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Traumatic cervical spine injuries: characteristics of missed injuries
Journal of Pediatric Surgery (2009) 44, 151–155
www.elsevier.com/locate/jpedsurg
Traumatic cervical spine injuries: characteristics of missed injuries Ankur R. Ranaa , Robert Drongowskia , Gretchen Brecknerb , Peter F. Ehrlicha,⁎ a
Section of Pediatric Surgery, Department of Surgery, The University of Michigan Medical School, Ann Arbor, MI 48109, USA The C.S. Mott Children’s Hospital, Ann Arbor, MI 48104, USA
b
Received 2 October 2008; accepted 7 October 2008
Key words: Pediatric; Trauma; Cervical spine
Abstract Purpose: Computed tomographic (CT) scanning has mostly replaced x-rays as an imaging modality, but concerns exist because of excess radiation, missed injuries, and whether it is the definitive procedure for intubated patients. The purpose of this study was to characterize missed cervical spine injuries (CSIs). Methods: All pediatric (b18) trauma patients from 2004 to 2006 were analyzed. Age, sex, Injury Severity Score (ISS), mechanism, time, and missed injuries were reviewed. Flexion/extension views were used in patients with prolonged intubation. Descriptive statistics, χ2, Student's t test, and bivariate correlation were used. ResultsThere were 1307 pediatric trauma patients admitted with 318 imaged for potential CSI. Computed tomography was the sole imaging study in 200, x-rays in 64, and both in 54. Time to C-spine clearance was similar for all modalities (P N.05). For CT, 34 (10.7%) were initially positive for CSI with 7 false-positives (FPs) and no false-negative (FN). There were 18 patients with CSI identified by x-ray, with 5 FPs and 5 FNs (missed injuries). The 5 FNs missed by x-ray were all positive by CT scan and required no intervention. None of the flexion/extension views revealed an additional injury. Sex, intubated patients, ISS, age, type, and injury location were not predictive of a missed injury (P N .05).The sensitivity of CT scan was 1.0, specificity was 0.976, and the positive predictive value was 79.4%. The sensitivity of plain x-ray was 61.5%, the specificity was 1.6%, and the positive predictive value was 61.5%. Conclusions: Our data suggest that CT scans should be the primary modality to image a CSI. Flexion/ extension views did not add to the decision making for C-spine clearance after CT evaluation. © 2009 Elsevier Inc. All rights reserved.
Modern imaging modalities such as computed tomography (CT) have replaced or are used in conjunction with
Presented at the 39th annual meeting of the American Pediatric Surgical Association, Phoenix, AZ, May 27-June 1, 2008. ⁎ Corresponding author. Section of Pediatric Surgery, University of Michigan Hospitals, F7822 Mott Children's Hospital SPC 5231, 1500 E Medical Center, Ann Arbor, MI, 48109, USA. Tel.: +1 734 613 3303. E-mail address: [email protected] (P.F. Ehrlich). 0022-3468/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2008.10.024
conventional radiography in the initial workup of trauma patients [1-3]. New generation scanners are fast, efficient, and have increased sensitivity over conventional radiographs. However, it is unclear whether single or both modalities should be used. In a previous study, we reviewed the role of thoracic CT scanning in injured children and demonstrated that routine chest x-ray provides clinically valuable information for the initial trauma evaluation at minimal radiation exposure and cost with little roll for routine thoracic CT scans [4].
152 Cervical spine injuries (CSIs) remain one of the most devastating consequences from trauma. A missed injury can result in lifelong morbidity; therefore, thorough evaluation is mandated when a spinal cord injury is suggested or suspected. Missed injuries leading to neurologic deterioration have been shown to be because of an improper radiographic evaluation in a large series of trauma patients [5,6]. Recent reports in the literature are advocating CT as the preferred screening tool for the adult cervical spine [7-11]. In addition, the results of one study suggests that CT allows a reduction of time in the trauma resuscitation area, an earlier time to diagnosis of injury, and quicker time to disposition when compared to plain films [12]. Cervical spine injuries are rare events (1%-2%) in pediatric trauma [1,2]. Data are limited on the use of CT for cervical spine imaging as compared to conventional imaging in pediatric trauma. Concerns exist for routine use of CT scanning for the cervical spine in pediatric patients because of excess radiation, low incidence of CSIs, increased costs, and the lack of data that demonstrate a significant advance of this modality over plain radiographs. This is contrasted against conventional radiograph's risk of missed injuries, incomplete films, and the requirement of often needing multiple films to clear the cervical spine. The purpose of this study was to review our experience with cervical spine imaging using CT and conventional films with injured children at a level I pediatric trauma center. We specifically characterized missed CSI and focused on cervical spine clearance with intubated children.
