without gender predilection.

TBI can be a missile or nonmissile injury. Missile injury results

from penetration of the skull, meninges, &/or brain by an

external object (such as a bullet).

Nonmissile closed head injury (CHI) can be caused by direct

blows, blasts, or penetrating injuries. However, nonmissile CHI

is a more common cause of neurotrauma. High-speed

accidents exert significant acceleration/deceleration forces,

causing the brain to move suddenly within the skull. Forcible

impaction of the brain against the unyielding calvaria and

hard, knife-like dura results in gyral contusion. Rotation and

abrupt changes in angular momentum may deform, stretch,

and damage long vulnerable axons, resulting in axonal injury.

Classification of Head Trauma

The most widely used clinical classification of brain trauma,

the GCS, depends on the assessment of 3 features: Best eye,

verbal, and motor responses. With the use of the GCS, TBI can

be designated as mild (13-15), moderate (9-12), or severe (≤ 8).

TBI can also be divided pathoetiologically into primary and

secondary injuries. Primary injuries occur at the time of initial

trauma. Skull fractures, epi- and subdural hematomas,

contusion, and axonal injuries are examples of primary

traumatic injuries.

Secondary injuries occur later and include cerebral edema,

perfusions, and brain herniations. Large arteries, such as the

internal carotid, vertebral, and middle meningeal arteries, can

be injured either directly at the time of initial trauma or

indirectly as a complication of brain herniations.

How to Image Acute Head Trauma

Imaging is absolutely critical to the diagnosis and

management of the patient with acute TBI. The goal of

emergent imaging is 2-fold: (1) identify treatable injuries and

(2) detect and delineate the presence of secondary injuries,

such as herniation syndromes.

MDCT: Multidetector row CT (MDCT) is the "workhorse" of

brain trauma imaging and is also used as a screening

procedure in a wide variety of clinical settings. Whenever

possible, helically acquired, thin-section, nonenhanced CT

scans from the foramen magnum to the vertex with both soft

tissue and bone algorithm should be obtained. Coronal and

sagittal images reformatted from the axial source data are

extremely helpful, especially in detecting thin peritentorial

subdural hematomas. Subdural windowing (e.g., window

width of 150-200 HU) of the soft tissue images on PACS (or

film, if PACS is not available) is also highly recommended. The

scout view should always be displayed and evaluated as part

of the study.

Whole-body, CT-based studies for patients with multiple

traumas are becoming increasingly more common. Soft tissue

and bone algorithm reconstructions with multiplanar (usually

coronal and sagittal) reformatted images of the spine are