Seat Belt Sign on the Neck Is a Serious Finding

 

 
 
 

Adam Fox, DPM, DO | Edward T. Dickinson, MD, NREMT-P, FACEP | From the April 2010 Issue | Wednesday, April 28, 2010


You and your partner are dispatched to a possible cerebrovascular accident (CVA). En route to the scene, you review the mobile data terminal update and are surprised that the patient’s age is 25. Somebody that young is having a stroke? 

You arrive on scene to find a young male in obvious distress, with right-sided weakness and trouble forming his words. The family reports he was healthy prior to his involvement in a car crash yesterday. They tell you he refused care from EMS at the time because he had complained only of pain over his left collarbone and neck and thought it was caused by the seat belt. His mother adds that she’s glad he had his seat belt on because "the car was destroyed." 

On examination, his ABCs appear to be fine, but his Cincinnati Stroke Screen is positive for right-sided arm weakness and an expressive aphasia. On secondary survey, you also note deep, linear abrasions over the left side of his neck. 

You initiate your normal CVA protocol (administer IV saline at 125 cc/hr, check his blood sugar, place an ECG monitor and place him in a supine position). You also board and collar him due to the motor vehicle collision (MVC) history and his now-evident neurological deficits. 

You transport the patient to the regional trauma center, where it’s discovered that he suffered an injury to his left carotid artery that caused his CVA.

The Seat Belt Sign
The seat belt sign -- an abrasion/hematoma in an area where the seat belt contacts a person's body -- has classically been thought of as involving the abdomen and possibly the chest. Because the sign marks a potential injury in the underlying cavity, much has been written about examining patients for its presence. 

The abdominal seat belt sign has long been a predictor of a potentially significant underlying intra-abdominal injury. Multiple studies have demonstrated the association of the abdominal seat belt sign and injuries to the lumbar spine, the abdominal organs and its mesentery.(1)

Recently, the importance of the seat belt sign of the neck has come to be considered significant. So, it’s important for EMS personnel to suspect and assess for serious injury when linear abrasions or bruising from the seat belt are discovered on any part of the body during primary or secondary trauma survey.

Finding a seat belt sign should prompt you to perform a more thorough examination. It’s important to recognize that the neck is traditionally immobilized in a rigid cervical collar very soon after a blunt injury, often by first responders prior to the arrival of the ambulance crew. Keep in mind that this might obscure and prevent a thorough exam of the neck. You must therefore visually inspect all potentially injured areas before (or after) they are covered by a device, sheet, blanket, etc. 

Neck Anatomy
The anatomy of the neck is complex. In addition to bone and soft tissue, there are many structures that can be injured in blunt trauma. It is, however, the carotid and vertebral arteries that are a concern when a neck seat belt sign is seen. 

Blunt carotid artery injury (BCAI) and blunt vertebral artery injury (BVAI) are usually grouped under the umbrella term, "blunt cerebrovascular injury" (BCVI), but certain injury patterns may predispose to one or the other. Both the carotid and vertebral arteries have their origins in the chest.

The vertebrals begin in the root of the neck as branches of the subclavian arteries. They then run cephalad on either side of the neck, passing through the transverse foramina of the first six cervical vertebrae and then into the skull through the foramen magnum. They reunite to form the basilar artery. 

The carotid arteries begin in the chest, coming off the aorta, and then ascend on either side of the anterior neck, where they divide into internal and external branches. The internal carotid then goes on to help form the circulation of the brain.

Diagnosing BCVI 
Multiple studies over the past decade have discussed the significance of BCVI. It turns out that the number of BCVI is higher than originally thought, mostly due to an increased amount of screening for it.(2) It has also been found that the sequelae of these injuries are worse than originally thought. The incidence of this injury process is between 1–2% of blunt trauma patients.(3-6)

If an injury of this type does in fact occur, the results -- usually a neurologic deficit in the form of a stroke -- may be devastating. Mortality alone has been described between 25–59%.(3-6,7)

Although the trauma community has known about these injuries for some time, there have been problems determining which patients to screen and how to actually make the diagnosis. External signs or neurologic deficits are usually enough to prompt investigation, but their absence isn’t enough to say there’s no underlying injury. 

Additionally, no literature suggests how often this sign exists in relation to a BCVI. So, without external injury or neurologic deficits, the need to develop a policy for screening at-risk patients for BCVI has become paramount. 

With the frequent absence of any external signs, patient screening has become the standard. Although no true consensus has been agreed upon, some injuries have been found more likely to be associated with BCVI (See Table 1, p. 34). The common underlying theme behind a BCVI is a high-energy mechanism to the torso, neck and head. From this, some potential screening triggers for BCVI have been developed (See Table 2). 

