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Safe cervical spine clearance in adult obtunded blunt trauma patients on the basis of a normal multidetector CT scan—A meta-analysis and cohort study
Injury, Int. J. Care Injured 44 (2013) 1589–1595
Contents lists available at SciVerse ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
Safe cervical spine clearance in adult obtunded blunt trauma patients on the basis of a normal multidetector CT scan—A meta-analysis and cohort study Mushahid Raza a,1,*, Samer Elkhodair b, Asif Zaheer c, Sohail Yousaf d a
Consultant Emergency Medicine, Frimley Park Hospital, Frimley, UK Consultant Emergency Medicine, University College London Hospitals, UK Specialist Trainee Emergency Medicine, Epsom and St Helier University Hospital, UK d Specialist Trainee Trauma and Orthpaedics, Brighton and Sussex University Hospital, UK b c
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 2 June 2013
Background: A true gold standard to rule out a significant cervical spine injury in subset of blunt trauma patients with altered sensorium is still to be agreed upon. The objective of this study is to determine whether in obtunded adult patients with blunt trauma, a clinically significant injury to the cervical spine be ruled out on the basis of a normal multidetector cervical spine computed tomography. Methods: Comprehensive database search was conducted to include all the prospective and retrospective studies on blunt trauma patients with altered sensorium undergoing cervical spine multidetector CT scan as core imaging modality to ‘‘clear’’ the cervical spine. The studies used two main gold standards, magnetic resonance imaging of the cervical spine and/or prolonged clinical follow-up. The data was extracted to report true positive, true negatives, false positives and false negatives. Metaanalysis of sensitivity, specificity, negative and positive predictive values was performed using Meta Analyst Beta 3.13 software. We also performed a retrospective investigation comparing a robust clinical follow-up and/or cervical spine MR findings in 53 obtunded blunt trauma patients, who previously had undergone a normal multidetector CT scan of the cervical spine reported by a radiologist. Results: A total of 10 studies involving 1850 obtunded blunt trauma patients with initial cervical spine CT scan reported as normal were included in the final meta-analysis. The cumulative negative predictive value and specificity of cervical spine CT of the ten studies was 99.7% (99.4–99.9%, 95% confidence interval). The positive predictive value and sensitivity was 93.7% (84.0–97.7%, 95% confidence interval). In the retrospective review of our obtunded blunt trauma patients, none was later diagnosed to have significant cervical spine injury that required a change in clinical management. Conclusion: In a blunt trauma patient with altered sensorium, a normal cervical spine CT scan is conclusive to safely rule out a clinically significant cervical spine injury. The results of this meta-analysis strongly support the removal of cervical precautions in obtunded blunt trauma patient after normal cervical spine computed tomography. Any further imaging like magnetic resonance imaging of the cervical spine should be performed on case-to-case basis. ß 2013 Elsevier Ltd. All rights reserved.
Keywords: Cervical Spine Spinal injuries Spinal fractures Clearance Obtunded Multidetector computed tomography Meta-analysis
Introduction and background The safe management of cervical spine (CS) injury in a patient with multiple trauma is one of the major challenges faced by trauma surgeons. The incidence of cervical spine injury in the
* Corresponding author. Tel.: +44 7833052551. E-mail addresses: [email protected], [email protected] (M. Raza). 1 Place where the study was conducted St George’s Hospital, London, UK. 0020–1383/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.injury.2013.06.005
majority of blunt trauma is 2–4% [1] but rises to 34.4% in unconscious patients [2]; potentially resulting in long-term morbidity and carrying with it medico-legal repercussions. ‘‘Clearing’’ the cervical spine implies declaring no significant injury and removing the spinal precautions based on clinical and/ or radiological grounds. An injury to the cervical spine is considered ‘‘significant’’ when if overlooked could result in irreversible neurological deterioration including paralysis and death. Early cervical spine clearance is of paramount importance as any delay in the clearance process can lead to difficulties in safe
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airway management, increased risk of aspiration, increased intracranial pressure [3], increased risk of thrombosis and decubitus ulceration [4]. In awake and alert patients with blunt cervical spine trauma, the absence of distracting injuries, no cervical spine tenderness or pain on full range of movements plus a normal neurological examination implies the cervical spine can be safely cleared on clinical grounds [5]. It is accepted that radiological screening is indicated in patients with pain or cervical spine tenderness, neurological deficit, patients with significant distracting injuries or the patients with altered sensorium. [2,6,7]. Guidelines are available to aid the safe clearance of the CS in most of the above-mentioned groups of patients [8]. Clearing the CS in obtunded blunt trauma patients without apparent neurological deficit however remains controversial. The term ‘‘obtunded’’ implies a state of cognitive dysfunction in which the clinical examination of a patient becomes unreliable due to decreased GCS including alcohol/drug intoxication. The ideal method for detecting CS injury should be highly sensitive, cost effective and readily available in the emergency department. Different approaches have been advocated to settle this dilemma. A well-defined algorithm hasn’t been agreed upon due to limited information on the validity and reliability of the imaging modalities, inconclusive best available evidence and the fear of devastating consequences in the event of missed injury. In 1998 the Eastern Association for the Surgery of Trauma (EAST) recommended that all patients who cannot have their cervical spines clinically cleared should have plain radiographs of the CS (anteroposterior, lateral and open mouth odontoid) followed by thin slice (3 mm) axial computed tomography (CT) with sagittal reconstructions of C1–C2 [7]. Additional focused CT scan was also recommended if on plain radiography a part of the CS could not be visualized or had suspicious findings. The focused CSCT as recommended by EAST was challenged by Bern et al. [2] and Diaz JJ [9] as it would fail to depict unstable CS injuries as diagnosed by complete CS-CT. The primary screening modality was then recommended to be cervical spine CT from occiput to T1 with sagittal and coronal reconstructions [10]. Cervical spine CT is a widely accepted initial imaging modality in patients with altered level of consciousness in trauma patients. Multidetector CT scanners image a volume of tissue rather than individual slices, the thickness of which is much less than in single slice CT scanners. In contrast to getting merely axial slices, multi planar slices are retrieved from one ‘sweep’ in 4–10 s giving thousands of images, which are in turn reconstructed into 3D Image [11]. Whether CS-MDCT could be solely used as a screening modality to safely clear the cervical spine is controversial with the available literature showing contradicting views [12]. Objective; the clinical dilemma In obtunded adult patients with blunt trauma, can a clinically significant injury be ruled out on the basis of a multidetector cervical spine CT scan being reported as normal? Methodology; the paper selection Inclusion criteria
Indication for cervical spine MDCT other than altered sensorium Literature search The different sources searched are as follows. 1. 2. 3. 4.
