetic resonance imaging in combination with helical computed tomography provides a safe and efficient method of cervical spine clearance in the obtunded trauma patient. J Trauma 60: , Stelfox HT, Velmahos GC, Gettings E, et al: Computed tomography for early and safe discontinuation of cervical spine immobilization in obtunded multiply injured patients. J Trauma 63: , Stiell IG, Clement CM, McKnight RD, et al: The Canadian C- spine rule versus the NEXUS low-risk criteria in patients with trauma. N Engl J Med 349: , Stiell IG, Wells GA, Vandemheen KL, et al: The Canadian C- spine rule for radiography in alert and stable trauma patients. JAMA 286: , Waydhas C: Intrahospital transport of critically ill patients. Crit Care 3:R83 R89, Widder S, Doig C, Burrowes P, et al: Prospective evaluation of computed tomographic scanning for the spinal clearance of obtunded trauma patients: preliminary results. J Trauma 56: , Williams J, Jehle D, Cottington E, et al: Head, facial, and clavicular trauma as a predictor of cervical-spine injury. Ann Emerg Med 21: , Yanar H, Demetriades D, Hadjizacharia P, et al: Pedestrians injured by automobiles: risk factors for cervical spine injuries. J Am Coll Surg 205: , Zabel DD, Tinkoff G, Wittenborn W, et al: Adequacy and efficacy of lateral cervical spine radiography in alert, high-risk blunt trauma patient. J Trauma 43: , 1997 Manuscript submitted July 14, Accepted July 29, Address correspondence to: Sherman C. Stein, M.D., Hospital of the University of Pennsylvania, Department of Neurosurgery, 3 Silverstein, 3400 Spruce Street, Philadelphia, Pennsylvania sherman.stein@uphs.upenn.edu. 9