The Abbreviated Injury Scale Score as related to head injuries may not relate as closely to the clinical outcome as in some other injuries. Most often injuries are based on the CT findings on initial presentation. The long term morbidity of head injuries in trauma patients is well established, though in much of the published data, the presence of a head injury and a severe ISS are often evaluated separately during multivariate logistic analyses. Injuries to brain structures or vasculature are all attributed AIS scores of 3–5 translating to a 9–25 point contribution to the overall ISS. Even clinical evidence of a TBI in the absence of anatomic injury such a clinically diagnosed concussion can carry a significant AIS score of 2–4.

Screening evaluation of the cervical spine should be considered in essentially all patients who suffer from blunt trauma. This includes clinical evaluation as well as typically radiographic evaluation. Current recommendations from the Eastern Association for the Surgery of Trauma (EAST) Practice Management Guidelines Committee are to perform initial evaluation with CT imaging for any patient with a high risk mechanism of injury which include motor vehicle crash (MVC) at >35 mph, fall from >3 ft, any neurologic deficit, when the mechanism includes an axial load on the spine, in those 65 years of age or older, or when a neurologic deficit is present [12]. In the absence of any of these CT is still indicated if the patient has any pain, tenderness, or altered mental status during the attempt to clinically clear the patient’s cervical spine. If the CT is felt to be negative after being evaluated by a trained surgeon or radiologist, accuracies of >99 % for excluding injury are often reported, with missed injuries usually of no clinical significance. Even with normal imaging, clinical evaluation should be performed prior to cervical collar removal. In patients who have pain with active range of motion despite a normal CT scan, the practitioner can choose to perform an MRI or repeat the clinical exam in 7–10 days prior to removing the collar. In patients with abnormal cervical spine CT scans, immediate consultation with a Neurosurgeon or Orthopedic Surgeon is indicated.

As with cervical spine screening, identifying unstable thoracolumbar fractures are important due to potential spinal cord compromise, so screening imaging should be considered in many cases of blunt traumatic injury [13]. As stated before, there is a 10 % rate of non-contiguous vertebral fractures with the first detected not always being the most clinically significant. Also as with the cervical spine, EAST Guidelines recommend CT as the modality of choice for screening evaluation of the thoracolumbar spine [14]. There are several reasons for this. X-ray has consistently been found to have a relatively low sensitivity for detecting injury ranging from 25 % to 75 % compared to >95 % for CT. Additionally, patients who would require imaging of their thoracic or lumbar spine based on mechanism such as fall >10 ft, high speed MVC, motor pedestrian crashes, or those who report back pain or tenderness often also meet criteria to have further thoracic or abdominal imaging. Protocols for Chest, Abdomen, and Pelvis CT scans for trauma now can include dedicated reformats of the thoracic and lumbar spine without need for additional time or radiation exposure.

Other unique fractures of the cervical spine include atlanto-occipital instability, C1, and C2 fractures. Occipital condyle fractures are often seen of CT imaging but frequently carry little clinical significance. Dens fractures are more often associated with spinal instability. They are classified as Type 1, involving just the tip of the dens, Type 2, involving the base (most common) and Type 3, involving the C2 body. Injury to the spinal cord at these levels can cause devastating neurologic outcomes including quadriplegia and death. Therefore early consultation with a Neurosurgeon or Orthopedic Surgeon is necessary to help determine the stability of the affected area [15]. MRI may be needed to evaluate ligamentous injury, and stabilization with either an aspen collar, halo vest device, or surgical fixation may be needed early in the course (Fig. 3.5).

Compression and Burst fractures occur as the result of axial load forces on the spinal cord. The most common compression fractures are anterior wedge compression fractures which occur as a result of hyper flexion as the upper body and torso continue travel forward while the lower body is restrained during deceleration. Wedge compression fractures typically only involve the anterior column and therefore are less likely to cause spinal instability. Burst fractures are more severe as they can involve both the anterior and middle columns and can have retropulsion into the spinal canal causing direct cord compromise. They are significant based on the effect they have on alignment, vertebral body height loss, percentage of canal compromise (increasing risk of cord damage) and risk of injury to the posterior longitudinal ligament leading to instability [16, 17]. Fractures in the lumbar region are often of greater concern due to the increased axial load on these vertebrae when standing, the altered directions of the forces due to the natural lordosis of the region and lack of stabilization by the rib cage that the thoracic vertebrae have (Figs. 3.6 and 3.7).

Flexion distraction injuries as described by Denis are unstable fracture patterns due to injuries of the middle and posterior columns usually due to hyperflexion injuries with vertebral compression while the most serious fracture dislocations usually result in jury to all three columns as a result of hyperextension or hyperflexion. Chance Fractures are similar to flexion distraction injuries however a fracture line in the axial plane of the vertebral body and spinous process forms rather than a compression fracture. These bony fractures are seen best on CT imaging though, there is a low threshold for MRI to evaluate for cord injury when any potential for neurologic deficit exists (Figs. 3.8 and 3.9).

Isolated transverse process (TP) fractures thoracolumbar spine are typically not clinically significant from a spinal stability standpoint and usually do not require special precautions or surgical evaluation. However, in the cervical spine, TP fractures will often include the transverse foramen. This injury pattern does not carry major significance to the spinal column or spinal cord but does warrant investigation of the vertebral artery with CT angiography (will be discussed further later in this chapter) (Fig. 3.10).