Electronic Indexed Bibliographic Databases Cochrane Database Grey literature Hand searches through references, relevant journals and correspondences
A search was carried out on the health information resources website (www.library.nhs.uk) using methodology and search terms as depicted in the following flow chart (Fig. 1). The search was conducted both as key words unmapped to MeSH (Medical Subject Headings) and through MeSH structure. The search was performed for literature published from 1998 onwards (the year when multidetector CT scanners were introduced), was limited to studies done on adult patients and had no language limits. All the search terms used were mapped to thesaurus to achieve comprehensive search results. A total of 10 studies including 2 from hand search directly addressing my clinical question were selected for detailed appraisal. The selection process involved review of the title and abstract of the relevant studies meeting the inclusion criteria. Results The details of the literature search are evident from the flow chart (Fig. 1). Any study involving alert patients or where CS MDCT wasn’t core-imaging modality was excluded. A fair number of studies had to be excluded due the fact that the CT scanners were not of multidetector type. In order to have homogenous sample for the meta-analysis, few more studies involving a combination of single row and multidetector CT scanners were also excluded. A total of 10 studies summarized in Tables 1 and 2 were selected to be included in the meta-analysis, four of them were of prospective cohort design. The sensitivity is the proportion of patients with abnormal CS by gold standard who has a positive result by CS MDCT. The specificity is the proportion of patients who have a normal CS with a negative CS MDCT. The PPV represents the probability that an abnormal CT scan correlates with an abnormal cervical spine. The NPV is the probability that a negative CT scan correlates with normal cervical spine. Data from all the 10 studies produces a NPV of 99.7% (99.4– 99.9%, 95% confidence interval) as detailed in Table 3 and Fig. 2. The positive predictive value and sensitivity was 93.7% (84.0–97.7%, 95% confidence interval). The values of sensitivity and positive predictive value are not conclusive as two of the studies had to be excluded whilst calculating these values being a weakness of our study. The studies by Khanna et al. and Stelfox et all had no true positive values so we are not sure how accurate the MDCT would have been in diagnosing a cervical spine injury should there be such a patient in these studies.
1. Adult blunt trauma patients with altered sensorium/obtunded 2. Multidetector CT of the cervical spine as the core imaging modality
The cohort study
Exclusion criteria
The medical records of 108 patients presenting to the ED of St Georges hospital in London between October 2007 and December 2008 were retrospectively reviewed. October 2007 was the date from when MDCT was considered the investigation of choice for
Studies done using single-slice CT scanners (axial/helical with single -row of detectors)
Methods
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Table 1 Summary of individual studies included in the meta-analysis. Paper
Study design
Study population
Results
Author’s conclusion
[13]
Retrospective
Hospital records of 366 obtunded patients who underwent multidetector CS-CT followed by CS-MR were looked into
CS-MR positive for ligamentous injury
4
NPV of CS- CT for Ligamentous injury NPV of CS -CT for Unstable CS injury
98.9% 100%
Unstable CS injuries can be excluded on the basis of normal CS multidetector CT in ‘‘unreliable’’ patients
[10]
Prospective
115 patients were included in the study; all of them had a negative CS-CT followed by MR-CS
Injuries identified on MR imaging None of these injuries required a change in the management
6 (5.2%)
CS-MR is unnecessary after a normal CS-CT for cervical spine clearance in OBTP
[14]
Prospective
Two groups intubated and ventilated, were compared over a 3-year period 2 protocols followed to clear CS, one of which involving MDCT as clearance modality
Patients evaluated by MDCT followed by clinical/MR protocol CS cleared on the basis of normal MDCT Missed CS injury in either group
140 75 0
MDCT is a safe and efficient way of clearance of the cervical spine in OBTP
[6]
Retrospective
367 obtunded blunt trauma patients were included who underwent multidetector CS-CT over a period of two years
Negative Predictive Value of CS-CT
99.7%
Authors concluded that cervical spine could be ‘‘cleared’’ on the basis of an initial normal MDCT Scan
Number of patients in who CS-CT failed to identify injury Mean delay in CS clearance
1
Abnormal MRI
18 (8.9%)
Cervical Collar given Operative repair given
14 2
Patients with acute traumatic findings on the MRI scan
38
[15]
Retrospective
203 blunt trauma patients who had both CS-MDCT and MR as a part of local clinical guideline
2.6 days Continued use of CS MRI scan was recommended as a part of CS clearance protocol
[16]
Retrospective
180 obtunded patients with blunt trauma were investigated who having had a normal MDCT scan underwent MR imaging of the cervical spine
CS-CT may be sufficient to exclude unstable CS injury in obtunded trauma patients.