A.R. Rana et al. If the patient complained of neck tenderness, had neurologic deficits, had an abnormal Glasgow Coma Scale (GCS) (because of head injury, drugs, alcohol), or distracting pain from another injury, the patient underwent cervical spine imaging. Plain C-spine radiographs, CT scan, or both were used, and the decision was made by the designated leader of the trauma team. If the radiographic imaging was negative for CSI, the initial stabilization collar was changed to a padded collar until a reliable examination could be performed. Flexion and extension views were performed in patients with continued cervical tenderness or if they required prolonged intubation (in addition to their initial workup). If pain persisted, patients were discharged home with cervical spine collar and followed up by the neurosurgery team for clearance. Age, sex, Injury Severity Score (ISS), GCS, intubation status, time from imaging to C-spine clearance, and treatment plan were analyzed. Missed injuries (by modality) and their clinical significance were identified. Data were analyzed using an SPSS statistical package (SPSS, Chicago, Ill) with a P value of less than .05 considered significant. Student's t test was used to compare the continuous data, and the χ2 test was used to evaluate categorical data. A false-positive on plain radiograph was defined as a report of a positive spine injury that was not visualized on a subsequent CT scan. A false-positive on CT scan was an initial report of an injury that was found not to be true after further clinical and radiographic review. False-negative was defined as no injury seen on the initial imaging modality but then diagnosed on subsequent imaging. Data are represented as mean SD, unless otherwise noted.
1. Methods This retrospective study was approved by the University of Michigan's Institutional Review Board (Ann Arbor, Mich). The University of Michigan CS Mott Children's Hospital is an American College of Surgeons–verified level I pediatric trauma center. All pediatric trauma patients (b18 years old) were identified from our trauma registry between 2004 and 2006. Inclusion criteria were those patients who had cervical spine imaging and/or a CSI. Patients without imaging for CSI or a CSI were excluded from the study.
2. Cervical spine imaging Our institutional protocol included an initial physical examination of the C-spine for all trauma patients. Patients with reliable examinations and who were fully awake without motor/sensory deficits, neck pain, evidence of intoxicating agents, and distracting injuries were clinically cleared in the trauma center by an Advanced Trauma Life Support–certified physician. No further evaluation of the cervical spine was performed after the stabilization collar was removed [13].
3. Results A total of 1307 evaluated and admitted pediatric trauma patients were identified for review. For 318 (24.3%) patients, radiographic imaging was performed to rule out a possible CSI. There were 203 (64%) males and 115 females (36%). The average age was 10.2 ± 5.7 years. The average ISS was 14.2 ± 12, and the average GCS was 13 ± 5. Seventy-eight (24%) patients were intubated before obtaining imaging for their cervical spine (Table 1). Cervical CT scanning was the Table 1
Age (y) Sex Male Female ISS GCS Intubated
Patient demographics All patients (N = 318)
Patients with CSI (n = 27)
10.2
12.6
203 (64%) 115 (36%) 14.2 13 78 (24%)
21 (78%) 6 (22%) 17.5 13 8 (30%)
Traumatic cervical spine injuries
Fig. 1
Breakdown of imaging modalities used.
sole imaging modality in 200 (63%) patients, and plain radiographs were the only study in 64 (20%). Fifty-four (17%) patients had both imaging modalities. Cervical spine injures were initially detected in 34 (10.7%) patients whom obtained a CT with 7 (3%) false-positives and no falsenegatives. Therefore, 27 patients had a CSI (Fig. 1). Twenty-three children who sustained a CSI had plain radiographs. Of these, 18 were identified and 5 were missed (false-negative). In addition, 5 children had reports of a CSI by plain radiographs that were later determined to be falsepositives by CT scan. All of the missed injuries were identified on CT scan (Table 2). Sex, intubated patients, ISS, GCS, age, and injury location were not predictive of a missed injury (P N .05). Flexion and extension views were obtained in patients with persistent neck pain and in intubated patients. None of the flexion/extension views revealed an additional injury. Twenty-seven patients were determined to have a true CSI. This group included 21 (78%) males and 6 (22%) females with an average age of 12.6 ± 4.9 years. Eight (30%) of these patients were intubated before obtaining imaging of the cervical spine (Table 1). Of these patients, 12 (44%) had injuries severe enough requiring an operative intervention (fusion, halo, or corpectomy). No patient with a missed injury on plain radiographs required any operative intervention. The average time to clear a cervical spine in patients with a suspected/suggested CSI was as 3067 minutes (51 hours) for plain radiographs vs 2507 minutes (42 hours) after CT (P N .05). In this study, the sensitivity of CT scan to identify a CSI was 1.0 with a specificity of 0.976 and a positive predictive value of 79.4%. Plain radiographs had a sensitivity of 61.5% with a specificity of 1.6% and positive predictive value of 61.5%.
