Blunt Cerebrovascular Injury - 2007

© Copyright 2007 – The Eastern Association for the Surgery of Trauma Blunt Cerebrovascular Injury Practice Management Guidelines East Practice Management Guidelines Committee Authors: William J. Bromberg, MD, chair Brombwi1@memorialhealth.com Bryan Collier, DO, vice-chair Bryan.collier@vanderbilt.edu Larry Diebel, MD ldiebel@med.wayne.edu Kevin Dwyer, MD Kevin.dwyer@inova.com Michelle Holevar, MD Michellehmail-career@yahoo.com David Jacobs, MD David.jacobs@carolinashelathcare.org Stanley Kurek, DO SKurek@mc.utmck.edu Martin Schreiber, MD schreibm@ohsu.edu Mark Shapiro, MD Mark.shapiro@umassmed.edu Todd Vogel, MD Todd.vogel@vanderilt.edu © Copyright 2007 – The Eastern Association for the Surgery of Trauma Scope of the Problem: Blunt injury to the carotid or vertebral vessels (blunt cerebrovascular injury – BCVI) is diagnosed in approximately 1/1000 (0.1%) patients hospitalized for trauma in the United States.1 However the vast majority of these injuries are diagnosed following the development of symptoms secondary to central nervous system ischemia with a resultant neurologic morbidity of up to 80% and associated mortality of up to 40%.2 When asymptomatic patients are screened for BCVI the incidence rises to 1% of all blunt trauma patients.3 Key issues that need to be addressed in the diagnosis and management of BCVI include what population (if any) merits screening for asymptomatic injury, what screening modality is best, what is the appropriate treatment for BCVI (both symptomatic and asymptomatic) and what constitutes appropriate follow-up for these injuries. Process: Identification of references A computerized search of the National Library of Medicine/National Institute of Health, Medline database was performed utilizing citations from 1965 to 2005 inclusive. The search terms “cerebrovascular trauma,” or “carotid artery” or “vertebral artery” AND wounds and injuries (mesh heading), AND “blunt” limited to the English language returned approximately 1500 citations. Titles and abstracts were reviewed to determine relevance and isolated case reports, small case series, editorials, letters to the editor, and review articles were eliminated. The bibliographies of the resulting full text articles were searched for other relevant citations and these were obtained when appropriate. One hundred sixty two articles were selected for review and of these 60 met criteria for inclusion and are excerpted in the attached evidentiary table. Quality of the references The Eastern Association for the Surgery of Trauma “Utilizing Evidence Based Outcome Measures to Develop Practice Management Guidelines: A Primer” was utilized as the quality assessment instrument applied to the development of this protocol.4 Articles were classified as Class I, II, or III according to the following definitions: Class I: Prospective, randomized, controlled trial (there were no Class I articles reviewed) Class II: Clinical studies in which the data was collected prospectively, and retrospective analyses which were based on clearly reliable data. Types of studies so classified include: observational studies, cohort studies, prevalence studies, and case control studies. There were 23 Class II studies identified. Class III: Studies based on retrospectively collected data. Evidence used in this class includes clinical series, database or registry reviews, large series of case reviews, and expert opinion. There were 37 Class III studies identified. Establishment of recommendations A committee consisting of 10 trauma surgeons was convened to review the data and establish these recommendations using these definitions:5 Level 1: The recommendation is convincingly justifiable based on the available scientific information alone. This recommendation is usually based on Class I © Copyright 2007 – The Eastern Association for the Surgery of Trauma data, however strong Class II evidence may form the basis for a Level 1 recommendation, especially if the issue does not lend itself to testing in a randomized format. Conversely, low quality or contradictory Class I data may not be able to support a Level 1 recommendation. No Level 1 guidelines were supported by the literature. Level 2: The recommendation is reasonably justifiable by available scientific evidence and strongly supported by expert opinion. This recommendation is usually supported by Class II data or a preponderance of Class III evidence. Seven Level 2 guidelines were establish by the literature. Level 3: The recommendation is supported by available data but adequate scientific evidence is lacking. This recommendation is generally supported by Class III data. This type of recommendation is useful for educational purposes and in guiding future clinical research. Nine Level 3 guidelines are proposed for this