Unstable injuries
0
[17]
Retrospective
96 trauma patients with GCS < 15 had CS CT followed by CS MR
Patients with abnormal CS MR Patients requiring extended period of cervical collar Operative fixation
15 7 1
CS MR continues to be a necessary CS clearance in patients with unreliable clinical examination
[18]
Prospective
402 intubated patients within ITU setting with blunt cervical spine injury who had both cervical spine MDCT and Dynamic Flexion Extension plain radiographs as a part of the ‘‘clearance’’ protocol were looked into
Total number of Patients
402
CT-MDCS can be used as a sole modality for CS clearance in obtunded blunt trauma patients
Abnormal F/E radiographs found Point Estimate for the proportion of missed injury One sided 95% Confidence Intervals
1 0.00248 (.25%) .01174- -58
[19]
Prospective
197 obtunded patients were followed up after CS CT
Patients followed up CS MR due to pain, all normal Autopsy revealed injury
175 5 1
CS CT is safe for clearing cervical spine in obtunded patients
[20]
Retrospective
150 trauma patients with GCS < 15 with negative CS CT followed by CS MR and clinical follow-up
Patients with abnormal CS MR CS MR with ligamentous/soft tissue injuries Unstable injuries detected by CS MR requiring a change in the management
51% 81% 0
CS MR adds little to the evaluation protocol of CS in obtunded/comatose patients with normal CS CT and normal neurological exam
Table 2 Sensitivity and specificity values for the individual studies. Study name
True positives
False negatives
True negatives
False positives
Sensitivity
Specificity
[13] [14] [10] [16] [15] [6] [17] [18] [19] [20]
12 0 6 38 18 1 15 1 1 0
0 0 0 0 0 0 0 0 0 0
354 140 109 142 185 366 81 401 196 150
0 0 0 0 0 0 0 0 0 0
0.962 0.500 0.929 0.987 0.974 0.750 0.969 0.750 0.750 0.500
0.999 0.996 0.995 0.997 0.997 0.999 0.994 0.999 0.997 0.997
Total
92
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MEDLINE “cervical vertebrae” OR “spinal injuries” OR “spinal fractures” AND
EMBASE “cervical spine injury” OR “cervical spine” OR “spine fractures”
3919
AND
6963
AND
AND
“computed tomography” OR “multidetector”
1591
AND
1072303
790
AND
737420
131
AND
16
AND
AND
“tomography X-ray computed”OR “multidetector”
201249
“tomography X ray computed”OR “multidetector”
192
17
1367
“clearance” OR “diagnosis”
31056
41960
5478
“obtunded” OR “coma”/exp uncon-sciousness OR “low AND GCS”
“clearance” OR “diagnosis”
“computed AND tomography” OR “multidetector computed tomography”
265224
AND
“obtunded” OR “unconsciousness” “low GCS”
“clearance” OR “diagnosis”
“clearance” OR “diagnosis”
CINAHL “cervical vertebrae” OR “spinal injuries” OR “spinal cord injuries”
AND
“obtunded” OR “unconscious ” OR “low GCS”
“obtunded” OR “unconscious” OR “low AND GCS” AND
10352
AMED “cervical vertebrae” OR “spinal injuries” OR
9236 11
0
Number after review, selection 29 * The studies obtained from hand searches of reference lists of the relevant papers
and removal of the duplicates
8+2*=10
Fig. 1. Flow chart of literature search methodology.
Table 3 Statistical results of the meta-analysis.
Table 4 Inclusion and exclusion criteria for the cohort study. 95% Confidence Interval
Specificty Sensitivity PV+ PV Accuracy DOR LR+ LR
Estimate
Lower
Upper
0.997 0.937 0.937 0.997 0.995 5421.860 346.410 0.078
0.993 0.840 0.840 0.993 0.991 1291.834 128.262 0.031
0.999 0.977 0.977 0.999 0.998 22755.687 935.586 0.194
assessing cervical spine in trauma patients. PACS (Picture Archiving and Communication System) and EPR (Electronic Patient Records) systems were reviewed for the patient records and reports of the imaging in addition to a hand search of the hospital notes. Out of a total of 108 patients, 53 patients fulfilled the inclusion criteria detailed in Table 4 with patient demographics detailed in Table 5. The primary outcome was to detect any cervical spine injury diagnosed by the time of hospital discharge, in the follow up appointments or in any readmissions, which had been missed on the initial CS-MDCT. Results Out of the 53 patients included in the study none were clinically diagnosed as having a cervical spine injury based on persistent cervical spine pain or tenderness. Five patients were found to have had further evaluation of the cervical spine with other imaging
Inclusion criteria Adult blunt trauma patients GCS 14 Intoxicated with alcohol or drugs Cervical Spine multidetector CT obtained on admission
Exclusion criteria Fracture identified on initial CS-MDCT Became examinable before additional CS imaging Died before CS clearance Discharge records not available Patients presenting to the ED before October 2007
modalities, none of which identified any acute cervical bony or ligamentous injuries that had been missed by the initial CS-MDCT. According to this study multidetector cervical spine CT scan has a sensitivity of 100% in detecting clinically significant cervical spine injuries. The additional imaging did however caused delays in cervical spine clearance. Our results add to an accumulating body of evidence that a normal MDCT is sufficient to safely clear the cervical spine in obtunded patients. Discussion Cervical spine computed tomography from the occiput to T1 with sagittal and coronal reconstructions is now advocated to be the primary screening modality in all the patients who cannot have CS clearance on clinical grounds [12]. Once the patient has a normal CT scan of the CS, clinical clearance is required in alert patients to exclude ligamentous injury. Absence of pain on full range of cervical spine movement leads to clinical clearance and CS immobilization is discontinued.
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Fig. 2. Plots of sensitivity and specificity for studies included in the meta-analysis.