4. Discussion The incidence of CSI in pediatric trauma patients remains low (1%), but the morbidity and mortality with these injuries are substantial. Kokoska et al [14] in a 5-year review from the National Pediatric Trauma Registry reported a 1.6% (n = 408/24,740, 17% mortality) incidence of blunt CSIs. Injury patterns were different by age with children (≤10 years) having a higher incidence of C1-C4 injuries vs C5-C7 injuries (85% vs 57%; P b .01). Brown et al [15] reviewed
153 the experience of 103 pediatric patients with CSI more than 9 years and found an 18% mortality rate. In neither of these 2 studies was the best method of diagnosis addressed. Physical examination in alert patients has been proven to be reliable; however, the question of which imaging modalities to perform on pediatric patients when a CSI is suspected, if when the patient has altered mental status or is intubated, remains controversial [13]. This study addresses this controversy by reviewing our experience with plain radiographic imaging, CT scans, and a flexion/extension protocol specifically focusing on diagnostic accuracy for intubated patients. Most data for the diagnosis of CSIs has been derived from the adult literature [16,17]. Griffen et al [8] described a retrospective study of 3018 blunt trauma patients of whom 1199 (40%) were at risk for CSI. Plain radiographs (3 views) and CT cervical spine were performed. One hundred sixteen patients had spinal injuries. Plain films failed to diagnose these injuries in 41 patients of which all were seen by CT scan. Importantly, all the 41 patients with missed injuries required treatment. A prospective study from Schnarts et al [18] compared the use of CT C-spine for the upper cervical spine (C0-C3) to plain films for adult trauma patients with altered mental status. Plain films only identified 54% of the injuries to the upper cervical spine in their series compared to 96% diagnosed with CT scan. In contrast to the previous study, 3 injuries seen on plain films were missed on CT including one atlanto-occipital dislocation in a patient with quadriplegia and 2 subluxations. The results of our study are similar to those in the adult trauma literature. Plain radiographs missed injuries and had a significantly lower sensitivity compared to CT scan (61% vs 100%). In addition, all our patients who remain intubated for 24 hours received flexion and extension views, but no new injuries were detected. This result also is supported in the adult trauma literature. Insko et al [19] reviewed the use of flexion-extension films and demonstrated 30% of the patients were unable to flex and extend adequately leading to further imaging with CT or magnetic resonance imaging. They concluded that these films are of limited diagnostic use in the acute setting for evaluation of the cervical spine. Not all missed injuries can be attributed to the imaging physics of each modality. Poonnoose et al [20] examined the contributing factors in missed CSI. In this study, 33 (6%) missed CSIs and 19 (3%) missed thoracic and lumbar spine injuries were examined. Radiographic errors such as poor Table 2
Cervical spine injuries
Type of CSI
CT scan-detected CSI
Missed CSI by plain films
C1-C2 fractures C3-T1 fractures Spinous fractures Ligament injury
10 11 4 2
3 1 1 0
154 quality (18/52 cases), inadequate visualization of area (11/52), and interpretation error (21/52) were important contributors of missed injuries. These issues were not addressed in this current study but will be looked at in a prospective future study. Radiation exposure from CT scans is an important concern and driving force for rational use of imaging in children. Adelgais et al [21] examined this issue in a prospective study reviewing the differences of radiation exposure between conventional radiographs and CT. In this study, the patients receiving CT had 1.25 times the effective radiation dose compared to plain films. However, the comparison groups were markedly different by the patients undergoing a CT scan were significantly sicker regarding having an abnormal head CT (41% vs 20%), intubated (20% vs 2%), or transferred to intensive care unit or operating room (46% vs 23%) when compared to the group only receiving plain films. Keenan et al [10] examined this issue from another perspective by reviewing the number of excess radiographs required to clear the cervical spine of injury compared to the use of CT scan. Patients who underwent CTof the neck on initial evaluation had significantly fewer repeated radiographs than patients without CT C-spine (mean, 2.1 ± 2.6 vs 3.6 ± 2.7 repeated radiographs; P = .04). The amount of radiation exposure was also determined, and the authors concluded that the children with initial CT did receive a higher effective dose (P b .001); however, patients with GCS less than 8 received equivalent doses compared to those not undergoing early CT C-spine (P = .15). To understand CT scan radiation exposure, a review of the studies that estimate cancer risks in children is warranted. These reports use a “relative” risk mechanism based on atomic bomb survivor data [22] and radiation exposure estimates in Western populations [23,24]. There are significant limitations regarding the actual dose given for a CT examination and cancer risk per unit dose in the pediatric population. In addition, the authors of these studies recognize that despite the high absolute estimated risks, the actual risk of increase in cancer over the natural background rate is low at 0.35% [24]. Furthermore, the authors from all these studies conclude that more research is needed with prospective trials to determine the actual risk of radiation-induced cancer in the pediatric population [21,24]. Finally, studies have suggested that pediatric CT exposure could be decreased by 30% to 50% through pediatric-specific protocols (which were used in this study population) relative to adult exposure with no change in quality of images that would lead to a reduction in radiation risks [24-28]. In choosing the evaluating diagnostic or therapeutic modality, there are risks and benefits. The potential morbidity from missed injuries and their possible negative neurologic outcomes reviewed in this study are important factors when considering the optimal radiographic imaging modality of choice for cervical spine screening in pediatric trauma patients. Our data from this study population suggest that CT scans should be the primary modality to image a CSI. Flexion/extension views did not add to the decision making for C-spine clearance after CT evaluation and are probably
A.R. Rana et al. not needed. This study is retrospective and requires further prospective research that includes radiation exposure.
