Radiologic assessment of maxillofacial, mandibular, and skull base trauma.

Cranio-maxillofacial injuries affect a significant proportion of trauma patients either in isolation or concurring with other serious injuries. Contrary to maxillofacial injuries that result from a direct impact, central skull base and lateral skull base (petrous bone) fractures usually are caused by a lateral or sagittal directed force to the skull and therefore are indirect fractures. The traditional strong role of conventional images in patients with isolated trauma to the viscerocranium is decreasing. Spiral multislice CT is progressively replacing the panoramic radiograph, Waters view, and axial films for maxillofacial trauma, and is increasingly being performed in addition to conventional films to detail and classify trauma to the mandible as well. Imaging thus contributes to accurately categorizing mandibular fractures based on location, into alveolar, mandibular proper, and condylar fractures-the last are subdivided into intracapsular and extracapsular fractures. In the midface, CT facilitates attribution of trauma to the categories central, lateral, or combined centrolateral fractures. The last frequently encompass orbital trauma as well. CT is the imaging technique of choice to display the multiplicity of fragments, the degree of dislocation and rotation, or skull base involvement. Transsphenoid skull base fractures are classified into transverse and oblique types; lateral base (temporal bone) trauma is subdivided into longitudinal and transverse fractures. Supplementary MR examinations are required when a cranial nerve palsy occurs in order to recognize neural compression. Early and late complications of trauma related to the orbit, anterior cranial fossa, or lateral skull base due to infection, brain concussion, or herniation require CT to visualize the osseous prerequisites of complications, and MR to define the adjacent brain and soft tissue involvement.