If the patient is unable to reliably report presence or absence of pain in the CS, one way is to wait until clinical examination can be performed [14], but such delays can be challenging both for the patient and the physician. For obtunded patients with blunt trauma two other screening modalities have been looked into, flexion extension views and MR of the cervical spine. Flexion extension views have been shown to be inadequate in 4% of the
patients due to incomplete visualization [9,21]. Quadriplegia has been also reported in one patient who underwent F-E views [21] hence their use in comatose patients or with altered sensorium is no longer supported [12]. There is a lot of literature supporting the use of MDCT for the CS clearance in obtunded blunt trauma patients [6,14,16,22]. However, ligamentous injury with potential CS instability in the
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Table 5 Patient demographics. Total number of Patients Male patients Mean age Mean GCS Mechanism of injury Fall Pedestrian VS car Road traffic collision Assault Collapsed with blunt head/CS Trauma
53 38 44.8 9 (9.14) 20 9 16 6 2
absence of a fracture or bony displacement undiagnosed on CSMDCT has been an area of major concern [23]. An unstable CS ligamentous injury implies an injury involving two adjacent ligaments support columns in the cervical spine [21,24]. What percentage of OBTP’s have such an injury which cannot be diagnosed on CS-MDCT, is unknown and the very existence of such an injury has been questioned [16]. Several studies have demonstrated little benefit in obtaining CS-MR after a normal CS-MDCT [10,14,16]. and whilst the studies supporting the use of CS-MR were able to detect minor ligament injuries none discovered CS instability by adding MR to the CT clearance protocol or resulted in significant change in patient management [17,18]. The values of sensitivity and PPV in our study are not as conclusive as specificity and NPV. This is due to the fact that two of the studies Stelfox et al. [14] and Khanna et al., [20] had to be excluded when calculating the overall sensitivity and PPV, as they did not report any true positive results. This leaves us unclear as to how sensitive the MDCT were in those studies in diagnosing cervical spine injuries. Another limitation of our study is that we analyzed a combination of prospective and retrospective cohort studies. There were no randomized controlled trials due to the inherent nature of the topic as such a study would have been impractical and unethical to conduct. Another potential weakness is that a relatively small cohort of 53 patients was retrospectively investigated to look for any injuries of the cervical spine missed on initial MDCT. However there was a robust investigation into the records of these patients to diagnose such an injury. We used prolonged clinical follow up as gold standard to diagnose any missed injuries on initial MDCT of the CS on all of these patients irrespective of whether they had CS MRI or not. Conclusion The ideal imaging modality should not only be able to detect a ligamentous CS injury but should also enable the reporting clinician to comment on the stability or not of the cervical spine as this might in turn require a significant change in patient management. A reference standard against which CS-CT might be compared has not yet been agreed upon. This significantly limits the quality of the various studies done on this topic as a wide variety of reference standards have been used including MRI, flexion extension views and clinical outcomes. Equally a methodologically sound and adequately powered randomized control trial is not practically possible due to ethical constraints. Based on this review and NPV of 99.7% and taking into consideration the degree of evidence [6,14,16,18,19] supporting the use of CS-MDCT as a sole clearance modality, we conclude that the CS can be safely cleared in OBTPs on the basis of a multidetector CT scan being reported as normal.
The appraisal of the published evidence goes against the use of further imaging modalities to clear the CS in all OBTPs and we suggest the use of MRI should be limited to specific circumstances based on the mechanism of injury [12], neurological signs and symptoms [25] and continued or delayed-onset clinical symptoms in the setting of a CS injury. Whilst it is reassuring that CS-MDCT is being safely and successfully used, there is an obvious need for a well constructed multi-institutional, prospective and appropriately powered study to compare cervical spine MDCT and MRI in obtunded blunt trauma patients; and ideally one which continues to follow up patients over the long term to detect any problems that develop looking specifically at ‘‘unstable’’ CS injuries.
References [1]. Grossman MD, Reilly PM, Gillett Tracy BS, Gillett D. National survey of the incidence of cervical spine injury and approach to cervical spine clearance in U.S trauma centres. Journal of Trauma 1999;47:684. [2]. Berne JD, Velmahos GC, El-Tawil Q, Demetriades D, Asensio M, James A. Value of complete cervical helical computed tomographic scanning in identifying cervical spine injury in the unevaluable blunt trauma patient with multiple injuries: a prospective study. Journal of Trauma 1999;47:896–903. [3]. Hunt K, Hallworth S. The effects of rigid collar placement on intracranial and cerebral perfusion pressures. Anaesthesia 2001;56:511–3. [4]. Ackland HM, Cooper JD, Malham GM, Kossmann T. Factors predicting cervical collar-related decubitus ulceration in major trauma patients. Spine 2007;32:423–8. [5]. Advanced Trauma Life Support. 