References [1] Dietrich AM, Ginn-Pease ME, Bartkowski HM, et al. Pediatric cervical spine fractures: Predominately subtle presentation. J Pediatr Surg 1991;26:995-1000. [2] Viccellio P, Simon H, Pressman BD, et al. A Prospective Multicenter Study of Cervical Spine Injury in Children. Pediatrics 2001;108:e20. [3] Buhs C, Cullen M, Klein M, et al. The pediatric trauma C-spine: is the odontoid view necessary. J Pediatr Surg 2000;35:994-7. [4] Renton J, Kincaid S, Ehrlich PF. Should helical CT scanning of the thoracic cavity replace the conventional chest x-ray as a primary assessment tool in pediatric trauma? An efficacy and cost analysis. J Pediatr Surg 2003;38:793-7. [5] Davis JW, Phreaner DL, Hoyt DB, et al. The etiology of missed cervical spine injuries. J Trauma 1993;34:342-6. [6] Davis JW, Phreaner DL, Hoyt DB, et al. The etiology of missed cervical spine injures. J Trauma 1993;34:342-6. [7] Nunez D, Zuluaga A, Fuentes-Bernardo D, et al. Cervical spine trauma: how much more do we learn by routinely using helical CT. Radiographics 1996;16:1307-18. [8] Griffen MM, Frykberk ER, Kerwin AJ, et al. Radiographic clearance of blunt cervical spine injury: plain radiograph or computed tomography scan. J Trauma 2003;55:222-7. [9] Gale SC, Gracias VH, Reilly PM, et al. The inefficiency of plain radiography to evaluate the cervical spine after blunt trauma. J Trauma 2005;59:1121-5. [10] Keenan HT, Hollingshead MC, Chung CJ, et al. Using CT of the cervical spine for early evaluation of pediatric patients with head trauma. AJR Am J Roentgenol 2001;177:1405-9. [11] Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. N Engl J Med 2000;343:94-9. [12] Nunez D, Ahmad A, Coln C, et al. Clearing the cervical spine in multiple trauma victims: a time-effective protocol using helical computerized tomography. Emerg Radiol 1994;1:273-8. [13] Marion DW, Domeier R, Dunham CM, et al. Practice management guidelines for identifying cervical spine injuries after trauma. Available at: http://www.EAST.org/tpg/chap3u.pdf. Accessed: January 23, 2008. [14] Kokoska ER, Keller MS, Rallo MC, et al. Characteristics of pediatric cervical spine injuries. J Pediatr Surg 2001;36:100-5. [15] Brown RL, Brunn MA, Garcia VF. Cervical spine injuries in children: a review of 103 patients treated consecutively at a level I pediatric trauma center. J Pediatr Surg 2001;36:1107-14. [16] Gerrelts BD, Petersen EU, Mabry J, et al. Delayed diagnosis of cervical spine injuries. J Trauma 1991;31:1622-6. [17] Davis JW, Kaups KL, Cunningham MA, et al. Routine evaluation of the cervical spine in the head-injured patient with dynamic fluoroscopy: a reappraisal. J Trauma 2001;50:1044-7. [18] Schenarts PJ, Diaz J, Kaiser C, et al. Prospective comparison of admission computed tomographic scan and plain films of the upper cervical spine in trauma patients with altered mental status. J Trauma 2001;51:663-9. [19] Insko EK, Gracias VH, Gupta R, et al. Utility of flexion and extension radiographs of the cervical spine in the acute evaluation of blunt trauma. J Trauma 2002;53:426-9. [20] Poonnoose PM, Ravichandran G, McClelland MR. Missed and mismanaged injuries of the spinal cord. J Trauma 2002;53:314-20. [21] Adelgais KM, Grossman DC, Langer SG, et al. Use of helical computed tomography for imaging the pediatric cervical spine. Acad Emerg Med 2004;11:228-36.