topic. Recommendations Question addressed: What patients should be screened for blunt cerebrovascular injury? Level 1: No Level 1 recommendations can be made. Level 2: 1. Patients presenting with any neurologic abnormality that is unexplained by a diagnosed injury should be evaluated for BCVI. 2. Blunt trauma patients presenting with epistaxis from a suspected arterial source following trauma should be evaluated for BCVI. Level 3: 1. Asymptomatic patients with significant blunt head trauma as defined below are at significantly increased risk for BCVI and screening should be considered. Risk factors: • GCS ≤8 • Petrous bone fracture • Diffuse axonal injury • Cervical spine fracture • Fracture through the foramen transversum • Lefort II or III facial fractures 2. Pediatric trauma patients should be evaluated using the same criteria as the adult population. © Copyright 2007 – The Eastern Association for the Surgery of Trauma Question addressed: What is the appropriate modality for the screening and diagnosis of BCVI? Level 1: No Level 1 recommendations can be made. Level 2: 1. Diagnostic four vessel cerebral angiography (FVCA) remains the gold standard for the diagnosis of BCVI. 2. Duplex ultrasound is not adequate for screening for BCVI. 3. CT angiography with a 4 (or less)-slice multidetector array is neither sensitive nor specific enough for screening for BCVI. Level 3: 1. Multi-slice (8 or greater) multidetector CTA has the same rate of detection for BCVI when compared to historic control rates of diagnosis with FVCA and should be considered as a screening modality in place of FVCA. Question: How should BCVI be treated? This references a grading scheme proposed by Biffl et al.6 Grading scale Grade I – intimal irregularity with <25% narrowing Grade II – dissection or intramural hematoma with >25% narrowing Grade III – pseudoaneurysm Grade IV – occlusion Grade V – transection with extravasation Level 1: No Level 1 recommendations can be made. Level 2: 1. Barring contraindications, Grade I and II injuries should be treated with antithrombotic agents such as aspirin or heparin. Level 3: 1. Either heparin or antiplatelet therapy can be used with seemingly equivalent results. A number of authors still recommend heparinization if there is no contraindication, reserving anti-platelet agents for those patients with relative contraindications to heparinization. 2. If heparin is selected for treatment, the infusion should be started without a bolus and titrated to an aPTT of 50-60 sec. 3. In patients in whom anticoagulant therapy is chosen conversion to warfarin titrated to a PT INR of 2-3 for 3-6 months is recommended. © Copyright 2007 – The Eastern Association for the Surgery of Trauma 4. Grade III injuries (pseudoaneurysm) rarely resolve with observation or heparinization and invasive therapy (surgery or angio-interventional) should be considered. N.B. carotid stents placed without subsequent anti-platelet therapy have been noted to have a high rate of thrombosis in this population.7 5. In patients with an early neurologic deficit and an accessible carotid lesion operative or interventional repair should be considered to restore flow. 6. In children who have suffered an ischemic neurologic event, aggressive management of resulting intracranial hypertension up to and including resection of ischemic brain tissue has improved outcome as compared to adults and should be considered for supportive management. Question addressed: For how long should antithrombotic therapy be administered? No recommendations can be made for this question. Question addressed: How should one monitor the response to therapy? Level 1: No Level 1 recommendation can be made. Level 2: 1. Follow-up angiography is recommended in Grade I-III injuries. In order to reduce the incidence of angiography-related complications this should be performed after 7 days post injury. Level 3: There are no Level 3 guidelines for this question. Scientific Foundation: Screening and Diagnosis Symptomatic patients that undergo FVCA for the indications of unexplained neurologic symptoms or arterial epistaxis the diagnosis of BCVI is made in a significant percentage of cases (38-100%) and is clearly recommended as a reason to pursue the diagnosis.8, 9, 10 Screening asymptomatic patients at risk for BCVI is more controversial. Multiple studies have indicated that patients with BCVI often present hours to days prior to the onset of symptoms.11, 12, 13 Failure to identify and treat these injuries can result in significant mortality and morbidity.14 It is clear that screening for BCVI by essentially any modality can diagnosis BCVI prior to the onset of symptoms at rates up to 10 times higher than previously identified.15 On the basis of this data a number of individuals recommend screening blunt trauma patients at risk for BCVI using 