8th Ed. American College of Surgeons Committee on Trauma; 2008: 166–71. [6]. Harris TJ, Blackmore CC, Mirza SK, Jurkovich GJ. Clearing the cervical spine in obtunded patients. Spine 2008;33:1547–53. [7]. Marion D, Domeier R. Practice management guidelines for identifying cervical spine injuries following trauma, EAST practice parameter working group for cervical spine clearance. EAST 1998:1–10. [8]. Marion D, Domeier R. Determination of cervical spine stability in trauma patients. EAST 2000:1–6. [9]. Diaz JJ, Gillman C, Morris JA, May AK, Carrillo YM, Guy J. Are five-view films of the cervical spine unreliable? a prospective evaluation in blunt trauma patients with altered mental status. Journal of Trauma 2003;55:658–64. [10]. Como JJ, Thompson MA, Anderson RNJS, Shah RR, Claridge JA, et al. Is magnetic resonance imaging essential in clearing the cervical spine in obtunded patients with blunt trauma? Journal of Trauma 2007;63:544–9. [11]. Goldman LW. Principles of CT: Multislice CT. Journal of Nuclear Medicine Technology 2008;36:57–68. [12]. Como JJ, Diaz JJ. 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. Journal of Trauma 2009;67:651. [13]. Hogan GJ, Mirvis SE, Shanmuganathan K, Scalea TM. Exclusion of unstable cervical spine injury in obtunded patients with blunt trauma: is MR imaging needed when multi-detector row CT findings are normal? Radiology 2005;237:106–13. [14]. Stelfox HT, Velmahos GC, Gettings E, Bigatello LM. Schmidt computed tomography for early and safe discontinuation of cervical spine immobilization in obtunded multiply injured patients. Journal of Trauma 2007;63:630–6. [15]. Menaker J, Philp A. Computed tomography alone for cervical spine clearance in the unreliable patient—are we there yet? Journal of Trauma 2008;64:898– 903. [16]. Tomycz ND, Chew BG, Chang YF, Darby JM, Gunn SR, et al. MRI is unnecessary to clear the cervical spine in obtunded/comatose trauma patients: the fouryear experience of a level I trauma centre. Journal of Truama 2008;64:1258–63. [17]. Menaker J, Stein Deborah M, Philip AS, Scalea TM. 40 slice Multidetector CT: is MRI still necessary for cervical spine clearance after blunt trauma. The American Surgeon 2010, February;76:157–63. [18]. Hennessey D, Widder Sandy Zygun D, Hurlbert RJ, Burrowes P, Kortbeek JB. Cervical spine clearance in obtunded trauma patients: a prospective study. Journal of Trauma 2010;68:576. [19]. Como JJ, Leukhardt William H, Anderson JS, Wilxzewski 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. The Journal of Truama 2011;2:345–51. [20]. Khanna P, Cam Chau Dublin A, Kim K, Wisner D. The value of cervical magnetic resonance imaging in the evaluation of the obtunded or comatose patient with cervical trauma, no other abnormal neurological findings, and a normal cervical computed tomography. Journal of Trauma 2011;72:699–702. [21]. Davis JW, Kaups KL, Cunningham MA, Parks SN, Nowak TP, Bilello JF, et al. Routine evaluation of the cervical spine in head injured patients with dynamic fluoroscopy: a reappraisal. Journal of Trauma 2001;50:1044–7. trauma patients.
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[24]. Denis F. Spinal instability as defined by the three-column spine concept in acute spinal trauma. Clinical Orthopaedics 1984;189:65–76. [25]. The College of Emergency Medicine Clinical Effectiveness Committee Guideline on the Management of Alert, Adult Patients with Potential Cervical Spine Injury in the Emergency Department. 2010, November.
Contents lists available at SciVerse ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
Safe cervical spine clearance in adult obtunded blunt trauma patients on the basis of a normal multidetector CT scan—A meta-analysis and cohort study Mushahid Raza a,1,*, Samer Elkhodair b, Asif Zaheer c, Sohail Yousaf d a
Consultant Emergency Medicine, Frimley Park Hospital, Frimley, UK Consultant Emergency Medicine, University College London Hospitals, UK Specialist Trainee Emergency Medicine, Epsom and St Helier University Hospital, UK d Specialist Trainee Trauma and Orthpaedics, Brighton and Sussex University Hospital, UK b c
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 2 June 2013
Background: A true gold standard to rule out a significant cervical spine injury in subset of blunt trauma patients with altered sensorium is still to be agreed upon. The objective of this study is to determine whether in obtunded adult patients with blunt trauma, a clinically significant injury to the cervical spine be ruled out on the basis of a normal multidetector cervical spine computed tomography. Methods: Comprehensive database search was conducted to include all the prospective and retrospective studies on blunt trauma patients with altered sensorium undergoing cervical spine multidetector CT scan as core imaging modality to ‘‘clear’’ the cervical spine. The studies used two main gold standards, magnetic resonance imaging of the cervical spine and/or prolonged clinical follow-up. The data was extracted to report true positive, true negatives, false positives and false negatives. Metaanalysis of sensitivity, specificity, negative and positive predictive values was performed using Meta Analyst Beta 3.13 software. We also performed a retrospective investigation comparing a robust clinical follow-up and/or cervical spine MR findings in 53 obtunded blunt trauma patients, who previously had undergone a normal multidetector CT scan of the cervical spine reported by a radiologist. Results: A total of 10 studies involving 1850 obtunded blunt trauma patients with initial cervical spine CT scan reported as normal were included in the final meta-analysis. The cumulative negative predictive value and specificity of cervical spine CT of the ten studies was 99.7% (99.4–99.9%, 95% confidence interval). The positive predictive value and sensitivity was 93.7% (84.0–97.7%, 95% confidence interval). In the retrospective review of our obtunded blunt trauma patients, none was later diagnosed to have significant cervical spine injury that required a change in clinical management. Conclusion: In a blunt trauma patient with altered sensorium, a normal cervical spine CT scan is conclusive to safely rule out a clinically significant cervical spine injury. The results of this meta-analysis strongly support the removal of cervical precautions in obtunded blunt trauma patient after normal cervical spine computed tomography. Any further imaging like magnetic resonance imaging of the cervical spine should be performed on case-to-case basis. ß 2013 Elsevier Ltd. All rights reserved.