Traumatic cervical spine injuries [22] Pierce DA, Shimizu Y, Preston DL, et al. Studies of the mortality of atomic bomb survivors. Report 12, part I. Cancer: 1950-1990. Radiat Res 1996;146:1-27. [23] BIER V (Committee on the Biological Effects of Ionizing Radiations). Health effects of exposure to low levels of ionizing radiation. Washington, DC: National Academy Press; 1990. [24] Brenner DJ, Ellistion CD, Hall EJ, et al. Estimated risks of radiationinduced fatal cancer from pediatric ct. AJR Am J Roentgenol 2001;176:289-96. [25] Coren ME, Ng V, Rubens M, et al. The value of ultrafast computed tomography in the investigation of pediatric chest disease. Pediatr Pulmonol 1998;26:389-95. [26] Ambrosino MM, Genieser NB, Roche KJ, et al. Feasibility of highresolution, low-dose chest CT in evaluating the pediatric chest. Pediatr Radiol 1994;24:6-10. [27] Kamel IR, Hernandez RJ, Martin JE, et al. Radiation dose reduction in CT of the pediatric pelvis. Radiology 1994;190:683-7. [28] Chan CY, Wong YC, Chau LF, et al. Radiation dose reduction in paediatric cranial CT. Pediatr Radiol 1999;29:770-5.
Discussion Speaker: That was a very nice paper. What percentage of your patients had magnetic resonance imagings (MRIs)—or did any have MRIs to evaluate potential swirl? Dr Rana (response): None of these patients had MRIs. The only patients that had the MRI were based on neurosurgery evaluation if there was an injury to the cervical spine, if they wanted further imaging for evaluation, if the patient needed to go to the OR or not. Dr Joseph Tepas (Jacksonville, Fla): Nice study. I have 2 questions. The first is actually more of a comment and
155 that is that in our trauma center CT of head, and C-spine is one word and it has kind of become the standard of care. I hate to use those terms. How many of those missed injuries resulted in an alteration of therapy because that is really where the rubber meets the road? Dr Rana (response): Right, that is a good question. None of the 5 missed injuries required any operative intervention so 12 of the 27 patients who did have a CSI did require an operative intervention but none of the missed injuries. Dr Arthur Cooper (New York, NY): I think it certainly is true that a CT scan is likely to pick up most injuries that plain films will pick up. However, the plain films carry nowhere near the radiation exposure risk that CT scans do. In follow-up of Dr Tepas' comment that the missed injuries on plain film required no specific intervention, I would just like to enter a plea to all of us that in circumstances where we can get cervical spine films rather than the CT, particularly in younger children, we may be able to avoid a whopping radiation dose to those kids where it is not needed. Dr Rana (response): There are new protocols now that do have decreased exposure to radiation. In talking to some of the radiologists at our institution, there are protocols with decreased radiation, which can still acquire the same information, so I think further studies are warranted to see if these lower dose radiation CT scans can also be as effective as the radiation doses we have used in the past.
www.elsevier.com/locate/jpedsurg
Traumatic cervical spine injuries: characteristics of missed injuries Ankur R. Ranaa , Robert Drongowskia , Gretchen Brecknerb , Peter F. Ehrlicha,⁎ a
Section of Pediatric Surgery, Department of Surgery, The University of Michigan Medical School, Ann Arbor, MI 48109, USA The C.S. Mott Children’s Hospital, Ann Arbor, MI 48104, USA
b
Received 2 October 2008; accepted 7 October 2008
Key words: Pediatric; Trauma; Cervical spine
Abstract Purpose: Computed tomographic (CT) scanning has mostly replaced x-rays as an imaging modality, but concerns exist because of excess radiation, missed injuries, and whether it is the definitive procedure for intubated patients. The purpose of this study was to characterize missed cervical spine injuries (CSIs). Methods: All pediatric (b18) trauma patients from 2004 to 2006 were analyzed. Age, sex, Injury Severity Score (ISS), mechanism, time, and missed injuries were reviewed. Flexion/extension views were used in patients with prolonged intubation. Descriptive statistics, χ2, Student's t test, and bivariate correlation were used. ResultsThere were 1307 pediatric trauma patients admitted with 318 imaged for potential CSI. Computed tomography was the sole imaging study in 200, x-rays in 64, and both in 54. Time to C-spine clearance was similar for all modalities (P N.05). For CT, 34 (10.7%) were initially positive for CSI with 7 false-positives (FPs) and no false-negative (FN). There were 18 patients with CSI identified by x-ray, with 5 FPs and 5 FNs (missed injuries). The 5 FNs missed by x-ray were all positive by CT scan and required no intervention. None of the flexion/extension views revealed an additional injury. Sex, intubated patients, ISS, age, type, and injury location were not predictive of a missed injury (P N .05).The sensitivity of CT scan was 1.0, specificity was 0.976, and the positive predictive value was 79.4%. The sensitivity of plain x-ray was 61.5%, the specificity was 1.6%, and the positive predictive value was 61.5%. Conclusions: Our data suggest that CT scans should be the primary modality to image a CSI. Flexion/ extension views did not add to the decision making for C-spine clearance after CT evaluation. © 2009 Elsevier Inc. All rights reserved.
