Value of Emergent Neurovascular Imaging for "Seat Belt Injury": A Multi-institutional Study

BACKGROUND AND PURPOSE

Screening for blunt cerebrovascular injury in patients after motor vehicle collision (MVC) solely based on the presence of cervical seat belt sign has been debated in the literature without consensus. Our aim was to assess the value of emergent neurovascular imaging in patients after an MVC who present with a seat belt sign through a large-scale multi-institutional study.

MATERIALS AND METHODS

The electronic medical records of patients admitted to the emergency department with CTA/MRAs performed with an indication of seat belt injury of the neck were retrospectively reviewed at 5 participating institutions. Logistic regression analysis was used to determine the association among age, sex, and additional trauma-related findings with blunt cerebrovascular injury.

RESULTS

Five hundred thirty-five adult and 32 pediatric patients from June 2003 until March 2020 were identified. CTA findings were positive in 12/567 (2.1%) patients for the presence of blunt cerebrovascular injury of the vertebral (n = 8) or internal carotid artery (n = 4) in the setting of acute trauma with the seat belt sign. Nine of 12 patients had symptoms, signs, or risk factors for cervical blunt cerebrovascular injury other than the seat belt sign. The remaining 3 patients (3/567, 0.5%) had Biffl grades I-II vascular injury with no neurologic sequelae. The presence of at least 1 additional traumatic finding or the development of a new neurologic deficit was significantly associated with the presence of blunt cerebrovascular injury among adult patients, with a risk ratio of 11.7 (P = .001). No children had blunt cerebrovascular injury.

CONCLUSIONS

The risk of vascular injury in the presence of the cervical seat belt sign is small, and most patients diagnosed with blunt cerebrovascular injury have other associated findings. Therefore, CTA based solely on this sign has limited value (3/567 =  a 0.5% positivity rate). We suggest that in the absence of other clinical findings, the seat belt sign does not independently justify neck CTA in patients after trauma.

The Utility of a Screening Neck Computed Tomographic Angiogram in Blunt Trauma Patients Presenting With a Seat Belt Sign in the Absence of Associated Risk Factors

OBJECTIVE

Blunt cerebrovascular injuries (BCVI) of the neck are a common cause for concern after blunt trauma. The purpose of this article is to demonstrate whether patients with a cervical seat belt sign in the absence of associated high-risk injuries or neurological symptoms are at an increased risk for developing a clinically significant vascular injury and therefore require a screening neck computed tomographic angiography (CTA).

METHODS

A retrospective review was performed of patients who presented after motor vehicle collision and received a neck CTA for an indication of "seat belt sign." Imaging was reviewed to determine the vascular injury grade, associated injuries, and, if available, follow-up imaging was reviewed to assess for interval change or resolution. The patients were split into 2 groups. Group 1 included patients without high-risk injuries, and group 2 included patients with high-risk injuries.

RESULTS

In group 1, 6 (2.9%) of 208 patients had BCVI. In group 2, 7 (18.9%) of 37 patients had BCVI. Patients in group 2 were 6.5 times more likely to suffer BCVI compared with group 1 (P < 0.001). No patient in group 1 was ever symptomatic, and only 1 (0.5%) patient underwent interventional treatment.

CONCLUSIONS

Patients presenting after blunt trauma with a seat belt sign and no other high-risk injuries as laid out by screening criteria demonstrate a low probability of BCVI and an even lower likelihood of adverse outcome.

Pattern Recognition: A Mechanism-based Approach to Injury Detection after Motor Vehicle Collisions

Motor vehicle collisions cause substantial mortality, morbidity, and expense worldwide. Certain types of injuries are more likely to result from frontal versus side-impact collisions, and knowledge of these specific patterns and why they occur aids in accurate and efficient diagnosis of traumatic injuries. Although the proper use of seat belts decreases crash-related mortality during frontal impact, certain injury patterns to the torso are directly attributed to restraint use. The spectrum of seat belt-related injuries ranges from mild skin and soft-tissue contusions to traumatic bowel injuries and unstable spine injuries that require surgery. Impact with the steering wheel or windshield during a frontal crash can cause characteristic injuries to the head, neck, torso, and distal upper extremity. Steering wheel deformity is an independent predictor of serious thoracic and abdominal injury among front-seat passengers. Impact of a flexed knee with the dashboard during a frontal collision can cause knee, thigh, and hip injuries. Distal lower extremity injuries are encountered frequently when the floorboard is driven into the foot. Lateral impact crashes often result in traumatic brain, thoracic, abdominal, and pelvic injuries, which are more often fatal to occupants on the side of the impact. The specific mechanism-based injury patterns are reviewed to establish a structured systematic search pattern that enables the radiologist to identify traumatic injuries with greater accuracy and speed, thereby improving the care of patients who experience acute trauma. ^©RSNA, 2019 See discussion on this article by Ballard and Mellnick .

Risk Factors in Pediatric Blunt Cervical Vascular Injury and Significance of Seatbelt Sign

Introduction

Computed tomography angiography (CTA) is used to screen patients for cerebrovascular injury after blunt trauma, but risk factors are not clearly defined in children. This modality has inherent radiation exposure. We set out to better delineate the risk factors associated with blunt cervical vascular injury (BCVI) in children with attention to the predictive value of seatbelt sign of the neck.

Methods

We collected demographic, clinical and radiographic data from the electronic medical record and a trauma registry for patients less than age 18 years who underwent CTA of the neck in their evaluation at a Level I trauma center from November 2002 to December 2014 (12 years). The primary outcome was BCVI.