Keywords: Cervical Spine Spinal injuries Spinal fractures Clearance Obtunded Multidetector computed tomography Meta-analysis
Introduction and background The safe management of cervical spine (CS) injury in a patient with multiple trauma is one of the major challenges faced by trauma surgeons. The incidence of cervical spine injury in the
* Corresponding author. Tel.: +44 7833052551. E-mail addresses: [email protected], [email protected] (M. Raza). 1 Place where the study was conducted St George’s Hospital, London, UK. 0020–1383/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.injury.2013.06.005
majority of blunt trauma is 2–4% [1] but rises to 34.4% in unconscious patients [2]; potentially resulting in long-term morbidity and carrying with it medico-legal repercussions. ‘‘Clearing’’ the cervical spine implies declaring no significant injury and removing the spinal precautions based on clinical and/ or radiological grounds. An injury to the cervical spine is considered ‘‘significant’’ when if overlooked could result in irreversible neurological deterioration including paralysis and death. Early cervical spine clearance is of paramount importance as any delay in the clearance process can lead to difficulties in safe
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airway management, increased risk of aspiration, increased intracranial pressure [3], increased risk of thrombosis and decubitus ulceration [4]. In awake and alert patients with blunt cervical spine trauma, the absence of distracting injuries, no cervical spine tenderness or pain on full range of movements plus a normal neurological examination implies the cervical spine can be safely cleared on clinical grounds [5]. It is accepted that radiological screening is indicated in patients with pain or cervical spine tenderness, neurological deficit, patients with significant distracting injuries or the patients with altered sensorium. [2,6,7]. Guidelines are available to aid the safe clearance of the CS in most of the above-mentioned groups of patients [8]. Clearing the CS in obtunded blunt trauma patients without apparent neurological deficit however remains controversial. The term ‘‘obtunded’’ implies a state of cognitive dysfunction in which the clinical examination of a patient becomes unreliable due to decreased GCS including alcohol/drug intoxication. The ideal method for detecting CS injury should be highly sensitive, cost effective and readily available in the emergency department. Different approaches have been advocated to settle this dilemma. A well-defined algorithm hasn’t been agreed upon due to limited information on the validity and reliability of the imaging modalities, inconclusive best available evidence and the fear of devastating consequences in the event of missed injury. In 1998 the Eastern Association for the Surgery of Trauma (EAST) recommended that all patients who cannot have their cervical spines clinically cleared should have plain radiographs of the CS (anteroposterior, lateral and open mouth odontoid) followed by thin slice (3 mm) axial computed tomography (CT) with sagittal reconstructions of C1–C2 [7]. Additional focused CT scan was also recommended if on plain radiography a part of the CS could not be visualized or had suspicious findings. The focused CSCT as recommended by EAST was challenged by Bern et al. [2] and Diaz JJ [9] as it would fail to depict unstable CS injuries as diagnosed by complete CS-CT. The primary screening modality was then recommended to be cervical spine CT from occiput to T1 with sagittal and coronal reconstructions [10]. Cervical spine CT is a widely accepted initial imaging modality in patients with altered level of consciousness in trauma patients. Multidetector CT scanners image a volume of tissue rather than individual slices, the thickness of which is much less than in single slice CT scanners. In contrast to getting merely axial slices, multi planar slices are retrieved from one ‘sweep’ in 4–10 s giving thousands of images, which are in turn reconstructed into 3D Image [11]. Whether CS-MDCT could be solely used as a screening modality to safely clear the cervical spine is controversial with the available literature showing contradicting views [12]. Objective; the clinical dilemma In obtunded adult patients with blunt trauma, can a clinically significant injury be ruled out on the basis of a multidetector cervical spine CT scan being reported as normal? Methodology; the paper selection Inclusion criteria
Indication for cervical spine MDCT other than altered sensorium Literature search The different sources searched are as follows. 1. 2. 3. 4.
Electronic Indexed Bibliographic Databases Cochrane Database Grey literature Hand searches through references, relevant journals and correspondences
A search was carried out on the health information resources website (www.library.nhs.uk) using methodology and search terms as depicted in the following flow chart (Fig. 1). The search was conducted both as key words unmapped to MeSH (Medical Subject Headings) and through MeSH structure. The search was performed for literature published from 1998 onwards (the year when multidetector CT scanners were introduced), was limited to studies done on adult patients and had no language limits. All the search terms used were mapped to thesaurus to achieve comprehensive search results. A total of 10 studies including 2 from hand search directly addressing my clinical question were selected for detailed appraisal. The selection process involved review of the title and abstract of the relevant studies meeting the inclusion criteria. Results The details of the literature search are evident from the flow chart (Fig. 1). Any study involving alert patients or where CS MDCT wasn’t core-imaging modality was excluded. A fair number of studies had to be excluded due the fact that the CT scanners were not of multidetector type. In order to have homogenous sample for the meta-analysis, few more studies involving a combination of single row and multidetector CT scanners were also excluded. A total of 10 studies summarized in Tables 1 and 2 were selected to be included in the meta-analysis, four of them were of prospective cohort design. The sensitivity is the proportion of patients with abnormal CS by gold standard who has a positive result by CS MDCT. The specificity is the proportion of patients who have a normal CS with a negative CS MDCT. The PPV represents the probability that an abnormal CT scan correlates with an abnormal cervical spine. The NPV is the probability that a negative CT scan correlates with normal cervical spine. Data from all the 10 studies produces a NPV of 99.7% (99.4– 99.9%, 95% confidence interval) as detailed in Table 3 and Fig. 2. The positive predictive value and sensitivity was 93.7% (84.0–97.7%, 95% confidence interval). The values of sensitivity and positive predictive value are not conclusive as two of the studies had to be excluded whilst calculating these values being a weakness of our study. The studies by Khanna et al. and Stelfox et all had no true positive values so we are not sure how accurate the MDCT would have been in diagnosing a cervical spine injury should there be such a patient in these studies.