Modern imaging modalities such as computed tomography (CT) have replaced or are used in conjunction with
Presented at the 39th annual meeting of the American Pediatric Surgical Association, Phoenix, AZ, May 27-June 1, 2008. ⁎ Corresponding author. Section of Pediatric Surgery, University of Michigan Hospitals, F7822 Mott Children's Hospital SPC 5231, 1500 E Medical Center, Ann Arbor, MI, 48109, USA. Tel.: +1 734 613 3303. E-mail address: [email protected] (P.F. Ehrlich). 0022-3468/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2008.10.024
conventional radiography in the initial workup of trauma patients [1-3]. New generation scanners are fast, efficient, and have increased sensitivity over conventional radiographs. However, it is unclear whether single or both modalities should be used. In a previous study, we reviewed the role of thoracic CT scanning in injured children and demonstrated that routine chest x-ray provides clinically valuable information for the initial trauma evaluation at minimal radiation exposure and cost with little roll for routine thoracic CT scans [4].
152 Cervical spine injuries (CSIs) remain one of the most devastating consequences from trauma. A missed injury can result in lifelong morbidity; therefore, thorough evaluation is mandated when a spinal cord injury is suggested or suspected. Missed injuries leading to neurologic deterioration have been shown to be because of an improper radiographic evaluation in a large series of trauma patients [5,6]. Recent reports in the literature are advocating CT as the preferred screening tool for the adult cervical spine [7-11]. In addition, the results of one study suggests that CT allows a reduction of time in the trauma resuscitation area, an earlier time to diagnosis of injury, and quicker time to disposition when compared to plain films [12]. Cervical spine injuries are rare events (1%-2%) in pediatric trauma [1,2]. Data are limited on the use of CT for cervical spine imaging as compared to conventional imaging in pediatric trauma. Concerns exist for routine use of CT scanning for the cervical spine in pediatric patients because of excess radiation, low incidence of CSIs, increased costs, and the lack of data that demonstrate a significant advance of this modality over plain radiographs. This is contrasted against conventional radiograph's risk of missed injuries, incomplete films, and the requirement of often needing multiple films to clear the cervical spine. The purpose of this study was to review our experience with cervical spine imaging using CT and conventional films with injured children at a level I pediatric trauma center. We specifically characterized missed CSI and focused on cervical spine clearance with intubated children.
A.R. Rana et al. If the patient complained of neck tenderness, had neurologic deficits, had an abnormal Glasgow Coma Scale (GCS) (because of head injury, drugs, alcohol), or distracting pain from another injury, the patient underwent cervical spine imaging. Plain C-spine radiographs, CT scan, or both were used, and the decision was made by the designated leader of the trauma team. If the radiographic imaging was negative for CSI, the initial stabilization collar was changed to a padded collar until a reliable examination could be performed. Flexion and extension views were performed in patients with continued cervical tenderness or if they required prolonged intubation (in addition to their initial workup). If pain persisted, patients were discharged home with cervical spine collar and followed up by the neurosurgery team for clearance. Age, sex, Injury Severity Score (ISS), GCS, intubation status, time from imaging to C-spine clearance, and treatment plan were analyzed. Missed injuries (by modality) and their clinical significance were identified. Data were analyzed using an SPSS statistical package (SPSS, Chicago, Ill) with a P value of less than .05 considered significant. Student's t test was used to compare the continuous data, and the χ2 test was used to evaluate categorical data. A false-positive on plain radiograph was defined as a report of a positive spine injury that was not visualized on a subsequent CT scan. A false-positive on CT scan was an initial report of an injury that was found not to be true after further clinical and radiographic review. False-negative was defined as no injury seen on the initial imaging modality but then diagnosed on subsequent imaging. Data are represented as mean SD, unless otherwise noted.
1. Methods This retrospective study was approved by the University of Michigan's Institutional Review Board (Ann Arbor, Mich). The University of Michigan CS Mott Children's Hospital is an American College of Surgeons–verified level I pediatric trauma center. All pediatric trauma patients (b18 years old) were identified from our trauma registry between 2004 and 2006. Inclusion criteria were those patients who had cervical spine imaging and/or a CSI. Patients without imaging for CSI or a CSI were excluded from the study.
2. Cervical spine imaging Our institutional protocol included an initial physical examination of the C-spine for all trauma patients. Patients with reliable examinations and who were fully awake without motor/sensory deficits, neck pain, evidence of intoxicating agents, and distracting injuries were clinically cleared in the trauma center by an Advanced Trauma Life Support–certified physician. No further evaluation of the cervical spine was performed after the stabilization collar was removed [13].