Results

We identified 11,446 pediatric blunt trauma patients of whom 375 (2.7%) underwent CTA imaging. Fifty-three patients (0.4%) were diagnosed with cerebrovascular injuries. The average age of patients was 12.6 years and included 66% males. Nearly half of the population was white (52%). Of those patients who received CTA, 53 (14%) were diagnosed with arterial injury of various grades (I-V). We created models to evaluate factors independently associated with BCVI. The independent predictors associated with BCVI were Injury Severity Score >/= 16 (odds ratio [OR] [2.35]; 95% confidence interval [CI] [1.11-4.99%]), infarct on head imaging (OR [3.85]; 95% CI [1.49-9.93%]), hanging mechanism (OR [8.71]; 95% CI [1.52-49.89%]), cervical spine fracture (OR [3.84]; 95% CI [1.94-7.61%]) and basilar skull fracture (OR [2.21]; 95% CI [1.13-4.36%]). The same independent predictors remained associated with BCVI when excluding hanging mechanism from the multivariate regression analysis. Seatbelt sign of the neck was not associated with BCVI (p=0.68).

Conclusion

We have found independent predictors of BCVI in pediatric patients. These may help in identifying children that may benefit from screening with CTA of the neck.

Shorter pregnant women restrained in the rear seat of a car are at risk for serious neck injuries: Biomechanical analysis using a pregnant crash test dummy

INTRODUCTION

When considering seat belt contacts to the neck in pregnant woman of shorter height sitting in the rear seat of a vehicle, subsequent injuries after a collision must be understood in the context of both maternal and fetal outcomes. To determine likely injuries to a pregnant woman sitting in the rear seat, we determined the kinematics of a "pregnant" crash test dummy by measuring neck compression forces and biomechanical parameters acting on the head and neck.

METHODS

Sled tests using a shorter-height pregnant woman crash test dummy (Maternal Anthropometric Measurement Apparatus, ver. 2B) were performed at the HYGE sled test facility representing full frontal impact at target velocities of 29km/h and 48km/h. Kinematics of the dummy and biomechanical parameters of the head, neck, and chest were measured. Pressure to the neck was measured using Prescale (Fujifilm, Tokyo, Japan).

RESULTS

During frontal collision tests, the shoulder belt compressed the neck at a pressure >12.8MPa, even during the low-velocity impact. In addition to neck flexion, right side bending and the head and chest moving in opposite directions were observed, with maximum differences of 42.4mm at high velocity and 33.7mm at low velocity.

CONCLUSIONS

This study provides data on the kinematics of pregnant women of short height sitting in the rear seat during a frontal collision using a pregnant woman crash test dummy. The knowledge gathered from this study should be useful for determining pregnant women passengers' kinematics at the time of collision and evaluating the relationship between the vehicle collision and fetal outcomes.

Neck seatbelt sign suspicion of injury score derived from emergency physician diagnostic imaging practice

Introduction

Neck abrasion/contusions from seatbelts after motor vehicle collisions may be associated with underlying bony or vascular injury. The decision to order imaging is highly subjective, and the yield is low. To date, there is no objective guidance in the literature regarding which patients need imaging. The aim of this study was to derive a scoring system from physical characteristics of seatbelt contusion photographs, based on emergency physician (EP) decisions to order imaging.

Methods

A survey of a convenience sample of practicing and academic EPs, given five photographs of a spectrum of seatbelt contusions and a standard brief patient description. Respondents were asked whether and which imaging they would perform for each photo. Respondents rated photos for overall clinical concern for underlying injury and for concern regarding color, size, depth, texture and location on a five-point Likert scale. Logistic regression to assess associations between these five features and overall clinical concern, and the strength of association between features, overall concern, and decision to image was conducted.

Results

Overall, 97 respondents (24% of those surveyed) provided 425 imaging decisions and 95% would image at least one hypothetical patient. However, 40% would not image at least one of the five patients. Decision to image for five photos ranged from 20.0% to 90.6%. Intra-class correlation coefficient for decision to image was fair (0.31, 95% CI 0.13–0.79), indicating variability in practice, and highlighting need for a scoring system. Computed tomography (CT) and CT angiography were used most often for bony and vascular imaging. A 12-point severity scoring system based on location, depth, size and color is proposed. This scale had strong correlation with decision to image (Pearson r = 0.94).

Conclusion

Physician practice shows variability in decision to image patients with neck seatbelt contusions after motor vehicle trauma. A proposed severity scoring system may begin to promote evidence based practice.

Imaging evidence and recommendations for traumatic brain injury: advanced neuro- and neurovascular imaging techniques

SUMMARY

Neuroimaging plays a critical role in the evaluation of patients with traumatic brain injury, with NCCT as the first-line of imaging for patients with traumatic brain injury and MR imaging being recommended in specific settings. Advanced neuroimaging techniques, including MR imaging DTI, blood oxygen level-dependent fMRI, MR spectroscopy, perfusion imaging, PET/SPECT, and magnetoencephalography, are of particular interest in identifying further injury in patients with traumatic brain injury when conventional NCCT and MR imaging findings are normal, as well as for prognostication in patients with persistent symptoms. These advanced neuroimaging techniques are currently under investigation in an attempt to optimize them and substantiate their clinical relevance in individual patients. However, the data currently available confine their use to the research arena for group comparisons, and there remains insufficient evidence at the time of this writing to conclude that these advanced techniques can be used for routine clinical use at the individual patient level. TBI imaging is a rapidly evolving field, and a number of the recommendations presented will be updated in the future to reflect the advances in medical knowledge.