1. Adult blunt trauma patients with altered sensorium/obtunded 2. Multidetector CT of the cervical spine as the core imaging modality
The cohort study
Exclusion criteria
The medical records of 108 patients presenting to the ED of St Georges hospital in London between October 2007 and December 2008 were retrospectively reviewed. October 2007 was the date from when MDCT was considered the investigation of choice for
Studies done using single-slice CT scanners (axial/helical with single -row of detectors)
Methods
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Table 1 Summary of individual studies included in the meta-analysis. Paper
Study design
Study population
Results
Author’s conclusion
[13]
Retrospective
Hospital records of 366 obtunded patients who underwent multidetector CS-CT followed by CS-MR were looked into
CS-MR positive for ligamentous injury
4
NPV of CS- CT for Ligamentous injury NPV of CS -CT for Unstable CS injury
98.9% 100%
Unstable CS injuries can be excluded on the basis of normal CS multidetector CT in ‘‘unreliable’’ patients
[10]
Prospective
115 patients were included in the study; all of them had a negative CS-CT followed by MR-CS
Injuries identified on MR imaging None of these injuries required a change in the management
6 (5.2%)
CS-MR is unnecessary after a normal CS-CT for cervical spine clearance in OBTP
[14]
Prospective
Two groups intubated and ventilated, were compared over a 3-year period 2 protocols followed to clear CS, one of which involving MDCT as clearance modality
Patients evaluated by MDCT followed by clinical/MR protocol CS cleared on the basis of normal MDCT Missed CS injury in either group
140 75 0
MDCT is a safe and efficient way of clearance of the cervical spine in OBTP
[6]
Retrospective
367 obtunded blunt trauma patients were included who underwent multidetector CS-CT over a period of two years
Negative Predictive Value of CS-CT
99.7%
Authors concluded that cervical spine could be ‘‘cleared’’ on the basis of an initial normal MDCT Scan
Number of patients in who CS-CT failed to identify injury Mean delay in CS clearance
1
Abnormal MRI
18 (8.9%)
Cervical Collar given Operative repair given
14 2
Patients with acute traumatic findings on the MRI scan
38
[15]
Retrospective
203 blunt trauma patients who had both CS-MDCT and MR as a part of local clinical guideline
2.6 days Continued use of CS MRI scan was recommended as a part of CS clearance protocol
[16]
Retrospective
180 obtunded patients with blunt trauma were investigated who having had a normal MDCT scan underwent MR imaging of the cervical spine
CS-CT may be sufficient to exclude unstable CS injury in obtunded trauma patients.
Unstable injuries
0
[17]
Retrospective
96 trauma patients with GCS < 15 had CS CT followed by CS MR
Patients with abnormal CS MR Patients requiring extended period of cervical collar Operative fixation
15 7 1
CS MR continues to be a necessary CS clearance in patients with unreliable clinical examination
[18]
Prospective
402 intubated patients within ITU setting with blunt cervical spine injury who had both cervical spine MDCT and Dynamic Flexion Extension plain radiographs as a part of the ‘‘clearance’’ protocol were looked into
Total number of Patients
402
CT-MDCS can be used as a sole modality for CS clearance in obtunded blunt trauma patients
Abnormal F/E radiographs found Point Estimate for the proportion of missed injury One sided 95% Confidence Intervals
1 0.00248 (.25%) .01174- -58
[19]
Prospective
197 obtunded patients were followed up after CS CT
Patients followed up CS MR due to pain, all normal Autopsy revealed injury
175 5 1
CS CT is safe for clearing cervical spine in obtunded patients
[20]
Retrospective
150 trauma patients with GCS < 15 with negative CS CT followed by CS MR and clinical follow-up
Patients with abnormal CS MR CS MR with ligamentous/soft tissue injuries Unstable injuries detected by CS MR requiring a change in the management
51% 81% 0
CS MR adds little to the evaluation protocol of CS in obtunded/comatose patients with normal CS CT and normal neurological exam
Table 2 Sensitivity and specificity values for the individual studies. Study name
True positives
False negatives
True negatives
False positives
Sensitivity
Specificity
[13] [14] [10] [16] [15] [6] [17] [18] [19] [20]
12 0 6 38 18 1 15 1 1 0
0 0 0 0 0 0 0 0 0 0
354 140 109 142 185 366 81 401 196 150
0 0 0 0 0 0 0 0 0 0
0.962 0.500 0.929 0.987 0.974 0.750 0.969 0.750 0.750 0.500
0.999 0.996 0.995 0.997 0.997 0.999 0.994 0.999 0.997 0.997
Total
92
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MEDLINE “cervical vertebrae” OR “spinal injuries” OR “spinal fractures” AND
EMBASE “cervical spine injury” OR “cervical spine” OR “spine fractures”
3919
AND
6963
AND
AND
“computed tomography” OR “multidetector”
1591
AND
1072303
790
AND
737420
131
AND
16
AND
AND
“tomography X-ray computed”OR “multidetector”
201249
“tomography X ray computed”OR “multidetector”
192
17
1367
“clearance” OR “diagnosis”
31056
41960
5478
“obtunded” OR “coma”/exp uncon-sciousness OR “low AND GCS”
“clearance” OR “diagnosis”
“computed AND tomography” OR “multidetector computed tomography”
265224
AND
“obtunded” OR “unconsciousness” “low GCS”
“clearance” OR “diagnosis”
“clearance” OR “diagnosis”
CINAHL “cervical vertebrae” OR “spinal injuries” OR “spinal cord injuries”
AND
“obtunded” OR “unconscious ” OR “low GCS”
“obtunded” OR “unconscious” OR “low AND GCS” AND
10352
AMED “cervical vertebrae” OR “spinal injuries” OR
9236 11
0
Number after review, selection 29 * The studies obtained from hand searches of reference lists of the relevant papers
and removal of the duplicates
8+2*=10
Fig. 1. Flow chart of literature search methodology.
Table 3 Statistical results of the meta-analysis.