Injuries to the ligamentous structures and spinal cord are not well seen on CT. Ligamentous injuries are extremely rare in the thoracolumbar spine in the absence of bony injury however persistent midline pain in the cervical spine despite a normal CT scan can warrant MRI prior to removal of a c-collar as a final method of excluding ligamentous injury. Fractures causing narrowing of the canal, clinical neurologic deficits, or unstable spine injuries seen on initial CT imaging can guide the clinician to pursue MRI imaging for evaluation for spinal cord infarcts, hemorrhages, contusions and epidural hematomas not seen on CT (Figs. 3.11 and 3.12).

As stated at the beginning of this section, injuries to the spinal column are assigned AIS scores in the area through which that portion traverses. Injuries to the brachial plexus are also included with the cervical spine. Cord injuries are assigned considerably higher values, often 4–5, regardless of the presence of a fracture based on the associated morbidity. Higher injuries (above C3) are also scored higher. Dedicated spinal cord imaging, usually MRI, is needed to assign these scores radio graphically unless CT shows obvious evidence of major cord injury. However, as imaging purely for the purposes of AIS scoring is not recommended, clinical evidence of a cord injury can be sufficient to assign an AIS score. Scores for fractures and dislocations are assigned based on imaging, however their inclusion in the patient’s ISS will only occur in the setting of no damage to the cord as the scores range from 1 to 3.

The AIS grading for extracranial carotid and vertebral injuries are scored in the neck section. Though the AIS system does not perfectly correlate with the Blunt Carotid Injury Grading Scale CTA or angiographic findings do help with injury scaling. Also, as with spinal cord trauma, the presence of neurologic deficits also can increase the AIS score for a specific arterial injury. Venous injuries, also included in the system are of more concern in non accidental and penetrating trauma. Lastly, though not described in detail here, injury to other structures of the neck including the thyroid and salivary glands, laryngeal and pharyngeal structures, and hyoid bone are also scored in this section.

Injuries included in the Face category of the AIS, including the eye and ear, are heavily biased towards bony fractures. The only nerve included in this area is the intraorbital portion of the optic nerve. Injuries to the globe itself, though often morbid due to impairment in vision, still receive fairly low AIS scores of 1 or 2. Fractures to the Mandible, Maxilla, and Orbit also carry reasonably low scores despite the fact they can require multiple operations and carry long term consequences in altering the cosmetic appearance of the face and in affect the psychologic recovery of the patient. Complex fractures of the maxilla that involve deeper bony structures including the pterygoid or sphenoid bones can lead to an overall higher ISS score as they are coded in both the facial and head categories (assuming no other intracranial injuries are present).

In the vast majority of patients with blunt cardiac injury, the injury does not pose significant danger, and those with the most significant injuries often do not survive long enough for them to be recognized. Screening for blunt cardiac injury begins with obtaining an Electrocardiogram (ECG) on arrival to the hospital in patients with a suspected injury and abnormality noted on telemetry [21]. Significant chest wall trauma should be an early warning sign, however studies have shown sternal fractures alone are infrequently associated with blunt cardiac injury [22]. The most common ECG findings include unexplained sinus tachycardia, frequent premature ventricular contractions, arrhythmias, heart block, or signs of ischemia. Though FAST exam in the hands of an experienced operator can help identify some of the more significant valvular disruptions and pericardial bleeding, ECG remains the screening modality of choice, with a negative predictive value (NPV) of >95 %. Cardiac enzymes including Troponin I have been evaluated as an additional measure, but have been found to be more indicative of cardiac ischemia than an actual cardiac injury [23]. If tested and elevated, concomitant myocardial infarction should be appropriately excluded, as elderly trauma patient can be at increased risk of MI as an inciting event or as a result of trauma. In patients with ECG abnormalities concerning for a blunt cardiac injury or otherwise unexplainable hemodynamic compromise, formal 2D Echocardiogram transthoracic or trans esophageal should be performed as a diagnostic test [24]. Screening with echocardiogram is not recommended due to the cost and low yield in low risk patients. Lastly, the role of CT and MRI in evaluation has long been limited by their speed and poor ability to detect abnormalities in a beating heart. As the technology improves especially with MDCT and the advent of ECG gated image acquisition, their role may expand. Presently, the utility of ECG gated imaging is limited to case reports and series and the feature is not widely available or part of most trauma imaging protocols.

Chest wall injuries, fractures of the ribs are among the most common injuries following blunt trauma, occurring in up to 70 % of injured patients, with injury to the underlying lung occurring frequently, even without bony fracture [25]. In selected young otherwise healthy patients with minimal associated injuries, non-displaced rib fractures with minimal symptoms can be insignificant enough to allow discharge directly from the emergency department. However, often times rib fractures carry a significant morbidity and mortality, especially in older patients, and therefore identifying them to develop an appropriate plan of care and rule out injuries to the lung is important. Fractures to >3 ribs has been suggested as potential criterion for transfer to a trauma center, and rib fractures in patients over the age of 65 are associated with a significantly increased morbidity and mortality. Chest wall imaging begins with the initial Chest X-ray during the Primary or Secondary Survey. Significant hemothoraces or pneumothoraces may require intervention at that time. A normal supine chest X-ray in an otherwise hemodynamically normal patient without a concerning mechanism of injury can be enough information to exclude the need for further CT imaging.