Prehospital Care 
Prehospital care for patients with potential BCVI is consistent with standard trauma care. However, special attention to the mechanism of injury and a compulsive physical examination of the neck prior to (or after) placement of a cervical collar is essential to identifying patients with potential BCVI. All patients with the cervicothoracic seat belt sign should be transported to a trauma center for further evaluation.

Because of the ultimate need to prevent a stroke, anticoagulation, antiplatelet therapy and vascular stenting (performed in the hospital using a metal tube to hold open a vessel) has become the mainstay of treatment for the BCVI. Although the optimal treatment has also been an ongoing source of research and controversy, outcomes are improved with some treatment rather than none. 

Other hospital treatment options include endovascular interventions (access to blood vessels via a needle stick), such as coil embolization and stenting, anticoagulation and antiplatelet agents and surgery. These endovascular interventions tend to be used in patients for whom medical therapy is contraindicated. 

Medical therapy has been divided into anticoagulation (Heparin and Coumadin) and antiplatelet agents (aspirin and Plavix). It’s not known which therapy is optimal or for how long treatment should take place. Recommendations have been made in the trauma literature that anticoagulation be the first-line therapy followed by antiplatelet agents given to patients for whom anticoagulation was contraindicated.

Summary
The seat belt sign as it extends to the neck can indicate underlying vascular injury. Existence of a carotid or vertebral artery injury is suggested by multiple injury mechanisms, signs or associated injury. We should have a high suspicion for BCVI when the seat belt sign is found. Failure to do so can result in potentially devastating consequences for our patient populations.

Significant Injuries Associated with BCVI
>> Head injury
>> Basilar skull fracture
>> Facial fracture
>> Other neck injury
>> Thorax injury
>> Abdominal injury

Potential Screening Triggers for BCVI

Mechanism
>> Hyperextension or hyperflexion of neck
External Signs
>> Seat belt signs
Neurological Deficits
>> Unexplained neurologic deficits
>> Diffuse axonal injury
>> Transient ischemic attack/cerebrovascular accident
Associated Injuries
>> LeFort (serious) facial fractures
>> Cervical spine fractures
Other spine fractures
>> Complex mandibular fractures
>> Basilar skull fractures

References

  1. 1. Bansal V, Conroy C, Tominaga GT, et al. The utility of seat belt signs to predict intra-abdominal injury following motor vehicle crashes. Traffic Injury Prevention. 2009;10:567–572.
  2. 2. Stein D, Boswell S, Sliker CW, et al. Blunt cerebrovascular injuries: Does treatment always matter? J Trauma. 2009;66:132–144.
  3. 3. Miller PR, Fabian TC, Croce MA, et al. Prospective screening for blunt cerebrovascular injuries: An analysis of diagnostic modalities and outcomes. Ann Surg. 2002;236:386–395.
  4. 4. Schneidereit NP, Simons R, Nicolaou S, et al. Utility of screening for blunt vascular neck injuries with computed tomographic angiography. J Trauma. 2006;60:209–216.
  5. 5. Utter GH, Hollingworth W, Hallam DK, et al. Sixteen slice CT angiography in patients with suspected blunt carotid and vertebral artery injuries. J Am Col Surg. 2006;203:838–848.
  6. 6. Cothren CC, Moore EE, Biffl WL, et al. Anticoagulation is the gold standard therapy for blunt carotid injuries to reduce stroke rate. Arch Surg. 2004;139:540–546.
  7. 7. Berne JD, Norwood SH, McAuley CE, et al. The high morbidity of blunt cerebrovascular injury in an unscreened population: More evidence for the need for mandatory screening protocols. J Am Coll Surg. 2001;192:314–321.

 

This article originally appeared in April 2010 JEMS as "Neck & Neck: Seat belt sign on the neck is as serious a finding as on the abdomen."




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Related Topics: Patient Care, Trauma, seatbelt sign of the neck, seatbelt sign of the abdomen, Jems Case of the Month

 

Adam Fox, DPM, DOis a trauma surgeon and assistant professor in the Division of Traumatology and Surgical Critical Care at the Hospital of the University of Pennsylvania, Philadelphia, as well as a JEMS editorial board member. He spent 10 years as an New York State AEMT-CC.

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Edward T. Dickinson, MD, NREMT-P, FACEPis an associate professor and director of prehospital field operations in the Department of Emergency Medicine, Hospital of the University of Pennsylvania in Philadelphia.

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