Evaluation of patients after penetrating neck injury has evolved over time. Previously, location of injury and symptoms were used to determine management. The contemporary management of penetrating neck injuries relies on physical examination. Patients with hard signs of vascular or aerodigestive tract injury require immediate operation, regardless of location of injury. Those with no signs can be observed. For the remainder with soft signs, multidetector computed tomographic angiography (MDCTA) is a highly sensitive and specific screening modality for evaluating the vasculature and aerodigestive structures in the neck. Utilizing MDCTA, the patient can be safely directed towards operative intervention, observation, or further investigation.

Keywords: Angiography, clinical decision-making, computed tomography, neck injury, penetrating trauma

Initial management of the patient with penetrating trauma proceeds in accordance with the general principles articulated by the American College of Surgeons Advanced Trauma Life Support (ATLS) course. Airway, breathing, and circulation are evaluated, and immediate life threats addressed. Current assessment of a patient with penetrating neck trauma integrates clinical findings with additional results, in clinically stable patients, from selective diagnostic investigation. Clinical findings have been traditionally classified as “hard” or “soft,” depending on whether obvious evidence of vascular or aerodigestive injury is present. “Hard” signs include active hemorrhage, shock unresponsive to initial fluid therapy, a pulsatile or expanding hematoma, bruit, or thrill, massive hemoptysis or hematemesis, or air bubbling through the wound. Patients presenting with “hard” signs require emergent operative exploration. “Soft” signs include venous oozing, non-expanding or non-pulsatile hematoma, minor hemoptysis, dysphonia, dysphagia, and subcutaneous emphysema. These patients, if they remain clinically stable, are suitable for further investigation. The site of anatomic injury, classified by dividing the neck into three distinct “zones,” has also traditionally been used to determine the need for operative exploration or selective diagnostic investigation. Zone 1 extends from the clavicles to the cricoid cartilage; zone 2, from the cricoid cartilage to the angle of the mandible; and zone 3, from the angle of the mandible to the base of the skull. A presumptive direct relationship between the superficial site of trauma and underlying injury to deeper structures underlies this approach. Zone 2 injuries are the most accessible to direct surgical exploration, whereas wounds in zone 1 and zone 3 are often challenging or inaccessible for surgical intervention and are best served by less-invasive diagnostic and therapeutic approaches. Although commonly utilized, this anatomic distinction can be problematic as an entry wound in zone 2 could easily affect structures in zone 1 or zone 3 without this being immediately apparent from the superficial wound site.

Previous to the evolution of MDCTA, conventional catheter-based angiography was the standard technique for evaluation of cervical vasculature injury. Although highly accurate, this technique is limited by logistic considerations as well as its invasive nature. Conventional angiography requires mobilization of a specialized team, composed of both radiologists and non-physician technical staff, a resource often unavailable with the 24-hour coverage required for the continuous care of trauma patients. Even in centers with on-call interventional radiologic teams, the time required to mobilize this group will often preclude their ability to assist with diagnosis and operative planning in all but the most stable of patients. Additionally, conventional angiography is associated with a low but nonetheless significant local complication rate. Dissection, thrombosis, or pseudoaneurysm of the access vessel; formation of an embolizing plaque; or local hematoma may all complicate conventional angiographic access.

Evaluation of the aerodigestive tract has traditionally been dependent on multiple, invasive modalities, including flexible fiberoptic laryngoscopy, esophagoscopy, bronchoscopy, and contrast esophagraphy. These methods are time-and resource-consuming, costly, and typically associated with low diagnostic yield when used as screening tools. As MDCTA technology increases in accuracy, the indications for these investigations are being increasingly re-evaluated.

At the Los Angeles County—University of Southern California (LAC+USC) Medical Center, the standard MDCTA neck protocol uses the following parameters: 120 kVp, 100 mA to 250 mA (depending on size of the patients, using dose modulation), gantry revolution speed of 0.5 second, beam pitch 0.656, beam collimation of 64 mm × 0.5 mm, variable field of view (depending on patient size), and standard body kernel. A line suitable for power contrast injection (18–20 gauge peripheral IV line in the antecubital fossa or a central venous catheter approved by the manufacturer for power injection) is utilized for injection of 75–100 mL of iohexol iodinated IV contrast material (Omnipaque 350; GE Healthcare, Princeton, NJ) at a rate of 4–5 mL/s, followed by a 40-mL saline flush, all administered by a Medrad power injector (Spectris; Medrad, Indianola, PA). Contrast bolus tracking with a trigger threshold of 180 HU is used with the region of interest placed in the carotid artery at the C2–3 level. Reconstruction with section thickness of 1 mm in the axial, coronal, and sagittal planes is performed and additional post-processing accomplished using a Vitrea reformatting workstation (Vital Images, Plymouth, MN), creating volume renderings, maximum intensity projections, and curved planar reformats as needed.

MDCTA is integrated into the diagnostic algorithm for neck injury at the LAC+USC Medical Center, used in conjunction with physical exam findings and plain radiographs. Through these modalities patients are selected for observation, operative or endovascular intervention, or further invasive diagnostic testing. Hemodynamic instability or “hard” signs of injury mandate immediate operative exploration. Asymptomatic patients, or those without signs of obvious injury, undergo observation. Patients who are clinically stable but possess “soft” signs of injury are further evaluated with a screening MDCTA. Positive findings prompt appropriate operative, endovascular intervention or further invasive investigation with traditional modalities (esophagram/esophagoscopy and bronchoscopy) in those with potential aerodigestive injury. In the presence of significant foreign body artifact or other technical limitation, or for studies that remain equivocal yet concerning, conventional angiography is employed.

Evaluation of the patient with penetrating neck trauma has traditionally relied primarily on physical exam findings and assessment of patient hemodynamics, in association with selective multi-modal, invasive investigation to rule out vascular or aerodigestive injury in clinically stable patients. Although an effective strategy, and much superior to previous policies of routine exploration for penetrating injury, this approach still relies heavily on resource-intensive and invasive exams. A protocol-driven approach, integrating MDCTA with physical exam findings, and the clinical distinction of “hard” signs, “soft” signs, and “no” signs of vascular or aerodigestive injury, minimizes both the rate of negative explorations and the need for further invasive testing, decreasing overall resource burden and preventing unnecessary patient morbidity. Patients with hard signs proceed directly to the operating room. Completely asymptomatic patients may be observed. In those with soft signs, initial screening with MDCTA has high sensitivity for vascular injury and allows risk stratification of patients with possible aerodigestive trauma for further diagnostic investigation or intervention. MDCTA should be the first-line test in the evaluation of these patients. Patients with negative MDCTAs can be safely observed and discharged. Clinically stable patients with equivocal or concerning MDCTA findings should undergo appropriate further evaluation with traditional angiography, contrast studies, or endoscopy.