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Craniocervical Junction Trauma Made Easy 2008

General Spine

Supriya Cardoza, MD,
Lorraine Manlolo, MD, Non ASSR Member
Vinodkumar Velayudhan, DO, Non ASSR Member
Steven Lev, MD, Non ASSR Member

Scientific Poster

Exhibit Panels: 1

Purpose

To present a core learning tool for understanding the wide spectrum of traumatic injury patterns encountered at the craniocervical junction (CCJ). Our approach emphasizes anatomical and craniometric considerations. The relative benefits of the various imaging modalities are highlighted, as well as an overview of radiological mimics and normal variants are presented.

Methods & Materials

We retrospectively reviewed the imaging studies of patients with blunt trauma to the CCJ presenting to our Level I Trauma Center over a 5-year frame. MDCT images including multiplanar reconstructions, CTA and MR correlation were utilized in this exhibit. Craniometric measurements were performed to assist in diagnosis. The viewer may challenge himself by tackling the cases as unknowns or may review the topic in didactic format.

Results

The structures that comprise the CCJ (the occiput, atlas, axis and supporting ligaments) differ considerably from the rest of the spinal neuraxis and require a unique diagnostic approach. Craniometrics is used as an indicator to exclude and quantify injury. Commonly used normal landmarks include the basion, opisthion, dens, and anterior arch of C1. Atlanto-occipital dislocation (AOD) is a potentially devastating injury, while subluxation is rarely fatal. Measurements used to assess AOD are based on midsagittal imaging and include the Powers ratio and the atlanto-dental (ADI), basion-axial (BAI) and basion-dental (BDI) intervals. Patient age should be taken into account when using these measurements. A normal ADI in a child, with greater ligamentous laxity, may be abnormal for an adult. It is imperative to also check the congruency of the atlanto-axial articulation, best appreciated on coronal and paramedian sagittal reformats. We present an unusual case of AOD associated with good outcome. Occipital condyle and atlas fractures depend on the mechanism of injury (axial loading, hyperextension or avulsion). Coronal views can enhance detection of fractures as well as help to identify assimilation. In the skeletally immature there are multiple synchondroses, ossification and chondrification centers of the atlas, which are not to be mistaken for a Jefferson burst fracture. Odontoid fractures are discussed in regards to location, stability, and differentiation from normal variants such as os odontoidium and fragmented dens. Traumatic spondylolisthesis of the axis (Hangman's fracture) presents with various patterns of C2 arch disruption, including the pedicles. CTA is an important tool in the evaluation of the CCJ and should be performed whenever vascular injury is suspected. We present an interesting case of a C1 burst fracture with an associated vertebral artery dissection. Our cases underscore the invaluable role of MR in the detection of hematomas and associated injuries of the cord and ligaments, which are key determinants of stability.

Conclusion

Traumatic injuries to the CCJ may be a diagnostic challenge, whether subtle or dramatic, and are of critical clinical importance. The Trauma Radiologist must have a systematic approach and be armed with a working knowledge of normal anatomy and variants. A speedy and accurate diagnosis can facilitate prompt treatment and prevent delayed neurological deficits in patients who survive.

References

Ross JS, et al. Diagnostic Imaging: Spine. First Edition. Salt Lake City, Utah: Amirys, 2005.