3. Results A total of 1307 evaluated and admitted pediatric trauma patients were identified for review. For 318 (24.3%) patients, radiographic imaging was performed to rule out a possible CSI. There were 203 (64%) males and 115 females (36%). The average age was 10.2 ± 5.7 years. The average ISS was 14.2 ± 12, and the average GCS was 13 ± 5. Seventy-eight (24%) patients were intubated before obtaining imaging for their cervical spine (Table 1). Cervical CT scanning was the Table 1
Age (y) Sex Male Female ISS GCS Intubated
Patient demographics All patients (N = 318)
Patients with CSI (n = 27)
10.2
12.6
203 (64%) 115 (36%) 14.2 13 78 (24%)
21 (78%) 6 (22%) 17.5 13 8 (30%)
Traumatic cervical spine injuries
Fig. 1
Breakdown of imaging modalities used.
sole imaging modality in 200 (63%) patients, and plain radiographs were the only study in 64 (20%). Fifty-four (17%) patients had both imaging modalities. Cervical spine injures were initially detected in 34 (10.7%) patients whom obtained a CT with 7 (3%) false-positives and no falsenegatives. Therefore, 27 patients had a CSI (Fig. 1). Twenty-three children who sustained a CSI had plain radiographs. Of these, 18 were identified and 5 were missed (false-negative). In addition, 5 children had reports of a CSI by plain radiographs that were later determined to be falsepositives by CT scan. All of the missed injuries were identified on CT scan (Table 2). Sex, intubated patients, ISS, GCS, age, and injury location were not predictive of a missed injury (P N .05). Flexion and extension views were obtained in patients with persistent neck pain and in intubated patients. None of the flexion/extension views revealed an additional injury. Twenty-seven patients were determined to have a true CSI. This group included 21 (78%) males and 6 (22%) females with an average age of 12.6 ± 4.9 years. Eight (30%) of these patients were intubated before obtaining imaging of the cervical spine (Table 1). Of these patients, 12 (44%) had injuries severe enough requiring an operative intervention (fusion, halo, or corpectomy). No patient with a missed injury on plain radiographs required any operative intervention. The average time to clear a cervical spine in patients with a suspected/suggested CSI was as 3067 minutes (51 hours) for plain radiographs vs 2507 minutes (42 hours) after CT (P N .05). In this study, the sensitivity of CT scan to identify a CSI was 1.0 with a specificity of 0.976 and a positive predictive value of 79.4%. Plain radiographs had a sensitivity of 61.5% with a specificity of 1.6% and positive predictive value of 61.5%.
4. Discussion The incidence of CSI in pediatric trauma patients remains low (1%), but the morbidity and mortality with these injuries are substantial. Kokoska et al [14] in a 5-year review from the National Pediatric Trauma Registry reported a 1.6% (n = 408/24,740, 17% mortality) incidence of blunt CSIs. Injury patterns were different by age with children (≤10 years) having a higher incidence of C1-C4 injuries vs C5-C7 injuries (85% vs 57%; P b .01). Brown et al [15] reviewed
153 the experience of 103 pediatric patients with CSI more than 9 years and found an 18% mortality rate. In neither of these 2 studies was the best method of diagnosis addressed. Physical examination in alert patients has been proven to be reliable; however, the question of which imaging modalities to perform on pediatric patients when a CSI is suspected, if when the patient has altered mental status or is intubated, remains controversial [13]. This study addresses this controversy by reviewing our experience with plain radiographic imaging, CT scans, and a flexion/extension protocol specifically focusing on diagnostic accuracy for intubated patients. Most data for the diagnosis of CSIs has been derived from the adult literature [16,17]. Griffen et al [8] described a retrospective study of 3018 blunt trauma patients of whom 1199 (40%) were at risk for CSI. Plain radiographs (3 views) and CT cervical spine were performed. One hundred sixteen patients had spinal injuries. Plain films failed to diagnose these injuries in 41 patients of which all were seen by CT scan. Importantly, all the 41 patients with missed injuries required treatment. A prospective study from Schnarts et al [18] compared the use of CT C-spine for the upper cervical spine (C0-C3) to plain films for adult trauma patients with altered mental status. Plain films only identified 54% of the injuries to the upper cervical spine in their series compared to 96% diagnosed with CT scan. In contrast to the previous study, 3 injuries seen on plain films were missed on CT including one atlanto-occipital dislocation in a patient with quadriplegia and 2 subluxations. The results of our study are similar to those in the adult trauma literature. Plain radiographs missed injuries and had a significantly lower sensitivity compared to CT scan (61% vs 100%). In addition, all our patients who remain intubated for 24 hours received flexion and extension views, but no new injuries were detected. This result also is supported in the adult trauma literature. Insko et al [19] reviewed the use of flexion-extension films and demonstrated 30% of the patients were unable to flex and extend adequately leading to further imaging with CT or magnetic resonance imaging. They concluded that these films are of limited diagnostic use in the acute setting for evaluation of the cervical spine. Not all missed injuries can be attributed to the imaging physics of each modality. Poonnoose et al [20] examined the contributing factors in missed CSI. In this study, 33 (6%) missed CSIs and 19 (3%) missed thoracic and lumbar spine injuries were examined. Radiographic errors such as poor Table 2