Table 4 Inclusion and exclusion criteria for the cohort study. 95% Confidence Interval
Specificty Sensitivity PV+ PV Accuracy DOR LR+ LR
Estimate
Lower
Upper
0.997 0.937 0.937 0.997 0.995 5421.860 346.410 0.078
0.993 0.840 0.840 0.993 0.991 1291.834 128.262 0.031
0.999 0.977 0.977 0.999 0.998 22755.687 935.586 0.194
assessing cervical spine in trauma patients. PACS (Picture Archiving and Communication System) and EPR (Electronic Patient Records) systems were reviewed for the patient records and reports of the imaging in addition to a hand search of the hospital notes. Out of a total of 108 patients, 53 patients fulfilled the inclusion criteria detailed in Table 4 with patient demographics detailed in Table 5. The primary outcome was to detect any cervical spine injury diagnosed by the time of hospital discharge, in the follow up appointments or in any readmissions, which had been missed on the initial CS-MDCT. Results Out of the 53 patients included in the study none were clinically diagnosed as having a cervical spine injury based on persistent cervical spine pain or tenderness. Five patients were found to have had further evaluation of the cervical spine with other imaging
Inclusion criteria Adult blunt trauma patients GCS 14 Intoxicated with alcohol or drugs Cervical Spine multidetector CT obtained on admission
Exclusion criteria Fracture identified on initial CS-MDCT Became examinable before additional CS imaging Died before CS clearance Discharge records not available Patients presenting to the ED before October 2007
modalities, none of which identified any acute cervical bony or ligamentous injuries that had been missed by the initial CS-MDCT. According to this study multidetector cervical spine CT scan has a sensitivity of 100% in detecting clinically significant cervical spine injuries. The additional imaging did however caused delays in cervical spine clearance. Our results add to an accumulating body of evidence that a normal MDCT is sufficient to safely clear the cervical spine in obtunded patients. Discussion Cervical spine computed tomography from the occiput to T1 with sagittal and coronal reconstructions is now advocated to be the primary screening modality in all the patients who cannot have CS clearance on clinical grounds [12]. Once the patient has a normal CT scan of the CS, clinical clearance is required in alert patients to exclude ligamentous injury. Absence of pain on full range of cervical spine movement leads to clinical clearance and CS immobilization is discontinued.
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Fig. 2. Plots of sensitivity and specificity for studies included in the meta-analysis.
If the patient is unable to reliably report presence or absence of pain in the CS, one way is to wait until clinical examination can be performed [14], but such delays can be challenging both for the patient and the physician. For obtunded patients with blunt trauma two other screening modalities have been looked into, flexion extension views and MR of the cervical spine. Flexion extension views have been shown to be inadequate in 4% of the
patients due to incomplete visualization [9,21]. Quadriplegia has been also reported in one patient who underwent F-E views [21] hence their use in comatose patients or with altered sensorium is no longer supported [12]. There is a lot of literature supporting the use of MDCT for the CS clearance in obtunded blunt trauma patients [6,14,16,22]. However, ligamentous injury with potential CS instability in the
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Table 5 Patient demographics. Total number of Patients Male patients Mean age Mean GCS Mechanism of injury Fall Pedestrian VS car Road traffic collision Assault Collapsed with blunt head/CS Trauma
53 38 44.8 9 (9.14) 20 9 16 6 2
absence of a fracture or bony displacement undiagnosed on CSMDCT has been an area of major concern [23]. An unstable CS ligamentous injury implies an injury involving two adjacent ligaments support columns in the cervical spine [21,24]. What percentage of OBTP’s have such an injury which cannot be diagnosed on CS-MDCT, is unknown and the very existence of such an injury has been questioned [16]. Several studies have demonstrated little benefit in obtaining CS-MR after a normal CS-MDCT [10,14,16]. and whilst the studies supporting the use of CS-MR were able to detect minor ligament injuries none discovered CS instability by adding MR to the CT clearance protocol or resulted in significant change in patient management [17,18]. The values of sensitivity and PPV in our study are not as conclusive as specificity and NPV. This is due to the fact that two of the studies Stelfox et al. [14] and Khanna et al., [20] had to be excluded when calculating the overall sensitivity and PPV, as they did not report any true positive results. This leaves us unclear as to how sensitive the MDCT were in those studies in diagnosing cervical spine injuries. Another limitation of our study is that we analyzed a combination of prospective and retrospective cohort studies. There were no randomized controlled trials due to the inherent nature of the topic as such a study would have been impractical and unethical to conduct. Another potential weakness is that a relatively small cohort of 53 patients was retrospectively investigated to look for any injuries of the cervical spine missed on initial MDCT. However there was a robust investigation into the records of these patients to diagnose such an injury. We used prolonged clinical follow up as gold standard to diagnose any missed injuries on initial MDCT of the CS on all of these patients irrespective of whether they had CS MRI or not. Conclusion The ideal imaging modality should not only be able to detect a ligamentous CS injury but should also enable the reporting clinician to comment on the stability or not of the cervical spine as this might in turn require a significant change in patient management. A reference standard against which CS-CT might be compared has not yet been agreed upon. This significantly limits the quality of the various studies done on this topic as a wide variety of reference standards have been used including MRI, flexion extension views and clinical outcomes. Equally a methodologically sound and adequately powered randomized control trial is not practically possible due to ethical constraints. Based on this review and NPV of 99.7% and taking into consideration the degree of evidence [6,14,16,18,19] supporting the use of CS-MDCT as a sole clearance modality, we conclude that the CS can be safely cleared in OBTPs on the basis of a multidetector CT scan being reported as normal.
The appraisal of the published evidence goes against the use of further imaging modalities to clear the CS in all OBTPs and we suggest the use of MRI should be limited to specific circumstances based on the mechanism of injury [12], neurological signs and symptoms [25] and continued or delayed-onset clinical symptoms in the setting of a CS injury. Whilst it is reassuring that CS-MDCT is being safely and successfully used, there is an obvious need for a well constructed multi-institutional, prospective and appropriately powered study to compare cervical spine MDCT and MRI in obtunded blunt trauma patients; and ideally one which continues to follow up patients over the long term to detect any problems that develop looking specifically at ‘‘unstable’’ CS injuries.
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