4-vessel cerebral angiography as the diagnostic modality.16, 17, 18, 19 There is some countervailing opinion. In a database review of thirty-five thousand patients Mayberry determined that only 17 were diagnosed with BCI of which 11 became symptomatic. Of these only 2 © Copyright 2007 – The Eastern Association for the Surgery of Trauma were asymptomatic for over 2 hours post admission, and of these 2, only 1 met criteria for screening. Based on this data Mayberry et al concluded that screening was futile in light of the inability to diagnose the injury prior to the development of symptoms.20 The majority of the available data does not support this finding. The preponderance of the evidence supports the recommendation that patients at risk for BCVI can be identified and diagnosed prior to the onset of symptoms with the application of an appropriate screening modality. Criteria for screening/Risk factors The mechanism of BCVI seems to be associated with cervical hyperextension and rotation, hyperflexion, or direct blow.21 The factors that are most closely associated with the finding of BCVI are direct evidence of neurologic deficits as noted above. In asymptomatic patients a number of factors have been associated with increased risk of BCVI. Biffl and colleagues performed linear regression analysis of a liberally screened patient population (N =249)and found that there were four independent risk factors for BCAI. These were: 1) GCS<6, 2) Petrous fracture, 3) Diffuse axonal injury, and 4) LeFort II or III fracture. Patients who had one risk factor had a risk of 41% for BCAI. This risk increased to 93% in the presence of all 4 factors. The only risk factor for BVAI was presence of cervical spine fracture. However 20% of patients diagnosed with BCVI selected for screening by the criteria in Table 1 did not have the independent risk factors identified by regression analysis indicating that broad selection criteria are necessary to prevent missed injuries.22 Cothren retrospectively reviewed patients with BVAI and found that complex cervical spine fractures involving subluxation, fracture into the foramen transversarium, or C1 to C3 fractures were closely associated with this injury.23 In a prospective review of screening with DFVCA Cothren et al utilized criteria similar to that proposed by Biffl and modified to incorporate those specific cervical spine fracture patterns shown to increase risk of BVAI to select patients for evaluation (Table 2). Seven hundred and twenty-seven patients (4.6%) of all blunt trauma patients were studied and 244 were diagnosed with BCVI for a screening yield of 34%.24 An isolated cervical seat belt sign without other risk factors and normal physical exam has failed to be identified as an independent risk factor in two retrospective studies and should not be utilized as the sole criteria to stratify patients for screening.25, 26 © Copyright 2007 – The Eastern Association for the Surgery of Trauma Table 1 Screening Criteria for BCVI adapted from Biffl et al9 (with permission) Table 2 Signs/symptoms of BCVI • Arterial hemorrhage • Cervical bruit • Expanding cervical hematoma • Focal neurological deficit • Neurologic examination incongruous with CAT scan findings • Ischemic stroke on secondary CAT scan Risk factors for BCVI • High-energy transfer mechanism with o Lefort II or III fracture o Cervical spine fracture patterns: subluxation, fractures extending into the transverse foramen, fractures of C1-C3 o Basilar skull fracture with carotid canal involvement o Diffuse axonal injury with GCS ≤6 o Near hanging with anoxic brain injury Denver Modification of Screening Criteria for BCVI adapted from Cothren et al59 (with permission) Injury mechanism • Severe cervical hyperextension/rotation or hyperflexion, particularly if associated with o Displaced midface or complex mandibular fracture o Closed head injury consistent with diffuse axonal injury • Near hanging resulting in anoxic brain injury Physical signs • Seat belt abrasion or other soft tissue injury of the anterior neck resulting in significant swelling or altered mental status Fracture in proximity to internal carotid or vertebral artery • Basilar skull fracture involving the carotid canal • Cervical vertebral body fracture © Copyright 2007 – The Eastern Association for the Surgery of Trauma Screening Modality Duplex Sonography Multiple studies have shown that duplex sonography is not sensitive enough for screening for BCVI with an overall sensitivity from as low as 38.5%27 to as high as 86% (the latter for carotid injuries alone).28, 29 Duplex US cannot be recommended as a screening modality for BCVI. Angiography Arguments have been made that DFVCA, in an appropriate group is safe, sensitive, and cost effective. Biffl et al report a 27% rate of positive screening angiogram when asymptomatic