Cervical spine injuries
Type of CSI
CT scan-detected CSI
Missed CSI by plain films
C1-C2 fractures C3-T1 fractures Spinous fractures Ligament injury
10 11 4 2
3 1 1 0
154 quality (18/52 cases), inadequate visualization of area (11/52), and interpretation error (21/52) were important contributors of missed injuries. These issues were not addressed in this current study but will be looked at in a prospective future study. Radiation exposure from CT scans is an important concern and driving force for rational use of imaging in children. Adelgais et al [21] examined this issue in a prospective study reviewing the differences of radiation exposure between conventional radiographs and CT. In this study, the patients receiving CT had 1.25 times the effective radiation dose compared to plain films. However, the comparison groups were markedly different by the patients undergoing a CT scan were significantly sicker regarding having an abnormal head CT (41% vs 20%), intubated (20% vs 2%), or transferred to intensive care unit or operating room (46% vs 23%) when compared to the group only receiving plain films. Keenan et al [10] examined this issue from another perspective by reviewing the number of excess radiographs required to clear the cervical spine of injury compared to the use of CT scan. Patients who underwent CTof the neck on initial evaluation had significantly fewer repeated radiographs than patients without CT C-spine (mean, 2.1 ± 2.6 vs 3.6 ± 2.7 repeated radiographs; P = .04). The amount of radiation exposure was also determined, and the authors concluded that the children with initial CT did receive a higher effective dose (P b .001); however, patients with GCS less than 8 received equivalent doses compared to those not undergoing early CT C-spine (P = .15). To understand CT scan radiation exposure, a review of the studies that estimate cancer risks in children is warranted. These reports use a “relative” risk mechanism based on atomic bomb survivor data [22] and radiation exposure estimates in Western populations [23,24]. There are significant limitations regarding the actual dose given for a CT examination and cancer risk per unit dose in the pediatric population. In addition, the authors of these studies recognize that despite the high absolute estimated risks, the actual risk of increase in cancer over the natural background rate is low at 0.35% [24]. Furthermore, the authors from all these studies conclude that more research is needed with prospective trials to determine the actual risk of radiation-induced cancer in the pediatric population [21,24]. Finally, studies have suggested that pediatric CT exposure could be decreased by 30% to 50% through pediatric-specific protocols (which were used in this study population) relative to adult exposure with no change in quality of images that would lead to a reduction in radiation risks [24-28]. In choosing the evaluating diagnostic or therapeutic modality, there are risks and benefits. The potential morbidity from missed injuries and their possible negative neurologic outcomes reviewed in this study are important factors when considering the optimal radiographic imaging modality of choice for cervical spine screening in pediatric trauma patients. Our data from this study population suggest that CT scans should be the primary modality to image a CSI. Flexion/extension views did not add to the decision making for C-spine clearance after CT evaluation and are probably
A.R. Rana et al. not needed. This study is retrospective and requires further prospective research that includes radiation exposure.
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Discussion Speaker: That was a very nice paper. What percentage of your patients had magnetic resonance imagings (MRIs)—or did any have MRIs to evaluate potential swirl? Dr Rana (response): None of these patients had MRIs. The only patients that had the MRI were based on neurosurgery evaluation if there was an injury to the cervical spine, if they wanted further imaging for evaluation, if the patient needed to go to the OR or not. Dr Joseph Tepas (Jacksonville, Fla): Nice study. I have 2 questions. The first is actually more of a comment and
155 that is that in our trauma center CT of head, and C-spine is one word and it has kind of become the standard of care. I hate to use those terms. How many of those missed injuries resulted in an alteration of therapy because that is really where the rubber meets the road? Dr Rana (response): Right, that is a good question. None of the 5 missed injuries required any operative intervention so 12 of the 27 patients who did have a CSI did require an operative intervention but none of the missed injuries. Dr Arthur Cooper (New York, NY): I think it certainly is true that a CT scan is likely to pick up most injuries that plain films will pick up. However, the plain films carry nowhere near the radiation exposure risk that CT scans do. In follow-up of Dr Tepas' comment that the missed injuries on plain film required no specific intervention, I would just like to enter a plea to all of us that in circumstances where we can get cervical spine films rather than the CT, particularly in younger children, we may be able to avoid a whopping radiation dose to those kids where it is not needed. Dr Rana (response): There are new protocols now that do have decreased exposure to radiation. In talking to some of the radiologists at our institution, there are protocols with decreased radiation, which can still acquire the same information, so I think further studies are warranted to see if these lower dose radiation CT scans can also be as effective as the radiation doses we have used in the past.