Does a cervical seatbelt sign mandate advanced imaging?

You are working in the emergency department when EMS brings in a middle aged female who was the restrained driver in a low speed head-on MVC. In the emergency department, she is slightly hypertensive and complaining of generalized stiffness. Her physical exam (including C-spine exam and neurologic exam) is unremarkable with the exception of an abrasion to the left side of her neck without surrounding hematoma concerning for a cervical seat belt sign.

Clinical Question:

In this otherwise well appearing patient you wonder – what is the best course of action? Does the physical finding of a cervical seat belt sign warrant additional imaging for vascular injury, such as a CT-A?

Literature:

One study that addressed this question was a retrospective review of patients who received neck CT angiograms based on the presence of a seatbelt sign alone at a Level I trauma center from 2008-2010. Over this time period, 418 patients underwent a CT-A. Eleven patients had positive vascular findings, two with blunt carotid injury (BCA) – giving an overall frequency vascular injury of 2.6%. Importantly, all of the patients who were found to have vascular injuries had a cervical spine fracture, rib fracture, thoracic spine fracture, facial fracture, skull fracture, large hematoma on the neck or a combination of the above injuries. The correlation between seatbelt sign and positive CT-A finding was overall very weak (r = .007). The above findings lead the authors to reasonably conclude that CT-A of the neck vascular injury can be “safely reserved for patients with a seatbelt sign and obvious injuries on physical examination and/or positive findings on standard trauma imaging.”

A second study prospectively evaluated trauma patients with cervical or thoracic seatbelt signs at a level I trauma center over a 17 month period. Out of 131 trauma pts with cervical or thoracic seatbelt signs, four (3%) were found to have carotid artery injuries. The presence of a carotid injury was strongly associated with a GCS < 14 (p< 0.0003), ISS > 16 (p < .0001), and the presence of a clavicle or first rib fracture (p < .0037). No vascular injuries were identified in patients with thoracic-only seatbelt signs. Each of the four patients had at least one identifiable significant injury ranging from scalp laceration + extremity fracture to clavicle + bilateral superior rib fractures. The authors of this study concluded that the cervical-thoracic seatbelt sign combined with an abnormal physical examination is an “effective screening combination for cervico-thoracic vascular injury.”

Take Home:

CT-angiogram is not necessarily indicated based on the finding of a cervical seatbelt sign alone in the absence of significant hematoma, neurologic symptoms, or other traumatic injuries.

References:

1) Dhillon, Ramandeep Singh, et al. "Seatbelt sign as an indication for four-vessel computed tomography angiogram of the neck to diagnose blunt carotid artery and other cervical vascular injuries." The American Surgeon 79.10 (2013): 1001-1004.
2) Rozycki, Grace S., et al. "A prospective study for the detection of vascular injury in adult and pediatric patients with cervicothoracic seat belt signs." The Journal of Trauma and Acute Care Surgery 52.4 (2002): 618-624.