patients were screened according to the criteria in Table 1.30 Cothren31 utilized DFVCA in 727 asymptomatic patients that met screening criteria (Table 2) in which he found 244 patients with injury (34% screening yield). In patients who were initially asymptomatic and could not have antithrombotic therapy there was a 21% (10/48) rate of ischemic neurologic event (INE) whereas in those treated with either heparin, low molecular weight heparin, or antiplatelet agents only one of 187 had an INE. Using this internal data Cothren estimated that the identification and treatment of asymptomatic BCVI in these 187 patients prevented 32 strokes. This comes at an expense (charge data) of $6500 per angiogram for a total of approx. $154 000 per stroke avoided. Cothren concludes that this is cost-effective and screening with DFVCA should be pursued. The argument against the utilization of DFVCA (aside from that against screening per se) is that it is expensive (approx $1500)32, carries an inherent risk of stroke (1-2%)33 and is impractical to apply at many institutions.34 Magnetic Resonance Angiography In so far as MRA is non-invasive and requires no contrast administration MRA/MRI has been gaining popularity as an alternative to DFVCA for the diagnosis of BCVI. Although a number of studies describe the use of MRA to identify BCVI 35, 36, 37, 38 at this time the few direct studies that do exist indicate that sensitivity and specificity is significantly lower than that of DFVCA. In a (albeit small) direct comparison of MRA vs. angiography Miller et al found a sensitivity of 50% for CAI and 47% for VAI.39 Levy also reported a significantly lower sensitivity for MRI and MRA than angiography for the diagnosis of BCVI.40 It seems that, based on this data MRA cannot be recommended as the sole modality for the screening of BCVI. Computed Tomographic Angiography Early CT angiography with 1 to 4 slice scanners is not sensitive enough to qualify as an adequate screening modality for BCVI. In a prospective study of CTA on a single slice scanner vs. DFVA Biffl et al report a sensitivity and specificity of 68% and 67% respectively.41 Similarly Miller et al compared 4-slice CTA vs. DFVCA and showed that CTA performed poorly with a sensitivity of 47% for CAI and 53% for VAI.42 Sensitivity and specificity seems to improve in direct relationship to improvements in technology, however. In a prospective study which included images obtained from single, four and eight-slice scanners Bub reports improvement in image quality and concomitant improvement in sensitivity and specificity as the number of detectors increases. The overall results for the mixed population (reported as ranges from different observers) was © Copyright 2007 – The Eastern Association for the Surgery of Trauma 83-92% sensitivity and 88-92% specificity for the carotid artery and 50-60% sensitivity and 90-97% specificity for the vertebral artery.43 Berne et al screened patients with 4- slice and, later, 16-slice scanner CTA in a study in which only positive CTA studies underwent confirmatory angiography showing an overall sensitivity (for symptomatic BCVI) and specificity of 100% and 94% respectively. Interestingly the incidence of BCVI detected went up from 0.6% with the earlier machine to 1.05% with the newer device, approaching historic incidence of BCVI as diagnosed by DFVCA and the comparative specificity improved from 90.8% to 98.7%.44 In a follow-up study Berne et al screened patients for BCVI solely with a 16-slice scanner. In this prospective study Berne showed that the detected incidence of BCVI goes up threefold when changing from a 4-slice scanner to a 16-slice scanner with a resulting incidence of 1.2% which is similar to that found by screening with DFVCA.45 In a similar study in which only positive 16-slice CTA studies were followed by DFVCA, Biffl et al reversed an earlier recommendation46 that CTA was not adequate for screening for BCVI reporting a sensitivity of 100% for symptomatic BCVI.47 Schneidereit and colleagues report similar findings and give a diagnosed incidence for BCVI of 1.4% using a 16-slice scanner.48 Although these studies are interesting obviously a true sensitivity can only be obtained via direct comparison between CTA and DFVCA. At this time only one study has directly compared 16-slice CTA vs. angiography for screening for BCVI. Eastman et al performed 162 CTAs followed by 146 confirmatory DFVA studies (12 patients refused consent, 4 were discharged, and 6 died of non-neurologic causes prior to the study being obtained). Twenty carotid injuries and 26 vertebral artery injuries were identified with one false negative CTA (a grade I vertebral artery injury) for a screened population incidence of 28.4% and an overall incidence of 1.25%. The overall sensitivity, specificity, positive predi